Muscle sympathetic nerve activity at rest compared to exercise tolerance.

Cardiovascular autonomic function is associated with physical performance and exercise training adaptation. The association between physical performance and sympathetic regulation is not well known. We hypothesized that sympathetic nervous system activity is associated with physical performance among male runners. The study population included 26 healthy male club runners [age 33 +/- 5 years, body mass index (BMI) 24 +/- 1 kg/m(2), VO(2max) 58 +/- 5 ml kg(-1) min(-1); mean +/- SD]. Muscle sympathetic nerve activity (MSNA) was assessed from the peroneal nerve by the microneurography technique during 5 min of supine rest. Physical performance was assessed by time to exhaustion during treadmill running. The mean resting MSNA was 20 +/- 6 bursts min(-1) (range 6-34). The mean time to exhaustion was 1,005 +/- 136 s (range 720-1260). When the study group was divided into tertiles according to their running performance (866 +/- 69, 994 +/- 30 and 1154 +/- 71 s in time to exhaustion, P < 0.0001 between the groups), MSNA was lower (P = 0.032) in the group with the best running performance (16 +/- 5 bursts min(-1)) compared to those with the worst running performance (23 +/- 7 bursts min(-1)). In conclusion, baseline sympathetic activity, measured by a microneurography at rest, may be associated with the maximal running performance of healthy subjects.