Leg Muscle Strength, Area And Contraction Velocity In Young, Old And Very Old Women
Bibliographic record
Abstract
Healthy adult aging is associated with a loss of muscle mass, known as sarcopenia, and functional alterations within the neuromuscular system. As a result, older adults exhibit less strength and slower voluntary contractile velocity. However, these parameters have not been studied fully in older women. PURPOSE: To determine the effect of aging on voluntary isometric strength and contraction velocity of the leg muscles of young (Y), old (O) and very old (VO) women. METHODS: Cross-sectional areas (CSAs) of the anterior and posterior compartments of the right leg were assessed with 3T magnetic resonance (MR) imaging in seven Y (23±2y), five O (65±4y) and six VO (76±3y) women. Maximal voluntary isometric contraction (MVC) torque and maximal contraction velocity (at a fixed load of ∼1Nm) of the dorsiflexors and plantar flexors were determined using a Biodex dynamometer. To determine normalized strength, MVC torque was expressed relative to muscle CSA. RESULTS: Anterior compartment CSA was ∼27% and ∼19% less in the VO compared with the Y and O, respectively, but there was no difference between the Y and O women. The VO had a ∼16% lower dorsiflexor MVC torque than the Y, but neither group differed significantly from the O women. No differences existed among groups for normalized dorsiflexor strength. Maximal voluntary contraction velocity was ∼15% less in the VO than the Y with no other group differences. In the posterior compartment, CSA was 25% less in the VO compared with the Y, but the O did not differ from either Y or VO. Similarly, plantar flexor MVC torque was ∼32% less in the VO compared with the Y women but not different between Y and O, or O and VO. Normalized plantar flexor strength was equivalent among the groups. The VO were 13% slower than the Y for plantar flexor maximal contraction velocity with no other differences between groups. CONCLUSIONS: Lower maximal strength observed in the dorsiflexors and plantar flexors of the VO women can be accounted for by an age-related decrease in muscle mass. Also, contraction velocity did not slow until the 8th decade of life and was similar for both the dorsiflexor and plantar flexor muscle groups. 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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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".