Quantifying Muscular Activation And Rest In A Discrete Functional Task Of Older Men And Women
Bibliographic record
Abstract
During the course of a typical day (8hrs) electromyography (EMG) recordings of older adults demonstrate greater bursts activity (Appl Physiol Nut Met 31(S22), 2006) and less periods of rest (gaps). It is possible that these age-related adaptations are due to performing daily activities at a higher percentage of maximum force. PURPOSE: To quantify burst and gap structure of EMG in young and old men and women during a discrete task of daily living. METHODS: Electromyography (EMG) was recorded in 8 young (∼ 23 yrs; 4 men, 4 women) and 8 older (∼77 yrs; 4 men and 4 women) adults. The task involved lifting a 4.54kg bag, walking 5m in one direction and then returning to the start position. A portable EMG device was utilized to record biceps brachii, triceps brachii, quadriceps femoris, and hamstrings activity. The signals were pre-amplified (1000x), band pass filtered (20–450Hz), stored on a 512MB nashcard and downloaded to Spike 6 for custom analysis. A burst was denned as an EMG amplitude <2% while a gap was >1 % of the maximum isometric effort (MVE), and an interval of >0.1 s was utilized for both measures. Total number of bursts and gaps, burst and gap duration (sec), burst and gap amplitude (%MVE), and burst and gap rate (#/s), were quantified. RESULTS: The number of gaps did not differ between old and young adults, but mean burst duration, burst area, and burst percent were greater (∼50%) in older men. Men showed an increase in number of bursts and rate of bursts (∼2 times greater) relative to women. However, the burst duration and area were significantly less in the men compared with the women. Overall the number of gaps in EMG activity and the amplitude, mean area, and rate of gap occurrences were greater in young adults compared with older adults (∼1.5 - 4 times). The presence of EMG gaps was greater in men compared with women, and the amplitude, rate and area of these gaps were also larger in men (p<0.05). CONCLUSIONS: These observations parallel earlier studies of daily activity that demonstrate a greater amount of EMG with fewer rest periods in older adults and women compared with young adults and men, respectively. Thus, age and gender differences in long-term EMG recordings likely result from working at different intensities relative to maximum strength.
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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".