# Influence of the Knee and Hip Joint Angles on the Knee Extensor Muscles and Tendon Shear Wave Velocity in Men and Prepubertal Boys

## TL;DR

This study compares how knee and hip angles affect muscle and tendon stiffness in men and prepubertal boys.

## Contribution

The study reveals age-specific differences in tendon shear wave velocity under varying joint angles.

## Key findings

- Boys and men showed similar shear wave velocity in the vastus lateralis and rectus femoris muscles.
- Boys had significantly lower patellar tendon shear wave velocity than men at knee angles from 30° to 90°.
- Hip angle interacted with knee angle to influence rectus femoris stiffness, with higher values at 0° hip extension.

## Abstract

This study aimed to compare the influence of the knee and hip joint angles on the quadriceps muscles and tendon shear wave velocity (SWV) between men and prepubertal boys.

Ten prepubertal boys and ten men participated in one experimental session, which included SWV measurements at rest for the vastus lateralis (VL), the rectus femoris (RF), and the patellar tendon (PT). Each volunteer was tested in ten randomized positions, including five knee joint angles (30, 50, 70, 90, and 110°, 0° = full extension) and two hip joint angles (0° and 80°, 0° = full extension). The SWV values were analyzed independently with a three‐way ANOVA, while considering the knee angle, hip angle, and the age group.

Significant knee angle × age interactions were observed for VL (p = 0.008), RF (p = 0.008), and PT (p < 0.001). Boys and men did not present a difference in VL and RF SWV. However, boys exhibited significantly lower PT SWV values than men from a 30° to 90° knee flexion angle (p < 0.001). Additionally, a hip angle × knee angle interaction (p < 0.001) has been observed for RF SWV and highlighted greater values with a 0° hip joint angle, whatever the knee joint angles.

These results suggested that boys and men present similar muscle elastic properties in VL and RF. However, lower SWV was observed for PT in boys up to 90° knee joint flexion.