Performance testing revealed that the males were able to jump significantly higher ... determine if these differences can predict the risk for ankle injuries in this ...
Journal of Athletic Training 1998;33(3):229-232 by the National Athletic Trainers' Association, Inc www.nata.org/jat
Anthropometric for
High
and Performance Measures School Basketball Players
Joseph J. Greene, MS, ATCt; Timothy A. McGuine, MS, ATCt; Glen Leverson, PhDt; Thomas M. Best, MD, PhD, FACSM* Department of Family Medicine and Orthopedic Surgery, t University of Wisconsin Hospital Sports Medicine Center, Madison, WI 5371 1; * Department of Surgery, University of Wisconsin Hospitals and Clinics, Madison, WI *
Objective: To determine possible anthropometric and performance sex differences in a population of high school basketball players. Design and Seffing: Measurements were collected during the first week of basketball practice before the 1995-1996 season. Varsity basketball players from 4 high schools were tested on a battery of measures chosen to detect possible anthropometric and performance sex differences. Subjects: Fifty-four female and sixty-one male subjects, from varsity basketball teams at high schools enrolled in the athletic training outreach program at the University of Wisconsin Hospital Sports Medicine Center in Madison, WI, volunteered to take part in this study. Measurements: We took anthropometric measurements on each of the 115 subjects. These included height, weight, body composition, ankle range of motion, and medial longitudinal arch type in weightbearing. Performance measures included the vertical jump, 22.86-m (25-yd) shuttle run, 18.29-m (20-yd) sprint, and single-limb balance time. Results: We compared anthropometric and performance characteristics using a 2-sample t test. The only exception to
H
igh school basketball enjoys immense popularity in this
country. In Wisconsin alone, an estimated 27,000 high school players compete in interscholastic programs each year.' Sports medicine professionals are often asked to comment on the characteristics that contribute to the prevention of injuries and to the overall success of these athletes.
While professional, international, and collegiate basketball players have been studied extensively,28 there is little information available on the high school basketball player. Since the adoption of Title IX in 1972, the number of women competing in sports involving physical contact, pivoting, jumping, and sprinting has increased dramatically. Coupled with this growth has been an increased awareness of performance and physiologic characteristics of female basketball players and of the sex differences that exist between them and their male counterparts. Many studies have reported much higher serious knee injury rates in females.2'6 9 However, little information has been published regarding sex differences and ankle injuries. What has been presented in the literature focuses on nonfunctional anthropometric characteristics.'0-15
this was for medial longitudinal arch type, where the 2 groups were compared using a 2-tailed Fisher's exact test. The male subjects were significantly taller and heavier, while the females had a significantly higher percentage of body fat. There were no
significant differences found for ankle plantar flexion and dorsiflexion, but the females had significantly more inversion and eversion range of motion. Analysis of medial longitudinal arch type found females to have a higher percentage of pronated arches and males to have a higher percentage of supinated arches. Performance testing revealed that the males were able to jump significantly higher and run the 22.86-m (25-yard) shuttle run and 1 8.29-m (20-yard) sprint significantly faster than the female subjects. There was no significant difference between the groups for single-limb balance time. Conclusions: We found significant anthropometric and performance sex differences in a cohort of high school basketball players. Further study of these measures is necessary to determine if these differences can predict the risk for ankle injuries in this particular population. Key Words: agility, arch, flexibility, body composition, proprioception, ankle
In particular, studies on the functional sex differences that may affect ankle injury rate are absent from the literature. Ankle ligament injuries are the most common injuries in sports and recreational activities in this country today.'6 Many factors are thought to increase the risk for these injuries, which affect 1 in every 10,000 persons each day, or 27,000 total daily in the United States.'0 Most importantly, ankle ligament injuries make up 25% of all injuries that occur in sports involving running and jumping.'7 In addition, ankle sprains make up 75% of ankle injuries overall.4"8 Soft tissue injuries, including ankle ligament injuries, are often overlooked in the research literature. Not only are these injuries the cause of a significant amount of lost playing time for the athlete, but there is also a significant cost to the medical system related to care for and rehabilitation from these injuries. In fact, one study concluded that sprains and strains represent the most frequent type of injury and can account for up to 43% of cases involving work and/or participation loss. '9 Our purpose was to identify and report anthropometric and performance differences between male and female high school
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basketball players. Percentage of body fat was assessed as a measure of body composition through the use of skinfold caliper measurements. Ankle range of motion and medial longitudinal arch type were assessed to determine if sex differences existed in flexibility and joint motion. The performance measures were selected to assess overall lower extremity power (vertical jump), agility (22.86-m (25-yard) shuttle run), speed (18.29-m (20-yard) sprint) and proprioception (single-limb balance time). These data will, we hope, provide insight into possible sex-related differences that may help explain injury rates, and perhaps more importantly, predict risk of injury to the ankle.
