Analysis of isokinetic knee extension / flexion in male elite adolescent wrestlers

Wrestling requires strength of the upper and lower body musculature which is critical for the athletic performance. Evaluation of the adolescent's skeletal muscle is important to understand body movement, especially including those involved in sports. Strength, power and endurance capacity are defined as parameters of skeletal muscle biomechanical properties. The isokinetic dynamometer is an important toll for making this type of evaluation. However, load range phase of range of motion has to be considered to interpret the data correctly. With this in mind we aimed to investigate the lover body musculature contractile characteristics of adolescent wrestlers together with detailed analyses of load range phase of motion. Thirteen boys aged 12 - 14 years participated to this study. Concentric load range torque, work and power of knee extension and flexion were measured by a Cybex Norm dynamometer at angular velocities from 450°/sec to 30°/sec with 30°/sec decrements for each set. None of the wrestlers were able to attain load range for angular velocities above 390°/sec and 420°/sec for extension and flexion respectively. Detailed analyses of the load range resulted in statistically significant differences in the normalized load range peak torque for extension at 270°/sec (1.44 ± 0.28 Nm·kg(-1) and 1.14 ± 0.28 Nm·kg(-1) for total and load range peak torque respectively, p < 0.05), and for flexion at 300°/sec (1.26 ± 0.28 Nm·kg(-1) and 1.03 ± 0.23 Nm·kg(-1) for total and load range peak torque respectively, p < 0.05), compared to total peak torque data. Similarly, the significant difference was found for the work values at 90°/sec (1.91 ± 0.23 Nm·kg(-1) and 1.59 ± 0.24 Nm·kg(-1) for total and load range work respectively for extension and 1.73 ± 0.21 Nm·kg(-1) and 1.49 ± 0.19 Nm·kg(-1) for total and load range work respectively for flexion, p < 0.05), and was evident at higher angular velocities (p < 0.001) for both extension and flexion. At extension, load range power values were significantly smaller than total power for all angular velocities except 150°/sec (p < 0.05 for 120 and 180°/sec, p < 0.001 for others). Finally, load range flexion power was found to be higher than total power with statistically significance (p < 0.05 for 60, 120, 150, 180, 210, 270 and 300°/sec, p < 0.001 for 240 °/sec). Extra caution is required for correct interpretation of load range data in terms of considering the load range during limb movement. Evaluation of muscle performance of these adolescent wrestlers at regular intervals may give us an opportunity to obtain a healthy maturation profile of these adolescent wrestlers. Key PointsConsideration of load range for peak torque, work and power calculation resulted significant differences in the data presented by isokinetic dynamometer. Therefore evaluation of the dynamometer data required consideration of the load range for correct analysis and interpretation.Contraction velocity has critical importance in determining the load range attaining ability for a moving limb during load range evaluation. In fact alterations in contraction speed may be due to a number of changes in muscle morphology, subjects' age and the ratio between type I and type II muscle fiber area.