Isokinetic profile and differences in tibial rotation strength between male and female athletes 11 to 17 years of age

Our objective was to examine age and sex associated development of isokinetic tibial rotation strength in 94 athletes aged 11 to 17 y. A calibrated Biodex system 3 was used to measure internal rotation (IR) and external rotation (ER) peak torque and time to peak torque (TPT) at 120 degrees/s and 180 degrees/s, and knee extension and flexion peak torque at 180 degrees/s. All data were normalized for body weight and ANOVA identified significant (p < 0.05) effects of lower limb dominance, age and gender. Males aged 14 to 17 y had significantly greater mean IR, ER, flexion, and extension peak torques than males aged I I to 13 y. No such age-related effect existed in females. There was no difference between genders aged 11 to 13 y in isokinetic strength. Males aged 14 to 17 y had on average 17% greater IR strength, 28% faster time to reach IR peak torque, 17% greater extension strength, and 20% greater knee flexion strength than age-matched females. To conclude, no sex differences were found in peak torque or TPT in knee IR, ER, extension or flexion in athletes I I to 13 y. Age related changes were found in these factors in males, but not in females.