Diagnostic ultrasound shows preferential activation of rectus abdominis segments with exercises targeting upper versus lower segments
Bibliographic record
Abstract
International Journal of Exercise Science 16(1): 1077-1086, 2023. Preferential activation of rectus abdominis sections during crunch or leg lifts has long been disputed. The objectives of this study were to both explore the activation of the rectus abdominis during these exercises. This study used a randomised independent measures design utilising both EMG and diagnostic ultrasound to record changes in rectus abdominis activity. Fifteen participants each performed multiple repetitions of a 45° crunch, a 90° sit-up, and finally a 90° leg raise, sufficient for an 8-second ultrasound recording utilising M-mode of all four unilateral abdominal segments during each of the exercises, resulting in 12 images per participant. There was a significant interaction between segment number and type of exercise when testing for percent difference (F6, 440 = 4.718, p < .01, η2 = .065). The mean thickness change of abdominis during a crunch manoeuvre was greater than the leg raise by 36.39 ± 3.21 % (p < .01). The mean thickness during the sit-up was also greater than the leg raise (32.49 ± 3.04 %). Rectus abdominis shortening and thickening was observed in all the exercises tested but was most pronounced in the abdominal crunch. Muscle recruitment seems to be biased closer to the load.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| 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 | 0.001 |
| 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 teacher head, 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".