Sports Med

DOI 10.1007/s40279-017-0755-6

REVIEW ARTICLE

Accentuated Eccentric Loading for Training and Performance:

A Review
John P. Wagle1 • Christopher B. Taber2 • Aaron J. Cunanan1 • Garett E. Bingham1 •

Kevin M. Carroll1 • Brad H. DeWeese1 • Kimitake Sato1 • Michael H. Stone1

Ó Springer International Publishing AG 2017

Abstract Accentuated eccentric loading (AEL) prescribes

eccentric load magnitude in excess of the concentric pre- Key Points
scription using movements that require coupled eccentric
and concentric actions, with minimal interruption to natural Accentuated eccentric loading (AEL) prescribes
mechanics. This method has been theorized to potentiate eccentric load magnitude in excess of the concentric
concentric performance through higher eccentric loading prescription using movements that require coupled
and, thus, higher concentric force production. There is also eccentric and concentric actions, with minimal
evidence for favorable chronic adaptations, namely shifts interruption to natural mechanics.
to faster myosin heavy chain isoforms and changes in IIx- The current research concerning both the acute
specific muscle cross-sectional area. However, research responses and chronic adaptations to AEL is
concerning the acute and chronic responses to AEL is inconclusive, but suggests it may be a superior
inconclusive, likely due to inconsistencies in subjects, method by which to enhance strength and power
exercise selection, load prescription, and method of pro- performance.
viding AEL. Therefore, the purpose of this review is to
Due to the potential benefits, but inconsistency and
summarize: (1) the magnitudes and methods of AEL
paucity of current literature, it would be
application; (2) the acute and chronic implications of AEL
advantageous for future research to first examine the
as a means to enhance force production; (3) the potential
acute response to practically applicable means and
mechanisms by which AEL enhances acute and chronic
magnitudes of AEL.
performance; and (4) the limitations of current research and
the potential for future study.

1 Introduction

It has been well documented that progressive resistance

training programs enhance force and power production
capabilities [1, 2]. These improvements are largely attrib-
uted to changes in skeletal muscle cross-sectional area
& John P. Wagle (CSA) and an array of neuromuscular adaptations [3–6].
johnwagle9@gmail.com
Traditional loading prescribes equivalent absolute loads for
1
Department of Sport, Exercise, Recreation, and Kinesiology, the concentric and eccentric portion of an exercise, but it
Center of Excellence for Sport Science and Coach Education, should be noted that skeletal muscle is capable of as much
East Tennessee State University, 1081 Roberts Bell Dr., as 50% more force production during maximum eccentric
Johnson City, TN 37601, USA
2
contractions compared to concentric contractions [7–9].
Department of Physical Therapy and Human Movement Therefore, loads encountered during traditional resistance
Science, Sacred Heart University, Fairfield, CT, USA

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 J. P. Wagle et al.

exercise loading are limited by concentric strength, leading 2 Literature Search Methods
practitioners to turn to alternative methods in order to more
optimally prescribe intensity relative to the force genera- The search was conducted in December 2016 using the
tion capabilities of eccentric muscle action. following databases: EBSCO, Google Scholar, PubMed,
Researchers and practitioners have employed eccentric- ScienceDirect, and SPORTDiscus. There were no limita-
only training in an attempt to properly load the eccentric tions regarding publication date. Three authors indepen-
action by eliminating the limitation of concentric force dently and separately conducted the search and retrieval of
production. The skeletal muscle response is largely pro- manuscripts through the search terms ‘‘accentuated
portional to the magnitude of mechanical stimulus and a eccentric load,’’ ‘‘eccentric accentuated load,’’ ‘‘enhanced
larger response has been observed in eccentric-only train- eccentric load,’’ and ‘‘eccentric overload.’’ Only original
ing, especially with regard to strength and size changes empirical articles published in peer-reviewed journals with
[10, 11]. Further, selective recruitment of high-threshold full document availability were considered for review. A
motor units has been observed in eccentric-only training total of 30 original papers met these criteria, with papers
[12]. However, eccentric-only training may be limited in its utilizing flywheel resistance excluded from consideration.
transfer to sport due to a lack of task-specificity and limited This exclusion was due to the inherent dependency of the
involvement of the stretch-shortening cycle (SSC) [10, 13]. flywheel eccentric load on concentric output and the cur-
Therefore, it is logical for researchers and coaches to seek rent lack of research quantifying progressive load under
a training means that applies an overload during eccentric this method.
action, but also enhances specificity and employs the SSC,
especially considering the involvement of the SSC in a wide
variety of sporting actions. Accentuated eccentric loading 3 Loading Considerations
(AEL) prescribes eccentric loads in excess of the concentric
prescription of movements that require coupled eccentric Prior studies have utilized various implements to apply
and concentric actions, while creating minimal interruption AEL, including elastic bands, counterbalance weight sys-
in the natural mechanics of the selected exercise. For tems, weight releaser devices, computer-driven adjust-
example, a coach may load a back squat to a prescribed ments, and manual adjustments by either the athlete or
weight for the eccentric portion, and then manually remove practitioner. The chosen implementation appears depen-
the weight prior to the initiation of the concentric action. dent on practicality, the magnitude of eccentric load pre-
This method has been theorized to enhance adaptation scription, or desired outcome. For example, lower
through higher eccentric loading and, thus, higher eccentric magnitude AEL prescriptions tend to use manual adjust-
and concentric force production. With this method of ments by either the coach or the athlete, while higher
training, there is evidence for shifts to faster myosin heavy magnitude AEL prescriptions use weight releasers or are
chain (MHC) isoforms and more favorable changes in IIx- technology driven. However, there has been little consis-
specific muscle CSA [14, 15]. These changes have often tency in the existing literature regarding the magnitude of
been accompanied by improvements in force and power eccentric overload or the resulting rate of eccentric phase
production [15–21]. Furthermore, previous findings report descent for the exercise prescribed. Differences in these
favorable changes in jumping and throwing actions, sug- loading considerations likely alter the stimulus of AEL and
gesting AEL may transfer well to sport tasks and perfor- may have implications for acute performance and chronic
mance when applied to both strength and plyometric training adaptations. Therefore, a discussion of loading considera-
exercises [22–29]. However, research concerning the acute tions—primarily the magnitude and the means of applica-
and chronic responses to AEL is currently inconclusive, tion—and their effects is warranted. Theoretically, AEL
likely due to inconsistencies in subjects, exercise selection, should increase the subsequent concentric action following
load prescription, and method of providing AEL loading acute application of eccentric overload, but changes will
strategy [14, 15, 17, 20–23, 27, 29–34]. likely be directly related to the characteristics and context
Therefore, the purpose of this review is to examine of application. Further, it is plausible that the magnitude of
potential mechanisms and applications of AEL as a training the load may have a more profound influence on adaptation
intervention. The review summarizes: (1) the magnitudes based on previously established neuromuscular and archi-
and method of loading; (2) the acute and chronic impli- tectural changes observed from high intensity eccentric
cations of AEL as a means to enhance maximal strength contractions [10, 12, 35–39].
and explosive performance; (3) the potential mechanisms Supramaximal loading, which prescribes an eccentric
by which AEL enhances acute and chronic performance; load in excess of concentric 1RM, is the most commonly
and (4) the limitations of current research and the potential utilized strategy of AEL. The rationale is based upon the
for future study.

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AEL for Training and Performance

higher force generation capabilities and selective recruit- more consistently yielded favorable performance
ment of high threshold motor units during eccentric muscle enhancements compared to supramaximal AEL, especially
actions, potentially eliciting neuromuscular responses in acute interventions. Ojasto and Häkkinen found peak
leading to desired adaptations, which will be discussed power and neuromuscular activity were both enhanced
later in further detail [12, 39]. Saxton and associates pro- through submaximal AEL, but was not related to a specific
vide a theoretical basis for supramaximal eccentric loading submaximal prescription [20]. Though a range of sub-
to potentially induce greater changes in muscle CSA maximal AEL conditions were used (eccentric/concentric:
through increased tension or metabolic damage [40]. Sev- 60/50% 1RM, 70/50% 1RM, 80/50% 1RM, 90/50% 1RM),
eral investigations have attempted to substantiate the the load condition where the highest peak power outputs
potential implications of supramaximal AEL to improve and muscle activation were subject specific [20]. There-
strength, force output, or muscle CSA [14–20, 30, 33, 34]. fore, there may be an individualized response to AEL, with
Despite a theoretical basis, supramaximal AEL has factors such as training experience, age, strength-level, or
yielded inconsistent results regarding acute responses and physiological characteristics influencing the outcomes.
chronic adaptations. Favorable acute changes in maximal Sheppard and Young, instead of prescribing relative per-
strength performance have been demonstrated [16, 17]. For centages, prescribed submaximal AEL with fixed absolute
example, Doan and associates found significantly enhanced loads of 20, 30, and 40 kg over a 40-kg concentric load
concentric performance in the bench press using supra- [29]. Subsequent bar displacement and peak acceleration
maximal AEL in moderately trained males [17]. They used values of the bench throw were both significantly higher
weight releasers to impart an eccentric overload equivalent following AEL [29]. In accordance with the findings of
to 105% concentric 1RM [17]. The concentric prescriptions Ojasto and Häkkinen, a notable finding of this study [29] is
started at 100% of preliminarily tested concentric 1RM, that the AEL prescription yielding the greatest performance
followed by attempts with progressively increased con- enhancement appears to be dependent on maximal strength,
centric loads of 2.27, 4.55, and 6.82 kg if prior attempts with stronger subjects requiring greater eccentric overload
were successful. Doan and colleagues provide some of the to elicit optimal concentric performance.
earliest evidence of the potentiating effect that supramax- Increased velocity during the eccentric phase enhances
imal AEL may have on subsequent concentric perfor- force production and power output during the subsequent
mance. Some theoretical mechanisms that may contribute concentric phase [45, 46]. The rapid eccentric phase of
to performance improvements resulting from supramaxi- plyometric exercises may be further enhanced via AEL,
mal eccentric loading include attenuated reflex inhibition with observed improvements in concentric force produc-
or increased myosin light chain (MLC) phosphorylation tion, jump height, and throw performance [25, 29, 47].
[41, 42]; however, supramaximal eccentric loading may Accentuated eccentric loading strategies that overload the
require careful consideration. Contractile history can have eccentric portion of plyometric exercises, though fitting
both fatiguing and potentiating effects on skeletal muscle within the scope of the operational definition of AEL of the
performance [43]. Providing a stimulus that elicits poten- present review, may potentiate concentric performance
tiating effects without fatiguing the athlete is one of the primarily via increasing the rate of the eccentric phase [48],
challenges facing supramaximal AEL prescription [44]. which could be considered an interruption to the natural
Ojasto and Häkkinen reported that subsequent 1RM and mechanics of the movement. Increasing the eccentric load
concentric force production both significantly decreased during plyometric movements may increase the rate of
using a range of supramaximal AEL (105–120% eccentric eccentric force production and impulse of the SSC, sub-
overload) in the bench press [20]. They proposed this sequently enhancing concentric force and power output
decline in performance was partially due to fatigue and [49, 50]. Overloading plyometric exercises is an advanced
suggest the potential need to use smaller eccentric loads application of AEL, as the athlete needs to have the
[20]. These inconsistent results and methods in the litera- capability to store and return elastic energy quickly during
ture using supramaximal AEL require further investigation, the concentric portion of the jump with minimal amorti-
but also have led to the study of other AEL strategies, zation phase [51, 52]. This may require higher levels of
particularly in more recent studies. strength and connective tissue development, and therefore
The magnitude of the eccentric load during submaximal such an application of AEL may be more appropriate for
AEL is prescribed relative to the concentric movement; more advanced athlete populations.
however, the eccentric overload does not exceed concentric One potential implementation involves elastic bands,
1RM. This relative loading strategy is often used in situa- which can be used to increase eccentric velocity during
tions where changes in explosive and plyometric perfor- countermovement (CMJ) and drop jumps [22, 23]. Accen-
mance are anticipated [20, 22–26]. Submaximal AEL may tuated eccentric loading estimated to provide an additional
also include movements more common in sports and has resistance equivalent to 30% of body mass during the

