Arm and intensity-matched leg exercise induce similar inflammatory responses

Introduction: The amount of active muscle mass can influence the acute inflammatory response to exercise, associated with reduced risk for chronic disease. This may affect those restricted to upper body exercise, for example due to injury or disability. The purpose of this study was to compare the inflammatory responses for arm exercise and intensity-matched leg exercise. Methods: Twelve male individuals performed three 45-min constant load exercise trials following determination of peak oxygen uptake for arm exercise (V[Combining Dot Above]O2peak A) and cycling (V[Combining Dot Above]O2peak C): (1) arm cranking exercise at 60%V[Combining Dot Above]O2peak A; (2) moderate cycling at 60%V[Combining Dot Above]O2peak C; and (3) easy cycling at 60%V[Combining Dot Above]O2peak A. Cytokine, adrenaline and flow cytometric analysis of monocyte subsets were performed before and up to 4h post exercise. Results: Plasma IL-6 increased from resting concentrations in all trials, however, post exercise concentrations were higher for arm exercise (1.73+/-1.04pg[BULLET OPERATOR]mL-1) and moderate cycling (1.73+/-0.95pg[BULLET OPERATOR]mL-1) compared with easy cycling (0.87+/-0.41pg[BULLET OPERATOR]mL-1,P<0.04). Similarly, the plasma IL-1ra concentration in the recovery period was higher for arm exercise (325+/-139pg[BULLET OPERATOR]mL-1) and moderate cycling (316+/-128pg[BULLET OPERATOR]mL-1) when compared with easy cycling (245+/-77pg[BULLET OPERATOR]mL-1,P<0.04). Arm exercise and moderate cycling induced larger increases in monocyte numbers and larger increases of the classical monocyte subset in the recovery period than easy cycling (P<0.05). The post-exercise adrenaline concentration was lowest for easy cycling (P=0.04). Conclusions: Arm exercise and cycling at the same relative exercise intensity induces a comparable acute inflammatory response; however, cycling at the same absolute oxygen uptake as arm exercise results in a blunted cytokine, monocyte and adrenaline response. Relative exercise intensity appears to be more important to the acute inflammatory response than modality, which is of major relevance for populations restricted to upper body exercise.