Greater Fatigability In Older Than Younger Men Is Related To The Rate Of Velocity Development
Bibliographic record
Abstract
It is unclear why older adults are usually less fatigable during isometric tasks, but are more fatigable during fast isotonic-like dynamic tasks when compared with younger adults. Potentially important factors related to contractile performance differences between younger and older adults that have not been well-explored are rate of torque development (RTD) and rate of velocity development (RVD) during voluntary dynamic contractions. PURPOSE: To investigate age-related differences in fatigability during fast high-intensity dynamic plantar flexions and to assess whether there is a relationship between the expected greater age-related reduction in peak power and either RVD or RTD, or both. METHODS: Neuromuscular properties were recorded from 10 old (∼78 years) and 10 young (∼24 years) men prior to, during, and following fifty maximal-effort dynamic unconstrained velocity plantar flexions against a resistance equivalent to 20% of maximal voluntary isometric contraction torque. RESULTS: Peak power, peak angular velocity, and concentric torque decreased by 30.4 ± 13.2%, 19.7± 6.9%, and 13.6 ± 9.0%, respectively, for the young (p < 0.05), and 45.8 ± 8.8%, 27.0 ± 5.9%, 28.5 ± 15.1%, respectively, for the old (p < 0.05) by the end of the task. RVD and RTD decreased by 23.8 ± 11.6 % and 24.5 ± 10.5 % in the young, respectively, and 39.7 ± 7.9 % and 47.7 ± 13.6 % for the old, respectively. For all parameters reported above, decreases were greater in the old than young (p < 0.05). The reduction in peak power was strongly related to a reduction in RVD (R2 = 0.92, p < 0.05) and peak velocity (R2 = 0.83, p<0.05), but only a moderate relationship was found between a reduction in peak power and reductions in RTD (R2 = 0.69, p < 0.05) and torque (R2 = 0.52, p < 0.05). CONCLUSIONS: Compared with the young, the old men exhibited greater fatigability, characterized by a larger decline in peak power. This reduction in power was strongly associated with a reduction in RVD and peak velocity, but only moderately associated with the torque-dependent measures. Thus, RVD likely reflects key factors contributing to peak power loss when performing a repetitive dynamic fatigue task in older adults.
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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".