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 J. P. Wagle et al.

eccentric phase of the CMJ increased peak power (23.21%), load prescription strategy for the desired performance
peak concentric force (6.34%), peak concentric velocity outcome given the population being trained.
(50.00%), and jump height (9.52%) compared to standard
CMJ in resistance and plyometric trained subjects [23].
Elastic bands providing downward tension during the drop 4 Performance Implications for Accentuated
and eccentric phases of the drop jump increased eccentric Eccentric Loading (AEL)
impulse, eccentric rate of force development (RFD), and
quadriceps muscle activity in a manner similar to increased 4.1 Maximum Strength
drop jump height [22]. Aboodarda and colleagues suggest
that the use of elastic bands during drop jumps may sub- As previously discussed, AEL has been suggested as a
stitute for increases in drop height, theoretically minimizing potential training modality for athletes due to an associa-
injury risk associated with high drop heights [48]. However, tion with improvements in force production [17, 21], RFD,
if the center of mass is still accelerating similarly due to the [23] velocity [27], power [23], athletic performance,
elastic bands when compared to a higher drop height, the [23, 27] and injury prevention [53]. Force production
ground reaction forces may still be similar. Moore and underpins all of the aforementioned enhancements to per-
associates provide a more precise AEL application in the formance and completion of both general and specific skills
jump squat, examining the potentiating effects eccentric [54]. The limited number of studies using AEL to improve
overloads of 20, 50, and 80% of back squat 1RM coupled force production have provided varying results apparently
with a concentric phase held constant at 30% of back squat due to differing protocols used in the investigations
1RM [31]. The load spectrum used by this group failed to (Tables 1, 2). In a 7-day study by Hortobagyi and col-
provide supporting evidence that AEL acutely enhanced leagues, the investigators demonstrated twofold greater
force, velocity, or power outputs of the concentric phase of strength gains in the knee extensors using an additional
the jump squat [31]. The lack of observed potentiation may 40–50% eccentric overload compared to traditional loading
be due to the subjects’ lack of familiarity with jumping in untrained females [47]. The drastic strength gains (27%)
tasks. Though the subjects were resistance trained, there observed during this study may be due to the novelty of
was no indication as to whether plyometric training was stimulus applied to an untrained population. Such results
included in their training prior to participation in the study should be explored further as the adaptive responses may
[31]. This is in contrast to the subjects in the study by have been similar between AEL and traditional loading
Aboodarda and colleagues, who were participating in both with a longer training period. Doan and colleagues pro-
resistance training and plyometric training prior to study vided additional evidence, finding increases in bench press
involvement [22]. 1RM of 2.27–6.80 kg in the subjects using supramaximal
Like supramaximal AEL, the lack of consensus using AEL of 105% of concentric 1RM during the eccentric
submaximal AEL may be due to subject and methodolog- phase compared to the traditional loading [17]. As previ-
ical differences between studies, such as means (e.g., ously discussed, the acute enhancement of force production
weight releasers, manual adjustment) or magnitude of capabilities observed may be induced via several potential
eccentric overload. From a practical standpoint, decisions mechanisms, including increased calcium sensitivity and
regarding implementation of AEL may be driven by fea- increased neural drive due to the eccentric overload pro-
sibility just as much as supporting evidence. Some methods vided by AEL [42]. However, AEL conditions during
may be financially restrictive, overly cumbersome, or have attempts to potentiate force production acutely must con-
little application or transfer to athletic performance. These sider the fatigue elicited by the selected AEL strategy
limitations notwithstanding, existing research suggests the [43, 44].
magnitude of AEL should, to some extent, reflect the Demonstrating the potential importance of load pre-
strength level of the subject and exercise selection in scription as it relates to maximal strength expression,
addition to the desired effects. Researchers have typically Ojasto and Häkkinen performed a bench press protocol that
used supramaximal eccentric overloads during strength and employed AEL in the bench press with physically active
hypertrophy training, yielding mixed results. With similar males [20]. This protocol compared four different loading
levels of consistently favorable outcomes, submaximal schemes for the eccentric portion with 100, 105, 110, and
eccentric overloads are typical in studies examining 120% of the concentric 1RM and failed to show
explosive performance or power output. Therefore, iden- improvements in concentric 1RM with AEL compared to
tifying and determining the influence of potential factors an isokinetic loading protocol. Though relatively strong
may allow for more precise and individualized submaximal subjects were used, it appears that the eccentric overload
AEL prescription. Coaches and practitioners, then, must spectrum employed by Ojasto and Häkkinen elicited a
first consider the most practical and suitable method and detrimental effect on maximal strength expression, likely

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 Table 1 Acute performance responses to accentuated eccentric loading. Cohen’s d effect size indicated in parentheses in the Results columns
Study Subjects Training status Loading strategy Loading magnitude Comparison Exercise Variables analyzed Results
methodology selection

Aboodarda et al. 15 males 6 months Elastic bands ?20/30% body mass BW CMJ CMJ Jump height Jump Peak
[23] (22.6 ± 5.3 years) Peak velocity height velocity

Peak force ACMJ20 ?5.3% ?0%

(0.67) (0.0)
Peak power
ACMJ30 ?10.5% ?16.7
(1.33) (0.38)
Peak force Peak
power
AEL for Training and Performance

ACMJ20 ?0.6% ?6.4%

(0.04) (0.41)
ACMJ30 ?2.9% ?30.2%
(0.06) (0.66)
Aboodarda et al. 15 males 6 months 29 BW Elastic bands ?20–30% body mass BW drop jump Drop jump Jump height Jump height
[22] (24.7 ± 5.7 years) back squat Takeoff velocity 20 cm—DJ20: 0%, (0.0), DJ30:
-2.4% (-0.14)
35 cm—DJ20: ?2.5% (0.14), DJ30:
?2.5% (0.14)
50 cm—DJ20: ?2.6% (0.14), DJ30:
?2.6% (0.14)
Takeoff Velocity
20 cm—DJ20: -0.4% (-0.04),
DJ30: -0.7% (-0.08)
35 cm—DJ20: ?0.4% (0.04), DJ30:
0% (0.0)
50 cm—DJ20: ?1.1% (0.12), DJ30:
?1.1% (0.12)

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 Table 1 continued
Study Subjects Training status Loading strategy Loading magnitude Comparison Exercise Variables analyzed Results
methodology selection

123
Bridgeman et al. 8 males [2 years Manual adjustment ?20% body mass Pre/post Drop jump Static jump CMJ jump height
[24] (26.3 ± 5.1 years) by athlete Session 1: 5 9 6 (52 cm box) CMJ 596 5 9 10
Session 2: 5 9 10 Squat force Post -5% ?0.1%
(-0.43) (0.01)
1h -2.2% ?1.9%
(-0.19) (0.19)
24 h –0.2% ?5.2%
(-0.02) (0.52)
48 h ?3.3% ?3.2%
(0.29) (0.32)
Static jump height
596 5 9 10
Post -4.0% ?0.3%
(-0.27) (0.02)
1h -1.7% ?4.1%
(-0.12) (0.35)
24 h ?1.3% ?6.1%
(0.09) (0.52)
48 h ?4.6% ?10.5%
(0.31) (0.89)
CON squat force
596 5 9 10
Post -4.3% -5.4%
(-0.14) (-0.19)
1h -7.3% -9.5%
(-0.25) (-0.34)
24 h ?1.7% ?6%
(0.06) (0.21)
48 h ?1.5% ?10.2%
(0.05) (0.37)
ECC squat force
596 5 9 10
Post -10.2% ?2.4%
(-0.35) (0.09)
1h -4.4% -0.2%
(-0.15) (-0.01)
24 h -4.6% ?6.9%
(-0.16) (0.25)
48 h -7.2% ?14.8%
(-0.25) (0.54)
J. P. Wagle et al.
 Table 1 continued
Study Subjects Training status Loading strategy Loading magnitude Comparison Exercise Variables analyzed Results
methodology selection

Bridgeman et al. 12 males [2 years Manual adjustment ?10/20/30% body mass Unloaded DJ, CMJ Drop jump Drop jump height Drop jump height
[25] (25.4 ± 3.5 years) 1.5 BW back squat by athlete additional Drop jump flight BW [ 10%/30% (0.39, 0.34)
time 20% [ 10%/30% (0.37, 0.32)
CMJ jump height Drop jump flight time
BW [ 10/30% (0.38, 0.34)
20% [ 10/30% (0.36, 0.32)
CMJ jump height
AEL for Training and Performance

