An Electromyography Analysis of 3 Muscles Surrounding the Shoulder Joint During the Performance of a Chest Press Exercise at Several Angles
Bibliographic record
Abstract
This study compared the activation of the clavicular head and the sternocostal head of the pectoralis major and the anterior deltoid when performing the bench press at several different angles. Fifteen healthy male subjects participated in this study. Subjects performed the chest press exercise at 0 (flat bench), 28, 44, and 56 degrees above horizontal using 70% of their respective 1 repetition maximum for each angle. Electromyographic activity was recorded during each repetition. Activation of the clavicular head of the pectoralis major was significantly greater at 44 degrees compared to 0 degrees (p = 0.010), at 56 degrees compared to 0 degrees (p = 0.013), and at 44 degrees compared to 28 degrees (p = 0.003). Activation of the sternocostal head of the pectoralis major was significantly greater at 0 degrees compared to 28 degrees (p = 0.013), at 0 degrees compared to 44 degrees (p = 0.018), at 0 degrees compared to 56 degrees (p = 0.001), at 28 degrees compared to 56 degrees (p = 0.003), and at 44 degrees compared to 56 degrees (p = 0.001). Activation of the anterior deltoid was significantly greater at 28 degrees compared to 0 degrees (p = 0.002), at 44 degrees compared to 0 degrees (p = 0.012), and at 56 degrees compared to 0 degrees (p = 0.014). To optimize recruiting the involved musculature, it would seem that performing both the flat and incline chest press exercises is necessary.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 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) | 0.002 | 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".