Effect of resistance taming on sympathetic nervous function in humans

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Resistance training develops not only muscular strength but also improving physiological function such as autonomic control system. However, rationale or the mechanisms are not clear. A goal of this project was to investigate how resistance-training influence muscle sympathetic nerve activity (MSNA) and cardiovascular response during exercise.High intensity handgrip exercise was used as resistance training. Unilateral (nondominant arm) handgrip training, which composed 3 set of 14 times of 10-sec maximal voluntary isometric contraction, was performed three days per week for 4 weeks. The training lead to increased maximal handgrip force in trained as well as untrained arm.Heart rate and MSNA response during 10 times intermittent static handgrip for 15 seconds performed with voluntary maximum effort was investigated before and after training. After training heart rate response to the handgrip increased for trained arm exercise and also for untrained arm exercise. MSNA was increased durin … More g contractions of either trained or untrained arm and the onset of the response was earlier than that before training. This suggests that cardiovascular and sympathetic nervous response may be due to central command that was generated in the higher brain center rather than muscle reflex.Effect of resistance training on muscle metaboreflex was tested during two minutes post exercise arterial occlusion followed rhythmic handgrip for one minute performed with maximal effort under the forearm ischemia. Although before training dominant arm exercise had a greater metaboreflex MSNA response than that of nondominant armor The MSNA response for trained arm (nondominant arm), but not untrained arm (control side) enhanced after training, while the size of response was not different between the arms.This study demonstrated that resistance training have great effect on heart rate and sympathetic nervous system. From these results suggest that strong exercise effort even if active muscle mass was small involved during exercise play an important role to cardiovascular control system. Less