Reducing Interval Length During Sprint Interval Training While Maintaining Total Exercise Time Improves Energy Expenditure
Bibliographic record
Abstract
Traditional sprint interval training (SIT; 4-6 x 30 sec “all-out” efforts with 4 min recovery periods) induces fat loss partially due to protracted increases in energy expenditure (EE). However, as performance benefits have been observed with shorter intervals (e.g. 10-15 sec), it is unknown if EE with such protocols is comparable to traditional SIT. PURPOSE: To examine the effects of manipulating sprint bout duration and recovery period length on EE using three SIT protocols with matched work-to-rest ratios (1:8). METHODS: Seven healthy males (age: 23.1±3.0 y; weight: 79.7±9.8 kg; VO2max: 48.8 ± 6.0 mlkg-1min-1) completed one control and three experimental sessions (with “all-out” running efforts): 1) 30:240 (4 x 30 sec efforts, 240 sec recovery); 2) 15:120 (8 x 15 sec efforts, 120 sec recovery); 3) 5:40 (24 x 5 sec efforts, 40 sec recovery); and 4) control no exercise (CTRL). All three SIT protocols involved 2 min of exercise and 16 min of recovery. Oxygen consumption (VO2) was measured continuously during and intermittently for 3 h post-exercise. EE was estimated from VO2 assuming 5 kcal per L O2 consumed. RESULTS: All three SIT protocols elicited greater EE during (P<0.001) and for 3 h post-exercise (P<0.01) compared to CTRL. EE during 5:40 (208.9±25.0 kcal) was greater (P<0.001) compared to both 15:120 (166.7±19.2 kcal) and 30:240 (138.8±18.0 kcal), while 15:120 was also greater than 30:240 (P<0.001). EE during the first hour post-exercise was not different between 30:240 (121.2±16.7 kcal) and both 15:120 (126.8±12.5 kcal; P=0.443) and 5:40 (110.6±11.0 kcal; P=0.081), though 15:120 was greater compared to 5:40 (P=0.007). EE during both the second (5:40, 97.8±6.7 kcal; 15:120, 100.7±8.3; 30:240, 98.3±6.4) and third (5:40, 92.9±7.2 kcal; 15:120, 97.7±7.1; 30:240, 95.8±7.3) hour post-exercise was not different between protocols (P>0.088). Total EE during the 3 h post-exercise period was not different (P<0.280) between 15:120 (325.3±27.0 kcal) and 30:240 (315.3±25.4 kcal) though both were greater (P=0.032) compared to 5:40 (301.3±22.9 kcal). CONCLUSION: These results suggest that modified SIT protocols with shorter work bouts (5-15 s) promote greater increases in EE during exercise, as well as comparable EE post-exercise compared to traditional SIT.
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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) | 0.001 | 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) | 0.002 | 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".