METHODS Fifty-four female and sixty-one male subjects, from basketball teams at high schools enrolled in the athletic training outreach program at the University of Wisconsin Hospital Sports Medicine Center, Madison, WI, volunteered to take part in this study. Informed consent was obtained from all subjects and their parents before the study began. We collected the data at 4 high schools during the first week of practice of the 1995-1996 basketball season. The anthropometric characteristics we measured included height, weight, and caliper skinfolds to determine percentage of body fat. We measured height using a stadiometer with a + 0.64-cm level of accuracy, and we measured weight on a beam balance platform scale with a level of accuracy of ± 0.11 kg. Skinfold sites were measured with a Lange skinfold caliper (Cambridge Scientific Industries, Inc, Cambridge, MD). All skinfold measurements were taken on the right side of the body in serial fashion by the same trained measurer. The sites we chose and the methods we used are reliable and valid for high school athletes when compared with hydrostatic weighing.20 Skinfold sites for males included the triceps, subscapularis, and umbilicus. Sites for females included the triceps, suprailiac area, and anterior thigh. Skinfold thickness was based on the average of 2 trials within 0.5 mm. If the 2 skinfold measures at the same site differed by more than 0.5 mm, a third measurement was taken and the mean value used in the analysis. Body density was predicted by the quadratic equations of Lohman21 for males and Jackson, Pollock, and Ward for females.22 Body density was converted to relative fat using the equation of Brozek et al.23 We measured ankle plantar flexion, dorsiflexion, inversion, and eversion range of motion using a goniometer.24 Each athlete was placed in a seated position on a table with the knees flexed at right angles. For ankle plantar flexion and dorsiflexion, the goniometer was placed using the lateral malleolus as an axis. The stationary arm for both measurements was aligned with the lateral midline of the leg projecting to the head of the fibula. The moving arm was placed parallel to the bottom of the calcaneus. Each subject then actively plantar flexed and dorsiflexed each ankle, and we recorded the measurements. Ankle inversion and eversion were measured using the position
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on the dorsal surface of the foot midway between the malleoli as an axis. The stationary arm was aligned with the midline of the leg projecting to the tibial tuberosity. The moving arm was
aligned with the dorsal surface of the second metatarsal shaft. Each subject then actively inverted and everted each ankle, and we recorded the measurements. We determined medial longitudinal arch structure in weightbearing using the Feiss line, which is a line drawn from the medial malleolus to the head of the first metatarsal.25 Each athlete was asked to stand with normal weightbearing on both feet. If the navicular tubercle intersected the line, the arch was graded as neutral. 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. We chose to express the results as the percentage of males and females having each type of medial longitudinal arch structure. The functional tests we asked the athletes to perform followed a standardized warm-up period that consisted of 5 to 10 minutes of stretching and light running. The tests were then administered in random order for all subjects. We measured vertical jump using a Vertec (Sports Imports Inc, Columbus, OH). After a single practice attempt, each subject performed 2 flat-footed jumps, and we recorded the highest jump. We measured agility by having the athlete perform a pro agility run (22.86-m shuttle). Standing at a center line, subjects moved to the right 4.57 meters, touched a line, moved back to the left 9.15 meters to touch a line, and finished by sprinting back to their right for 9.15 meters. Each subject was allowed a single practice attempt before the best of 2 trials was recorded to the nearest hundredth of a second. We measured 1 8.29-m (20-yard) sprint speed using a Speed Trap infrared timer (Brower Timing Systems, Draper, UT). Timing started on the athlete's first movement and was completed when the subject tripped the infrared sensor. Each subject performed 2 trials, with the fastest time recorded to the nearest hundredth of a second. We carried out proprioceptive testing by having the athlete perform a series of 3 single-limb (stork) tests and averaging the scores. Hand-held timers were used to measure the duration of time (± 0.5 s) the subject balanced up to a total of 30 s. If athletes lost their balance, the time was recorded when they contacted the ground with the nonweightbearing leg. After data collection, we turned the data over for statistical analysis to statisticians within the Department of Surgery at the University of Wisconsin Hospital and Clinics. The anthropometric and performance characteristics were compared between the males (n = 61) and females (n = 54) using a 2-sample t test. We used a significance level of P < .05 for all the characteristics that we measured. The only exception to this was for the comparison of medial longitudinal type. In this case, we compared the males and females using a 2-tailed Fisher's exact test. All analyses were performed using SAS Statistical Software (version 6.11, SAS Institute Inc, Cary, NC).
