Original Research Reports

Journal of Spod Rehabilitation, 1994, 3, 125-1 34 O 1994 Human Kinetics Publishers, Inc.

Effects of Two Semirigid Prophylactic Ankle Stabilizers on Speed, Agility, and Vertical Jump

Christine Bocchinfuso, Michael R. Sitler, and Iris F. Kimura

The purpose of this study was to compare the effects of two semirigid prophylactic ankle stabilizers on vertical jump, 8 0 4 sprint, shuttle run, and four-point run performance. Eight male and seven female high school basketball players, who denied prior ankle injury and prophylactic ankle stabilizer experience, completed the four performance events under the conditions of Active Ankle Training Brace, Aircast SportStimp, and nonbraced control. Data analyses consisted of four 1 x 3 ANOVAs with repeated measures on the independent variable of brace .condition. Results of the analysis revealed no significant differences among the experimental conditions for any of the performance events tested. In conclusion, the Active Ankle Training Brace and Aircast SportStimp did not facilitate or adversely affect performance involving speed, agility, and vertical jump of high school basketball players.

The talocrural, or ankle, joint is one of the most frequently injured joints of the body. It is estimated that each year one million people experience acute ankle injuries (15), the most common of which is the inversion sprain (2, 8, 11, 13). Within the athletic setting, acute ankle sprains account for approximately 15% of all injuries (3, 6, 7, 12).

Various intervention methods have been implemented to reduce the incidence of ankle sprains. Taping has been the most traditional method used to prevent capsuloligamentous injuries of the ankle. An alternative to ankle taping is the prophylactic ankle stabilizer (PAS). Many types of PASs are marketed, and although variations exist, most can be categorized according to design: lace- on or semirigid construction. Greene and Hillman (7) reported that two advantages of PASs over tape are their ease of application and cost-effectiveness.

PASs have been tested under a variety of experimental conditions. Clinically, PASs have been shown to be effective in reducing the incidence of ankle injuries in the athletic setting (18-20). Biomechanically, PASs have been reported to significantly limit ankle inversion and eversion range of motion before, during, and after exercise (1, 4, 7-1 1).

Christine Bocchinfuso, Michael R. Sitler, and Iris F. Kimura are with the Department of Physical Education, 125 Pearson, Temple University, Philadelphia, PA 19122. Direct correspondence to Michael R. Sitler.

1 26 Bocchinfuso, Sifler, and Kimura

Research conducted on the performance efficacy of PASs is inconclusive. Greene and Hillman (7) conducted a study using the Ankle Ligament Protector and concluded that it had no significant effect on female collegiate volleyball players' vertical jump performances. Conversely, Robinson et al. (17) determined that obstacle course performance time significantly increased with the use of a modified high-top basketball shoe with "stiffers" sewn into the seams. Comparing three different PASs, Greene and Wight (9) reported that the Aircast SportStirrup significantly impaired the base-running ability of 12 female collegiate softball players when compared to the Swede-0 Ankle Brace and Ankle Ligament Protector. In a study assessing broad jump, vertical leap, 10-yd shuttle run, and 40-yd sprint performance, Burks et al. (5) reported a significant increase in running times for 30 varsity collegiate athletes when wearing the Swede-0 Ankle Brace.

Maidment (14) tested 13 high school varsity football players and concluded that the McDavid Ankle Guard, Aircast Airstirrup, and tape significantly decreased performance in the Right Boomerang Run Agility Test when compared to a nonbraced control condition. A recent study conducted by Paris (16) resulted in no significant differences in speed, balance, or agility for 18 elite male soccer players when tested under the experimental conditions of tape, Swede-0 Ankle Brace, McDavid Ankle Guard, New Cross PAS, and nonbraced control. Vertical jump, however, was significantly reduced when the New Cross PAS was worn.

Differences in research findings among the PAS performance studies are attributed to variability in research design, PASs tested, and functional tests employed. No study has been reported regarding the functional aspect of PASs using basketball players, who are at increased risk of ankle injury (6, 15, 20). Additional research is needed to further delineate the effect that semirigid PASs have on performance. The purpose of this study was to compare the effect of two semirigid PASs on performance in events involving speed, agility, and vertical jump.

