Skeletal Muscle Metabolic and Performance Adaptations After Short Sprint Interval Training (SIT).
Bibliographic record
Abstract
0152 Recent work by our group showed that 6 bouts of SIT over 2 wks dramatically improved cycle endurance capacity, such that mean time to exhaustion increased from ∼25 to 51 min during exercise at 80%VO2peak (Hughes et al., Med. Sci. Sports Exerc., 35:S337, 2003). PURPOSE: We examined the effect of SIT on: (1) skeletal muscle metabolic adaptations during an incremental cycle exercise Challenge Ride (CR); and (2) since many events require athletes to complete a fixed amount of work in as short a time as possible (i.e., a race), we assessed changes in Time Trial (TT) performance. METHODS: 8 recreationally active men (21.1±0.5 yr) performed 6 sessions of SIT (6 bouts × 4–7 “all out” 30-sec Wingate tests, separated by 4 min of recovery) over a 2 wk period. Before and 2–3 d following the SIT protocol, subjects completed (1) a CR that consisted of 10 min @ 50% followed by 10 min @ 80%VO2peak, and biopsies were obtained at rest and after each workload; and (2) a 250 kJ selfpaced TT on a cycle ergometer with no temporal, verbal or physiological feedback. Extensive familiarization trials were performed prior to the study, and method error reproducibility (CV) for the TT was 5.5% when subjects were tested 1 wk apart with no SIT intervention (Day 1: 16.8±2.1 vs Day 2: 17.1±1.4 min). RESULTS: The maximal activity of citrate synthase was 18% higher after SIT (Post: 11.8 ± 0.4 vs Pre: 10.0 ± 0.8 mmol·kg−1·min−1 wet wt., P<0.05). Resting muscle [glycogen] increased by 53% after SIT (Post: 377±21 vs Pre: 247±14 mmol·kg−1 dry wt., P<0.05). Net muscle glycogenolysis was lower during the CR after SIT, and muscle [lactate] was reduced after 10 and 20 min of exercise (P<0.05). TT performance improved by 10.4% (Post: 15.3±1.5 vs Pre: 17.3±2.7 min) and average power increased from 247±37 to 272±24 W (both P<0.05). CONCLUSION: 6 sessions of SIT performed over 2 wks (∼15 min total exercise time) increased muscle oxidative capacity and altered muscle glycogen metabolism during exercise in recreationally active young men. SIT appeared to decrease reliance on non-oxidative energy metabolism during cycling at a given absolute load (CR), and decreased the time required to complete a fixed amount of work (TT). Supported by NSERC Canada, an ACSM Research Endowment Grant, and a Gatorade Sports Science Institute Student Research Award (KAB).
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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 | 0.001 |
| 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".