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Ankle sprains are the most common musculoskeletal injury
that occurs in athletes, and several studies have noted that
sports that require sudden stops and cutting movements,
such as basketball and soccer, cause the highest percentage of
these injuries.
†
Ankle sprains not only result in numerous
visits to emergency care facilities
13
and significant time loss
from sports participation,
2,25
but they can also cause long-
term disability
2,6,8
and have a major impact on health care
costs and resources
1,2
(US Consumers Product Safety
Commission, written communication, March 2005). The
financial impact of these injuries on society is borne out by
the fact that in the United States alone, 4.8 million grade
school and 1.7 million high school athletes participate in
supervised soccer and basketball programs
17
and, on average,
15% (1 million) of these athletes sustain ankle sprains each
year.
12,18,21
The costs associated with treating this number of
sprains are staggering. In 2003 alone, the US Consumer
Products Safety Commission estimated that the direct medi-
cal cost of treating ankle sprains in high school soccer and
basketball players (ages 15-18 years) was $70 million, and
the indirect costs were $1.1 billion.
26
Despite the enormous health care costs associated with
this injury, critical reviews have identified only a limited
number of studies that have the appropriate methodology
to examine the effectiveness of ankle sprain prevention
measures in general
3,9,16,24
and 2 studies that examine the
efficacy of proprioceptive training in particular.
4,27
The most rigorous studies have documented that
ankle disk training will significantly reduce the risk of
ankle sprains in adult athletes with a history of an ankle
sprain.
4,11,22,23,25,26
However, the efficacy of a balance train-
ing program as a primary intervention for the prevention
of sprains in athletes with healthy ankles remains to be
determined. In addition, the studies published to date do
not indicate whether proprioceptive training programs
reduce the severity of initial or subsequent ankle sprains
The Effect of a Balance Training Program
on the Risk of Ankle Sprains
in High School Athletes
Timothy A. McGuine,* PhD, ATC, and James S. Keene, MD
From the University of Wisconsin, Hospital and Clinics, Sports Medicine Center,
Madison, Wisconsin
Background: Ankle sprains are the most common musculoskeletal injuries that occur in athletes, and they have a profound
impact on health care costs and resources.
Hypothesis: A balance training program can reduce the risk of ankle sprains in high school athletes.
Study Design: Randomized controlled clinical trial; Level of evidence, 1.
Methods: Seven hundred and sixty-five high school soccer and basketball players (523 girls and 242 boys) were randomly
assigned to either an intervention group (27 teams, 373 subjects) that participated in a balance training program or to a control
group (28 teams, 392 subjects) that performed only standard conditioning exercises. On-site athletic trainers recorded athlete
exposures and sprains.
Results: The rate of ankle sprains was significantly lower for subjects in the intervention group (6.1%, 1.13 of 1000 exposures
vs 9.9%, 1.87 of 1000 exposures; P = .04). Athletes with a history of an ankle sprain had a 2-fold increased risk of sustaining a
sprain (risk ratio, 2.14), whereas athletes who performed the intervention program decreased their risk of a sprain by one half
(risk ratio, 0.56). The ankle sprain rate for athletes without previous sprains was 4.3% in the intervention group and 7.7% in the
control group, but this difference was not significant (P = .059).
Conclusion: A balance training program will significantly reduce the risk of ankle sprains in high school soccer and basketball
players.
Keywords: ankle sprain; prevention; soccer; basketball; high school
1103
*Address correspondence to Timothy A. McGuine, PhD, ATC, 621
Science Drive, Madison, WI 53711 (e-mail: ta.mcguine@hosp.wisc.edu).
†
References 1, 3, 7, 9, 12, 14, 17, 18, 21, 30.
Presented at the 31st annual meeting of the AOSSM, Keystone,
Colorado, July 2005.
No potential conflict of interest declared.