20% [ Pre/BW/10/30% (0.47, 0.48,

0.37, 0.34)
Doan et al. [17] 8 males (23.9 years) Moderately trained Weight releaser CON—100% 1RM 1RM Bench press Concentric 1RM ?3.2% 1RM
ECC—105% 1RM
Moore et al. [31] 13 males [6 months squat Weight releaser 30% CON/?20, 50, 80% Squat jump—30% Jump squat Peak velocity Peak velocity
(22.8 ± 2.9 years) training, squat back squat 1RM ECC 1RM Peak force ECC20%: (-0.14)
1RM [1.5 BM
Peak power ECC50%: (-0.14)
ECC80%: (0.05)
Peak force
ECC20%: (0.01)
ECC50%: (-0.08)
ECC80%: (-0.09)
Peak power
ECC20%: (0.02)
ECC50%: (0.00)
ECC80%: (0.14)
Ojasto and 11 males Bench press relative Weight releaser Max Str Max Str Bench press Mean ECC force Higher ECC load decreased mean
Hakkinen [20] (32.4 ± 4.3 years) strength = 1.2- 105%/100%, 110%/100%, 100%/100% Mean CON force CON force
1.4 9 body mass 120%/100% Higher ECC load increased mean ECC
Explosive Str CON peak Power
Explosive Str force
50%/50%, 60%/50% CON mean power
70%/50%, 80%/50%, 90%/ Mean and peak CON power
50% *77.3 ± 3.2%/50%

Sheppard and 14 males N/A Weight releaser ?20, 30, 40 kg ECC, 40 kg 40 kg Bench throw Bench throw Barbell Barbell displacement vs. 40/40
Young [29] (25.0 ± 1.0 years) CON Displacement 20: (0.30)
30: (0.25)
40: (0.33)
Sheppard et al. 11 males Trained high- Manual adjustment Athletes held 20 kg (10 kg/ Volleyball block Block jump Jump height Jump height: ?4.3% (0.20)
[27] (18.9 ± 2.6) performance by athlete hand) and dropped weight jump allowing arm Peak power Peak power: ?9.4% (0.39)
volleyball players when initiating jump swing during
familiar with AEL concentric action Peak force Peak force: ?3.9% (0.19)
Peak velocity Peak velocity: ?3.1% (0.25)

ACMJ20 Accentuated countermovement jump ?20% body mass, ACMJ30 Accentuated countermovement jump ?30% body mass, AEL accentuated eccentric loading, BW body weight, CMJ countermovement jump, CON concentric,
DJ20 accentuated drop jump ?20% body mass, DJ30 accentuated drop jump ?30% body mass, ECC eccentric, ECC20% eccentric overload of 20% in excess of concentric load, ECC50% eccentric overload of 50% in excess of
concentric load, ECC80% eccentric overload of 80% in excess of concentric load

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 Table 2 Chronic performance responses to accentuated eccentric loading. Cohen’s d effect size indicated in parentheses in the Results columns
Study Subjects Training Loading strategy Loading Comparison Exercise Study Variables Results
status magnitude methodology selection duration analyzed

123
Barstow et al. 8 males [3 months Negator AEL TRAD Arm curl 12 wk Concentric 1RM 1RM
[30] 31 females (counterbalance CON—66% Weeks 1–4: 29/wk Isometric force AEL: ?15.5%,
weight system 1RM (10°, 25°, 60°,
3 9 7–10 TRAD: ?13.8%
providing 85°, 110°)
ECC—100% RM Isometric force
concentric
1RM Weeks 5–8: Isokinetic force
assistance) Non-statistically significant
Weeks 1–4: (40°/s)
3 9 6–8 change
3 9 7–10 RM RM Isokinetic force
Weeks 5–8: Weeks Non-statistically significant
3 9 6–8 RM 9–12: change
Weeks 9–12: 4–6 RM
4–6 RM
Brandenburg 18 males (university [1 year Manual adjustment 3 9 10 75% 4 9 10 75% Arm curl 9 wk Strength: elbow Strength:
and aged) bench by coach CON/ 1RM Arm Wk 1–2: flexion/ TRAD—flexion: ?11%,
Docherty press C BM 110–120% extension 2 extension extension: ?15%
[16] CON 1RM IN
Wk 3–9: AEL—flexion: ?9%,
ECC
3 extension: ?24%
Friedmann 16 males No RT within Computer-driven 3 9 25 ea leg, 6 9 25 ea Leg 4 wk Strength STR
et al. [14] 1 year 30% CON/ leg, 30% extension 39/wk Str-End TRAD: non-statistically
?70% 1RM (45 s/ significant change
equivalent set)
AEL: ?5%
ECC (30%
ECC 1RM, STR-END
2.32 9 higher TRAD: ?8%
load) AEL: non-statistically
significant change
Friedmann- 25 males (±years) [ 1 year Computer-driven 5 9 8 RM 6 9 8 RM Leg 6 wk Concentric 1RM Concentric 1RM leg extension
Bette et al. strength CON: 8 RM extension 39/wk leg extension Non-significant difference
[15] training Squat jump between groups
ECC:
*1.9 9 CON Squat jump
AEL significantly greater than
TRAD
Godard et al. 16 males N/A Computer-driven 80% CON/ 8–12 reps Leg 10 wk Strength Strength:
[18] 12 females ?40% ECC 80% CON extension 29/wk (CON 1RM TRAD: ?95.1% (3.50)
(22.4 ± 3.7 years) 1RM torque) AEL: ?93.6% (3.94)
Control Control: ?6.4% (0.21)
Group
J. P. Wagle et al.
 Table 2 continued
Study Subjects Training Loading strategy Loading Comparison Exercise Study Variables Results
status magnitude methodology selection duration analyzed

Hortobagyi 30 females Untrained Manual adjustment plus 40–50% 5–6 9 10–12 Leg 7 days Maximal 3 RM—eccentric
et al. [47] (20.9 ± 1.2 years) (exercised by coach from CON 60% 1RM extension isometric TRAD—?11%
no more load (60% strength,
AEL—?27%
than 1 day/ 1RM CON) maximal
wk for prior isokinetic 3RM—concentric
year) strength, 3 RM TRAD—?26%
leg extension AEL—?27%
AEL for Training and Performance

(CON and ECC)

Max isometric/isokinetic
strength
TRAD—ECC: ?9.9%, CON:
?13.1%, ISO: ?6.0%
AEL—ECC: ?23%, CON:
?14.6%, ISO: ?12.9%
Johnson [73] Male and female Students Manual adjustment Enough force to N/A Pushups 13 wk Repetition Men Women
(20 years) by coach (push/ make ECC last Dips 39/wk maximums Push- ?18.6 ?12.9
pull during ECC 5s ups reps reps
Pull ups
phase)
Chin- ?3 reps ?1.6
ups reps
Dips ?5.4 ?2.1
reps reps
Overall ?3.23% ?12.3%
Kaminski 27 males No lower Negator 2 9 8 RM 2 9 8 RM Leg curl 6 wk Strength (1RM/ Strength:
et al. [19] (22.9 ± 3.2) body RT in (counterbalance 40% CON/100% 80% CON 29/wk BW), isokinetic TRAD: ?19.0%, AEL:
previous weight system) ECC 8 RM 1RM peak torque (60, 28.8%
6 months 180)
ECC isokinetic PT 60
TRAD: NS, AEL: ?37.7%
ECC isokinetic PT 180
TRAD: NS, AEL: ?22%
CON isokinetic PT 60
TRAD: ?13.9% (0.73), AEL:
?17.4% (2.22)
CON isokinetic PT 180
TRAD: ?2.5% (0.15), AEL:
?25% (1.24)

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 Table 2 continued
Study Subjects Training Loading strategy Loading Comparison Exercise Study Variables Results
status magnitude methodology selection duration analyzed

123
Sheppard 10 males [2 years Athlete dropped Overloaded CMJ BW CMJ CMJ 5 wk Jump height Jump height
et al. 6 females weights prior to Male: 40 kg 39/wk Peak velocity BMJ: -2%, AEJ: ?11%
[27] concentric phase
(21.8 ± 4.9 years) Female: 20 kg Peak force Peak velocity
Peak power BMJ: -3%, AEJ: ?16%
Peak force
BMJ: ?3%, AEJ: ?4%
Peak power
BMJ: ?1%, AEJ: ?20%
Walker et al. 28 males 0.5–6 years Weight releaser Session 1: 6 RM Session 1: Leg press 2 9 5 wk Strength (1RM), 1RM
[21] (21 ± 3 years) (leg press); CON/?40% 3 9 6 RM and leg 29/wk Repetitions to TRAD: ?35.8% (1.71), AEL:
Manual ECC Session 2: extension failure, CON/ ?29.6% (1.91)
adjustment by Session 2: 10 3 9 10 RM ECC/ISO
Reps to failure (volume)
coach (leg RM CON/ Torque
extension) TRAD: ?19.6% (0.76), AEL:
?40% ECC
?25.2% (0.87)
Torque
CON—TRAD: ?8% (0.39),
AEL: ?9.4% (0.66)
ECC—TRAD: N/A, AEL:
?9.1% (0.60)
ISO—TRAD: ?10.2%
(0.53), AEL: ?17.7% (1.17)
Yarrow et al. 22 males Untrained (no MaxOut AEL (3 9 6): TRAD Bench 5 wk Bench press 1RM Bench press 1RM
[34] (22.1 ± 0.8 years) RT within (counterbalance 40/100%, (4 9 6): press and 39/wk Back squat 1RM TRAD: ?10.1% (1.77)
6 months) weight system in 41/103%, 52.5, 58, back
AEL: ?9% (1.39)
which electric 43/107%, 64, 69 73% squat
motors assist 45/112%, Back squat 1RM
during the 46/117%, TRAD: ?25.4% (3.39)
concentric 49/121% AEL: ?18.6% (4.15)
action)
1RM/BM one-repetition maximum to body mass ratio, AEJ accentuated eccentric jump, AEL accentuated eccentric loading, BM body mass, BMJ body mass jump, BW body weight, CMJ
countermovement jump, CON concentric, ECC eccentric, ISO isometric, PT peak torque, RM repetition maximum, RT resistance training, TRAD traditional/isokinetic loading
J. P. Wagle et al.
AEL for Training and Performance

