Changes in masseter muscle blood flow during voluntary isometric contraction in humans

summary The effect of jaw clenching on local blood flow in the masseter muscle was measured using the hydrogen clearance method in 13 healthy subjects. Sustained isometric masseter‐muscle contraction levels of 25 and 50% of maximum voluntary contraction (MVC) were investigated. The blood flow at 25% MVC before contraction, during contraction and after contraction was 12·3 ± 10·9, 19·2 ± 12·1 and 78·8 ± 63·9 mL min−1 (100 g)−1 (mean ± s.d.), respectively. At 50% MVC, it was 14·2 ± 12·9, 18·6 ± 10·0 and 80·1 ± 61·8, respectively. The volume of blood flow was significantly greater after contraction as compared with before contraction at both levels (P