Lower Neurohemodynamic Transduction In Young Females Versus Males With Similar Aerobic Fitness And Sympathetic Outflow
Bibliographic record
Abstract
Conflicting reports exist as to whether younger females have similar, or smaller, pressor responses to spontaneous bursts of resting muscle sympathetic nerve activity (MSNA) compared to age-matched males. Greater aerobic fitness and higher resting MSNA burst frequency are associated with blunted sympathetic neurohemodynamic transduction in younger males. As such, variations in aerobic fitness and resting sympathetic outflow may be contributing factors related to these inconsistent findings concerning sex differences in sympathetic transduction. PURPOSE: To compare sympathetic neurohemodynamic transduction between younger females and males matched for age, aerobic fitness and resting MSNA burst frequency. METHODS: On separate days, relative peak oxygen consumption (V̇O2peak; via graded cycle ergometry) and supine resting peroneal MSNA recordings (via microneurography) were originally assessed in 14 females and 25 males. Twelve females (24 ± 6 yrs, 36.0 ± 4.8 ml/kg/min, 12 ± 5 bursts/min) and 12 males (27 ± 8 yrs, 37.2 ± 5.2 ml/kg/min, 13 ± 5 bursts/min) were subsequently matched based on relative V̇O2peak and resting MSNA burst frequency. Beat-by-beat mean arterial blood pressure (MAP; via finger photoplethysmography) was simultaneously recorded during the microneurography sessions. Absolute changes in MAP were tracked for 12 cardiac cycles following each burst of MSNA. The average peak increases in MAP were used to quantify sympathetic neurohemodynamic transduction. RESULTS: In addition to relative V̇O2peak (P = 0.567) and MSNA burst frequency (P = 0.477), no sex differences were observed in burst incidence (Females: 19 ± 7 versus Males: 23 ± 10 bursts/100 heartbeats, P = 0.273) or resting MAP (Females: 80 ± 7 mmHg versus Males: 85 ± 10 mmHg, P = 0.218). However, females exhibited blunted peak MAP (1.4 ± 0.7 mmHg) responses to spontaneous MSNA bursts compared to males (2.2 ± 1.0 mmHg, P = 0.035). CONCLUSION: These findings suggest that the lower sympathetic neurohemodynamic transduction observed in younger females was independent of corresponding variations in aerobic fitness and resting sympathetic outflow. Whether blunted pressor responses to MSNA bursts in females are related to the vascular protective effects of estrogen warrant further investigation.
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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 | 0.000 |
| 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 | 0.001 |
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".