due to fatigue. In this design, subjects first had to determine protocol, however, used four sets of ten repetitions to
their bench press 1RM under traditional loading, then concentric failure at an absolute intensity of 75% 1RM
proceed to the prescribed AEL condition to ascertain if that [16]. Unlike the findings of Godard and colleagues, Bran-
enhanced their maximal strength levels for that day. By denburg and Docherty observed no changes in muscle CSA
completing two separate maximal strength evaluations within either training group, suggesting that the strength
within the same session, it is likely that the potentiating changes can likely be attributed to decreased neural inhi-
effects observed by Doan and colleagues would not be bition and subsequent increases in motor unit discharge
present, and subjects instead saw a decrease in maximal rate, leading to higher levels of voluntary activation and
strength performance related to acute fatigue [17, 20, 44]. increased strength capabilities without changes in mor-
Overall, acute intervention with AEL (Table 1) has yielded phology [55]. This is supported by the findings of Walker
inconsistent results regarding maximal concentric force and associates, who observed significant increases in vol-
production, at least in part due to study design, load pre- untary muscle activation under AEL in the vastus lateralis,
scription, or population used. Acute maximal strength vastus medialis, and superficial quadriceps with no differ-
enhancement via AEL has sound theoretical basis and ences in CSA following a 10-week protocol [21]. The
should be further explored. Further study of acute inter- increase in voluntary activation may explain the higher
ventions using AEL may elucidate optimal loading strate- percent change in isometric strength with AEL compared
gies to potentiate maximal strength and may provide a to traditional loading in the leg extension [21].
framework by which to explore chronic adaptations. Despite the seemingly robust application of the potential
Longer term studies exploring the effects of AEL on mechanisms and adaptations to AEL, exercise selection may
strength (Table 2) have also yielded multiple outcomes limit the transfer of training effects to sporting actions and
depending on protocol, duration, and subjects’ character- athlete populations [16, 21]. An investigation by Yarrow and
istics. Godard and colleagues found non-statistically sig- associates is one of the only examples of AEL using exercises
nificant increases in concentric knee extensor strength that typically appear in sport training regimens (i.e., back
favoring AEL (eccentric/concentric: 120/80% 1RM) com- squat and bench press), albeit with untrained male subjects
pared to traditional loading (80% 1RM) [18]. Further, [34]. The researchers found similar increases of 10% for the
significant changes in thigh girth were observed under both bench press concentric 1RM and 22% for the squat concentric
isokinetic and AEL conditions. Due to the greater observed 1RM under both AEL (100–121% eccentric overload) and
changes in strength, such findings may suggest that AEL traditional loading. Though the outcomes are similar when
imparted greater degrees of neural adaptation while elic- considered superficially, Yarrow and colleagues used atypi-
iting similarly favorable changes in muscle morphology. cal concentric loads within the AEL condition (up to 49%
However, it is difficult to assign sound rationale or prac- 1RM), where the traditionally loaded condition had more
tical application to the changes observed, as the subject appropriate loads (up to 75% 1RM) [56]. Therefore, consid-
pool consisted of untrained males and females that were ering the findings of other investigations, it is reasonable to
not grouped for analysis, thereby limiting the depth of the speculate that strength improvements for the AEL condition
observations. Also using untrained subjects, Kaminski and would have been greater had the concentric workloads been
colleagues provided evidence that AEL may impart greater equalized [16, 18, 21]. It is also noteworthy that the AEL
strength gains in the hamstrings, using an eccentric over- group achieved similar results with a lower total volume
load equivalent to 100% concentric 1RM paired with a load—this difference resulted from the completion of one less
concentric load equivalent to 40% 1RM [19]. After only set per session in the AEL group compared to the traditional
6 weeks of training, significant improvements in relative loading group. Nevertheless, it is possible that AEL may be
and absolute strength levels were observed in the leg curl more work efficient compared to traditional loading and may
compared to traditional loading. Due to the brevity of the elicit similar strength gains compared to traditional loading.
study and the improvement in relative strength, it is likely Thus, one potential application of AEL may be to retain
that subjects experienced minimal changes in morphology maximum strength while emphasizing higher movement
and the favorable strength outcomes may be primarily velocities or reducing volume load due to other training
explained by neural alterations. stressors. Overall, chronic training studies using AEL have
Supporting such a hypothesis, Brandenburg and Doch- elicited favorable changes in strength, primarily due to
erty made similar comparisons of strength and muscle advantageous changes in neural drive and secondarily to
morphology changes between AEL and isokinetic loading changes in muscle morphology. However, due to the incon-
in moderately trained males over 9 weeks [16]. The AEL sistent nature of study design and the paucity of literature
condition used an eccentric load of 110–120% 1RM and a using exercise selection typical of athletic populations, fur-
concentric load of 75% 1RM, performing three sets of ten ther investigations are warranted to determine the chronic
repetitions to concentric failure. The isokinetic loading effects of AEL. Given the varying nature of the findings, it is

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 J. P. Wagle et al.

important first to identify the acute responses and potential compared the effects of AEL on a countermovement vol-
mechanisms that would support the chronic changes in leyball block jump versus traditional volleyball block jump
maximal strength observed in the longer term studies. performance, where arm swing was limited. Contrary to
Moore and colleagues [31], the investigators found statis-
4.2 Explosive Performance tically greater jump height, peak power, and peak velocity
(p \ 0.05) for the AEL group, with moderate magnitude
AEL has been used to examine changes in explosive per- effect sizes (ES = 0.1–0.4). The difference in findings may
formance and is commonly investigated using static jumps, be due to the aforementioned influence of exercise selec-
CMJs, drop jumps, and throws. Sheppard and Young [29] tion and loading methodology on the SSC. Sheppard and
demonstrated that greater concentric performance in the colleagues [28], using an absolute eccentric overload of
bench throw can be achieved through the addition of 20 kg, allowed for minimal interruption in the natural
eccentric loading. Regarding explosive performance, the mechanics of the block jump through their chosen AEL
main finding of this investigation comes in the significant application of dropping dumbbells, which allow for a rapid
changes in peak acceleration across all eccentric overload return of stored energy and enhanced jump performance
conditions [29]. Aboodarda and associates [23] used three [51, 52].
different CMJ conditions to assess the effects of enhanced Bridgeman and colleagues also used AEL drop jumps to
eccentric loading on CMJ performance. Only the CMJ potentiate jump performance [25]. Considering each sub-
condition using an additional 30% of body mass provided ject’s optimal drop height, five drop jump repetitions were
via band-induced tensile force, increased vertical ground completed under each of four dumbbell loading conditions,
reaction forces (6.34%), power output (23.21%), net impulse consisting of no load, 10, 20, or 30% additional eccentric
(16.65%), and jump height (9.52%) compared to the body load [25]. After each loading condition the athletes com-
weight CMJ condition. In a follow-up study, this time pleted three CMJs at 2, 6, and 12 min rest. Bridgeman and
investigating drop jumps, Aboodarda and associates [22] colleagues found that drop jumps with additional load
found greater eccentric impulse and RFD using an additional equivalent to 20% body mass produced significantly
30% of body mass provided via band-induced tensile force, greater CMJ height and peak power after 2 and 6 min
but no difference in drop jump performance compared to compared to the 12-min trials [25]. This indicates that not
traditional drop jumps. Aboodarda and colleagues [22, 23] only are there optimal loading conditions for potentiating
observed different outcomes despite virtually identical pro- effects on power performance, but there may be a time-
tocols. One potential cause may be the difference in exercise dependent window that these effects can be realized. In the
selection, where Aboodarda and associates [22] utilized drop lone study exploring chronic explosive performance
jumps instead of CMJs [23] in the initial investigation. In changes with AEL, Sheppard and associates demonstrated
this regard, differences in participant strength levels were increases in displacement (11%), velocity (16%), and
not considered in either study, which would greatly influ- power (20%) in high-achieving volleyball players follow-
ence jump performance, especially in the drop jump, where ing AEL CMJs compared to bodyweight CMJs [27].
stronger subjects are more likely to be able to store and Despite the paucity of investigations regarding the chronic
reutilize elastic energy as well as have a shorter amortization adaptations to AEL related to explosive performance, it has
phase [22, 23, 52, 57–59]. Further, the latter study imple- been previously demonstrated that higher eccentric veloc-
mented an aerobic-emphasis warm-up, possibly affecting the ities elicit greater changes in power and SSC utilization
potentiation effects of the intervention. [60, 61]. Eccentric overload prescribed for plyometric
The ability to quickly return stored elastic energy is an movements may add to the gravitational forces, causing a
especially important consideration in using AEL for shorter eccentric duration, and thus causing more favorable
explosive performance. Moore and colleagues [31] used explosive performance adaptations. As is the case with
jump squats equal to 30% of the subjects’ back squat 1RM acute changes in explosive performance, there would likely
with additional eccentric loading of 20, 50, and 80% of the be a requisite relative strength level necessary to maintain
back squat 1RM, failing to produce acute changes in force, the efficacy of advanced means like AEL in this context.
velocity, or power in resistance-trained men. The large
range of motion required in jump squats paired with the
high magnitude eccentric load selection may have been 5 Potential Mechanisms to Acute AEL
inappropriate in eliciting favorable explosive performance
outcomes, possibly due to lengthening the amortization 5.1 Neural
phase and subsequently limiting the use of the SSC for
concentric potentiation [51, 52]. In a study of elite male The exact contributions of the nervous system during AEL
volleyball players, Sheppard, Newton, and McGuigan [28] that acutely improve performance have yet to be fully

