Abstract
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°/s and 180°/s, and knee extension and flexion peak torque at 180°/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 11 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 11 to 13 y. Age related changes were found in these factors in males, but not in females.