Isometric strength and thickness relationships in human quadriceps muscle

Abstract

The isometric Maximum Voluntary Contraction (MVC) of the right quadriceps femoris muscle was measured in 82 females and 58 males using a chair dynamometer and their mid-thigh quadriceps thickness was measured using real-time B-mode ultrasound. Statistically significant relationships (ranging from P < 0.001 to P < 0.0001) were found between quadriceps MVC, quadriceps thickness and body weight for both males and females. A significant inter-sex difference was present in the MVC-weight and MVC-thickness relationships, with males tending to have a higher MVC for a given body weight (P < 0.0001) and for a given muscle thickness (P < 0.0001). The inter-sex difference in the force-size relationship may relate to the previously demonstrated larger size of type 2b fibres and to the greater force generating capacity of these fibres compared with type 1 fibres.