Evidence of centrally‐induced cholinergic vasodilatation in skeletal muscle during voluntary one‐legged cycling and motor imagery

Centrally‐induced vasodilatation occurs in non‐contracting vastus lateralis muscle (VL) at the onset of voluntary one‐legged cycling (Ishii et al. J Appl Physiol , 2012). To test whether the vasodilatation is mediated by a cholinergic mechanism in humans, seven subjects were asked to perform voluntary one‐legged cycling and motor imagery of the one‐legged cycling before and after intravenous injection of atropine sulfate. The concentration of oxygenated‐hemoglobin (Oxy‐Hb) in the bilateral VLs was measured as an index of muscle blood flow with near‐infrared spectroscopy. The Oxy‐Hb increased not only the non‐contracting VL but also the contracting VL at the onset of voluntary one‐legged cycling. Atropine blunted the increases in the Oxy‐Hb of both non‐contracting and contracting VL. Furthermore, motor imagery of the one‐legged cycling induced increases in the Oxy‐Hb of bilateral VLs, which were decreased by atropine. These results suggest that centrally‐induced cholinergic vasodilatation occurs in both non‐contracting and contracting skeletal muscle during voluntary exercise and motor imagery.