The Journal of Sports Medicine and Physical Fitness

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Performance and Reliability of the Y-Balance Test in High

School Athletes
Laura J SMITH, James R. CREPS , Ryan BEAN, Becky RODDA, Bara ALSALAHEEN

The Journal of Sports Medicine and Physical Fitness 2017 Nov 07

DOI: 10.23736/S0022-4707.17.07218-8

Article type: Original Article

© 2017 EDIZIONI MINERVA MEDICA

Article first published online: November 07, 2017

Manuscript accepted: October 30, 2017
Manuscript revised: October 16, 2017
Manuscript received: November 21, 2016

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Title: Performance and Reliability of the Y-Balance  Test™  in  High  School  Athletes  
Authors:
* Corresponding Author: Laura J. Smith, PT, PhD, DPT, OCS, MTC, FAAOMPT a
a
University of Michigan-Flint
Physical Therapy Department
2157 William S. White Building, 303 E. Kearsley Street
Flint, MI 48502-1950
johlaur@umich.edu

James R. Creps, PT, DScPT, OCS, CMPT a

a
University of Michigan-Flint
Physical Therapy Department
2157 William S. White Building, 303 E. Kearsley Street
Flint, MI 48502-1950
jcreps@umich.edu

Ryan Bean, PT, DPT, OCS, OMPT a

a
University of Michigan-Flint
Physical Therapy Department
2157 William S. White Building, 303 E. Kearsley Street
Flint, MI 48502-1950
ryanbean@umich.edu

Becky Rodda, PT, DPT, OCS, OMPT a

a
University of Michigan-Flint
Physical Therapy Department
2157 William S. White Building, 303 E. Kearsley Street
Flint, MI 48502-1950
brodda@umich.edu

Bara Alsalaheen, PT, PhDa,b,c

a
University of Michigan-Flint,
Physical Therapy Department
2157 William S. White Building, 303 E. Kearsley Street
Flint, MI 48502-1950
alsalahe@umich.edu
b
Department of Neurology, University of Michigan-Ann Arbor
c
Michigan NeuroSport, Michigan Medicine

Funding: This work was supported by an Internal Grant - University of Michigan-Flint Physical Therapy
Department; the Research and Creative Activity Fund – University of Michigan-Flint and the Bryer Foundation
Medical Research Fund – University of Michigan-Flint.

Contributions: All authors have read and approved the final version of the manuscript, and agree with the
order of the presented authors.
Competing Interests: None of the authors declare competing financial interests.

*Corresponding Author:
Laura Smith, PT, PhD, DPT, OCS, MTC, FAAOMPT
Assistant Professor, Physical Therapy Department
Director Orthopedic Residency & Certificate Program
University of Michigan-Flint
2157 William S. White Building, 303 E. Kearsley Street
Flint, MI 48502-1950
(810) 762-3373 (phone)
johlaur@umich.edu

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Abstract
Background: Lower extremity injuries account for 32.9% of the overall injuries in high
school athletes. Previous research has suggested that asymmetry greater than 4cm using the
Y-Balance  Test™  Lower  Quarter  (YBT-LQ) in the anterior direction is predictive of non-
contact injuries in adults and collegiate athletes. The prevalence of asymmetries or abnormal
YBT-LQ performance is not well documented for adolescents. The primary purposes of this
study are: 1) to characterize the prevalence of YBT-LQ asymmetries and performance in a
cross-sectional sample of adolescents, 2) to examine possible differences in performance on
the YBT-LQ between male and female adolescents, and 3) to describe the test-retest
reliability of the YBT-LQ in a subsample of adolescents.
Methods: Observational cross-sectional study. High-school athletes completed the YBT-LQ
as main outcome measure.
Results: 51 male, 59 female high-school athletes participated in this study. Asymmetries
greater than 4cm in the posteromedial (PM) reach direction were most prevalent for male
(54.9%) and female (50.8%) participants. Females presented with slightly higher composite
scores. Good reliability (ICC = 0.89) was found for the anterior (ANT) direction, and
moderate reliability with 0.76 for posterolateral (PL) and 0.63 for PM directions. The
MDC95 for the ANT direction was 6% and 12% for both the PL and PM directions.
Conclusion:
The YBT-LQ performance can be beneficial in assessing recovery in an injured extremity
compared to the other limb. However, due to the large MDC95, noted in the PM and PL
directions, the differences between sequential testing cannot be attributed to true change in
balance unless they exceed the MDC95. In this study, 79% of the athletes presented with at
least one asymmetry in YBT-LQ reach distances. Moderate reliability in the PL and PM
directions warrants reexamination of the definition of asymmetry in these directions.
Key Words: Balance, Lower Extremity, Asymmetry, Adolescents, Injury, Screening

