Change in Central Cardiovascular Function in Response to Intense Interval Training: A Systematic Review and Meta-analysis
Bibliographic record
Abstract
INTRODUCTION: High-intensity interval training and sprint interval training significantly increase maximal oxygen uptake (V̇O 2max ), which enhances endurance performance and health status. Whether this response is due to increases in central cardiovascular function (cardiac output (CO) and blood volume) or peripheral factors is unknown. PURPOSE: This study aimed to conduct a systematic review and meta-analysis to assess the effects of high-intensity interval training and sprint interval training (referred to as intense interval training) on changes in central cardiovascular function. METHODS: We performed a systematic search of eight databases for studies denoting increases in V̇O 2max in which CO, stroke volume (SV), blood volume, plasma volume, end-diastolic/systolic volume, or hematocrit were measured. RESULTS: Forty-five studies were included in this analysis, comprising 946 men and women of various health status (age and V̇O 2max , 20-76 yr and 13-61 mL·kg -1 ·min -1 ) who performed 6-96 sessions of interval training. Results showed an increase in V̇O 2max with intense interval training that was classified as a large effect ( d = 0.83). SV ( d = 0.69), and CO ( d = 0.49) had moderate effect sizes in response to intense interval training. Of 27 studies in which CO was measured, 77% exhibited significant increases in resting CO or that obtained during exercise. Similarly, 93% of studies revealed significant increases in SV in response to intense interval training. Effect sizes for these outcomes were larger for clinical versus healthy populations. Plasma volume, blood volume, and hematocrit had small effect sizes after training ( d = 0.06-0.14). CONCLUSIONS: Increases in V̇O 2max demonstrated with intense interval training are attendant with increases in central O 2 delivery with little contribution from changes in hematocrit, blood volume, or plasma volume.
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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 | 0.011 | 0.026 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.018 | 0.026 |
| Bibliometrics | 0.005 | 0.007 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| 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".