Isometric strength and thickness relationships in human quadriceps muscle.
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.
D000328:Adult; D001835:Body Weight; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*; D012727:Sex Characteristics; D014463:Ultrasonography