Effect of sex on the acute skeletal muscle response to sprint interval exercise
Bibliographic record
Abstract
New Findings What is the central question of this study? Are there sex‐based differences in the acute skeletal muscle response to sprint interval training (SIT)? What is the main finding and its importance? In response to a SIT protocol that involved three 20 s bouts of ‘all‐out’ cycling, the expression of multiple genes associated with mitochondrial biogenesis, metabolic control and structural remodelling was largely similar between men and women matched for fitness. Our findings cannot explain previous reports of sex‐based differences in the adaptive response to SIT and suggest that the mechanistic basis for these differences remains to be elucidated. A few studies have reported sex‐based differences in response to several weeks of sprint interval training (SIT). These findings may relate to sex‐specific responses to an acute session of SIT. We tested the hypothesis that the acute skeletal muscle response to SIT differs between sexes. Sedentary but healthy men ( n = 10) and women ( n = 9) were matched for age (22 ± 3 versus 22 ± 3 years old) and cardiorespiratory fitness [45 ± 7 versus 43 ± 10 ml O 2 (kg fat‐free mass) −1 min −1 ], with women tested in the mid‐follicular phase of their menstrual cycles. Subjects performed three 20 s ‘all‐out’ cycling efforts against a resistance of 5% of body mass, interspersed with 2 min of recovery. Relative mean power outputs [7.6 ± 0.5 versus 7.5 ± 0.9 W (kg fat‐free mass) −1 ] were similar between men and women ( P > 0.05). Furthermore, there were no differences in the exercise‐induced changes in mRNA expression of PGC‐1α , PRC , PPARD , SIRT1 , RIP140 , HSL , HKII , PDK4 , PDP1 , FOXO3 , MURF‐1 , Myf5 , MyoD and VEGFA at 3 h of recovery versus rest ( P < 0.05, main effect of time). The only sex‐specific responses to exercise were an increase in the mRNA expression of GLUT4 and LPL in women only and Atrogin‐1 in men only ( P < 0.05). Women also had higher expression of HKII and lower expression of FOXO3 compared with men ( P < 0.05, main effect of sex). We conclude that the acute skeletal muscle response to SIT is largely similar in young men and women. The mechanistic basis for sex‐based differences in response to several weeks of SIT that has been previously reported remains to be elucidated.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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".