Isokinetic measurement in preadolescent males.

Eighteen preadolescent males (mean age 11.4 +/- 0.59 years) performed 15 knee flexion-extension repetitions on both legs. Peak torque (T peak) and torque acceleration energy (TAE) were measured using the Cybex II Isokinetic system, which permitted a study of the effect of limb velocity on T peak, TAE, and reciprocal muscle group ratios. The effect of limb dominance was also assessed. The results indicated (Student's t test) that an increase in limb velocity from 1.05 rad/s to 4.2 rad/s produced a significant decrease in the T peak generated (P less than 0.001). A similar increase in limb velocity resulted in a significant increase in the TAE recorded (P less than 0.001). The limb velocity was also shown to influence the T peak and TAE ratios in reciprocal muscle groups. At a limb velocity 1.05 rad/s mean T peak ratios of 0.64 and 0.66 were recorded for the dominant and nondominant limbs, respectively. At 4.2 rad/s, ratios recorded for dominant and non-dominant limbs were 0.79 and 0.80, respectively. The limb velocity of 1.05 rad/s produced TAE ratios of 0.21 (dominant) and 0.14 (nondominant), and at 4.2 rad/s, ratios of 0.28 and 0.24 were recorded for dominant and non-dominant limbs, respectively. No significant difference (P less than 0.001) was observed between T peak and TAE values recorded for the dominant and non-dominant limbs under the same conditions. These results indicate that young boys show velocity-related isokinetic strength characteristics similar to adults. Although they have lower absolute levels, the children showed typical adult reciprocal muscle group ratios. Limb dominance at this age is not reflected in strength differences.