RESULTS Wisconsin high school athletes.25 Comparing body fat percentWe evaluated all 115 subjects with the measurements ages with those previously reported is difficult since the described. Analysis of our anthropometric data (Table) found different age groups, sites, and equations make any comparison the male basketball players to be taller (tl13 = 11.52, P < .05) somewhat unreliable.2022'25 Whether overall fitness has a and heavier (tl = 6.78, P < .05). In addition, the males in our direct effect on lower extremity injury rate is unknown. Our findings involving ankle range of motion indicate that study also had a lower percentage of body fat as opposed to the the ankle of the female athlete has an increased amount of females (t 13 = 10.11, P < .05). eversion and inversion when compared with that of the male The measures related to foot and ankle structure and athlete. Additionally, the female athletes demonstrated a trend function found the females to have an increased amount of inversion (t228 = 3.38, P < .05), and eversion (t228 = 1.50, toward a pronated medial longitudinal arch when weightbearP < .05). Differences were not found to be significant for ing. Further prospective clinical study in this area is necessary plantar flexion and dorsiflexion. Analysis of medial longitudi- to determine if these differences contribute to functional nal arch structure by a 2-tailed Fisher's exact test revealed no instability of the ankle joint and to an increased risk of ankle differences in arch type between males and females. However, sprains. Such a study could perhaps incorporate hindfoot and female subjects were found to have a greater percentage of forefoot motion measurements in weightbearing to better pronated feet (42.5% versus 26.2%), while the males had a describe how the multiple articulations in the foot affect greater percentage observed to be neutral (65.6.% versus biomechanics and influence how the foot performs in func53.1%) and supinated (8.1% versus 0.03%). tional activity. Analysis of performance testing by a 2-sample t test (Table) Sex differences were observed for all functional measures revealed the males jumped higher (tl = 10.77, P < .05), ran tested except single-limb balance time. The 30-second balance the 18.29-m (20-yard) sprint faster (tl13 = 7.16, P < .05), and test we used did not account for extrinsic variables such as executed the pro agility run quicker (t,13 = 8.66, P < .05) than uninvolved extremity motion and the amount of postural sway their female counterparts. No significant difference was noted needed to maintain balance. It may be that a more sensitive for single-limb balance time. measure of proprioception will detect differences. We recom13
13
DISCUSSION Our literature review on anthropometric and functional of basketball players revealed a focus primarily on international, professional, and collegiate athletes.2 8 In gen eral, we found that such measures of high school athletic populations have been largely unreported by sport scientists. However, it is generally accepted that, at all levels, the ability to jump higher, run faster, and demonstrate greater agility are skills that a successful basketball player must possess. Our results are consistent with previous data that indicated a significantly higher percentage of body fat in females than their male counterparts.20 The calculations used in our study have been reported as valid and reliable in and for a population of measures
mend that future prospective studies in this area involve the use of stabilimetry to assess proprioception more sensitively. Similar sex differences in functional measures have been reported for various athletic populations.5'8 A recent study on the neuromuscular performance of male and female athletes by Huston and Wojtys5 documented that female subjects had significantly less strength in their quadriceps and hamstrings and significantly slower time to peak torque for knee flexion than their male counterparts. It would be interesting to determine if similar differences exist in the ankle musculature. Such differences could perhaps explain why the females performed significantly worse in our performance testing and illustrate the need for future study to determine if these potential deficits are a risk factor for ankle injury.
Anthropometric and Performance Measures (Means and Standard Deviations) for High School Basketball Players Female Male Variable
Mean
SD
Mean
Age (y) Height (cm) Weight (kg) Body fat (%) Inversion (degrees) Eversion (degrees) Plantar flexion (degrees) Dorsiflexion (degrees) Single-limb balance time (s) Vertical jump (cm) Pro agility run (s) 18.29-m (20-yd) sprint (s)
16.02 166.19 61.54 20.45 36.25 16.54 30.35 10.33 27.25 46.36 6.14 3.46
1.16 7.42 8.68 4.65 6.98 3.98 9.33 4.35 5.14 5.59 0.32 0.27
16.21 182.34 74.95
11.98 31.95 14.52 27.94 8.72 28.19 64.01 5.63 3.13
Journal of Athletic Training
SD 1.07 7.59 12.02 4.30 6.63 4.59 8.71
3.55 3.72 10.82 0.31 0.21
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Injuries to the ankle continue to be the most common injuries in athletics17 and place a significant cost burden on the health care industry, as well as causing a large amount of work and/or participation loss.19 The sports medicine community is currently devoting vast amounts of time and energy to understanding why females are suffering more anterior cruciate ligament injuries than males. It may be that female athletes are sustaining injuries to the ankle and other parts of the body at a higher rate as well. Possible reasons that should be investigated include an increase in generalized joint laxity, slower muscle reaction time, less muscle strength, and less muscle endurance. Our current study documents sex differences for various anthropometric and performance measures in high school basketball players. These data are intended for future use in prospective studies to evaluate if these differences have an effect on ankle injury rates. Further study of anthropometric and performance measures and their relation to the incidence of ankle injury in high school athletes is necessary to facilitate potential ankle injury prevention and overall performance enhancement.
