Is The Physiological Tremor An Error Source For Balance Regulation, Inducing Body Sway During Standing?
Bibliographic record
Abstract
It has been reported that for healthy individuals a pair of motor units in the soleus muscle synchronizes at about 10 Hz during quiet standing. This motor activity is similar to the physiological tremor that can usually be observed in fingers. In our previous studies, we confirmed the presence of the physiological tremor using surface electromyograms of all three ankle extensors. PURPOSE: 1) To identify a synchronized recurring activity among ankle extensors, and 2) to test the hypothesis, that the physiological tremor generates spontaneous body sway during quiet standing in the simulation study. METHODS: The experiment was carried out with fifteen healthy individuals who were asked to stand quietly with their eyes open or closed. Muscle activities in the right ankle extensors were measured using rectified electromyograms. Also measured were the approximated center of mass displacement, which is the representative variable of body sway, and the center of pressure displacement, which is an approximation of the ankle torque. Both variables were measured in the anterior-posterior direction only, and auto- and cross-spectral analyses were performed with the recordings. Two PD controllers, a mechanical and a neural controller, were used in the simulations to control an inverted pendulum. The physiological tremor was simulated using an autoregressive process and was implemented as an error source in the motor command in order to induce body sway. The motor command was converted to ankle torque using a second-order critically damped filter. The objective of our analysis in the simulation study was to test whether the physiological tremor can produce the observed amount of body sway or not. RESULTS: We found an assembled muscle activity at about 9 Hz. It was also revealed that the physiological tremor was synchronized among the three ankle extensors, inducing an ankle torque fluctuation at the corresponding frequency. In the simulation study, we demonstrated that the physiological tremor as added to the motor command successfully induced a body sway as large as the one observed in experiments with able bodied individuals. CONCLUSIONS: We conclude that the physiological tremor component can be an error source for balance regulation, inducing spontaneous body sway during quiet standing.
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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 | 0.008 |
| 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 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".