Changes In Corticospinal Excitability During Repeated Sprint Exercise In Hypoxia And With Blood Flow Restriction
Bibliographic record
Abstract
PURPOSE: The purpose of the study was to examine the effects of repeated cycling sprints performed to exhaustion under conditions of normoxia, hypoxia, and blood flow restriction on corticospinal excitability. METHODS: Ten subjects (27.7 ± 3.3 yrs, body height 171.8 ± 4.3 cm, body mass 68.9 ± 11.8 kg) performed repeated sprint exercise until exhaustion on a recumbent bike in 4 conditions (normoxia at sea-level, N; normoxia with 45% of total resting blood flow restriction, N-BFR; normobaric hypoxia simulating 3800 m, H; H with 45% BFR, H-BFR). At time points (pre, every 5 sprints, immediately post, and 3 min post exercise), pedals were blocked, and voluntary contractions were performed at three targeted percentages (100, 75, and 50%) of maximum voluntary isometric contractions (MVIC) where transcranial magnetic stimulation was used to assess corticospinal excitability/inhibition with measurements of motor evoked potential (MEP) and silent period (SP) from the vastus lateralis. MEP was normalized to the M-wave to account for changes in peripheral factors. RESULTS: Only main effects of condition (average of time points) resulted with MEP/Mmax area displayed across different MVIC percentages in the figure. MEP/Mmax area for H was less than N no matter the MVIC level (all p < 0.05). MEP/Mmax area for H-BFR was less than in N for 100 and 75% (all p < 0.001), and less than N-BFR for 50% (p < 0.01). SP was longer for all force levels in N-BFR than N (269 ± 42, 225 ± 22 ms, respectively, all p < 0.05), and for 75% MVIC in H-BFR than H (252 ± 85, 209 ± 12 ms, respectively, p < 0.05). SP was shorter for all force levels in H than N-BFR (212 ± 28, 269 ± 42 ms, respectively, all p < 0.001), and for 100% and 50% in H-BFR than N-BFR (220 ± 21, 267 ± 43 ms, respectively, all p < 0.01). CONCLUSIONS: Lower MEP/Mmax in H and H-BFR suggests that hypoxia led to decreased corticospinal excitability. Additionally, longer SP in BFR suggests greater inhibition, while shorter SP in H warrants further investigation.
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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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".