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Introduction
Participation in high school sports in the United States has grown significantly to an
estimated 7.8 million adolescents in 2014-2015.1 With this increase in sports participation
and many students participating in multiple sports, published anecdotal evidence
documented an increase in sport related injuries.2 Lower extremity injuries account for
32.9% of the overall injuries in high school athletes.3 Previous research demonstrated that
adolescent athletes may be at higher risk for sustaining lower extremity non-contact injuries
as compared to adult athletes participating in the same sport.4

Dynamic balance, the ability for an individual to maintain center of mass stability during
movement,4 has been suggested as a  potential  indicator  of  an  athlete’s  risk  for  injury,  most  
notably in the knee and ankle.5,6 Clinical tests of dynamic balance, such as the Y-Balance
Test™  Lower  Quarter  (YBT-LQ) (Move2Perform, Evansville, IN) and the Star Excursion
Balance Test (SEBT),7 are widely used as screening methods for dynamic balance deficits.
The YBT-LQ measures an individual’s  maximum  reach  distance  in  three  directions  anterior  
(ANT), posterolateral (PL), and posteromedial (PM) while maintaining balance on a stance
leg.8 The YBT-LQ is scored by comparing reaching ability to normalized scores as well as
identification of asymmetry between the right and left lower extremity.4,8-10 Previous
research has suggested that asymmetry greater than 4cm using the YBT-LQ in the anterior
direction is predictive (OR, 2.20; 95% CI, 1.09-4.46) of non-contact injuries in collegiate
athletes of both gender groups.11 Furthermore, despite the lack of empirical validation,
asymmetry in the PL and PM directions greater than 4cm has been commonly used as a
suggested cut off score to identify asymmetry.4,10-13 However, the prevalence of asymmetries
or abnormal YBT-LQ performance is not documented for adolescents.

Gender has been proposed as a risk factor that may influence balance performance when
using screening tools.8,10,14 For example, female athletes experience injuries differently than
their male counterparts, with higher overuse injuries (62.5%) than males (41.9%), and more
patellofemoral pain (14.3% vs 4.0%) than males.15 Previous authors report varying
performance on screening tools related to gender when investigating differences between
male and female collegiate athletes.13,14 However, the data on gender differences and YBT-
LQ performance is limited for high school10 populations warranting further investigation.

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The utility of YBT-LQ depends in part on its ability to reproduce error-free scores upon
sequential administration (i.e.test-retest reliability). The test-retest reliability for the YBT-
LQ has been reported in adult populations11,16, but not in adolescents. Examining the test-
retest reliability of YBT-LQ in adolescents allows the clinican to discern if a change in
YBT-LQ performance is attributed to measurement error or attributed to true change in
performance. The Minimal detectable change (MDC95) is the smallest amount of change in a
variable to reflect a true difference.17

Due to the lack of studies documenting gender-specific performance of adolescents on YBT-

LQ, and the lack of studies documenting test-retest reliability of YBT-LQ in healthy
adolescents, this study was conducted with the following purposes: 1) characterize the
prevalence of YBT-LQ asymmetries and performance in a cross-sectional sample of
adolescents, 2) examine possible differences in performance on the YBT-LQ between male
and female adolescents, and 3) describe the test-retest reliability and the minimal detectable
change (MDC95) of the YBT-LQ in a subsample of adolescents.

