Muscle Oxygen Extraction is a Key Performance Adaptation in Sprint Canoe-Kayak
Bibliographic record
Abstract
BACKGROUND: The aerobic contribution to sprint canoe-kayak performance ranges from ~37% to ~85% of total energy expenditure from shortest (200m) to longest (1000m) events. While systemic VO2max is a strong predictor of performance in 500m and 1000m races, the respective role of central and peripheral adaptations is poorly understood. PURPOSE: The purpose of this study was therefore to characterize the changes in oxygenation derived from portable near-infrared spectroscopy (NIRS) in various muscles during a VO2max test and two on-water time trials (TT: 200m and 500m or 1000m), and to examine the link between muscle oxygenation, cardiac output and performance. METHODS: Twenty one well-trained sprint canoe-kayak athletes (12 men: 8 kayakers (MK) and 4 canoeists (MC); 9 women: 4 kayakers (WK) and 5 canoeists (WC)) participated in three testing sessions: 1) an incremental VO2max test on a canoe or kayak ergometer; 2) a 200-m TT; and 3) a 500-m (WK and WC) or 1000-m (MK and MC) TT. NIRS monitors were placed on the latissimus dorsi (LD), biceps brachii (BB), and vastus lateralis (VL) during the 3 testing sessions to assess changes in muscle O2 saturation (SmO2, % from baseline). Cardiac output was measured by impedance during the VO2max test in a subset of 9 athletes. RESULTS: Performance in the 200m time trial correlated with both LD final SmO2 (R=0.700, p=0.01) and VL final SmO2 (R=0.568, p=0.02). Performance during the 500-1000m time trials correlated with BB final SmO2 obtained during the VO2max test (R=0.519, p=0.033) and with VO2max (L/min: R=-0.560, p=0.03). Maximal cardiac output was low (men: 26.2 ± 4.7L/min, women: 24.0 ± 2.6 L/min) and did not correlate with 200m (R=0.253) or 500-1000m (R=0.028) performance. CONCLUSION: These results confirm that systemic VO2max is related to performance in the longer canoe-kayak events, and suggest that peripheral adaptations (i.e., the muscle ability to extract oxygen during the effort) rather than central factors better contribute to success in this sport. The ability to extract oxygen during the effort appears to be a predictor of performance for both short and long events. These results indicate that training for sprint canoe-kayak athletes should emphasize the development of the peripheral component of oxygen consumption.
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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 | 0.001 |
| 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) | 0.002 | 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".