Effect of Sex on Muscle Sympathetic Nerve Responses to Static and Dynamic Exercise
Bibliographic record
Abstract
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.).
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".