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AEL for Training and Performance

elucidated, but several have been postulated. Lesser leading to greater neural adaptation compared with tradi-
recruitment and discharge rates have been observed during tional loading. This task-specific neural adaptation may
eccentric action when compared to concentric under sim- transfer favorably to sporting movements involving
ilar absolute loading conditions, which provides justifica- eccentric muscle action, such as SSC.
tion for higher magnitude eccentric loading [62, 63].
Additionally, higher loading of the eccentric phase may 5.2 Metabolic and Endocrine
increase force production during the concentric phase via
enhanced neural drive [31]. Enhanced neural drive may be Existing literature on the hormonal and metabolic
due in part to enhanced motor cortex activation compen- responses to AEL is also limited. Yarrow and associates
sating for spinal inhibition during eccentric action [64]. [33, 34] found no differences in concentrations or
This response is similar under both maximal and sub- responses for total and bioavailable testosterone or growth
maximal loading conditions, indicating that the nervous hormone following either AEL (eccentric/concentric:
system employs unique activation strategies during 100/40% 1RM) or traditional loading (52.5% 1RM con-
eccentric contractions [36]. centric) of bench press and squat exercise in a pair of
For example, higher or faster eccentric loading via AEL studies [33, 34]. However, there was an observed statis-
may allow for the incorporation and selective recruitment tically significant decrease in bioavailable testosterone at
of high threshold motor units during the eccentric con- all time points (15, 30, 45, and 60 min) in the initial design
traction leading to a greater force production during the [33] and at all but one time point (15 min) post-training in
subsequent concentric muscle action. It has been docu- the follow-up study [34] under both loading conditions.
mented that during eccentric contractions, selective This may indicate that more testosterone was bound to
recruitment of high threshold motor units may be possible, androgen receptors, which would subsequently stimulate
leading to greater eccentric force production by contribu- protein synthesis and is consistent with previous findings
tion of larger motor unit pools [12]. Further, muscle may regarding resistance training [70]. Metabolically, Yarrow
function closer to its optimal length and at reduced short- and colleagues first observed a statistically greater
ening velocities through tendon elongation during the increase in blood lactate concentration after AEL com-
eccentric phase, which minimizes muscle fiber lengthening pared to traditional loading [33]. This finding supports the
[65, 66]. It is also likely that elastic energy stored in the results of Ojasto and Häkkinen [32], who reported a trend
series and parallel elastic components during the eccentric for higher blood lactate concentrations with progressively
phase may be used during the concentric phase [46, 49, 67]. higher AEL loads ranging from 80–100% concentric 1RM
This increased tension and stretch initiates another favor- prescribed in the eccentric phase with concentric pre-
able neuromuscular mechanism by which AEL acts— scription held constant at 70% 1RM. Although these
stimulation of Type Ia afferent nerves, inducing a myotatic results did not reach statistical significance, this group also
reflex that enhances the subsequent concentric contraction discussed the potential of an individualized response to
[49]. different AEL intensities based on maximal strength level,
In addition to increased neural drive and selective as a significant correlation was found between the loading
recruitment of high threshold motor units, eccentric condition that yielded the highest lactate response and
lengthening may lead to other alterations in recruitment relative strength ratio [32]. Though higher lactate accu-
strategies compared to concentric muscle actions mulations have been consistently observed, Yarrow and
[31, 36, 38]. These strategies may be related to smaller associates [34] expanded their consideration to lactate
motor-evoked potentials, delayed motor-evoked potentials, recovery in their follow-up design, observing a statistically
delayed motor-evoked potential recovery time, and reduced significant improvement at 45 and 60 min post-training in
H-reflex responses [68]. Due to reduced activity in the AEL compared to isokinetic loading, all while completing
motor cortex and the spinal cord during active muscle less total mechanical work. The findings of Ojasto and
lengthening, the resultant response is decreased motor- Häkkinen [32] paired with those of Yarrow and associates
evoked potentials and H-reflex responses [37, 69]. Fur- [33, 34] suggest AEL may provide a primarily glycolytic
thermore, during submaximal and maximal contractions stimulus, providing potential value in training of strength
the electromyographic muscle activity displays a special- and power athletes.
ized motor unit activation pattern during lengthening Bridgeman and associates measured creatine kinase
compared with shortening [37]. These altered patterns (CK) as a marker of exercise induced muscle damage
associated with lengthening suggest a task-specific differ- following drop jumps with AEL equivalent to 20% of
ence between concentric and eccentric actions [6]. More- subjects’ body mass provided via dumbbells [24]. CK
over, due to task-specific differences in contraction type, levels peaked 24 h after both an initial session and a sub-
the inclusion of AEL may provide a unique stimulus sequent bout two weeks later, with smaller effect sizes for

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 J. P. Wagle et al.

all but one measured time point of the subsequent bout Muscle hypertrophy, already linked to positive changes
compared to the initial session [24]. Interestingly, CK in a variety of performance outcomes, is a possible con-
levels were reported as smaller during the initial bout tributor to the favorable performance changes observed in
versus the subsequent bout, even at rest [24]. However, this AEL. It does seem that differential hypertrophy may occur
is likely due to a dose-response relationship and little to do based on training [74, 75]. Thus, hypertrophy’s influence
with AEL itself, as the first bout included 5 9 6 whereas on performance is potentially dependent on the specificity
the subsequent bout included 5 9 10, thus changing the of the stimulus inducing the adaptation. There appears to
volume applied from session to session. Such an acute be a regional specificity to hypertrophic changes, with
increase in volume may explain the greater CK concen- eccentric training increasing muscle CSA at the distal
tration, which, if taken as an index of muscle damage, may portion of the muscle and concentric training within the
indicate the need for careful prescription of advanced muscle belly [76, 77]. Additionally, eccentric-only training
training means. However, it is also worth noting that CK is has been shown to favor increases in fascicle length and
not the only indicator of muscle damage, as other enzymes hypertrophy of the distal portions of a muscle while con-
and cytokines may also need to be considered [71, 72]. centric-only training results in pennation angle increases
When taken together, these results would indicate that and greater hypertrophy mid-muscle [76–80]. These dif-
AEL provides a substantial acute homeostatic disruption of ferential changes suggest that eccentric training may be
the cellular environment (Table 3). The increased lactate more favorable for contraction velocity, as hypertrophy
response coupled with enhanced lactate recovery provides tends to be more evenly distributed throughout the muscle,
some indication that some AEL protocols target the gly- while concentric training may favor force production as
colytic system’s capacity and efficiency. Further, it appears hypertrophy is localized centrally in the muscle where a
that AEL elicits at least a similar protein synthetic endo- majority of tissue resides. Due to AEL, it is plausible that
crine response compared to traditional loading. With greater hypertrophy will occur in the distal portion of the
regard to coaching application, some AEL protocols may muscle while maintaining the proximal muscle changes
provide a similar metabolic stimulus to that observed in associated with traditional loading. Of four studies exam-
traditionally loaded, higher volume strength endurance ining anatomical cross-sectional area (aCSA) after pre-
training blocks. However, under identical volume pre- scribed AEL, three have found no difference between AEL
scription, it may do so using a higher magnitude of loading, and traditional loading [15, 16, 21], with one exception
thereby increasing force production demands and providing [14]. However, the typical measurement methodology may
a specific increase in volume load that may be advanta- have influenced the interpretation of such results. For
geous for strength-power athletes. example, though all four studies considered measurements
from both the distal ends of the muscle and the muscle
belly, only one considered them separately for analysis
[21], while the others averaged the measurements for
6 Potential Mechanisms in Chronic AEL consideration of whole muscle aCSA changes [14–16]. Of
the three studies which observed no between-group dif-
Longer duration training studies may be better suited to ferences in aCSA, AEL produced statistically greater
explain the potential adaptations to AEL training compared improvements in strength [16, 21] and jump performance
to acute studies. Unfortunately, there are few studies to [15]. The changes in jump performance may be attributed
date examining the effects of AEL lasting longer than to increased contraction speed via in-series specific
12 weeks. These available experiments shape our current hypertrophy from the overloaded eccentric, while the
understanding of AEL for practical purposes and adaptive changes in strength may be due to in-parallel specific
mechanisms (Table 4). An early study [73] using manual hypertrophy from the traditional loaded concentric [76].
resistance of body-weight exercises was one of the first The similarities in aCSA changes combined with favorable
known training studies employing AEL. The results of this performance results may indicate that neural mechanisms
study indicated relative strength may be enhanced by may be affecting training outcomes following AEL, but the
overloading the eccentric portion of various exercises. lack of region-specific consideration in analysis of CSA
Although performance increased following AEL imple- may have also influenced this interpretation [14–16].
mentation, it provided little information that allowed for Despite the paucity of direct evidence regarding changes
hypothesis generation with regard to reasons for the in muscle morphology under AEL, there have been
observed changes. This simple intervention did, however, enhancements in factors involved in anabolic signaling.
generate interest and subsequent completion of several Friedmann-Bette and associates [15] found that AEL pro-
studies examining the chronic effects of AEL on strength duced significantly greater changes in androgen receptor
and muscle size. content compared to traditional loading, which can likely

123
 Table 3 Acute physiological responses to accentuated eccentric loading. Cohen’s d effect size indicated in parentheses in the Results columns
Study Subjects Training status Loading strategy Loading magnitude Comparison Exercise Variables Results
methodology selection analyzed

Bridgeman 8 males [2 years Dumbbells ?20% body mass Pre/post Drop Creatine kinase Creatine kinase
et al. [24] (26.3 ± 5.1 years) dropped before (Session 1: 5 9 6 jump 596 5 9 10
concentric (52 cm)
Session 2: 5 9 10) Post -13.5% ?6.3%
(-0.32) (0.15)
1h -1.8% ?1.2
(-0.04) (0.03)
AEL for Training and Performance

24 h ?10.3% ?18.3%
(0.25) (0.43)
48 h -10.7% ?6%
(-0.26) (0.14)
Ojasto and 11 males BP 1RM of Weight releaser CON—70% 1RM 70% 1RM Bench La La
Hakkinen (32.4 ± 4.3 years) 1.2–1.4 BM ECC—80, 90, 100% 1RM bench press press GH vs. 70% Per Rep
[32]
EMG 80% ?7.4% ?6.7
(0.51) (0.29)
90% ?18.5% ?30%
(1.27) (1.29)
100% ?15.1% ?36.7%
(1.03) (1.57)
GH
vs.70% Per Rep
80% ?33.1% ?16.7
(0.24) (0.08)
90% ?146.2% ?166.7%
(1.07) (0.75)
100% ?93.8% ?133.3%
(0.68) (0.60)
EMG—no difference between
conditions, all conditions
show pre/post increases
Yarrow 22 males Untrained (no Max out CON—40% 1RM TRAD (4 9 6): Bench Total No differences in total
et al. [33] (22.09 ± 0.8 years) RT within (concentric ECC—100% 1RM 52.5% press testosterone testosterone or bioavailable
6 months) phase motor Back Bioavailable testosterone
assisted) squat testosterone GH
GH AEL: ?3700% 15-post,
La TRAD: ?250 15-Post
La
AEL: 130–180% higher than
bout 1 and TRAD

123
 Table 3 continued
Study Subjects Training status Loading strategy Loading magnitude Comparison Exercise Variables Results
methodology selection analyzed

