title: Sex-Related and Age-Related Differences in Knee Strength of Basketball Players Ages 11-17 Years.
abstract: OBJECTIVE: To assess hamstrings and quadriceps strength of basketball players ages 11-13 and 15-17 years. DESIGN AND SETTING: This cross-sectional study occurred during the 2000 American Youth Basketball Tour National Tournament. We investigated whether sex- or age-related strength differences existed among study participants. SUBJECTS: Forty-one tournament participants (22 girls, 19 boys; 11-13 or 15-17 years old) who reported no history of knee sprain or surgery were recruited. MEASUREMENTS: We used a Cybex II dynamometer to obtain isokinetic concentric peak torques relative to body mass (Nm/kg) at 60 degrees /s for hamstrings and quadriceps bilaterally. From average peak torques, we determined ipsilateral hamstrings:quadriceps and homologous muscle-group ratios. RESULTS: Correlations between hamstrings and quadriceps strength measures ranged from 0.78 to 0.97. Players 15-17 years old had greater relative hamstrings and quadriceps strength than 11- to 13-year-old athletes. Age and sex interacted significantly for quadriceps strength. The quadriceps strength of 15- to 17-year-old girls did not differ from that of 11- to 13-year-old girls, whereas 15- to 17-year-old boys had stronger quadriceps than 11- to 13-year-old boys. Boys 15-17 years old had greater quadriceps strength than girls 15-17 years old. CONCLUSIONS: This study is unique in providing normative data for the hamstrings and quadriceps strength of basketball players 11-13 and 15-17 years old. Age-related strength differences did not occur consistently between the sexes, as girls 11-13 and 15-17 years old had similar relative quadriceps strength.
authors: Bowling Green State University, Bowling Green, OH.
authors: Patricia A.
authors: PA
authors: Buchanan
authors: Vassilios G.
authors: VG
authors: Vardaxis