The American Journal of Sports Medicine, Vol. 34, No. 7
DOI: 10.1177/0363546505284191
© 2006 American Orthopaedic Society for Sports Medicine
1104 McGuine and Keene The American Journal of Sports Medicine
or increase the number of exposures before an ankle sprain
occurs.
The primary objective of this randomized intervention
trial was to determine if a program of balance training,
implemented in the preseason and maintained throughout
the season, would reduce the risk of ankle sprains in male
and female high school athletes. This study also sought to
determine whether (1) the effect of the intervention was
the same for athletes with or without a history of an ankle
sprain; (2) the rate of ankle sprain was affected by inde-
pendent variables such as gender, sport, leg dominance,
use of ankle supports, and ankle laxity; and (3) balance
training reduced the severity of ankle sprains.
METHODS
Sample size
Previous authors have reported an incidence of acute
ankle sprains in athletes that ranged from 11% to
20%.
3,7,21,24,26
On the basis of these data, we projected a
sprain rate for this study of 15% in the control group and
7.5% in the intervention group. Using these rates, we cal-
culated the sample size to determine statistical signifi-
cance by using cluster randomization as well as a 2-tailed
test with α=.05 and 1-β=.80. The estimated sample size
for this study thus obtained was 680 (340 in both the inter-
vention and control groups).
Randomization
Randomization into intervention and controls was per-
formed using groups of two based on a schedule provided
by the statistician (Figure 1). In this type of randomiza-
tion, each member of an individual team was assigned to
the same intervention or control group. The group ran-
domization procedure we used is not considered optimum
in randomized clinical trials. However, this procedure is
widely used and accepted in sports injury prevention trials
as a way to limit contamination between intervention and
control groups.
4,27,28
In addition, each school district had a
similar policy that stated any intervention must be offered
to all members of a class or team as a group rather than as
individuals.
Subjects
Seven hundred and sixty-five basketball and soccer play-
ers (523 girls and 242 boys) from 12 area high schools that
utilized certified athletic trainers (ATCs) from our Sports
Medicine Clinic agreed to participate in the study. Subjects
were recruited by giving study materials to potential sub-
jects, posting flyers in the schools, sending letters to school
administrators, meeting with coaches, and talking with
parents at preseason team meetings.
To be included in the study, subjects had to be on the
interscholastic basketball or soccer team roster compiled
by their head coach. In addition, each subject had to
be able to practice or play the first day of the preseason
drills and practices without restrictions due to a prior
injury. Finally, each subject (and the parents if under age
18 years) had to complete the informed consent and Health
Insurance Portability and Accountability Act of 1996
(HIPAA) forms.
Subject Data
At each school, our on-site ATCs collected the anthro-
pometric data (gender, height, weight, ankle laxity, and
leg dominance), as well as sprain history, on each subject
(Table 1). Height was measured with a stadiometer
(±0.5 cm). Weight was measured on digital platform scale
(±0.1 lb).
Each subject was required to complete a detailed ques-
tionnaire regarding whether he or she had a prior ankle
sprain and whether that sprain occurred during the previ-
ous 12 months. When possible, this information was cross-
checked with the injury information compiled during the
previous school year by our on-site ATCs. To determine
ankle ligament laxity, the trainer performed an anterior
drawer test on the ankle with the subject in a seated posi-
tion. Leg dominance was determined by asking the athlete
which leg he or she would use to kick a ball.
The configuration of the medial longitudinal arch was
determined by using the Feiss line, which was measured
when the athlete stood with his or her weight on both
feet.
19
The Feiss line is a line drawn from the medial malle-
olus to the head of the first metatarsal. If the navicular
tubercle intersected the line, the arch was graded as neu-
tral. If the tubercle was above the line, the arch was graded
as supinated. If the tubercle was below the line, the arch
was graded as pronated.
Team
randomization
blocked by 2.
12 schools agreed to
allow their teams to participate
in the study. August 2001
126 teams (coaches) contacted.