123
Yarrow 22 males Untrained (no Max out AEL (3 9 6): 40/100%, TRAD (4 9 6): Bench Total La
et al. [34] (22.1 ± 0.8 years) RT within (concentric 41/103%, 43/107%, 52.5, 58, 64, press testosterone Lower in AEL vs. TRAD at
6 months) phase motor 45/112%, 46/117%, 49/121% 69, 73% Back BT 30-min post, AEL return to
assisted) squat baseline by 60-min post
GH
La Total testosterone
Blood draws Resting—AEL vs. TRAD:
taken after ?13.8% (1.13)
final session AUC—AEL vs. TRAD:
?16.7% (1.38)
BT
Resting—AEL vs. TRAD:
?2.9% (0.33)
AUC—AEL vs. TRAD:
?5.9% (0.75)
GH
No difference between groups
AEL accentuated eccentric loading, BT bioavailable testosterone, CON concentric, ECC eccentric, EMG electromyography, GH growth hormone, La lactate, RT resistance training, TRAD
traditional/isokinetic loading
J. P. Wagle et al.
 Table 4 Chronic physiological responses to accentuated eccentric loading. Cohen’s d effect size indicated in parentheses in the Results columns
Study Subjects Training status Loading strategy Loading magnitude Comparison Exercise selection Study Variables Results
methodology duration analyzed

Brandenburg and 18 males [1 year, bench Coach removed 3 9 10 4 9 10 Arm curl and arm 9 wk CSA: elbow CSA
Docherty [16] (university aged) press weight for CON CON—75% 1RM 75% 1RM extension Wk 1–2: flexor/extensor TRAD—flexor: ?3.1% (0.22),
1RM C BM phase 29/wk Specific tension extensor: ?1.7% (0.08)
ECC—110–120% 1RM
Wk 3–9: AEL—flexor: -0.3% (0.02),
39/wk extensor: ?1.7% (0.16)
Specific tension
TRAD—flexor: ?8.8% (0.93),
extensor: ?13.2% (0.90)
AEL for Training and Performance

AEL—flexor: ?8.9% (0.72),

extensor: ?22.4% (1.67)
Friedmann et al. 16 males No resistance Computer-driven 3 9 25 ea leg, 30% 6 9 25 each leg Leg extension 4 wk CSA FCSA (% FT distribution)
[14] (24.5 ± 3.4 years) training CON/?70% 30% 1RM 39/wk FCSA TRAD AEL
within 1 year equivalent ECC (30%
ECC 1RM, (45 s/set) mRNA Type I ?1% -14.2%
2.32 9 higher load) expression (0.04) (-0.67)
(MHC, Type ?5.7% ?25.7%
PFK, LDH A, IIa (0.32) (0.89)
LDH B)
Type -19.4% ?3.8%
IIx (-0.26) (0.06)
FCSA (lm2)
TRAD AEL
Type I ?28.5% ?15.3%
(0.72) (0.68)
Type ?13.5% ?26.5%
IIa (0.29) (0.88)
Type ?12.2% ?12.6%
IIx (0.24) (0.39)
MHC mRNA
Type I: no change for either
group
Type IIA—TRAD: -25%
(-37 to ?54%), AEL: ?30%
(?4 to ?84%)
Type IIX—TRAD: -24%
(-98 to ?634%), AEL: ?320%
(-7 to ?463)
PFK mRNA
No difference of change
LDH A mRNA
TRAD: -58 to ?66%
AEL: 70% (?20 to ?122%)
LDH B mRNA
No significant group or test effect

123
 Table 4 continued
Study Subjects Training status Loading strategy Loading magnitude Comparison Exercise selection Study Variables Results
methodology duration analyzed

123
Friedmann- 25 males [1 year Computer-driven 5 9 8 RM 6 9 8 RM Leg extension 6 wk CSA CSA
Bette et al. [15] (24.4 ± 3.9 years) strength CON: 8 RM 39/wk FCSA Both groups significant increase
training
ECC: *1.99 CON Fiber type FCSA
distribution AEL: statistically significant in
mRNA IIx,
expression non-statistically significant
changes in I and IIa
TRAD: No change
Fiber type distribution (%)
No difference
mRNA
AEL: statistically significant
different response of
MHC 4, and androgen receptor
(change in
AR negatively correlated with
changes
in Type II fiber changes)
Statistically significant changes
pre/post in AEL
only: LDH A, MCT 4, IGFBP4,
EIF2B5,
MRF4, Myostatin, HGF,
MHCneo
Godard et al. [18] 16 males N/A Manual adjustment by 80% CON/?40% ECC 8–12 reps 80% Leg extension 10 wk Thigh Girth Thigh girth
12 females coach CON 1RM 29/wk CON/ECC: ?6.2% (0.71)
(22.4 ± 3.7 years) CON/ECC? : ?5.0% (0.50)
Control: ?0.6% (0.07)
Walker et al. [21] 28 males 0.5–6 years Weight releaser (leg Session 1: 6 RM CON/ Session 1: 3 9 6 Leg press and 2 9 5 wk CSA CSA
(21 ± 3 years) press); manual ?40% ECC RM Leg extension 29/wk Muscle activation VL50—TRAD: ?9.7% (0.50),
adjustment by coach Session 2: 10 RM CON/ Session 2: AEL: ?11.3% (0.36)
(leg extension) ?40% ECC 3 9 10 RM VM33—TRAD: ?15.4% (0.84),
AEL: ?9.4% (0.42)
VLVI67—no changes
within/between groups
Muscle activation
TRAD AEL
ECC ?12.5% ?28.6%
(abs) (0.25) (0.60)
ECC ?8.3% ?8.3%
(rel) (0.25) (0.25)
CON ?14.6% ?35.7%
(abs) (0.60) (1.5)
CON ?0%, ?0%,
(rel) (0.00) (0.00)
J. P. Wagle et al.
 Table 4 continued
Study Subjects Training Loading strategy Loading magnitude Comparison Exercise Study Variables Results
status methodology selection duration analyzed

ISO ?20.7% ?23.5%

(abs) (0.60) (0.80)
ISO ?0%, ?0%,
(rel) (0.00) (0.00)
M-wave
VL—AEL: ?54.8% (1.13)
VM—AEL: ?26% (0.87)
AEL for Training and Performance

Yarrow 22 males Untrained MaxOut ECC (3 9 6): 40/100%, 41/103%, 43/107%, TRAD (4 9 6): Bench press 5 weeks BM BM
et al. [34] (22.1 ± 0.8 years) (no RT (counterbalance 45/112%, 46/117%, 49/121% 52.5%, 58%, and 39/week Body fat TRAD: -0.4% (0.10)
within weight system 64%, 69% 73% back
6 months) in squat La AEL: ?1.2% (0.19)
which electric Total BF
motors testosterone TRAD: ?2.1% (0.19)
assist during the BT
concentric AEL: ?1.5% (0.12)
action) GH La
Lower in AEL by 30-min post
Total Testosterone, BT, GH
No difference between groups

AEL accentuated eccentric loading, BF body fat, BM body mass, BT bioavailable testosterone, CON concentric, CSA cross-sectional area, ECC eccentric, FCSA fiber cross-sectional area, GH growth hormone, ISO isometric, La
LACTATE, LDH A lactate dehydrogenase A, LDH B lactate dehydrogenase B, MHC myosin heavy chain,, PFK phosphofructokinase, TRAD traditional/isokinetic loading, TT total testosterone, VL50 vastus lateralis at 50% femur
length, VLVI67 vastus lateralis ? intermedius at 67% femur length, VM33 vastus medialis at 33% femur length

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be attributed to the overloaded eccentric phase and may favorable changes in maximal strength due to AEL are
influence the effects of hormones like testosterone in highly related to Type IIa fCSA (r = 0.966) [14].
stimulating muscle protein synthesis [81]. Though no dif- A later study from Friedmann-Bette and associates [15]
ferences were observed between traditional loading and also comparing AEL to traditional loading using 10-s timed
AEL, increased androgen receptor content may explain the sets of eight repetitions of leg extensions, noted significant
observations of Yarrow and associates [33, 34] regarding increases in Type IIx fCSA for AEL but not traditional
diminished bioavailable testosterone levels following loading. This study also presented significant correlations
training. Additionally, AEL produced increases in several between maximal strength and Type IIx and Type IIa fCSA
insulin-like growth factors, including IGF-1. The (R = 0.612 and R = 0.600, respectively) for AEL only.
mechanical load-induced anabolic effects of IGF-1 are These correlations for AEL only suggest additional
robust and include satellite cell activation and proliferation, underlying mechanisms and intrinsic muscle properties
which also may explain the increases in factors related to may influence fiber-type specific hypertrophy and subse-
muscle growth and regeneration observed by Friedmann- quently maximum strength and power performances. One
Bette and colleagues [15, 82]. Specifically, several myo- such mechanism may be MHC content. The mRNA of
genic regulatory factors (myoD, myogenin, MYF5, MRF4, MHC4 isoforms, which is associated with faster muscle
HGF, and myostatin) were significantly increased under the phenotypes, were observed to be significantly increased
AEL condition, while some were not changed under tra- following AEL, while a slight decrease was observed fol-
ditional loading [15]. The increases in such factors further lowing traditional loading [15, 93]. No other MHC or MLC
suggest an increase in satellite cell proliferation, which mRNA differences were observed in this study [15].
may be provided by both the increased mechanical tension However, a different study revealed statistically greater
and stretch of the overloaded eccentric as well as the MHC IIa mRNA after AEL compared to traditional loading
stimulation of the concentric action [15, 83]. [14]. Additionally, a non-significant average increase of
The increased anabolic signaling may be primarily 320% in Type IIx mRNA concentration following AEL and
within faster muscle fiber types (i.e., Type IIa and IIx), a 24% decrease following traditional loading were
leading to changes to specific CSA and intrinsic muscle observed, although high variability may impact the inter-
properties, which could have positive implications for pretation of these results. The increases in Type IIx mRNA,
strength and power performances [84–87]. Friedmann and combined with statistically greater increases in LDH A
colleagues [14] observed decreases in Type I fiber-type isoform indicate that AEL may elicit unique skeletal
percentage and increases in Type IIa and Type IIx fiber- muscle adaptations, particularly in faster, more explosive
type percentages in the vastus lateralis following AEL muscle isoforms [14]. Such changes may explain the
using 45-s timed sets of 25 leg extensions (eccentric/con- findings of other studies, particularly Yarrow and associ-
centric: 70/30% 1RM), but only statistically significant ates [34]. As previously discussed, this group found greater
changes occurred in the Type IIa fibers. Conversely, in the increases in lactate concentration following AEL compared
traditionally loaded group, a slight nonsignificant increase to traditional loading. Further, Yarrow and colleagues
in Type IIa fiber-type percentage and slight decrease in found that lactate clearance abilities were also enhanced
Type IIx fiber-type percentage was noted, which is con- via AEL, which is supported by the significant increase in
sistent with previous research using traditional loading LDH A mRNA content following AEL but not traditional
[88, 89]. Relatively no change was observed in Type I loading [14, 34]. These studies suggest that AEL may
fibers, which may be due to the high movement rate impart chronic training adaptations similar to traditional
required [14]. The fiber CSA (fCSA) results did not reach resistance training, and it is plausible that AEL may have
significance for any variable; however, more pronounced additional benefits towards strength and power-specific
increases were observed in Type I fCSA for the tradition- gains such as Type IIx-specific shifts in MHC concentra-
ally loaded group. Though both traditional loading and tion and bioenergetic anaerobic adaptations.
AEL yielded favorable changes in Type IIa fCSA, more
marked increases of Type IIa fCSA were observed under
the AEL condition [14]. Though the changes in this fiber 7 Conclusions and Direction of Future Research
type have been vastly noted in traditional loading condi-
tions [84, 90–92], the greater changes in glycolytic fiber A paucity of peer-reviewed literature currently exists
types under AEL may be due to the potentially greater regarding AEL, especially involving trained subjects or
stress applied to the glycolytic system, evidenced by the athletic populations. Within the current literature, there is a
increased lactate response observed by Yarrow and asso- great deal of inconsistency in loading means and magnitude,
ciates as well as Ojasto and Häkkinen [32–34]. Moreover, which makes it difficult to apply the findings of such
the findings of Friedmann and colleagues [14] suggest the research, especially pertaining to acute applications of AEL.

