Velocity-specific knee strength between professional and under-17 female volleyball players

Alexandre R M Pelegrinelli; Laís F Dela Bela; Mariana F Silva; Lucas C R Rodrigues; João P Batista Jr; Leandro C Guenka; Josilainne M Dias; Lee E Brown; Rodrigo L Carregaro; Felipe A Moura; Jefferson R Cardoso

doi:10.4102/sajp.v75i1.478

Velocity-specific knee strength between professional and under-17 female volleyball players

S Afr J Physiother. 2019 Jun 11;75(1):478. doi: 10.4102/sajp.v75i1.478. eCollection 2019.

Affiliations

¹ Laboratory of Biomechanics and Clinical Epidemiology, Research Group in Physical Therapy Assessment and Intervention (PAIFIT), Universidade Estadual de Londrina, Londrina, Brazil.
² Laboratory of Applied Biomechanics, Universidade Estadual de Londrina, Londrina, Brazil.
³ Department of Geriatric Medicine, Uniklinik - Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University Hospital, Aachen, Germany.
⁴ Department of Kinesiology, California State University, Fullerton, United States.
⁵ School of Physical Therapy, Universidade de Brasília, Brasília, Brazil.

Abstract

Background: Many studies have investigated isokinetic performance in volleyball players but not through surface maps.

Objectives: The goals of this study were to assess velocity-specific isokinetic knee extensor-flexor muscle strength and to compare the isokinetic knee extensor-flexor muscles between professional (PRO) and under-17 (U17) female volleyball players.

Method: This cross-sectional laboratory study was developed with two groups: PRO (n = 12), median_age = 21.3 years, and U17 (n = 9), median_age = 15 years. Peak torque, total work, mean power, angle of peak torque, hamstring-quadriceps torque ratio (H-Q ratio) and torque-angle-velocity surface maps were analysed from knee extension-flexion at 60, 120 and 300 degrees per second (°/s).

Results: Significant differences were identified for extensor peak torque between PRO x = 202.3 Newton metre (N·m) (standard deviation [SD] = 24.4) and U17 x = 141.6 N·m (30.1) at 60 °/s (p < 0.001; d = 2.21) as well as flexor peak torque (PRO x = 75.7 N·m [10.3] and U17 x = 57.7 N·m [11.4]) at 120 °/s (p < 0.001; d = 1.65) for the dominant limb. There were also significant group differences for total work and mean power at all velocities for extension and flexion. Surface maps demonstrated higher torque at lower speeds for both groups with smaller torque changes across velocities for flexion.

Conclusion: Different groups of female volleyball players showed contrasting concentric knee muscle strength across isokinetic velocities.

Clinical implications: These results demonstrate the importance of specific strength training for different age groups, even within the same sport, and provide insight into muscle strength.

Keywords: dynamometer; knee; muscle strength; sports; volleyball.