Oct. 2001 – May 2004
Controls*
28 teams agreed to participate
Total athletes = 458
Intervention*
27 teams agreed to participate
Total athletes = 473
Subjects Enrolled
n = 373
Subjects Enrolled
n = 392
Figure 1. Subject recruitment and randomization.
Vol. 34, No. 7, 2006 Balance Training Program and Ankle Sprains 1105
The Balance Training Program
Subjects in the intervention group performed a 5-phase
balance training program, the components of which are
shown in Table 2. The program was based on a compilation
of the rehabilitation and balance training protocols vali-
dated and published in prior studies.
5,10,11,15,18,20,22,25
Phases
1 through 4 consisted of 5 exercise sessions per week for
4 weeks before the start of the season. In phase 5 (mainte-
nance phase), the subjects performed the program 3 times
per week for 10 minutes throughout the competitive season.
In all phases, each exercise was performed for 30 seconds,
and the legs were alternated during a 30-second rest inter-
val between each exercise.
The exercise program included (1) maintaining a single-
leg stance on a flat surface with eyes open and closed; (2)
performing functional sport activities such as throwing,
catching, and dribbling on 1 leg; (3) maintaining double-leg
stance while rotating the balance board; (4) maintaining a
single-leg stance on the balance board with eyes open and
closed; and (5) performing functional sport activities while
in single-leg stance on the board (Figures 2-6). The balance
board that was used consisted of a wooden disk 16 inches in
diameter with a 4-inch half sphere attached to the bottom
(Fitter International, Calgary, Alberta, Canada). The sphere
allowed approximately 17° of angulation in all planes.
Members of each team were encouraged to take part in
the intervention program as a group and were given the
option of performing the exercises before or after practice.
Teams did not perform the intervention on competition
days. If a subject missed 4 consecutive balance training
sessions, he or she was considered noncompliant with the
balance training protocol. Control subjects did not take
part in any prevention or balance training exercises beyond
their normal conditioning exercises as directed by their
coaches.
Definitions and Data Collection
The ATCs assigned to each school monitored each subject
throughout the season and recorded all athlete exposures,
acute sprains, use of ankle supports, and compliance with
the intervention protocol. An athlete exposure was defined
as any coach-directed competition, practice, or conditioning
session. Ankle supports were defined as any external sup-
port such as athletic tape or lace-up or hard-shell braces.
The definitions of an acute injury and injury severity were
similar to the criteria used by Powell and Barber-Foss
21
in
their studies on high school athletes. For this study, an ankle
sprain was defined as trauma that (1) disrupted the liga-
ments of the ankle;(2) occurred during a coach-directed com-
petition, practice,or conditioning session; and (3) caused the
athlete to miss the rest of a practice or competition or miss
the next scheduled coach-directed practice or competition.
Injury severity was determined by counting the calendar
days lost because of the sprain. Sprains were classified as
minor (1-7 days lost), moderate (8-21 days lost), or severe
(more than 21 days lost). The ATCs at the school determined
the occurrence, diagnosis, and severity of each sprain.
An injured athlete was only allowed to return to activity
under the direction of his or her athletic trainer and phy-
sician. To return, each injured athlete was required to
demonstrate full ankle strength and pain-free range of
motion. In addition, each injured athlete had to be able to
complete a running program that included a series of func-
tional activities (running, jumping, hopping, and cutting
drills) similar to the demands of his or her individual sport.
Data Analysis
Ankle sprain rates were summarized as both the percentage
of athletes injured and sprains per 1000 athlete exposures.