Materials and Methods

Subjects: Participants included male and female high school athletes between the ages of
13-18 years who were currently participating on a high school sports team (Table I).
Participants were excluded if they were currently medically restricted from sport
participation. All participants (and legal guardians if under age 18) provided written consent
and participants under 18 years old also provided written assent. Prior to recruitment, the
study protocol was approved by the Institutional Review Board (IRB) of University of ABC.
To examine the reliability of the YBT-LQ, a subset of participants completed the YBT-LQ a
second time after approximately 60 minutes. As described by Walter et al., we estimated the
required number of participants   for   reliability   studies   when   β   =   0.20,   α   =   0.05,   n   is   the  
number  of  performances  per  participant,  and  the  values  ρ1 and  ρ0 are  specified  values  of  the  
intraclass  correlation  coefficient  (ICC)  reflecting  an  ideal  and  minimally  acceptable  levels  of  
reliability, respectively.18 We specified values  of  ρ1 =  0.90  and  ρ0 = 0.60 as ICC of 0.90 has
been suggested as a value for use in many measures of clinical practice17, and 0.60 is an ICC
reflecting   the   threshold   for   moderate   reliability   as   described   by   Baumgartner   et   al. 19 This
calculation required 12 participants to be tested over 2 trials. To account for possible
attrition, fifteen participants were randomly selected to repeat the YBT-LQ a second time.

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Procedures: On the testing day, participants were asked to complete a demographic

questionnaire. After the completion of the demographic questionnaire, participants
completed the YBT-LQ testing station.

Y-Balance Test Protocol: Participants were given a standardized familiarization period

with the YBT-LQ before testing and were given six practice attempts in each testing
direction on each leg.8 Participants were instructed to practice movements in the ANT, PM,
and PL directions in relationship to the stance leg, beginning first in the ANT direction on
the right stance leg (right ANT) followed by left ANT, before advancing to PM and PL
directions. After the familiarization period, testing order included three consecutive trials in
each direction, beginning with right ANT, followed by left ANT, right PM, left PM, right PL
and left PL directions using the Y Balance Test Kit.8 Shoes were removed prior to testing to
eliminate additional variability between subjects. Participants were instructed to maintain the
toes of the stance foot behind the indicator line on the starting block to standardize the
starting location for each trial. A trial was deemed unacceptable if the participant did not
return to the start position with controlled movement, contacted the floor or top of indicator
plate with the reach leg to gain additional support, or attempted to kick the indicator plate for
added distance. If any of these occurred, the trial was discarded and the subject was re-
tested up to six times to achieve three valid attempts. This part of the testing procedure was
consistent with the protocol described by Plisky et al.8
The three reach attempts for each direction were recorded. Consistent with previous
research, the longest distance for each direction was used in the final analysis.8 Right lower
extremity limb length was measured from the anterior superior iliac spine to the most distal
aspect of the medial malleolus and recorded in centimeters following the protocol by Plisky
et al.8 For this study, the reach distances were normalized to the right limb length. This
procedure is consistent with the standard procedure for YBT-LQ testing.8 Normalized
values were calculated as reach distance divided by right limb length multiplied by 100.
Composite reach scores were calculated by taking the sum of the longest reach for each of
the three directions, dividing by three times limb length and then multiplying by 100.5
Additionally, the asymmetries in normalized reach distances were compared between both
extremities using previously validated cutoff scores where a difference in any reach direction
that is greater than or equal to 4 cm is considered asymmetrical.4,10-13

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Statistical Methods
Descriptive statistics were used to describe the participant demographic characteristics. The
normality of the demographic variables and the composite scores for the normalized reach
distances (NRD) for the YBT-LQ were examined using the Kolomogrov-Smirnov test.
Participants were classified as asymmetrical if there was a difference in their reach scores
between the right and left sides greater than or equal to 4 centimeters in the ANT direction,
the PM or PL directions.4,10-13 To examine if the proportion of participants with asymmetry
was significantly different between gender groups, the Pearson Chi-Square   test   (χ2   )   was  
completed in the ANT, PM, and PL direction. Regardless of the direction of the asymmetry,
the prevalence of participants with no asymmetries, asymmetries in one, two and three
directions were reported.

