Motor unit number estimates in world‐class masters athletes: is 80 the new 60?
Bibliographic record
Abstract
Despite age‐related loss of functioning motor units (MU), masters athletes (MA) in their 7th decade of life retained more MUs than recreationally active controls in the tibialis anterior (TA). It is unknown whether MAs beyond the 7th decade would show similar results. The purpose was to estimate the number of functioning MUs (MUNE) in world‐class, older male (n=4; 80 ± 5 y) and female (n=4; 80 ± 8 y) MAs ranging from 75 to 93 y. A maximal compound muscle action potential (CMAP) was recorded from the TA. Decomposition‐enhanced spike‐triggered averaging was used to analyze surface and intramuscular EMG from the TA during voluntary dorsiflexion contractions in order to derive a MUNE. For both sexes, CMAP was ~43% greater than previously reported in age‐matched normative data in males (6.7 ± 0.9 vs 4.7 ± 1.0 mV) (McNeil et al 2005), which may suggest a maintenance of excitable muscle mass in MAs. Mean surface MU potential (SMUP) size was similar between female MAs (64.3 ± 8.1 μV ) and normative data (78.2 ± 19.3 μV ), whereas male MAs had greater SMUP size than either group (138.0 ± 58.5 μV ). The resultant MUNE for female and male MAs was 100 ± 9 and 55 ± 24 MUs, respectively (p<0.05), with females but not males being higher than age norms. These preliminary results may indicate a sex‐specific protection of MUs in elite MAs >; 75 y of age, where MAs of both sexes may better maintain excitable muscle mass with aging. Supported by: CIHR (MOP 84408 to T.T.)
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.002 |
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".