ACKNOWLEDGMENTS We thank the athletic training, exercise physiology, physical therapy, and fitness center staffs of the University of Wisconsin Hospital Sports Medicine Center for their assistance in the testing process. In addition, we thank the high school basketball coaches and studentathletes from Madison Memorial, Madison West, Waunakee, and Deforest High Schools.
REFERENCES 1. Wisconsin Interscholastic Athletic Association. Sport Participation Summary in Wisconsin Public High Schools. Stevens Point, WI: WIAA; 1996. 2. Arendt E, Dick R. Knee injury patterns among men and women in collegiate basketball and soccer: NCAA data and review of literature. Am J Sports Med. 1995;23:694-701. 3. Berg K, Blanke D, and Miller M. Muscular fitness profile of female college basketball players. J Orthop Sports Phys Ther. 1985;7:59-64. 4. Garrick JG, Requa RK. The epidemiology of foot and ankle injuries in sports. Clin Sports Med. 1988;7:29-36. 5. Huston LJ, Wojtys EM. Neuromuscular performance characteristics in elite female athletes. Am J Sports Med 1996;24:427-436.
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6. Malone TR, Hardaker WT, Garrett WE, et al. Relationship of gender to anterior cruciate ligament injuries in intercollegiate basketball players. J South Orthop Assoc. 1993;2:36-39. 7. Smith HK, Thomas SG. Physiological characteristics of elite female basketball players. Can J Sport Sci. 1991;16:289-295. 8. Wojtys EM, Huston LJ, Taylor PD, Bastian SD. Neuromuscular adaptations in isokinetic, isotonic, and agility training programs. Am J Sports Med. 1996;24:187-192. 9. Lindenfeld TN, Schmitt DJ, Hendy MP, Mangine RE, Noyes FR. Incidence of injury in indoor soccer. Am J Sports Med. 1994;22:364-371. 10. Baumhauer JF, Alosa DM, Renstrom PA, Trevino S, Beynnon B. A prospective study of ankle injury risk factors. Am J Sports Med. 1995;5: 564-570. 11. Dahle LK, Mueller M, Delitto A, et al. Visual assessment of foot type and relationship of foot type to lower extremity injury. J Orthop Sports Phys Ther. 1991;14:70-74. 12. Ekstrand J, Tropp H. The incidence of ankle sprains in soccer. Foot Ankle. 1990;1 1:41-44. 13. Godshall RW. The predictability of athletic injuries: an eight year study. J Sports Med. 1975;3:50-54. 14. Milgrom C, Shlamkovitch N, Finestone A, et al. Risk factors for the lateral ankle sprain: a prospective study among military recruits. Foot Ankle. 1991;12:26-30. 15. Rubin G, Witten M. The talar-tilt angle and the fibular collateral ligaments: a method for the determination of talar tilt. J Bone Joint Surg Am. 1960;42:311-326. 16. Garrick JG. The frequency of injury, mechanism of injury, and epidemiology of ankle sprains. Am J Sports Med. 1977;5:241-242. 17. Tropp H. Pronator muscle weakness in functional instability of the ankle joint. Int J Sports Med. 1986;7:291-294. 18. Mack RP. Ankle injuries in athletics. Clin Sports Med. 1982;1:71-84. 19. Burkett LN. Causative factors in hamstring strains. Med Sci Sports. 1970;2:39-41. 20. Clark RR, Kuta JM, Oppliger RA. The Wisconsin wrestling minimal weight project: cross validation of prediction equations. Ped Exerc Sci. 1992;4:117-127. 21. Lohman TG. Skinfolds and body density and their relation to body fatness: a review. Hum Biol. 1981;53:181-225. 22. Jackson AS, Pollock ML, and Ward A. Generalized equations for predicting body density of women. Med Sci Sports Exerc. 1980;12:175182. 23. Brozek JF, Grande F, Anderson JT, et al. Densitometric analysis of body composition: revision of some quantitative assumptions. Ann NYAcad Sci. 1963;1 10:113-140. 24. Norkin CC, Levangie PK. Joint Structure and Function: A Comprehensive Analysis. Philadelphia, PA: FA Davis Company; 1983:386-387. 25. Palmer ML, Epler ME. Clinical Assessment Procedures in Physical Therapy. Philadelphia, PA: JB Lippincott Company; 1990:301-302.
