Biomechanics of Postural Stability in the Elderly
Bibliographic record
Abstract
Falls cause substantial death and morbidity in the elderly.Fall risk depends on ability to maintain balance during daily activities and ability to recover balance following a perturbation such as a slip or trip.To guide the design of fall prevention programs, we need an improved understanding of the biomechanical variables that govern ability to recover balance.The aims of this thesis were to determine (1) the relative importance of strength versus speed-of-response variables in explaining age differences in balance recovery performance with the ankle strategy, and (2) the association between variables related to ability to recover balance and variables related to ability to maintain balance.To address Aim 1, young and elderly women were supported in a forward leaning position by a horizontal tether and instructed to recover an upright vertical stance by contracting their ankle muscles.The maximum initial lean angle where they could recover balance without release of the tether (which depends primarily on strength) was 19.6% smaller for elderly than young.The maximum initial lean angle where they could recover balance after the tether was suddenly released (which depends on strength and speed-of-response) was 36.1% smaller for elderly.Moreover, between-group differences in performance were related to both strength and speed-of-response.Peak ankle torque was 7.7% smaller in elderly than young during tether release trials, reaction time was 27% slower in elderly, due to a lengthened muscle response latency, and rate of ankle torque generation was 15.6% slower in elderly.These results suggest that exercise-based fall prevention programs should include balance and agility training, in addition to strength training.To address Aim 2, the same elderly subjects participated in postural steadiness experiments, where the amplitude, velocity, and frequency of their centre-of-pressure displacement were measured during quiet stance.Postural steadiness during quiet stance and ability to recover balance with the ankle strategy were not associated, perhaps because postural steadiness during quiet stance is controlled partly by anticipatory strategies, while balance recovery following a perturbation is governed by reactive strategies.These results support the need to measure both balance recovery and postural steadiness in balance assessments of the elderly. Table of Contents..
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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".