The effect of chronic resistance training on spinal excitability of the biceps brachii
Bibliographic record
Abstract
One major benefit of resistance training (RT) is increasing strength. However, the neurophysiological changes that chronic RT produces in the nervous system remain unclear. To address this, seventeen participants (9 males and 8 females) were recruited and divided into non-resistance and chronic resistance-trained groups to explore different levels of corticospinal tract excitability using a transcranial magnetic stimulation (TMS) that produces motor evoked potentials (MEP), and transmastoid electrical stimulation (TMES) that produces cervicomedullary evoked potentials (CMEP), and Erb’s point stimulation that produces maximal compound muscle action potentials (Mmax). All participants performed a maximum voluntary contraction (MVC) of the biceps brachii, followed by determining the stimulation intensities during a 20% MVC for TMS to achieve a 150-200ms silent period and TMES that produced a CMEP amplitude that was 75% of Mwave. The main task included five isometric elbow contractions at 25%, 50%, and 75% of MVC for eight seconds, with three stimulation techniques applied at 3, 4.5, and 6 seconds in a randomized order. Participants received a Mwave, five TMS, five TMES, and five conditioned TMES (100ms after MEP) at each contraction intensity. Data analysis using t-tests and two-way ANOVAs with contraction intensity and group and contraction intensity and sex as factors revealed that the chronic RT group required less TMS output to achieve the desired silent period (p=0.003) and had a lower active motor threshold (p<0.001). The chronic RT group exhibited 50% and 90.1% higher amplitude in conditioned and unconditioned CMEP, respectively compared to the non-RT group. Furthermore, males had 50.5% and 112.7% higher amplitudes in conditioned and unconditioned CMEP, respectively compared to females. In conclusion, chronic RT induces neurophysiological adaptations that alter the spinal excitability, showing that it is sex dependent. The alteration in corticospinal tract excitability may occur at the spinal motoneuron.
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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) | 0.002 | 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".