EFFECT OF VELOCITY ON ELBOW FLEXOR HYPERTROPHY FOLLOWING ECCENTRIC HIGH-RESISTANCE TRAINING IN YOUNG MALES
Bibliographic record
Abstract
Eccentric as opposed to concentric muscle actions recruit less motor units for a given load, which places a greater stress (i.e., force per active motor unit) on the muscle, resulting in greater muscle damage. Increasing the velocity of eccentric muscle actions also generates higher muscle forces, to a point, after which force plateaus. Performing eccentric actions at a higher velocity may maximize muscle stress, result in greater muscle damage and generate a greater stimulus for hypertrophy, versus slower eccentric actions. PURPOSE We wished to determine if the velocity of isokinetic eccentric muscle actions - FAST (3.66 rad/s) versus SLOW (0.35 rad/s) - had an impact on the degree of fibre hypertrophy of the elbow flexors during an 8 wk high-resistance training program. METHODS Young males (N=9, 25±5 yrs; means±SE) had their arms randomly assigned to be resistance trained (3d/wk × 8 wk; elbow flexion) on an isokinetic dynamometer at a FAST eccentric velocity, while their contralateral arm was trained using a SLOW velocity. Changes in the cross-sectional area (CSA) of muscle fibres were evaluated from muscle biopsy samples taken from both elbow flexors pre-training and post-training. Biopsies were stained using traditional ATPase histochemistry and analyzed using image analysis software. RESULTS Type I fibres showed significant hypertophy as a result of the protocol, but there was no difference between FAST and SLOW. Type II muscle fibre (IIx, IIa/x, IIa) CSA was increased as a result of the protocol, but the increase was significantly greater in the elbow flexors that performed FAST eccentric actions versus SLOW. For type IIx, IIa/x, and IIa fibres respectively: FAST: +31±5, +22±5 and +17±5 vs. SLOW: +9±5, +10±3 and +5±2\%, all p < 0.05. CONCLUSION A FAST eccentric contraction velocity, 10-fold greater than the corresponding SLOW eccentric velocity, produced a greater hypertrophic gain in elbow flexor fast twitch fibre CSA following 8 wk of isokinetic high-resistance training in young men. Supported by NSERC.
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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".