Athlete exposures were tabulated for each noninjured subject
throughout the sports season and for injured subjects up to
the date of their first acute ankle sprain. A small number
(n = 11) of athletes dropped out of the study when they
stopped participating on their interscholastic team and were
included in the analysis through the last day of their team
membership. A total of 34 intervention subjects were classi-
fied as noncompliant (missed 4 consecutive balance training
sessions). All subjects were included in the analysis under the
intent-to-treat principle, which mandates that all subjects
TABLE 1
Subject Demographics (N = 765)
a
Controls Intervention
Variable (n = 392) (n = 373)
Gender
Female 262 (66.8) 261 (69.9)
Male 130 (33.1) 112 (30.1)
Age, y 16.6 ± 1.1 16.4 ± 1.2
Height, cm
Female 167.4 ± 6.0 166.1 ± 6.9
Male 173.7 ± 11.7 174.8 ± 10.4
Weight, kg
Female 61.2 ± 7.0 60.5 ± 7.4
Male 69.4 ± 11.6 71.6 ± 10.8
Level of competition
Varsity 317 (80.8) 320 (85.7)
Subvarsity 58 (14.7) 22 (5.8)
Freshman 17 (4.3) 31 (8.3)
Previous ankle injury
Yes 93 (23.7) 89 (23.8)
No 299 (76.3) 284 (76.2)
Leg dominance
Right 352 (89.7) 336 (90.0)
Left 40 (10.2) 37 (10.0)
Arch type
Pronated 126 (32.1) 98 (26.2)
Neutral 244 (62.2) 248 (66.4)
Cavus 22 (5.6) 27 (7.2)
Use of ankle supports
Yes 74 (18.9) 70 (18.7)
No 318 (81.1) 303 (81.3)
Ankle laxity (drawer test)
≤ 5 mm 387 (99.3) 364 (97.9)
5+ mm 5 (0.7) 9 (2.1)
a
All data are presented as n (%), except age, height, and weight,
which are presented as mean ± SD.
1106 McGuine and Keene The American Journal of Sports Medicine
TABLE 2
The Balance Training Program
a
Phase Surface Eyes Exercise
I Floor Open Single-leg stance
Week 1 Open Single-leg stance while swinging the raised leg
Open Single-leg squat (30°-45°)
Open Single-leg stance while performing functional activities
(dribbling, catching, kicking)
II Floor Closed Single-leg stance
Week 2 Closed Swinging the raised leg
Closed Single-leg squat (30°-45°)
III Board Open Single-leg stance
Week 3 Open Swinging the raised leg
Open Single-leg squat (30°-45°)
Open Double-leg stance while rotating the board
IV Board Closed Single-leg stance
Week 4 Open Swinging the raised leg
Open Single-leg squat (30°-45°)
Open Single-leg stance while rotating the board
V Board Closed Single-leg stance
Week 5+ Open Single-leg squat (30°-45°)
Open Single-leg stance while rotating the board
Open Single-leg stance while performing functional activities
(dribbling, catching, kicking)
a
Phases I through IV were performed 5 days per week. Phase V was performed 3 days per week for the rest of the season. Each exercise
was performed for a duration of 30 seconds per leg, and legs were alternated during a rest period of 30 seconds between repetitions.
Figure 2. Single-leg stance with eyes open.
Figure 3. Single-leg stance while dribbling.
Vol. 34, No. 7, 2006 Balance Training Program and Ankle Sprains 1107
are included in all analyses, regardless of whether they
completed the intervention program.
Various statistical procedures were performed on the
data using P < .05 as the level of significance. Ankle sprain
rates were estimated using the methods of Kaplan and
Meier survival analysis and compared between the inter-
vention and control groups using a log-rank test. The Cox
Proportional Hazards model was used to examine the rela-
tionship between ankle sprains and several independent
variables (intervention, gender, height, weight, sport, etc).
In addition, Fisher exact tests were used to determine if
the intervention program was equally effective for subjects
with and without a history of an ankle sprain. All statistical
analyses were performed using SAS software, version 6.12
(SAS Institute, Cary, NC).
