Comparison Of Ankle Torque Control Error In Healthy Older And Young Subjects During Quiet Standing
Bibliographic record
Abstract
It has been reported various times that spontaneous sway during quiet standing is larger in older (O) than in young (Y) healthy subjects. Though it is hypothesized that the larger body sway must imply balance inabilities in O, it has not been shown to date, how the larger sway is caused and how its properties can be concretized. PURPOSE To test the following hypotheses: 1) Due to the larger control error of the ankle torque in O defined as the distance from the center of pressure (COP) to the gravity line projection (GLP) of the center of mass (COM) of the body (COP-COM), the body sway is larger in O than in Y. 2) The defined control error is attributed to the neural regulation of balance. METHODS Fifteen O (73+6yrs) and eleven Y (29+8yrs) male subjects participated in this study. Each subject was requested to keep a quiet stance with his or her eyes open or closed. The modified 'zero-point-to-zero-point double integration technique' using a force platform was adopted to estimate the GLP path, which was applied to calculate COP-COM. The body acceleration (ACC), which is theoretically a proportional parameter to COP-COM, was calculated using the measured horizontal force. Crosscorrelation analysis was adopted to investigate the relation between ACC and the surface electromyogram from the right soleus. RESULTS The effect of age was significant in the standard deviations of COP-COM with a 2-way-ANOVA, which were also larger in O than in Y (EO 0.12 vs. 0.08, EC 0.20 vs. 0.12 cm, p=0.007), while the effect of eye condition was insignificant. ACC significantly correlated with muscle activity in both age groups (EO O r=.29, Y r=.32; EC O r=.33, Y r=.35, p<0.01 for all). CONCLUSIONS The larger control error of ankle torque causes the larger body sway in O compared to Y for both eye conditions. The result that ACC correlated with muscle activity suggests that the larger error, which is proportional to ACC, is generated neurally. Therefore, we conclude that neural inability to control the ankle torque accurately is a cause of the larger sway in O.
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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".