Methods

Subjects

Fifteen subjects, 8 males and 7 females, who denied prior ankle injuries within the last year and experience with PASs, volunteered to participate in the study. Subjects were freshman high school basketball players (mean age 14.3 years, mean weight 64.0 kg, mean height 169 cm) during the 1992-93 winter basketball season. In accordance with the Institutional Review Board of Temple University, appropriate parental and subject informed consent were obtained prior to data collection.

Semirigid PASs Tested

Semirigid PASs were chosen for this study because of their increased popularity in the sports medicine and athletic training settings. In addition, several studies have demonstrated that semirigid PASs restrict ankle range of motion significantly m m than do canvas lace-on PASs (1, 7-11). Controversy exists, however, as

Prophylactic Ankle Stabilizers 1 27

to the effect that semirigid PASs have on performance, and further study is needed.

The two semirigid PASs tested in the present study were the Active AnkIe Training Brace (Active AnkIe Systems, Inc., Louisville, ICY) and Aircast Sportstirrup (Aircast, Inc., Summit, NJ). The Aircast Sportstirrup was chosen because of its popularity in the sports medicine and athletic train'ig settings; the Active Ankle Training Brace was selected because it is relatively new to the PAS market.

The Active Ankle Training Brace (Figure I) consists of bilateral thermoplas- tic shells. The shells are lined with rubber padding and connect to a molded plastic heel stirrup via a uniaxial hinge. The brace attaches to the lower leg via two Velcro straps and a third strap that encircles the Achilles tendon.

The Aircast Sportstirrup (Figure 2) consists of medial and lateral thermo- plastic shells lined with inflatable air sacs. The shells are connected to a pliable heel pad via Velcro attachment. Two Velcro straps secure the shells to the lower leg.

Performance Events

Subjects completed the four performance tests as follows: Vertical Jump. Standing perpendicular to the test wall and with fingertips

chalked, subjects crouched and then jumped vertically as far as they could, touching the wall at the height of their jump. The vertical jump height was identified by the chalk mark on the wall and recorded in centimeters. The differ-

Figure 1 - Active Ankle Training Brace.

128 Bocchinfuso, Sitler, and Kirnura

Figure 2 - Aircast SportStirrup.

ence between a standing vertical reach and the vertical jump height was recorded as the criterion measure for the vertical jump.

80-Ft Sprint. Subjects ran forward 80 ft as fast as possible from a standing start, beginning and ending on a taped white line. Times were measured to the nearest hundredth of a second with a handheld stopwatch.

Shuttle Run. From a standing start, beginning at a taped white line, subjects ran forward 20 ft and touched a second line with one foot, turned around, ran back and touched the starting line with one foot, and turned. Subjects repeated this sequence three more times, increasing the distance by 20 ft each subsequent run. Times were measured to the nearest hundredth of a second with a handheld stopwatch.

Four-Point Run. This test consisted of five taped Xs placed 15 ft apart in the shape of a cross (Figure 3). Touching each X in the cross pattern with one foot, subjects began the test at the start and ran north 15 ft, sidestepped east 15 ft, sidestepped west 15 ft, ran north 15 ft, backpedaled south 15 ft, sidestepped west 15 ft, sidestepped east 15 ft, and backpedaled south 15 ft to the finish. Times were measured to the nearest hundredth of a second with a handheld stopwatch.

Measurement Reliability

Intraclass correlation coefficients were computed to determine data collector measurement reliability. Measurement reliability was established a priori with

... subjects similar -to those wwho participated in the-study?- Running event tim

Prophylactic Ankle Stabilizers

Figure 3 - Four-point run.

were compared to those of a digital millisecond timer, Model Number 14-15ms (Marietta Apparatus Company, Marietta, OH). Vertical jump was assessed via a test-retest format. Measurement reliability was determined to be high: vertical jump, r(2, 1) = .99; 80-ft sprint, r(2, 1) = .85; shuttle run, r(2, 1) = .99; four- point run, r(2, 1) = .98.

