Open Access Journal of Sports Medicine Dovepress

open access to scientific and medical research

Open Access Full Text Article Original Research

Do physiological measures predict selected

CrossFit® benchmark performance?

This article was published in the following Dove Press journal:

Open Access Journal of Sports Medicine
31 July 2015
Number of times this article has been viewed

Scotty J Butcher 1,2 Purpose: CrossFit® is a new but extremely popular method of exercise training and competition
Tyler J Neyedly 3 that involves constantly varied functional movements performed at high intensity. Despite the
Karla J Horvey 1 popularity of this training method, the physiological determinants of CrossFit performance have
Chad R Benko 2,4 not yet been reported. The purpose of this study was to determine whether physiological and/
or muscle strength measures could predict performance on three common CrossFit “Workouts
1
Physical Therapy, University of
Saskatchewan, 2BOSS Strength of the Day” (WODs).
Institute, 3Physiology, University of Materials and methods: Fourteen CrossFit Open or Regional athletes completed, on separate
Saskatchewan, 4Synergy Strength and days, the WODs “Grace” (30 clean and jerks for time), “Fran” (three rounds of thrusters and
Conditioning, Saskatoon, SK, Canada
pull-ups for 21, 15, and nine repetitions), and “Cindy” (20 minutes of rounds of five pull-ups,
ten push-ups, and 15 bodyweight squats), as well as the “CrossFit Total” (1 repetition max
[1RM] back squat, overhead press, and deadlift), maximal oxygen consumption (VO2max), and
Wingate anaerobic power/capacity testing.
Results: Performance of Grace and Fran was related to whole-body strength (CrossFit Total)
(r=−0.88 and −0.65, respectively) and anaerobic threshold (r=−0.61 and −0.53, respectively);
however, whole-body strength was the only variable to survive the prediction regression for
both of these WODs (R2=0.77 and 0.42, respectively). There were no significant associations
or predictors for Cindy.
Conclusion: CrossFit benchmark WOD performance cannot be predicted by VO2max, Wing-
ate power/capacity, or either respiratory compensation or anaerobic thresholds. Of the data
measured, only whole-body strength can partially explain performance on Grace and Fran,
although anaerobic threshold also exhibited association with performance. Along with their
typical training, CrossFit athletes should likely ensure an adequate level of strength and aerobic
endurance to optimize performance on at least some benchmark WODs.
Keywords: strength, aerobic, anaerobic, high-intensity, training, exercise, functional

Introduction
CrossFit® (CrossFit, Inc., Washington, DC, USA) is a relatively new but extremely
popular form of multimodal exercise training that encompasses many types of func-
tional movement patterns within a single exercise session, conducted at high intensity.1
These types of exercises are incorporated group workout sessions called “Workouts
of the Day”, or WODs, usually involving a combination of movements performed in a
Correspondence: Scotty J Butcher circuit format with little to no rest periods. Although the structure of each session will
School of Physical Therapy, University
of Saskatchewan, 1121 College Dr,
vary between affiliates, each session is typically 1 hour and comprises of a specific
Saskatoon, SK, S7N 0W3, Canada warm-up, strength and/or skill technique work, a programmed strength or conditioning
Tel +1 306 966 1711
Fax +1 306 966 6575
workout for 10–30 minutes, and cool down and/or mobility work. Despite CrossFit, Inc.
Email scotty.butcher@usask.ca affiliating over 11,000 gyms, and the over 200,000 athletes participating in the 2014

submit your manuscript | www.dovepress.com Open Access Journal of Sports Medicine 2015:6 241–247 241
Dovepress © 2015 Butcher et al. This work is published by Dove Medical Press Limited, and licensed under Creative Commons Attribution – Non Commercial (unported, v3.0)
http://dx.doi.org/10.2147/OAJSM.S88265
License. The full terms of the License are available at http://creativecommons.org/licenses/by-nc/3.0/. Non-commercial uses of the work are permitted without any further
permission from Dove Medical Press Limited, provided the work is properly attributed. Permissions beyond the scope of the License are administered by Dove Medical Press Limited. Information on
how to request permission may be found at: http://www.dovepress.com/permissions.php
Butcher et al Dovepress

