Forearm endurance training attenuates sympathetic nerve response to isometric handgrip in normal humans

V. K. Somers, K. C. Leo, R. Shields, M. Clary, A. L. Mark

Research output: Contribution to journalArticlepeer-review

69 Scopus citations

Abstract

Recent evidence indicates that muscle ischemia and activation of the muscle chemoreflex are the principal stimuli to sympathetic nerve activity (SNA) during isometric exercise. We postulated that physical training would decrease muscle chemoreflex stimulation during isometric exercise and thereby attenuate the SNA response to exercise. We investigated the effects of 6 wk of unilateral handgrip endurance training on the responses to isometric handgrip (IHG: 33% of maximal voluntary contraction maintained for 2 min). In eight normal subjects the right arm underwent exercise training and the left arm sham training. We measured muscle SNA (peroneal nerve), heart rate, and blood pressure during IHG before vs. after endurance training (right arm) and sham training (left arm). Maximum work to fatigue (an index of training efficacy) was increased by 1,146% in the endurance-trained arm and by only 40% in the sham-trained arm. During isometric exercise of the right arm, SNA increased by 111 ± 27% (SE) before training and by only 38 ± 9% after training (P < 0.05). Endurance training did not significantly affect the heart rate and blood pressure responses to IHG. We also measured the SNA response to 2 min of forearm ischemia after IHG in five subjects. Endurance training also attenuated the SNA response to postexercise forearm ischemia (P = 0.057). Sham training did not significantly affect the SNA responses to IHG or forearm ischemia. We conclude that endurance training decreases muscle chemoreflex stimulation during isometric exercise and thereby attenuates the sympathetic nerve response to IHG.

Original languageEnglish (US)
Pages (from-to)1039-1043
Number of pages5
JournalJournal of applied physiology
Volume72
Issue number3
DOIs
StatePublished - Jan 1 1992

Keywords

  • autonomic nervous system
  • exercise
  • physical training

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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