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AEL for Training and Performance

Furthermore, chronic interventions vary in duration and eccentric exercise in trained men. Med Sci Sports Exerc.
often employ exercise selection and AEL means dissimilar 2006;38(10):1770–81.
12. Nardone A, Schieppati M. Selective recruitment of high threshold
to those encountered in training athletic populations, which human motor units during voluntary isotonic lengthening of
may be where AEL is most logically applied. Despite these active muscles. J Physiol. 1989;409:451–71.
limitations, AEL has shown promise in a variety of acute 13. Higbie EJ, Cureton KJ, Warren GL III, Prior BM. Effects of
and chronic applications. Acutely, AEL has demonstrated concentric and eccentric training on muscle strength, cross-sec-
tional area, and neural activation. J Appl Physiol.
the ability to enhance concentric force and power production 1996;81(5):2173–81.
[15–21]. Through chronic application of AEL, the ability to 14. Friedmann B, Kinscherf R, Vorwald S, Muller H, Kucera K,
shift MHC towards faster isoforms and elicit favorable Borisch S, et al. Muscular adaptations to computer-guided
changes in Type IIx specific muscle cross sectional area strength training with eccentric overload. Acta Physiol Scand J.
2004;182:77–88.
have been demonstrated [14, 15]. Due to the potential 15. Friedmann-Bette B, Bauer T, Kinscherf R, Vorwald S, Klute K,
benefits, but high level of inconsistency and lack of current Bischoff D, et al. Effects of strength training with eccentric
literature, it would be advantageous for future research to overload on muscle adaptation in male athletes. Eur J Appl
first examine the acute response to practically applicable Physiol. 2010;108(4):821–36.
16. Brandenburg JP, Docherty D. The effects of accentuated eccen-
means and magnitudes of AEL. Such findings would allow tric loading on strength, muscle hypertrophy, and neural adap-
for a more precise and logical implementation to investi- tations in trained individuals. J Strength Cond Res.
gations regarding chronic adaptations. 2002;16(1):25.
17. Doan BK, Newton RU, Marsit JL, Triplett-McBride NT, Koziris
Compliance with Ethical Standards LP, Fry AC, et al. Effects of increased eccentric loading on bench
press 1RM. J Strength Cond Res. 2002;16(1):9–13.
Conflicts of interest and study funding John P. Wagle, Christopher 18. Godard MP, Wygand JW, Carpinelli RN, Catalano S, Otto RM.
B. Taber, Aaron J. Cunanan, Garett E. Bingham, Kevin M. Carroll, Effects of accentuated eccentric resistance training on concentric
Brad H. DeWeese, Kimitake Sato, and Michael H. Stone declare that knee extensor strength. J Strength Cond Res. 1998;12(1):26–9.
they have no conflicts of interest. No financial support was received 19. Kaminski TW, Wabbersen CV, Murphy RM. Concentric versus
for the conduct of the study or preparation of this manuscript. enhanced eccentric hamstring strength training: clinical impli-
cations. J Athl Train. 1998;33(3):216–21.
20. Ojasto T, Hakkinen K. Effects of different accentuated eccentric
load levels in eccentric-concentric actions on acute neuromus-
References cular, maximal force, and power responses. J Strength Cond Res.
2009;23(3):996–1004.
1. Hakkinen K, Pakarinen A, Alen M, Kauhanen H, Komi P. Neu- 21. Walker S, Blazevich AJ, Haff GG, Tufano JJ, Newton RU,
romuscular and hormonal adaptations in athletes to strength Hakkinen K. Greater strength gains after training with accentu-
training in two years. J Appl Physiol. 1988;65(6):2406–12. ated eccentric than traditional isoinertial loads in already
2. Kraemer WJ, Ratamess NA, French DN. Resistance training for strength-trained men. Front Physiol. 2016;7:149.
health and performance. Curr Sports Med Rep. 22. Aboodarda SJ, Byrne JM, Samson M, Wilson BD, Mokhtar AH,
2002;1(3):165–71. Behm DG. Does performing drop jumps with additional eccentric
3. Aagaard P, Simonsen EB, Andersen JL, Magnusson P, Dyhre- loading improve jump performance? J Strength Cond Res.
Poulsen P. Increased rate of force development and neural drive 2014;28(8):2314–23.
of human skeletal muscle following resistance training. J Appl 23. Aboodarda SJ, Yusof A, Osman NAA, Thompson MW, Mokhtar
Physiol. 2002;93(4):1318–26. AH. Enhanced performance with elastic resistance during the
4. Pensini M, Martin A, Maffiuletti N. Central versus peripheral eccentric phase of a countermovement jump. Int J Sports Physiol
adaptations following eccentric resistance training. Int J Sports Perform. 2013;8:181–7.
Med. 2002;23(08):567–74. 24. Bridgeman LA, Gill ND, Dulson DK, McGuigan MR. The effect
5. Sale DG. 5 Influence of exercise and training on motor unit of exercise-induced muscle damage after a bout of accentuated
activation. Exerc Sport Sci Rev. 1987;15(1):95–152. eccentric load drop jumps and the repeated bout effect. J Strength
6. Tesch P. Skeletal muscle adaptations consequent to long-term Cond Res. 2017;31(2):386–94.
heavy resistance exercise. Med Sci Sports Exerc. 1988;20(5 25. Bridgeman LA, McGuigan MR, Gill ND, Dulson DK. The effects
Suppl):S132–4. of accentuated eccentric loading on the drop jump exercise and
7. Jorgensen K. Force-velocity relationship in human elbow flexors the subsequent postactivation potentiation response. J Strength
and extensors. Int Ser Biomech. 1976;1:145–51. Cond Res. 2017;31(6):1620–26.
8. Westing SH, Seger JY, Karlson E, Ekblom B. Eccentric and 26. Hughes JD, Massiah RG, Clarke RD. The potentiating effect of
concentric torque-velocity characteristics of the quadriceps an accentuated eccentric load on countermovement jump per-
femoris in man. Eur J Appl Physiol Occup Physiol. formance. J Strength Cond Res. 2016;30(12):3450–5.
1988;58(1–2):100–4. 27. Sheppard J, Hobson S, Barker M, Taylor K, Chapman D,
9. Katz B. The relation between force and speed in muscular con- McGuigan M, et al. The effect of training with accentuated
traction. J Physiol. 1939;96(1):45. eccentric load counter-movement jumps on strength and power
10. Hortobagyi T, Barrier J, Beard D, Braspennincx J, Koens P, characteristics of high-performance volleyball players. Int J
Devita P, et al. Greater initial adaptations to submaximal muscle Sports Sci Coach. 2008;3(3):355–63.
lengthening than maximal shortening. J Appl Physiol. 28. Sheppard J, Newton R, McGuigan M. The effect of accentuated
1996;81(4):1677–82. eccentric load on jump kinetics in high-performance volleyball
11. Vikne H, Refsnes PE, Ekmark M, Medbø JI, Gundersen V, players. Int J Sports Sci Coach. 2007;2(3):267–73.
Gundersen K. Muscular performance after concentric and