CrossFit Open, there is very little reported in the literature would limit their ability to perform high-intensity exercise.
regarding the physiological aspects of CrossFit training or Participant characteristics are presented in Table 1.
performance.
Within the currently available literature, CrossFit training Design
has been shown to elicit a high acute cardiovascular training This study had a descriptive design, whereby participants
response2 as well as large increases in aerobic and anaerobic completed three phases of data collection, including screen-
performance,3,4 while being time-efficient and enjoyable.5 ing, the completion of CrossFit benchmark workouts, and
Despite the emergence of these few studies, there remains a physiological testing. Phase 1 included screening of par-
paucity of research examining the performance of CrossFit ticipants with the Physical Activity Readiness Questionnaire
tests, or benchmarks, or of the physiological requirements of (PAR-Q)8 to determine the eligibility for the study, and report-
CrossFit sport competition. CrossFit benchmark WODs are ing of their total number of months of dedicated CrossFit
designed to be reflective of multiple dimensions of physical training experience, which was recorded for the analysis.
fitness and are usually performed and repeated often within In phase 2, participants performed four CrossFit bench-
an athlete’s training cycle to monitor progress. In other sports, mark workouts. The three common benchmarks used as
progress is often monitored by physiological and/or fitness dependent variable for the analysis of performance were
tests, and their performance can be partially predicted by the Fran, Cindy, and Grace workouts. In addition, partici-
physiological and/or muscle performance data.6,7 Given that pants’ maximal strength was assessed using the benchmark
CrossFit competition involves using many aspects of fitness “CrossFit Total”. Each of these workouts is described in
in a sport environment, it is possible that performance can more detail below.
be at least partially explained by physiological measures, Phase 3 of testing involved participants performing two
which would have implications for directing training pro- physiological performance measurements – a VO2max test
gram design. and the 30-second Wingate Anaerobic Test (WAnT) – as
The purpose of this study was to determine the physiolog- described below. VO2max testing was performed at the Inte-
ical predictors of performance in three CrossFit benchmark grative Clinical Exercise Physiology Lab at the University
workouts performed by competitive CrossFit athletes. We of Saskatchewan. The WAnT was performed at one of the
hypothesized that: 1) physiological performance measures CrossFit affiliates by research staff.
of maximal oxygen consumption (VO 2max), anaerobic
threshold (AT), respiratory compensation threshold (RCT), Methodology
anaerobic power and capacity, or 1 repetition max (1RM) Benchmark workouts
back squat, press, and deadlift strength would be related to The CrossFit benchmark workouts were selected as common
CrossFit benchmark workouts “Grace”, “Fran”, and “Cindy” workouts in CrossFit that theoretically represent a range of
and 2) physiological parameters could partially predict Cross- aerobic, anaerobic, and muscle performance variables. While
Fit benchmark workout performance. all benchmark workouts likely have components of each of
the predominant energy systems and of muscle strength and/
Materials and methods or power, we can speculate that each benchmark would have
Participants greater elements of one or more components and that the use
Fourteen participants were recruited from CrossFit affili- of different benchmarks may elicit different results. Fran is a
ates in the Canada West Region and had at least 1 year fast WOD that likely has more anaerobic components, Grace
of CrossFit training experience. Participants competed
in the 2014 CrossFit Open and/or Regional competitions Table 1 Participant characteristics
and could perform the benchmark workouts with the pre- All Males Females
scribed loads. Nine participants completed the Open only, n 14 10 4
and five participants were also Regional competitors. All Age (years) 32.7±5.7 33.0±5.6 31.7±6.4
participants gave written consent for the study, which was Height (cm) 174.2±9.0 177.7±6.0 161.3±3.1
Weight (kg) 81.5±10.9 86.2±6.1 64.4±2.8
approved by the ­University of Saskatchewan Biomedical
BMI (kg/m2) 26.8±1.8 27.3±1.7 24.7±1.2
Ethics Review Board in the spirit of the Declaration of CrossFit® experience (months) 46.3±24.2 44.5±20.5 51.2±28.1
Helsinki. ­Participants were excluded if they reported any Note: The values are expressed as mean ± SD.
­cardiovascular, respiratory, or musculoskeletal concerns that Abbreviations: BMI, body mass index; SD, standard deviation.