RESULTS
Subject Population
The characteristics and demographics for the subjects in
the intervention and control groups were similar and are
summarized in Table 1. Although the number of male and
female athletes recruited for the study was comparable,
542 (68.3%) of the subjects who ultimately enrolled were
girls. This finding did not affect the analysis, however,
because the percentage of girls in the intervention and
control groups (69.9% vs 66.8%) was similar.
Description of the Ankle Sprains
Sixty-two of the 765 subjects (8.1%) sustained an acute
ankle sprain during their sports season (Table 3). Overall,
the rate of ankle sprains was 1.51 per 1000 exposures.
Fifty-six (90.3%) were lateral ankle sprains, 4 (6.4%) were
medial sprains, and 2 (3.2%) were syndesmotic sprains.
The mean number of days lost from the sprains was
7.6 days (range, 2-26 days). A majority (64.5%) of the ankle
sprains were minor and caused the athlete to miss 1 to
7 days, whereas 29% were classified as being of moderate
severity (the athlete missed 8-21 days), and 6.4% were
severe (the athlete was out for more than 21 days). Three
subjects sustained a sprain near the end of the season and
did not return to competition before the season ended. In
these cases, the trainer stopped counting days lost on the
last day the team practiced or competed.
Balance Training Subjects Versus Control Subjects
Kaplan-Meier survival analysis documented the exposure
date of each sprain and the number of athletes exposed for
that particular day, thereby calculating the relative risk of
sprain during the course of the season (Figure 7). The sprain
rates for the intervention subjects were significantly lower
than for controls (χ
2
= 4.00, df = 1, P = .045). The risk of ankle
injury for subjects taking part in the balance training pro-
gram was 62.0% (95% confidence interval [CI], 37.8%-
101.7%) of that in the control group (Table 4).
Figure 4. Double-leg stance while rotating the board. Figure 5. Balancing on the board while the eyes are closed.
1108 McGuine and Keene The American Journal of Sports Medicine
In athletes without previous ankle sprain, 7.7% (23 of
299) of the controls and 4.2% (12 of 284) of the subjects tak-
ing part in the intervention sustained an ankle sprain. The
risk of ankle injury in the intervention group was 54.9%
(95% CI, 27.9%-108.3%) of that in the control group.
Although the training program appeared to reduce the
incidence of ankle sprains in subjects without a history
of ankle sprain, these results did not achieve significance
(χ
2
= 3.42, df = 1, P = .059). However, the small number of
sprains and the sample size limited the statistical power
in this analysis to detect any difference in injury rates
between the 2 groups.
There were no adverse events from participating in the
balance training program. Specifically, the on-site trainers
did not observe or report any injuries from athletes who
fell off of the board during the balance training.
Effect of the Independent Variables
on the Risk of Ankle Sprain
The effect each variable had on the rate of ankle sprain is
shown in Table 5. The risk of sustaining an ankle sprain
was twice as high (risk ratio, 2.14; 95% CI, 1.25-3.65;
P = .005) for subjects who had sustained an ankle sprain
within the previous 12 months. Taking part in the inter-
vention program significantly reduced the risk of an ankle
sprain (risk ratio, 0.56; 95% CI, 0.33-0.95; P = .033). This
finding indicates that the intervention program was very
effective in reducing the number of ankle sprains.
The remaining variables evaluated, including gender,
sport, leg dominance, use of ankle supports, and ankle laxity,
did not have a significant effect on the rate of ankle sprains
(Table 5).
Ankle Sprain Severity
The mean number of days lost was 5.8 ± 5.5 days for
subjects in the intervention group and 8.1 ± 6.6 days for
subjects in the control group. The distribution of ankle
sprains by severity (mild, moderate, severe) is summarized
in Table 6. The percentage of minor sprains in the interven-
tion group was higher than in the control group (74% vs
59%), whereas the percentage of moderate sprains in the
intervention group was lower than in the control group
(22% vs 33%).
A Fisher exact test was used to determine whether there
was a significant difference in the distribution of injury
Figure 6. Balancing on the board while performing functional
activities (dribbling).