Test Protocol

Testing was conducted on 3 different days with a minimum of 5 and a maximum of 8 days between test sessions. Experimental conditions (two PASs and a nonbraced control) were randomly assigned over the three test sessions. Within each test session, subjects completed the four performance events (vertical jump, 80-ft sprint, shuttle run, and four-point run) three times. Event order of testing within each session was randomized to minimize the effects of learning and fatigue. The best score for each event was used as the criterion measure for data analysis.

Prior to testing, subjects completed a warm-up consisting of jogging for 7 min, stretching, and a submaximal warm-up trial. The submaximal warm-up trial was completed in order to familiarize each subject with the test protocol. Subjects rested approximately 2 rnin between trials and 10 rnin between performance events and remained seated when not being tested. Subjects were not verbally encouraged during testing. In order to ensure consistency of brace application, the same investigator (C.B.) applied all PASs according to manufacturer specifica- tions.

Subjects wore their own high-top basketball shoes for all testing and were required to be consistent in the footwear worn across trials and test sessions. All testing was performed on a wooden gymnasium floor.

Data Analysis

The criterion measure for each of the four performance events (vertical jump, 80-ft sprint, shuttle run, and four-point run) was analyzed. The data analyses consisted of four 1 x 3 ANOVAs with repeated measures on the independent

130 Bocchinfuso, Sitler, and Kirnura

variable of brace condition: Aircast SportStirmp, Active Ankle Training Brace, and nonbraced control. The data were analyzed with Minitab Statistical Software: Release 7 (Minitab, Inc., State College, PA). All statistical analyses were com- pleted in the null form, and the -05 level of probability was considered significant.

Results and Discussion

Means and standard deviations for the four performance events are presented in Tables 1-4. Statistical analyses showed no significant differences among the treatments of Aircast SportStirmp, Active Ankle Training Brace, and nonbraced control for any of the performance events tested.

The results of this study revealed that the Aircast SportStirmp and Active Ankle Training Brace had no significant effect on vertical jump, 80-ft sprint, shuttle run, or four-point run performance. In general, the findings of this study are in agreement with those reported by Burks et al. (5), Greene and Hillman (7), Greene and Wight (9), and Paris (16).

Specific to PAS use and vertical jump performance, varying results have been reported. Greene and Hillman (7) and Paris (16) reported that the Ankle Ligament Protector, Swede-0 Ankle Brace, and McDavid Ankle Guard had no significant effect on vertical jump performance. These findings were attributed to the fact that dorsiflexion and plantar flexion were not restricted with PAS use. Because movement in the sagittal plane was not impeded, vertical jumping performance was not compromised. Conversely, Burks et al. (5) reported that vertical jumping performance was significantly decreased when the Swede-0

Table 1 Means and Standard Deviations (in centimeters) for Vertical Jump

Treatment M SD

Aircast SportStirrup Active Ankle Training Brace Nonbraced control

Note. ANOVA = F(2, 14) = 2.5, p = .lo.

Table 2 Means and Standard Deviations (in seconds) for 80-Ft Sprint

Treatment M SD

Aircast SportStirrup Active Ankle Training Brace Nonbraced control

Note. ANOVA = F(2, 14) = 0.8, p = .SO.

Prophylactic Ankb Stabilizers

TabIe 3 Means and Standard Deviations (im seconds) for Shuttle Run

Treatment M SD

Aircast SportStirmp 31.7 2.3 Active AnkIe Training Brace 32.3 3.1 Nonbraced control 32.1 2.1

Note. ANOVA = F(2, 14) = 0.8, p = .50.

Table 4 Means and Standard Deviations (in seconds) for Four-Point Run

Treatment M SD

Aircast SportStirmp Active Ankle Training Brace Nonbraced control

Note. ANOVA = F(2, 14) = 1.6, p = .20.

Ankle Brace and Kallassy Ankle Support were worn. Burks et al. attributed the decreased performance to a restriction in ankle dorsiflexion and plantar flexion. In the Paris and Burks et al. studies the same type of PAS (soft shell) was used but the research findings were different. Methodological differences may have influenced the results of the two studies. Subjects in Paris's study wore the PASs for 2 weeks prior to testing in order to facilitate brace use familiarity. This did not occur in Burks et al.'s study; subjects were not permitted to acclimate to PAS use prior to testing. Acclimation to PAS use was also not permitted in the present study. Accordingly, brace acclimation may be a factor in PAS use and optimal vertical jump performance.