242 submit your manuscript | www.dovepress.com Open Access Journal of Sports Medicine 2015:6
Dovepress
Dovepress CrossFit physiology and performance

is a repeated power WOD that likely has aerobic, strength, Physiological testing
technique, and anaerobic elements, and Cindy likely has Testing for aerobic and anaerobic performance was com-
aerobic and muscle endurance elements. Each workout pleted at two separate sessions. Participants were asked to
was performed at the participant’s home affiliate under the not train for at least 48 hours prior to each test session.
supervision of, and scored by, a CrossFit Level 1 trainer
VO2max
and/or certified CrossFit coach, to ensure the movement and
An individualized test of VO2max, as a measure of aerobic
workout standards were met. All participants performed the
power, was performed on a Trackmaster TMX 425C tread-
prescribed exercises and workouts with no modifications or
mill (Trackmaster, Newton, KS, USA), using a TrueOne
scaling. Participants were asked to complete these workouts
Metabolic Cart (ParvoMedics, Sandy, UT, USA) for the
on separate days following at least 48 hours of recovery from
collection of respiratory gases, and a Polar heart rate (HR)
a previous workout.
monitor (Polar Electro Canada; Lachine, QC, Canada) for
measuring HR. After a standardized warm-up of 3 minutes
“Fran”
at 5.5 kph and 1.0% grade, the test began with a speed of
This workout is a couplet of barbell thrusters (a front squat
7.5 kph and 1.0% grade. The speed was increased by 1.0 kph
to push press) and pull-ups following a 21-15-9 repetition
until participants reached a self-determined fast but com-
scheme, where 21 thrusters were completed, then 21 pull-
fortable running pace. Once the desired speed was selected,
ups completed, 15 thrusters and 15 pull-ups, nine thrusters,
the grade was increased 1.5% every minute until volitional
and nine pull-ups completed for time. Variations of pull-
exhaustion. The participant was asked to rate their rate of
ups, including butterfly and kipping, were encouraged.
perceived exertion (RPE) on a modified ten-point Borg
Thrusters were performed with 43.2 kg for males and
Scale.12 Maximum HR, RPE, and respiratory exchange ratio
29.5 kg for females. The time to complete all repetitions
(RER) values were used to determine whether a maximal test
was recorded.9
had been completed. If any two out of the following three
measures was attained, the test was deemed maximal: 1) over
“Cindy”
90% of predicted maximal HR, calculated as
A triplet of five repetitions of pull-ups, ten repetitions of
push-ups, and 15 repetitions of bodyweight squats made up
Maximum HR = 220 – participant’s age; (1)
one round of Cindy. Participants had 20 minutes to complete
as many rounds and repetitions as possible. Total rounds and
2) RER over 1.1; and 3) RPE greater than 8/10. Respi-
repetitions were scored and converted to total number of
ratory data was used to calculate the VO2 at AT, at RCT,
repetitions in 20 minutes for the analysis.9
and at maximum.13 AT and RCT were used as measures of
aerobic capacity.
“Grace”
In Grace, 30 clean and jerks are performed for time. Power WAnT
cleans or full cleans and jerk, push jerk, and split jerk varia- The WAnT was performed per standardized procedures,14
tions were allowed. Male participants were required to use using 10% of participants’ bodyweight for the brake weight
61.4 kg and females to use 43.2 kg.10 applied to the flywheel. Participants completed a self-paced
5-minute warm-up on the cycle ergometer (Monark 894 E;
“CrossFit Total” Monark, Vansbro, Sweden). Continual standardized encour-
In the CrossFit Total, participants were given 90 minutes to agement was given to the participant throughout the test.
find, under supervision, their 1RM for back squat, press, and The fixed 5-second average maximum (anaerobic power),
deadlift. For each lift starting with the back squat, an indi- minimum, and 30-second mean power outputs (anaerobic
vidually progressed 10-minute warm-up for each lift began at capacity), as well as the fatigue index, calculated as
approximately 50% of participants’ previously known or esti-
mated 1RM. After the lift-specific warm-up, participants were ( maximum power − minimum power )
Fatigue index = × 100,
allowed three attempts to reach a 1RM, with 3–5 minutes rest maximum power
encouraged between attempts. This procedure was also used  (2)
for the press and deadlift. The individual 1RM loads were
summed to determine overall score.11 were used in the analysis.

