The Effect Of Exercise- And Passive-induced Heat Stress On The Autophagic Response In Older Adults
Bibliographic record
Abstract
Autophagy is vital for cell survival during acute physiological and environmental stress through the breakdown of damaged cellular constituents. In recent work, we showed that autophagy is activated in an intensity-dependent manner during aerobic exercise and passive heat stress in young adults, although older adults exhibit impaired heat-induced autophagic regulation. However, differences in autophagic activation associated with elevations in core temperature (Tco) induced by a passive (non-metabolic) and exercise-induced (metabolic) heat load remain unclear. PURPOSE: To assess the effect of equivalent elevations in Tco induced through exercise and warm-water immersion (WI) on autophagy in older males. METHODS: Nine older males (mean [SD] 70 [5] years) performed 30 min of vigorous semi-recumbent cycling at 70% of their pre-determined maximal oxygen consumption. Thereafter, on a separate day, participants were immersed to the clavicle in warm water for 30 min, with water temperature adjusted to induce an increase in Tco (indexed by rectal temperature) comparable to exercise. Proteins associated with autophagic activity (light chain 3 beta [LC3-II]) and autophagic initiation (Unc-51-like kinase 1 [ULK1]) were assessed before and after each respective exposure (exercise or WI) and during a 6-hour seated recovery in a temperate environment (~22 °C). Data were normalized to β-actin (expressed as a relative quantity [RQ] from baseline) and analyzed via a two-way repeated measures ANOVA with Bonferroni test (α=0.05). RESULTS: Tco increased similarly after 30-min (+0.77 [0.27] and +0.78 [0.35]°C, respectively; p=0.90) in both conditions, with both returning to baseline after 3 hours. End-exercise LC3-II was significantly higher than end-WI (2.43 RQ [0.97] vs 0.97 [0.52], respectively; p=0.01), as well as following 3h (3.38 RQ [2.15] vs 0.88 [0.49], respectively; p=0.02) and 6 h (3.86 RQ [3.00] vs 0.78 [0.44], respectively; p=0.02) of recovery. Conversely, ULK1 increased in response to exercise and WI, and remained elevated throughout the 6h recovery (time main effect: p=0.03). CONCLUSION: We showed that despite comparable elevations in autophagic initiation, exercise elicits greater activation of autophagy when compared to an equivalent increase in Tco induced by a passive heat stress in older males. Natural Sciences and Engineering Research Council of Canada and Mitacs
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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) | 0.001 | 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".