To examine the test-retest reliability of YBT-LQ test, the two-way random intraclass
correlation coefficient (ICC2,1) and its 95% confidence intervals (CIs) were calculated. The
interpretation of the ICC values followed guidelines suggested by Baumgartner et al. where
coefficients exceeding 0.80 suggests good reliability, coefficients between 0.60 and 0.79
suggests moderate reliability and coefficients below 0.60 suggest poor reliability. 19 The
standard error of the measurement (SEM) is used as a reliability measure which estimates the
standard error in a set of repeated scores.17 The SEM values were calculated using the
following   formula   SEM   =   SD√(1- ICC2, 1). The minimal detectable change (MDC95) was
calculated using the following formula MDC95 =   SEM*1.96*√2.   For all analyses, the
Statistical Package for the Social Sciences (SPSS version 21) was used (SPSS Inc., Chicago,
Illinois).

Results
A total of 110 high school athletes (51 male, 59 female) participated in this study.
Participants represented football, basketball, lacrosse, softball and soccer as their primary
sport.
(HERE) Table I. Characteristics of Participants

The mean age for male and female participants was 15.9 and 16.1 years, respectively.
Approximately one third (18/51) of male participants, and almost half (44.1%) of females
had YBT-LQ reach asymmetry greater than 4 cm in one direction. Approximately one third

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of both males and females had asymmetry greater than 4 cm in 2 directions, and less than
10% of each group had asymmetry in all three reach directions (Table II).
In both genders, asymmetries in the PM direction were most prevalent (54.9% and 50.8%)
for male and female participants, respectively. Asymmetries in the PL direction were the
second most common asymmetry for both gender groups, followed by the asymmetry in the
ANT direction. Nonetheless, there was no difference in the proportion of asymmetries
between males and females for any directions (Table II). Female participants experienced
better normalized reaching distances. Female participants presented with significantly better
right composite score excursion (M = 92.87, SD = 7.9) compared to the male participants (M
= 88.49, SD = 7.7), t108 = -2.934, p = 0.004. Similarly, female participants exhibited better
left composite score (M = 94.30, SD = 7.6) compared to the male participants (M = 89.44,
SD = 7.6), t108 = -3.326, p = 0.001.

(HERE) Table II. Reach Asymmetries (chi-square test table)

Test-retest reliability for the ANT reach direction was the highest (ICC2,1 = 0.89), followed
by the PL (ICC2,1 = 0.76) and PM (ICC2,1 = 0.63) directions, respectively. The minimal
detectable change (MDC95) the ANT reach normalized direction was 5.4%. This value for
the PL and PM directions was 11.6%. (Table III.)

(HERE) Table III. Test Retest Reliability for Normalized Scores

Discussion
The findings of this study indicate that 79% of all of the athletes presented with one or more
asymmetries in functional reach. Despite the better normalized reach distance observed for
female participants, the asymmetries in both gender groups were equally prevalent.
Additionally, poorer YBT-LQ scores were associated with larger body mass index, but not
history of recent lower extremity injury.

A high percentage of adolescents (79.4%) exhibited asymmetry in one direction. The fact
that a considerable number of athletes exhibited multidirectional reach asymmetries suggests
that ANT reach may not be the only direction of concern when interpreting the YBT-LQ
scores. The prevalence of PM and PL reach asymmetries were higher than the prevalence of

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ANT asymmetry, and this has been similarly reported in a previous study of high school
athletes.10 No differences in reach asymmetries for the ANT, PM, or PL directions has been
reported in soccer players4 or in college athletes.11 However, in this study, asymmetries in
the PL and PM directions were equally problematic for both genders, and female participants
demonstrated better performance on the YBT-LQ as indicated by the NRDs. This is in
contrast to a previous investigation in which male high school players were found to have
better YBT-LQ performance compared to females.10 A possible explanation for this
difference may be that participants represented different sports.