Open Access Journal of Sports Medicine 2015:6 submit your manuscript | www.dovepress.com
243
Dovepress
Butcher et al Dovepress

Statistical analysis Table 3 Correlations between CrossFit® benchmark performance

and physiological measures
Data analysis was performed with Statistica 8.0 (StatSoft,
Tulsa, OK, USA). Simple Pearson’s r correlations were used Fran (s) Grace (s) Cindy CF
(reps) Total (kg)
to determine the associations between benchmark perfor-
Height (cm) 0.05 -0.28 -0.32 0.49
mance data, and the physiological and strength measures. P=0.86 P=0.26 P=0.26 P=0.07
For each of the dependent benchmark variables, a forward Body mass (kg) -0.34 -0.67 -0.02 0.77*
stepwise linear regression model was created using the P=0.24 P=0.01 P=0.95 P=0.00
significant correlative data. The probability of F used for CF Total (kg) -0.65* -0.88* 0.44 N/A
P=0.01 P=0.00 P=0.11
variables to enter the model was less than or equal to 0.05, AT VO2 -0.53* -0.61* 0.19 0.68*
and to remove variables was greater than or equal to 0.10. P=0.05 P=0.02 P=0.52 P=0.00
Multicollinearity was assessed by examining each signifi- RCT VO2 -0.36 -0.46 0.04 0.50
cant variable in an independent regression model. Statistical P=0.21 P=0.1 P=0.90 P=0.07
VO2max -0.21 -0.34 –0.05 0.39
significance was set a priori at an alpha of 0.05. The data is
P=0.48 P=0.23 P=0.87 P=0.17
reported as mean and standard deviation, unless otherwise Anaerobic peak -0.39 0.09 0.09 0.78*
indicated. power (W) P=0.17 P=0.75 P=0.75 P=0.00
Anaerobic mean -0.44 0.07 0.07 0.78*

Results power (W)

Anaerobic min
P=0.15
-0.31
P=0.81
0.05
P=0.80
0.05
P=0.00
0.78*
Performance data and correlations power (W) P=0.23 P=0.87 P=0.87 P=0.00
The performance measurements are shown in Table 2, and the Note: *significant correlation P,0.05.
Abbreviations: AT VO2, VO2 at anaerobic threshold; CF, CrossFit®; min, minimum;
correlations between independent and dependent variables
RCT VO2, VO2 at respiratory compensation threshold; VO2max, maximal oxygen
are shown in Table 3. The results demonstrate that the bench- consumption; reps, repetitions; s, seconds.
marks Grace and Fran correlated strongly with the strength
data (CrossFit Total) as well as with the oxygen consumption For Cindy, there was no measured variable that survived the
at AT but not the remaining physiological data. There were regression analysis.
no significant associations for Cindy.
Discussion
Performance regression The overall purpose of this study was to determine the
The results of the linear regression are presented in Table 4. physiological predictors of performance across three CrossFit
For both Grace (Figure 1) and Fran (Figure 2), the only benchmark workouts. We hypothesized that physiological
predictor of performance was the CrossFit Total. Laboratory performance measures of aerobic, anaerobic, and strength
physiological data had no further impact on either prediction. performance would be related to benchmark workouts and
that the physiological measurements would predict perfor-
Table 2 Performance data mance in benchmark workouts. Our data indicated partial,
Mean SD Range not full, support for our hypotheses. There were only small
AT (mL/kg/min) 47.2 4.3 40.5–52.6 associations between some of the physiological data and
RCT (mL/kg/min) 51.2 4.9 44.0–58.4 benchmark performance (AT for Grace and Fran); however,
VO2max (mL/kg/min) 54.7 5.6 46.3–64.7 this physiological data did not predict CrossFit benchmark
Anaerobic peak power (W) 953 222 565–1,180
Anaerobic mean power (W) 710 161 435–903
Anaerobic min power (W) 460 85 305–620 Table 4 Regression analysis for CrossFit® benchmark workouts
Fatigue index (%) 50.6 6.5 38.0–58.0 Fran and Grace
CrossFit® Total (kg) 401.5 83.1 240.9–548.6
Fran Grace
Press (kg) 69.1 16.6 38.6–93.2
Squat (kg) 147.0 36.6 88.6–220.5 R2
0.42 0.77
Deadlift (kg) 185.4 32.8 113.6–235.0 P 0.01 0.00
Grace (seconds) 136 32 93–194 β -0.65 –0.88
Fran (seconds) 203 48 130–289 SE of β 0.22 0.14
Cindy (repetitions) 698 113 489–1,010 Partial eta2 0.42 0.77
Abbreviations: AT, VO2 at anaerobic threshold; RCT, VO2 at respiratory
Observed power 0.78 0.99
compensation threshold; SD, standard deviation; VO2max, maximal oxygen Note: There were no significant regression variables for the benchmark Cindy.
consumption; min, minimum. Abbreviation: SE, standard error of the mean.