It has been reported that running speed is affected to varying degrees with PAS use. Greene and Wight (9) reported that the Ankle Ligament Protector had no significant effect on intercollegiate softball players' base-running times. This was not the case for the Aircast Airstimp; base-running times were significantly reduced with Aircast Airstinup use. Greene and Wight attributed the decrease in performance to the weight and bulkiness of the Aircast Airstirrup. In partial agreement with the findings of Greene and Wight, Burks et al. (5) determined that the Swede-0 Ankle Brace significantly decreased sprinting performance times of intercollegiate athletes whereas the Kallassy Ankle Support did not. The difference in performance outcome between the two PASs tested was attributed to the latter being more comfortable than the former. The extent to which brace comfort affects sprinting performance is not known, but ostensibly, a positive relationship potentially exists.

The effect that PASs have on agility has been studied to a Eimited extent. AIthough a variety of agility tests exist, only one other researcher has tested the

132 Bocchinfuso, Sitler, and Kirnura

effect that PASs have on shuttle run performance. Burks et al. (5) conducted a study using intercollegiate athletes and reported no significant difference in shuttle run times among nonbraced control, Swede-0 Ankle Brace, and Kallassy Ankle Support conditions. The results of the present study are in agreement with those of Burks et al.; PAS use had no significant effect on shuttle run times.

Another aspect of PAS use and agility testing is the obstacle course. Only two other researchers have tested the effect that PASs have on obstacle course performance. Robinson et al. (17) reported a negative relationship between exter- nal ankle support "stiffness" and performance. The use of a specially designed high-top basketball shoe with "stiffers" sewn into the seams resulted in a signifi- cant increase in obstacle run course times. Maidment (14) reported that obstacle course performance times significantly increased when the McDavid Ankle Guard and Aircast SportStirmp were worn. He proposed that increased restriction in ankle range of motion was the reason performance decreased with PAS use.

Although the obstacle course performance results of these two studies are not in agreement with the findings of the present study, several methodological differences exist that may explain the outcome variance. Robinson et al. did not test any one particular PAS but used a modified basketball shoe, simulating an external ankle support. Maidment conducted his study on consecutive days during a preseason football training camp when athletes were least likely to be fit. In contrast, subjects in the present study were tested in the middle of their competitive basketball season when their physical fitness levels were thought to be optimal. Thus it is unclear whether a conditioning effect exists with regard to PAS use and agility performance.

Several researchers have studied the effect that semirigid PASs have on ankle range of motion pre- and postexercise. Greene and Hillman (7) reported that the Ankle Ligament Protector significantly reduced inversion and eversion range of motion before and after 3 hr of intercollegiate volleyball practice. Vertical jump performance, however, was not affected. Greene and Wight (9) determined that the Ankle Ligament Protector and Aircast AirStirmp significantly decreased ankle inversion and eversion range of motion after 90 min of intercolle- giate softball practice. The effect on base-running times was brace dependent; only the Aircast AirStirmp significantly decreased performance. Interestingly, while the Ankle Ligament Protector significantly restricted ankle range of motion it did not compromise base-running performance.

Specific to the present investigation, although the differences in speed, power, and agility among the experimental conditions were not statistically signif- icant, several trends did exist. Concerning the shuttle and four-point run agility events, subjects' performances improved more with the Aircast SportStirmp than with the Active Ankle Training Brace or with no brace. A posteriori calculations revealed statistical power to be approximately .20. Further research is needed to delineate the extent to which these differences can be attributed to sampling error and sample size.

The external validity of the research findings of the present study must be qualified. Nonimpaired individuals with no prior ankle injury history served as subjects for the present study. We encourage others to clarify the impact of these findings on basketball players under different treatment levels of the independent variable of ankle injury history.

Prophylactic Ankle Stabilizers 133

References

1. Alves, J.W., R.V. Alday, D.L. Ketcham, and L. Lentell. A comparison of the passive support provided by various ankle braces. J. Orthop. Sports Phys. Ther. 15:lO-18, 1992.

2. Attarian, D., H. McCrackin, and D. Devito. Biomechanical characteristics of human ankle ligaments. Foot Ankle 2:54-58, 1985.

