New field ergometer to reproducibly measure maximum strength and rate of force development of hamstrings

Objectives. - Hamstring strain injuries are common in sprint-based activities and multifactorial. One of the main risk factors is the deficit of hamstring eccentric strength, which is not easily assessed in field conditions. Therefore, a new ergometer named ``Hamtech'' has been developed to accurately and practically assess hamstring force output. The aim of this study was to test the reproducibility of this novel ergometer during maximal isometric and eccentric contractions. Materials and methods. - Thirteen soccer players (age: 20.7 +/- 1.6 years; stature: 178.1 +/- 4.9 cm; body mass: 72.1 +/- 6.3 kg) were recruited. After two familiarization sessions, hamstring force production was recorded during maximal isometric and eccentric contractions using the Hamtech. The coefficients of variations and intra-class correlations coefficients were used to quantify reproducibility. Results. - This ergometer allows reproducible measurements of unilateral (isometric + eccentric) and bilateral (eccentric) peak force. However, the reproducibility was moderate to good (unilateral) and poor (bilateral) for the knee angle at the eccentric peak force. A good reproducibility was observed for the rate of force development at 200-ms during maximal isometric contractions. The Hamtech offers a simple and reproducible solution to measure hamstring force production during isometric and eccentric contractions. The use of unilateral hamstring muscles at long muscular length might provide a valuable alternative to the classical bilateral condition to assess the hamstring force production. (c) 2022 Published by Elsevier Masson SAS.