244 submit your manuscript | www.dovepress.com Open Access Journal of Sports Medicine 2015:6
Dovepress
Dovepress CrossFit physiology and performance

215

195

Grace (seconds)
175

155

135
R=−0.88
115
P=0.00

95

75
200 250 300 350 400 450 500 550 600
CF Total (kg)
Figure 1 Association between Grace and CrossFit® Total.
Abbreviation: CF, CrossFit.

performance for any of the workouts utilized in this study. although not in Cindy. Although the exercises themselves in
The stronger associations were between the composite total both Grace and Fran are different from those in the Cross-
body strength score, as measured by the CrossFit Total, and Fit Total, all three workouts were barbell-based. The skill
benchmark performance, and the CrossFit Total was the only required to perform well on barbell exercises may partially
predictor of performance in the benchmark workouts Fran explain the closer association among these three workouts
and Grace. than with the nonbarbell workout, Cindy. In addition, whole-
In our selected benchmark CrossFit workouts, whole- body strength is very important for many sports15 and in
body strength played an important role in determining per- particular, when the intensity of the sport/activity is high6,16
formance, more so than the physiological data. The measure compared with lower intensity, longer duration activity.7
of whole-body strength, the CrossFit Total, explained 77% When examining the role of strength in the sport of weight-
and 42% of the variance in Grace and Fran, respectively, lifting, performance of the clean and the snatch can be each

300

280

260

240
Fran (seconds)

220

200

180

160
R=−0.65
140 P=0.01

120

100
200 250 300 350 400 450 500 550 600
CF Total (kg)
Figure 2 Association between Fran and CrossFit® Total.
Abbreviation: CF, CrossFit.

Open Access Journal of Sports Medicine 2015:6 submit your manuscript | www.dovepress.com
245
Dovepress
Butcher et al Dovepress

