Posture Modifies Neuro‐Cardiac Heart Rate Responses at the Onset of Moderate Intensity Isometric Handgrip Exercise
Bibliographic record
Abstract
Background The heart rate (HR) response at the onset of moderate intensity isometric handgrip (IHG) exercise is related to neural control of the heart, primarily vagal withdrawal. If so, modest modifications in neuro‐cardiac function by postural shifts should modify the HR response to exercise. Objective This study examined the effect of supine versus seated postures on the changes in HR and heart rate variability (HRV) at the onset of IHG. Methods 13 healthy adults (24±3 years; 6 females) performed IHG at 35% and 50% of maximal voluntary contraction strength (MVC), each lasting 30 seconds and separated by at least one minute of rest. HR (electrocardiogram) and root mean square of successive differences (RMSSD) were recorded from the last 30 seconds of the 1 minute baseline prior to handgrip, and the last 10 seconds of each 30 second handgrip. Results Baseline HR increased from 68bpm to 76bpm (p<0.001; d=1) and RMSSD decreased from 56ms to 44ms (p=0.25; d=0.4) when shifting from supine to seated positions. Compared to the supine position, the ΔHR with 35% IHG decreased in the seated position (7bpm to 3bpm; p=0.01; d=0.71). Similarly, the ΔRMSSD with 35% IHG tended to be less in the seated versus supine positions (−31ms to −16ms; p=0.07; d=0.7). During 50% MVC work, the seated position exerted only a modest effect on the IHG‐induced ΔHR compared to supine (18bpm to 13bpm; p=0.06; d=0.47) whereas the ΔRMSSD from baseline to IHG was diminished in seated versus supine positions (−47ms to −22ms; p=0.001; d=0.78). Conclusion With RMSSD as an indicator of changes in cardiovagal influence, these preliminary results indicate that small changes in posture modify parasympathetic modulation of HR responses at the onset of moderate‐intensity isometric handgrip. Support or Funding Information Supported by the Natural Sciences and Engineering Research Council of Canada. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.001 | 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".