TABLE 3
Description of the Ankle Sprains
n%
Ankle sprains 62 8.1
Exposures 41 078
Sprains/1000 exposures 1.51
Severity (days lost) Mean = 7.6 + 5.3
Mild 40 64.5
Moderate 18 29.0
Severe 4 6.4
Type of sprain
Lateral 56 90.3
Medial 4 6.4
Syndesmotic 2 3.2
0%
4%
8%
0 5 10 15 20 25 30 35 40 45 50 55 60
12%
Exposures
% Injured Controls % Injured Interventions
Figure 7. Rate of ankle sprains for high school subjects in
the control and intervention groups. The rate of ankle sprains
was significantly lower in subjects in the intervention group.
(Kaplan-Meier survival estimate: χ
2
= 4.00, df = 1, P = .045.)
Vol. 34, No. 7, 2006 Balance Training Program and Ankle Sprains 1109
severity between both groups. However, because of the
small number of sprains in the moderate and severe cate-
gories, these categories were collapsed into a single cate-
gory (more than 7 days lost). After collapsing the data, no
difference was detected (P = .281) in sprain severity.
DISCUSSION
The primary objective of this study was to determine
whether a balance training program could reduce the rate
of ankle sprains in high school athletes. The results of this
study document that a simple, inexpensive, balance train-
ing program performed during a high school sport season
will reduce the rate of ankle sprains by 38% in male and
female high school soccer and basketball players. This
result has several important ramifications. First, the age
group included in this study represents a large (1.7 million)
population of athletes participating in high school soccer
and basketball programs. Second, ankle sprains represent
the highest rate of time loss injuries in this population of
athletes. A decrease of 38% of ankle sprains in this group
of high school soccer and basketball players (as found in
this study) would result in a reduction of $26 million in
direct health care costs and $380 million in indirect costs
per year if the program were used on a national level for
these 2 sports alone. Third, many of the athletes in high
schools across the country do not have access to the equip-
ment or the skilled personnel necessary to participate in
an ankle sprain prevention program. Fourth, the balance
boards are not expensive. Balance boards similar to those
used in this study can be purchased for $30 to $60 and will
last for several years. Purchasing 10 to 12 balance boards
would allow many members of a team to use the boards at
the same time, thus causing little disruption of other team
activities and practices. Finally, the 5-phase program used
in this study is time efficient and can easily be adapted to
most athletic team practices and physical education class
settings.
Male and female high school (adolescent) athletes in the
United States are a population that has been sparsely
studied regarding prevention of ankle sprains. In fact, this
study is the first to show that balance training, as a single
intervention, will significantly reduce ankle sprains in this
population. One prior study also used adolescent athletes
to evaluate the efficacy of balance training (an ankle disk
program) for reducing ankle sprains in female team hand-
ball players (ages 16-18 years).
28
However, their preven-
tion program also included one warm-up activity for each
muscle group to ensure a thorough warm-up and training
of all muscle groups. The authors found that the number of
ankle sprains was significantly lower in the intervention
group and concluded that the specific training of balance
and proprioception had an important role in the prevention
of ankle sprains in young female handball players. However,
they could not determine whether the balance training or
the regular warm-up was the major cause for the reduction
in injury rates.
The second objective of this study was to determine
whether a balance training program was equally effective in
reducing the rate of ankle sprains in subjects with and with-
out a history of an ankle sprain. None of the prior studies has
been able to document that a proprioceptive training pro-
gram will significantly reduce the incidence of ankle sprains
in athletes without a prior sprain.
4,11,25,27-29
Our results sug-
gest that a balance training program will reduce the rate of
ankle sprains in athletes who have not had a prior ankle
sprain. However, our results approached (P < .059) but did
TABLE 4
Rate of Ankle Sprains for Control and Intervention Subjects
Subjects (n) Ankle Sprains Rate per Player (%) Exposures Sprains/1000 Athletic Exposures
Controls 392 39 9.9 20 828 1.87
Intervention 373 23 6.1
a
20 250 1.13
Total 765 62 8.1 41 078 1.51
a
The risk ratio for subjects in the intervention group was 62% of that of controls.
