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Effect of isometric handgrip exercise on heart rate variability with and without somatosensory stimulation
Author(s) -
Baker Jacquie,
Shoemaker Kevin J
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.lb833
Subject(s) - isometric exercise , heart rate , heart rate variability , medicine , stimulation , somatosensory system , skeletal muscle , cardiology , chemistry , blood pressure , psychiatry
Sub‐motor somatosensory electrical stimulation (STIM) of skeletal muscle increases heart rate variability (HRV). Short duration (<30 sec) isometric handgrip exercise (HG) increases heart rate (HR) and decreases HRV largely through vagal withdrawal. The current study aimed to determine whether a gated effect exists when HG and STIM are combined. We tested the hypothesis that changes due to STIM would dominate over HG induced changes. Twelve volunteers (7 female; aged 24±2 yr.) performed 3 protocols: 1) four × 20s HG at 30, 40 & 50% of their maximal voluntary contraction (MVC), 2) seven × 30s STIMs, and 3) a combination of HG+STIM. Compared to rest, STIM increased HRV (Rest: 61±80ms 2 , STIM: 69±84ms 2 , p<0.05). In contrast, HRV decreased at all HG levels (ΔHRV@30%: −39±51ms 2 , 40%: −29±39ms 2 , 50%: −25±39ms 2 ). The effects of HG were reversed during HG+STIM (ΔHRV@30%STIM: −1.7±40ms 2 , 40%STIM: 5.5±37ms 2 , 50%STIM: −4.2±19ms 2 , p<0.05). Heart rate did not change during STIM (Rest: 59±7bpm; STIM: 58±6bpm). However HR increased above baseline and progressively at each level of HG (50% vs. 30%, p<0.001; 50% vs. 40%, p<0.001; 40% vs. 30%, p<0.05). Heart rate was not different between HG and HG+STIM, p=0.095. The results indicate somatosensory stimulation can reverse the changes in HRV induced by handgrip suggesting muscle afferent signals may gate descending signals affecting heart rate variability. Funded by CIHR.