Comparison of the Eccentric Exercise Effects on the Myotendinous Elastic Properties between Men and Prepubertal Boys: A Shear Wave Elastography Study.

Abstract

This study aimed to compare the effects of a fatiguing eccentric exercise on the myotendinous elastic properties between men and prepubertal boys. Ten prepubertal boys and 10 men performed a fatiguing exercise composed of five sets of 20 maximal isokinetic eccentric contractions of the knee extensors. Before the exercise, the elastic properties of the vastus lateralis, the rectus femoris (RF), and the patellar tendon were assessed using shear wave elastography to measure the shear wave velocity (SWV). These measurements were repeated immediately after the exercise (Post), 30 min after (Post 30 min), and 48 h after (Post 48 h). A significant time effect was observed for SWV vastus lateralis ( P = 0.005), but no difference was revealed by the post hoc tests. A significant time × age interaction ( P = 0.05) was observed for SWV RF and revealed an increase at Post ( P = 0.004; + 24.37% ± 36.67) and Post 30 min ( P = 0.010) compared with Pre for men, while no modification was observed for boys (Post: P = 1.000; + 0.86% ± 16.92). For patellar tendon, a significant time effect was observed ( P < 0.001) and revealed an increase from Pre at Post ( P < 0.001) and Post 30 min ( P = 0.002), whatever the age group. The alterations of the myotendinous elastic properties after an eccentric exercise were age dependent. Indeed, they were only observed in the tendon tissue in boys, while they were observed in the RF and tendon tissues in men.