TABLE 5
Relationship of Independent Variables and the Risk
of Ankle Sprain for High School Soccer
and Basketball Players
a
Risk
Variable χ
2
P Ratio 95% CI
Balance training 4.513 .033
b
0.56 0.33-0.95
program
Age 0.007 .929 1.01 0.78-1.31
Level of 0.696 .404 0.76 0.41-1.42
competition
Use of ankle 3.821 .051 1.75 0.99-3.09
support
Height 0.564 .452 0.79 0.43-1.45
Weight 0.293 .588 1.03 0.90-1.18
Body mass index 0.495 .481 0.74 0.32-1.69
Leg dominance 1.490 .222 0.78 0.15-1.55
History of ankle 7.891 .005
b
2.14 1.25-3.65
sprain
History of knee 0.395 .529 0.74 0.29-1.88
injury
Arch type, pronated 0.918 .338 0.75 0.43-1.33
Arch type, supinated 0.040 .840 0.89 0.31-2.55
Ankle laxity 0.074 .785 0.75 0.10-5.69
Gender 0.330 .565 0.81 0.40-1.63
Sport 1.232 .266 1.39 0.77-2.48
a
Cox Proportional Hazards Model (χ
2
= 30.032, df = 15); CI,
confidence interval.
b
Denotes a significant value (P < .05).
1110 McGuine and Keene The American Journal of Sports Medicine
not attain statistical significance. This finding was attributed
in large part to the fact that there were fewer sprains (n = 62)
than the number we projected (n = 87) based on the incidence
of acute sprains reported in other studies.
3,7,21,24,26
The results substantiate that a balance training pro-
gram was effective in significantly reducing the rate of
recurrent ankle sprains in those high school athletes who
had prior ankle sprains. This result is in accord with the
results of prior studies. Verhagen et al,
26
who studied the
effect that a 36-week balance board training program had
on reducing ankle sprains in adult Dutch volleyball play-
ers, found that the number of self-reported ankle sprains
was significantly lower in athletes completing the inter-
vention program. This result, however, was seen only in
players with a history of an ankle sprain.
Tropp et al
25
compared the efficacy of a semirigid ankle
orthosis and ankle disk training for reducing ankle
sprains. However, the ankle disk training program was
only given to the 65 athletes who had previous ankle prob-
lems. Both the semirigid orthosis and the ankle disk pro-
gram significantly reduced the number of ankle sprains in
those with prior ankle sprains.
In 1997, Bahr et al
4
reported on a 3-year cohort study
that evaluated a proprioceptive prevention program that
included a didactic session on risk factors, a 2-hour training
session on a balance board for players with previous ankle
sprains, and technical training that emphasized safe take-
off and landing techniques.They found that the incidence of
ankle sprains was reduced by 47% from the first to the third
years, but they could not determine to what degree each of
the program’s elements contributed to the overall results.
Three other studies also examined the effect that bal-
ance training had on athletes with a history of an ankle
sprain. Each of these studies also found that the interven-
tion group, which did a balance training program, had a
significantly lower rate of re-sprains compared with the
control group.
11,23,29
The third goal of this study was to examine the relation-
ship that various independent variables had on the risk of
sustaining an ankle sprain. Sustaining an ankle sprain
within the previous 12 months more than doubled the risk
of another sprain (risk ratio, 2.14). This finding is consis-
tent with previous publications that reported that sustain-
ing an ankle sprain predisposes a person to a subsequent
ankle sprain.
9,24,29
The variable that was associated with the lowest risk
of an ankle sprain was performing the balance training
program. This program reduced the risk of injury by nearly
half (risk ratio, 0.56). This finding, coupled with the risk
ratio of 2.14 for reinjury reported above for those who had
prior sprains, further emphasizes the importance of per-
forming balance training exercises to reduce the rate of
ankle sprains.
