Premium
Effect of Sex on Muscle Sympathetic Nerve Responses to Static and Dynamic Exercise
Author(s) -
Notay Karambir,
Doherty Connor J.,
Incognito Anthony V.,
Burns Matthew J.,
Nardone Massimo,
Seed Jeremy D.,
Millar Philip J.
Publication year - 2017
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.31.1_supplement.1056.7
Subject(s) - microneurography , heart rate , medicine , blood pressure , cardiology , cycling , sympathetic nervous system , physical therapy , physical medicine and rehabilitation , baroreflex , archaeology , history
Previous studies investigating sex differences in sympathetic outflow during exercise have produced conflicting results, demonstrating either similar or attenuated increases in muscle sympathetic nerve activity (MSNA) during static handgrip in women. Further, to our knowledge, no studies have investigated whether MSNA responses to low‐to‐moderate intensity dynamic leg exercise, a stimulus which decreases sympathetic outflow, differs between men and women. Therefore, the purpose of the present study was to examine the effect of sex on MSNA responses to static handgrip and dynamic one‐legged cycling. Heart rate (HR), mean arterial pressure (MAP), and MSNA (left fibular nerve; microneurography) were measured continuously in 9 men (22±3 yrs) and 9 women (21±3 yrs) at rest and during 2 minutes of static handgrip (30% maximal voluntary contraction), unloaded one‐legged cycling, and moderate intensity one‐legged cycling (30% of peak power output) in the recumbent position. All cycling was performed with the right leg using a modified arm ergometer. Static and dynamic exercise were separated by 10 minutes of rest. All variables were assessed as the change (Δ) from baseline to the second minute of exercise. Resting HR and MAP were similar between men and women (Both p>0.05) whereas MSNA burst frequency was higher in men (28±6 vs. 23±4; p=0.03). During static handgrip, the increases in HR (Δ11±8 vs. 9±7 bpm; p=0.55), MAP (Δ21±7 vs. 16±4 mmHg; p=0.10), MSNA burst frequency (Δ4±5 vs. 8±9 bursts/min, p=0.26), and total MSNA (Δ11±12 vs. 4±5 a.u./min; p=0.18) were similar between men and women. During one‐legged cycling, changes in HR (unloaded: Δ10±7 vs. 8±5 bpm, p=0.49; loaded: Δ23±6 vs. 23±5 bpm, p=0.94), MAP (unloaded: Δ8±4 vs. 6±5 mmHg, p=0.45; loaded: Δ12±6 vs. 11±4 mmHg, p=0.86), MSNA burst frequency (unloaded: Δ−5±4 vs. −3±4 bursts/min, p=0.39; loaded: Δ−3±8 vs. −1±6 bursts/min, p=0.70), and total MSNA (unloaded: Δ0±3 vs. −3±3 a.u./min, p=0.07; loaded: Δ1±4 vs. 0±4 a.u./min, p=0.36) were comparable between men and women. In summary, these results suggest that sex does not impact muscle sympathetic or blood pressure responses to moderate intensity static handgrip or dynamic one‐legged cycling. Support or Funding Information This research was supported by a Natural Science and Engineering Research Council (NSERC) of Canada Discovery Grant (P.J.M), the Canada Foundation for Innovation (P.J.M.), and a Canadian Institutes of Health Research Fredrick Banting and Charles Best Canada Graduate Scholarship (A.V.I.).