123
 J. P. Wagle et al.

29. Sheppard JM, Young K. Using additional eccentric loads to 52. Komi PV. Physiological and biomechanical correlates of muscle
increase concentric performance in the bench throw. J Strength function: effects of muscle structure and stretch-shortening cycle
Cond Res. 2010;24(10):2853–6. on force and speed. Exerc Sport Sci Rev. 1984;12(1):81–122.
30. Barstow IK, Bishop MD, Kaminski TW. Is enhanced-eccentric 53. LaStayo PC, Woolf JM, Lewek MD, Snyder-Mackler L, Reich T,
resistance training superior to traditional training for increasing Lindstedt SL. Eccentric muscle contractions: their contribution to
elbor flexor strength? J Sports Sci Med. 2003;2:62–9. injury, prevention, rehabilitation, and sport. J Orthop Sports Phys
31. Moore CA, Weiss LW, Schilling BK, Fry AC, Li Y. Acute effects Ther. 2003;33(10):557–71.
of augmented eccentric loading on jump squat performance. 54. Suchomel TJ, Nimphius S, Stone MH. The importance of mus-
J Strength Cond Res. 2007;21(2):372–7. cular strength in athletic performance. Sports Med.
32. Ojasto T, Hakkinen K. Effects of different accentuated eccentric 2016;46(10):1419–49.
loads on acute neuromuscular, growth hormone, and blood lactate 55. Aagaard P. Training-induced changes in neural function. Exerc
responses during a hypertrophic protocol. J Strength Cond Res. Sport Sci Rev. 2003;31(2):61–7.
2009;23(3):946–53. 56. Häkkinen K. Research overview: factors influencing trainability
33. Yarrow JF, Borsa PA, Borst SE, Sitren HS, Stevens BR, White of muscular strength during short term and prolonged training.
LJ. Neuroendocrine responses to an acute bout of eccentric-en- Strength Cond J. 1985;7(2):32–7.
hanced resistance exercise. Med Sci Sports Exerc. 57. Cormie P, McBride JM, McCaulley GO. Power-time, force-time,
2007;39(6):941–7. and velocity-time curve analysis of the countermovement jump:
34. Yarrow JF, Borsa PA, Borst SE, Sitren HS, Stevens BR, White impact of training. J Strength Cond Res. 2009;23(1):177–86.
LJ. Early-phase neuroendocrine responses and strength adapta- 58. Cormie P, McGuigan MR, Newton RU. Influence of strength on
tions following eccentric-enhanced resistance training. J Strength magnitude and mechanisms of adaptation to power training. Med
Cond Res. 2008;22(4):1205–14. Sci Sports Exerc. 2010;42(8):1566–81.
35. Colliander EB, Tesch PA. Effects of eccentric and concentric 59. Stone MH, O’bryant HS, Mccoy L, Coglianese R, Lehmkuhl M,
muscle actions in resistance training. Acta Physiol Scand J. Schilling B. Power and maximum strength relationships during
1990;140:31–9. performance of dynamic and static weighted jumps. J Strength
36. Duchateau J, Enoka RM. Neural control of lengthening con- Cond Res. 2003;17(1):140–7.
tractions. J Exp Biol. 2016;219(Pt 2):197–204. 60. Farthing JP, Chilibeck PD. The effects of eccentric and concen-
37. Enoka RM. Eccentric contractions require unique activation tric training at different velocities on muscle hypertrophy. Eur J
strategies by the nervous system. J Appl Physiol. Appl Physiol. 2003;89(6):578–86.
1996;81(6):2339–46. 61. Liu C, Chen C-S, Ho W-H, Füle RJ, Chung P-H, Shiang T-Y. The
38. Kay D, St Clair Gibson A, Mitchell MJ, Lambert MI, Noakes TD. effects of passive leg press training on jumping performance,
Different neuromuscular recruitment patterns during eccentric, speed, and muscle power. J Strength Cond Res.
concentric and isometric contractions. J Electromyogr Kinesiol. 2013;27(6):1479–86.
2000;10:425–31. 62. Pasquet B, Carpentier A, Duchateau J, Hainaut K. Muscle fatigue
39. Nardone A, Schieppati M. Shift of activity from slow to fast during concentric and eccentric contractions. Muscle Nerve.
muscle during voluntary lengthening contractions of the triceps 2000;23(11):1727–35.
surae muscles in humans. J Physiol. 1988;395:363–81. 63. Tesch P, Dudley G, Duvoisin M, Hather B, Harris R. Force and
40. Saxton JM, Clarkson PM, James R, Miles M, Westerfer M, Clark EMG signal patterns during repeated bouts of concentric or
S, et al. Neuromuscular dysfunction following eccentric exercise. eccentric muscle actions. Acta Physiol. 1990;138(3):263–71.
Med Sci Sports Exerc. 1995;27(8):1185–93. 64. Gruber M, Linnamo V, Strojnik V, Rantalainen T, Avela J.
41. Dietz V, Schmidtbleicher D, Noth J. Neuronal mechanisms of Excitability at the motoneuron pool and motor cortex is specifi-
human locomotion. J Neurophysiol. 1979;42(5):1212–22. cally modulated in lengthening compared to isometric contrac-
42. Sweeney H, Bowman B, Stull J. Myosin light chain phosphory- tions. J Neurophysiol. 2009;101(4):2030–40.
lation in vertebrate striated muscle: regulation and function. Am J 65. Gans C, Gaunt AS. Muscle architecture in relation to function.
Physiol Cell Physiol. 1993;264(5):C1085–95. J Biomech. 1991;24:53–65.
43. Sale DG. Postactivation potentiation: role in human performance. 66. Griffiths R. Shortening of muscle fibres during stretch of the
Exerc Sport Sci Rev. 2002;30(3):138–43. active cat medial gastrocnemius muscle: the role of tendon
44. Rassier D, Macintosh B. Coexistence of potentiation and fatigue compliance. J Physiol. 1991;436:219.
in skeletal muscle. Braz J Med Biol Res. 2000;33(5):499–508. 67. Cronin J, McNair PJ, Marshall RN. Velocity specificity, combi-
45. Cavagna GA, Dusman B, Margaria R. Positive work done by a nation training and sport specific tasks. J Sci Med Sport.
previously stretched muscle. J Appl Physiol. 1968;24(1):21–32. 2001;4(2):168–78.
46. Komi PV, Bosco C. Muscles by men and women. Med Sci Sports 68. Balshaw TG. Acute neuromuscular, kinetic, and kinematic
Exerc. 1978;10:261–5. responses to accentuated eccentric load resistance exercise.
47. Hortobagyi T, Devita P, Money J, Barrier J. Effects of standard University of Stirling; 2013.
and eccentric overload strength training in young women. Med 69. Abbruzzese G, Morena M, Spadavecchia L, Schieppati M.
Sci Sports Exerc. 2001;33(7):1206–12. Response of arm flexor muscles to magnetic and electrical brain
48. Bobbert MF, Huijing PA, Van Ingen Schenau GJ. Drop jumping. stimulation during shortening and lengthening tasks in man.
II. The influence of dropping height on the biomechanics of drop J Physiol. 1994;481(Pt 2):499.
jumping. Med Sci Sports Exerc. 1987;19(4):339–46. 70. Vingren JL, Kraemer WJ, Ratamess NA, Anderson JM, Volek JS,
49. Bobbert MF, Gerritsen KG, Litjens MC, Van Soest AJ. Why is Maresh CM. Testosterone physiology in resistance exercise and
countermovement jump height greater than squat jump height? training. Sports Med. 2010;40(12):1037–53.
Med Sci Sports Exerc. 1996;28:1402–12. 71. Brancaccio P, Lippi G, Maffulli N. Biochemical markers of
50. Komi PV, Bosco C. Muscles by men and women. Med Sci Sport. muscular damage. Clin Chem Lab Med. 2010;48(6):757–67.
1978;10:261–5. 72. Sorichter S, Mair J, Koller A, Gebert W, Rama D, Calzolari C,
51. Thys H, Faraggiana T, Margaria R. Utilization of muscle elas- et al. Skeletal troponin I as a marker of exercise-induced muscle
ticity in exercise. J Appl Physiol. 1972;32(4):491–4. damage. J Appl Physiol. 1997;83(4):1076–82.

123
AEL for Training and Performance

73. Johnson RM. Effects of manual negative accentuated resistance 84. Fry AC. The role of resistance exercise intensity on muscle fibre
on strength and/or muscular endurance. 1974. adaptations. Sports Med. 2004;34(10):663–79.
74. Antonio J. Nonuniform response of skeletal muscle to heavy 85. Fry AC, Schilling BK, Staron RS, Hagerman FC, Hikida RS,
resistance training: can bodybuilders induce regional muscle Thrush JT. Muscle fiber characteristics and performance corre-
hypertrophy? J Strength Cond Res. 2000;14(1):102–13. lates of male Olympic-style weightlifters. J Strength Cond Res.
75. Fisher J, Steele J, Smith D. Evidence-based resistance training 2003;17(4):746–54.
recommendations for muscular hypertrophy. Sports Med. 86. Gehlert S, Suhr F, Gutsche K, Willkomm L, Kern J, Jacko D,
2013;17(4):217–35. et al. High force development augments skeletal muscle sig-
76. Franchi MV, Atherton PJ, Reeves ND, Flück M, Williams J, nalling in resistance exercise modes equalized for time under
Mitchell WK, et al. Architectural, functional and molecular tension. Pflügers Archiv Eur J Physiol. 2015;467(6):1343–56.
responses to concentric and eccentric loading in human skeletal 87. Yan Z, Biggs R, Booth FW. Insulin-like growth factor
muscle. Acta Physiol. 2014;210(3):642–54. immunoreactivity increases in muscle after acute eccentric con-
77. Seger JY, Arvidsson B, Thorstensson A, Seger JY. Specific tractions. J Appl Physiol. 1993;74(1):410–4.
effects of eccentric and concentric training on muscle strength 88. Campos GE, Luecke TJ, Wendeln HK, Toma K, Hagerman FC,
and morphology in humans. Eur J Appl Physiol Occup Physiol. Murray TF, et al. Muscular adaptations in response to three dif-
1998;79(1):49–57. ferent resistance-training regimens: specificity of repetition
78. Abe T, Kawakami Y, Kondo M, Fukunaga T. Comparison of maximum training zones. Eur J Appl Physiol.
ultrasound-measured age-related, site-specific muscle loss 2002;88(1–2):50–60.
between healthy Japanese and German men. Clin Physiol Funct 89. Staron R, Karapondo D, Kraemer W, Fry A, Gordon S, Falkel J,
Imaging. 2011;31(4):320–5. et al. Skeletal muscle adaptations during early phase of heavy-
79. Abe T, Kumagai K, Brechue WF. Fascicle length of leg muscles resistance training in men and women. J Appl Physiol.
is greater in sprinters than distance runners. Med Sci Sports 1994;76(3):1247–55.
Exerc. 2000;32(6):1125–9. 90. Baumann H, Jäggi M, Soland F, Howald H, Schaub MC. Exercise
80. Reeves ND, Maganaris CN, Longo S, Narici MV. Differential training induces transitions of myosin isoform subunits within
adaptations to eccentric versus conventional resistance training in histochemically typed human muscle fibres. Pflügers Archiv Eur J
older humans. Exp Physiol. 2009;94(7):825–33. Physiol. 1987;409(4):349–60.
81. Bamman MM, Shipp JR, Jiang J, Gower BA, Hunter GR, 91. Pette D, Staron RS. Myosin isoforms, muscle fiber types, and
Goodman A, et al. Mechanical load increases muscle IGF-I and transitions. Microsc Res Tech. 2000;50(6):500–9.
androgen receptor mRNA concentrations in humans. Am J 92. Pette D, Staron RS. Transitions of muscle fiber phenotypic pro-
Physiol Endocrinol Metab. 2001;280(3):E383–90. files. Histochem Cell Biol. 2001;115(5):359–72.
82. Matheny RW Jr, Nindl BC, Adamo ML. Minireview: Mechano- 93. Smerdu V, Karsch-Mizrachi I, Campione M, Leinwand L, Schi-
growth factor: a putative product of IGF-I gene expression affino S. Type IIx myosin heavy chain transcripts are expressed in
involved in tissue repair and regeneration. Endocrinology. type IIb fibers of human skeletal muscle. Am J Physiol Cell
2010;151(3):865–75. Physiol. 1994;267(6):C1723–8.
83. Jacobs-El J, Zhou M-Y, Russell B. MRF4, Myf-5, and myogenin
mRNAs in the adaptive responses of mature rat muscle. Am J
Physiol Cell Physiol. 1995;268(4):C1045–52.

123