It is interesting that the use of ankle supports appeared
to lead to an increase in the risk of ankle sprain. However,
this finding should be interpreted with caution. We defined
ankle support as any tape or brace used by the athlete. We
suspect that a number of athletes used braces that they
had purchased on their own that provided limited support.
In addition, some athletes relied on coaches and team-
mates to tape them when they competed away from their
own school. We have no doubt that if equivalent, well-
constructed braces were used on all athletes and taping was
done only by an ATC, we would not have found that the
risk of ankle sprains was higher in subjects who used
ankle supports.
The last objective of the study was to determine whether
the balance training program would reduce the severity of
ankle sprains. We found that the balance training program
did not affect the severity of the sprain. Specifically, it did
not reduce the mean number of days lost and did not affect
the distribution of sprains classified as mild, moderate, or
severe. This finding is similar to that of Verhagen et al,
27
who found that the average time lost from volleyball after
an ankle sprain was not affected by taking part in a bal-
ance training program.
Study Limitations
Recall bias may have occurred with the subjects when they
completed the self-report questionnaire regarding their
sprain history. We tried to minimize this bias by review-
ing the responses with each subject and cross-checking
responses whenever possible with the school injury records
from previous sport seasons.
The lack of blinding may also be a limitation. Subjects
performing the intervention knew they were doing so to
prevent sprains. In addition to the lack of subject blinding,
the ATCs at the schools knew which teams were in the con-
trol and intervention groups. Such limitations have been
discussed in reviews,
9,24,26
which have concluded that these
problems are inherent in these types of studies.
In this study, female subjects outnumbered male sub-
jects by a ratio of 2 to 1. Before each season, equal numbers
TABLE 6
Distribution of the Ankle Sprains by Severity (Days Lost)
a
Minor, 1-7 d Moderate, 8-21 d Severe, >21 d Total
Group n % n % n % n
Intervention 17 73.9 5 21.7 1 4.3 23
Control 23 58.9 13 33.3 3 7.6 39
Total 40 64.5 18 29.0 4 6.0 62
a
There were no significant differences in injury severity between the 2 groups. Because of the small number of injuries, the category of
Minor injuries was compared with the combined categories of Moderate and Severe injures. Fisher exact test, P = .281.
Vol. 34, No. 7, 2006 Balance Training Program and Ankle Sprains 1111
of male and female teams were contacted and recruited to
participate in the study, so there were no logistical reasons
why more female subjects were enrolled. However, we did
notice that the parents of female athletes seemed more
interested in having their daughters take part in this
research. This may be because of the intense reporting dur-
ing the past several years on injuries such as anterior cru-
ciate ligament tears in young female basketball and soccer
players. In general, they seemed to be more diligent in ask-
ing questions during the parent meetings we attended and
in returning all informed consent and HIPAA documents
before the start of the sport season so that their daughters
could participate in the study.
CONCLUSIONS
This study documented that a balance training program,
implemented throughout a sports season, will reduce the
rate of ankle sprains by 38% in high school basketball and
soccer players. The balance training program included
simple exercises and employed an inexpensive device that
should be readily available to high school and adolescent
athletes across the United States. Further research is
needed to determine whether this exercise program can sig-
nificantly reduce the rate of ankle sprain in athletes without
a history of a sprain or reduce ligament sprains in the knee
and other lower extremity joints in high school athletes.
ACKNOWLEDGMENT
The authors gratefully acknowledge the work of Glen
Leverson, PhD, Biostatistician, at the University of
Wisconsin Medical School who provided consultation on the
research design and performed the statistical analyses for
this study. Funding for this study was provided by the
University of Wisconsin Surgical Associates Research Fund
and UW Sports Medicine Classic Fund.
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