highly explained by the athletes’ 1RM back squat strength.17 Games participants) or to beginners. There are very little
Stone et al17 found that back squat strength explained 87% data available at present with which we can compare the
of the variance in the 1RM performance of the clean. This results of our study; however, the physiological data on our
prediction is slightly higher than that obtained in the present participants were very similar to those obtained by Smith
study for the clean- and jerk-based Grace, which is likely et al for the above-average athlete level of VO2max3 and those
explained by the fact that Grace is repeated for 30 repetitions of Outlaw et al for both VO2max and anaerobic power.4 It is
and likely has an element of fatigue tolerance not captured reasonable to assume that our data is likely representative
purely by strength data or the physiological data collected of most experienced Open- and Regional-level competi-
for this study. Fatigue across multiple repetitions of strength tors for the WODs assessed; however, future work should
exercises reduces the efficiency of biomechanical technique examine whether these relationships and predictors remain
and may have an impact on lifting performance.18 In contrast, across all levels of athlete and for different WODs. In addi-
whole-body strength did not play an important role in the tion, these data are limited to cross-sectional analysis, and
performance of the bodyweight movement workout Cindy. the longitudinal outcomes of various methods of training
It is possible that because performance of Cindy involves should be examined.
the difficult bodyweight movement pull-ups and push-ups,
specific strength in these movements or other physiological Practical implications
measures may play more important roles than the movements The constantly varied nature of CrossFit training and
tested in the CrossFit Total and the physiological measures benchmark performance likely necessitates a focus on
used in this study. Further study is required to determine the multiple physiological adaptations; however, along with
validity of this proposition. their training, CrossFit athletes should ensure an adequate
Given that the CrossFit is the self-proclaimed “Sport of amount of whole-body strength to optimize CrossFit
Fitness”,1 the lack of association between the physiologi- benchmark performance, at least for the benchmarks
cal fitness data collected in this study and the benchmark Grace and Fran. In addition, because of the small associa-
workouts is somewhat surprising. However, CrossFit defines tion between Grace and Fran and AT, there is likely an
fitness as the development of increased work capacity across impact of the development of an adequate aerobic base on
broad time and modal domains,1 rather than as single or a the performance of these WODs, although this can likely
combination of traditional fitness measures, such as VO2max be accomplished through regular CrossFit training with
or anaerobic capacity. Contrary to our hypotheses, our data varied programming.3 Future research should address, in
support the assertion that these traditional measures cannot more detail, the physiological adaptations that occur with
adequately predict performance for the benchmarks assessed. CrossFit training and their relationship with benchmark
The only associations, albeit moderate ones, between Cross- WOD performance.
Fit benchmark performance and our physiological data were
with AT for Grace and Fran. These associations support pre- Conclusion
vious findings of a limited importance of the aerobic energy The performance of three common CrossFit Benchmark
system in optimal performance of higher intensity, repeated WODs (Grace, Cindy, and Fran) cannot be adequately
anaerobic work.19–21 Because different CrossFit benchmark predicted by traditional measures of aerobic and anaerobic
WODs, as well as those programmed for CrossFit compe- power and capacity. Whole-body strength, as measured with
titions, such as the CrossFit Games, likely have different the CrossFit Total, was a greater predictor of performance on
physiological demands, the results of our study are not be select CrossFit benchmarks than were the treadmill VO2max
applicable across all WODs. For example, WODs with a run- and WAnT tests, in Open- and Regional-level CrossFit
ning component, such as “Helen” (400 m run, 21 kettlebell athletes, while AT had only a small association with Grace
swings, and 12 pull-ups, for three rounds) or “Nancy” (400 and Fran.
m run and 15 overhead squats, for five rounds) may be better
reflected by physiological data collected during a running Acknowledgments
VO2max test. The authors would like to acknowledge the valued assistance
The results of our study are limited to a small number of of the athlete participants and coaches at CrossFit Brio,
experienced CrossFit Open and Regional athletes and may Synergy Strength and Conditioning (CrossFit Saskatoon),
therefore not apply to the more elite athletes (ie, CrossFit and Reebok CrossFit 306.

246 submit your manuscript | www.dovepress.com Open Access Journal of Sports Medicine 2015:6
Dovepress
Dovepress CrossFit physiology and performance