3. Blythe, D.S., and F.O. Mueller. An Epidemiological Study of High School Football Injuries in North Carolina 1968-1974: Final Report. Washington, DC: Consumer Product Safety Commission, 1974.

4. Bunch, R.P., K. Bednarski, D. Holland, and R. Macinanti. Ankle joint support: A comparison of reusable lace-on braces with taping and wrapping. Phys. Sportsmed. 13:59-62, 1985.

5. Burks, R.T., B.G. Bean, R. Marcus, and H.B. Barker. Analysis of athletic performance with prophylactic ankle devices. Am. J. Sports Med. 19: 104-106, 1991.

6. Garrick, J.C. The frequency of injury, mechanism of injury, and epidemiology of ankle sprains. Am. J. Sports Med. 5:241-242, 1977.

7. Greene, T.A., and S.K. Hillman. Comparison of support provided by a semirigid orthosis and adhesive ankle tape before, during and after exercise. J. Orthop. Sports Phys. Ther. 18:498-505, 1990.

8. Greene, T.A., and C. Roland. A comparative isokinetic evaluation of a functional ankle orthosis on talocalcaneal function. J. Orthop. Sports Phys. Ther. 11:245-252, 1989.

9. Greene, T.A., and C.R. Wight. A comparative support evaluation of three ankle orthoses before, during and after exercise. J. Orthop. Sports Phys. Ther. 11:453-466, 1990.

10. Gross, M.T., C.L. Ballard, H.G. Mears, and E.J. Watkins. Comparison of Donjoy Ankle Ligament Protector and Aircast Sportstirrup orthoses in restricting foot ankle motion before and after exercise. J. Orthop. Sports Phys. Ther. 16:60-67, 1992.

11. Gross, M.T., A.K. Lapp, and J.M. David. Comparison of Swede-0-Universal Ankle Support and Aircast Sportstinup orthoses and ankle tape in restricting eversion- inversion before and after exercise. J. Orthop. Sports Phys. Ther. 13:ll-19, 1991.

12. Jackson, D.W., R.L. Ashley, and J.W. Powell. Ankle sprains in young athletes. Clin. Orthop. Rel. Res. 101:201-215, 1974.

13. Lassiter, T.E., T.R. Malone, and J.C. Garrick. Injury to the lateral ligaments of the ankle. Orthop. Clin. North Am. 20:629-640, 1989.

14. Maidment, J.S. The Effect of Ankle Prophylactic Devices on Agility. Unpublished master's thesis, Springfield College, Springfield, MA, 1990.

15. Miller, E.A., and A.C. Herge~oeder. Ankle bracing. Ped. Clin. North Am. 37:1175- 1185, 1990. .

16. Paris, D.L. The effects of the Swede-0, New Cross, and McDavid ankle braces and adhesive ankle taping on speed, balance, agility and vertical jump. J. Athletic Training 27:253-256, 1992.

17. Robinson, J.R., E.C. Frederick, and L.B. Cooper. Systematic ankle stabilization and the effect on performance. Med. Sci. Sports Exerc. 18:625-628, 1986.

18. Rovere, G.D., T.J. Clarke, C.S. Yates, and K. Burley. Retrospective comparison of taping and ankle stabilizers in preventing ankle injuries. Am. J. Sports Med. 16:228- 233, 1988.

134 Bocchinfuso, Sitter, and Kimura

19. Sitier, M., J. Ryan, B. Wheeler, J. McBride, R. Arciero, J. Anderson, and M. Horodyski. ESficacy of a Semirigid Ankle Brace to Reduce Acute Ankle Injuries in Basketball: A Randomized Clinical Study at West Point. Abstract presented at the 18th annual meeting of the American Orthopaedic Society for Sports Medicine, San Diego, CA, 1992.

20. Tropp, H., C. Askling, and J. Gillquist. Prevention of ankle sprains. Am. J. Sports Med. 13:259-262, 1985.

Acknowledgments

The authors thank Aircast Inc., Summit, New Jersey, and Active Ankle Systems, Inc., Louisville, Kentucky, for providing the PASS used for testing in this study, and Linda Muraresku for her assistance in preparation of the manuscript.