The good reliability in the ANT direction (ICC = 0.89) in this study was consistent with that
reported for collegiate athletes (0.91)11 and for adult service members (0.93).16 However,
adolescents demonstrated moderate reliability in the PL (0.76) and PM (0.63) directions
compared to the previously reported reliability coefficients of adult service members (0.85
and 0.91, respectively).16 The poorer reliability scores observed in adolescents in the PL and
PM directions, but not in the ANT direction may be attributed to the visual dependency of
adolescents. In the ANT direction, the adolescents were able to utilize their vision and,
therefore, their reliability scored were comparable to adults. In the absence of visual input in
the PM and PL directions, adolescents may have not been able to utilize a reproducible
motor control strategy, which may have negatively affected the reliability of the PM and PL
scores. Attributed to poorer reliability in the PM and PL directions, a greater change is
required in NRDs before the conclusion can be drawn that it represented a true change (i.e.
MDC95). While a 6% change in the ANT direction is needed to be considered as a true
change, 12% is the minimal change required for both the PM and PL directions before they
can be considered as meaningful changes. The measurement error, particularly in the PM
and PL directions could have profound clinical implications, although the conventional
cutoff of greater than 4 cm asymmetry in the ANT direction has been utilized in this report
based upon findings in previous literature.4,10,11,20 The reliability findings of this study
suggest that the operational definition of asymmetries must be reestablished for each of the
test directions. From a clinical perspective, clinicians using the YBT-LQ should exercise
caution in using the findings of YBT-LQ  to  make  assumptions  on  athlete’s  dynamic  balance  
or risk of injury. In the context of clinical care, YBT-LQ performance can be beneficial in
assessing recovery in an injured extremity compared to the other limb. However, due to the

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large MDC95, noted in the PM and PL directions, the differences between sequential testing
cannot be attributed to true change in balance unless they exceed the MDC95.

It is important to note that this study has limitations. The participants were high school
athletes which may limit generalizations of the results to athletes of different ages.
Furthermore, only 5 sports were represented in this study which limits the generalizibility to
all high school athletes. Lastly, the short test retest interval of 60 minutes used in this study
was selected to minimize the confounding variables that may influence performance with a
longer test-retest interval. However, this is likely different than retest-intervals utilized in
clinical practice.

Conclusions
In this study of high school athletes, asymmetries in the PM reach direction were most
prevalent for male and female participants. Female high school athletes presented with
slightly higher scores than male participants in completion of the YBT-LQ. Due to the
moderate reliability in the PM and PL directions, the definition of asymmetry in these
directions must be reexamined. Future research in this area should prospectively examine if
the YBT-LQ has any utility for predicting future injury in athletes.

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Table I. Characteristics of Participants

Male (n=51) Female (n = 59) Statistic

Age (years) 15.9 ± 1.2 16.1± 1.2 t108 = -1.224, p = 0.224
Height (cm) 178.6 ± 9.9 164.5 ± 10.4 t108 = 7.057, p < 0.001
Weight (kg) 168.6 ± 33.3 145.2 ± 27.7 t108 = 4.034, p < 0.001
Grade
9 25 20
10 13 17
11 5 11
12 8 11
Primary Sport, n (%)

Football 30 (58.8%)

Basketball 12 (23.5%) 34 (57.7%)

Lacrosse 8 (15.7%)

Softball 10 (16.9%)

Soccer 1(2.0%) 15 (25.4%)

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Table II. Reach Asymmetries (chi-square test table)

Male Female Statistic

Number of participants n (%) n (%)
with asymmetries

Anterior (ANT) 15 (29.4%) 14 (23.7%) χ2  (1,  n  =110)  =  0.455,  p  =  0.523

direction (>4cm)
Posteromedial (PM) 28 (54.9%) 30 (50.8%) χ2  (1,  n  =110)  =  0.180,  p  =  0.705
direction (>4cm)
Posterolateral (PL) 24 (47.0%) 27 (45.8%) χ2  (1,  n  =110)  =  0.018,  p  =  1.000
direction (>4cm)

Categories in which
participant is abnormal

0 11 (21.5%) 12 (20.3%)
1 18 (35.3%) 26 (44.1%)
2 17 (33.3%) 18 (30.5%)
3 5 (9.8%) 3 (5.1%)

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Table III. Test Retest Reliability for Normalized Scores

Test 1 Test 2 ICC ICC (95% CI) SEM MDC

Anterior (ANT) 65.34 ± 5.14 65.90 ± 6.72 0.89 (.73, .96) 1.94 5.38
Posteromedial (PM) 106.54 ± 7.33 108.71 ± 6.47 0.63 (.24, .85) 4.19 11.60
Posterolateral (PL) 101.95 ± 8.45 105.70 ± 8.51 0.76 (.30, .92) 4.17 11.56
Note:
ICC = Intraclass Correlation Coefficient, SEM = Standard error of measurement
MDC = Minimal Detectable Change

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