Disclosure 8. Canadian Society for Exercise Physiology. PAR-Q and You. Ottawa,
ON: Canadian Society for Exercise Physiology; 2002. Available from:
SB is an unpaid consultant with Synergy Strength http://www.csep.ca/cmfiles/publications/parq/par-q.pdf. Accessed July 6,
and Conditioning (CrossFit Saskatoon), which is a 2015.
9. Glassman G. Benchmark workouts. CrossFit Journal. 2003;13:1–5.
registered CrossFit affiliate. CB is co-owner of Synergy 10. Glassman G. The New Girls. CrossFit Journal. 2004;4:1–2.
Strength and Conditioning (CrossFit Saskatoon), which is 11. Rippetoe M. The CrossFit Total. CrossFit Journal. 2006;52:1–4.
a registered CrossFit affiliate. The authors report no other 12. Borg GA. Psychophysical Bases of Perceived Exertion. Med Sci Sports
Exerc. 1982;14(5):377–381.
conflicts of interest in this work. 13. Simon J, Young JL, Gutin B, Blood DK, Case RB. Lactate accumula-
tion relative to the anaerobic and respiratory compensation thresholds.
References J Appl Physiol Respir Environ Exerc Physiol. 1983;54(1):13–17.
14. Bar-Or O. The Wingate anaerobic test. An update on methodology,
1. Glassman G. Understanding CrossFit. CrossFit Journal. 2007;56:1–2.
reliability and validity. Sports Med. 1987;4(6):381–394.
2. Babiash PE. Determining The Energy Expenditure and Relative Intensity
15. Stone MH, Moir G, Glaister M, Sanders R. How much strength is
of Two CrossFit Workouts [master’s thesis]. La Crosse: University of
necessary? Phys Ther Sport. 2002;3(2):88–96.
Wisconsin – La Crosse; 2013.
16. Stone MH, Sands WA, Carlock J, et al. The importance of isometric
3. Smith MM, Sommer AJ, Starkoff BE, Devor ST. Crossfit-based high-
maximum strength and peak rate-of-force development in sprint cycling.
intensity power training improves maximal aerobic fitness and body
J Strength Cond Res. 2004;18(4):878–884.
composition. J Strength Cond Res. 2013;27(11):3159–3172.
17. Stone MH, Sands WA, Pierce KC, Carlock J, Cardinale M, Newton RU.
4. Outlaw JJ, Wilborn CD, Smith-Ryan AE, et al. Effects of a pre-and post-
Relationship of maximum strength to weightlifting performance. Med
workout protein-carbohydrate supplement in trained crossfit individuals.
Sci Sports Exerc. 2005;37(6):1037–1043.
Springerplus. 2014;3:369.
18. Hooper DR, Szivak TK, Distefano LJ, et al. Effects of resistance
5. Heinrich KM, Patel PM, O’Neal JL, Heinrich BS. High-intensity com-
training fatigue on joint biomechanics. J Strength Cond Res. 2013;
pared to moderate-intensity training for exercise initiation, enjoyment,
27(1):146–153.
adherence, and intentions: an intervention study. BMC Public Health.
19. Bishop D, Edge J, Goodman C. Muscle buffer capacity and aerobic
2014;14:789.
fitness are associated with repeated-sprint ability in women. Eur J Appl
6. Akça F. Prediction of rowing ergometer performance from functional
Physiol. 2004;92(4–5):540–547.
anaerobic power, strength and anthropometric components. J Hum Kinet.
20. Bogdanis GC, Nevill ME, Boobis LH, Lakomy HK. Contribution
2014;41:133–142.
of phosphocreatine and aerobic metabolism to energy supply during
7. Dellagrana RA, Guglielmo LG, Santos BV, Hernandez SG, da Silva SG,
repeated sprint exercise. J Appl Physiol (1985). 1996;80(3):876–884.
de Campos W. Physiological, anthopometric , strength, and muscle power
21. McGawley K, Bishop DJ. Oxygen uptake during repeated-sprint exercise.
characteristics correlates with running performance in young runners.
J Sci Med Sport. 2015;18(2):214–218.
J Strength Cond Res. 2015;29(6):1584–1594.

Open Access Journal of Sports Medicine Dovepress

Publish your work in this journal
Open Access Journal of Sports Medicine is an international, Visit http://www.dovepress.com/testimonials.php to read real quotes
peer-reviewed, open access journal publishing original research, from published authors.
reports, reviews and commentaries on all areas of sports
medicine. The manuscript management system is completely
online and includes a very quick and fair peer-review system.
Submit your manuscript here: http://www.dovepress.com/open-access-journal-of-sports-medicine-journal

Open Access Journal of Sports Medicine 2015:6 submit your manuscript | www.dovepress.com
247
Dovepress