Effects of Static versus Ballistic Stretching on Hamstring: Quadriceps Strength Ratio and Jump Performance in Ballet Dancers and Resistance Trained Women
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Bibliographic record
Abstract
Stretching, while enhancing joint flexibility, may also decrease the hamstring:quadriceps (H:Q) strength ratio, which is used to identify knee strength imbalances and lower extremity muscle and ligament injury risk in the practice of sports and other physical activities. Stretching may also decrease muscle force and jump performance. However, these effects may depend on the population in question and mode of stretching. The purpose of this study was to compare the effects of static stretching (SS) and ballistic stretching (BS) on concentric H:Q ratio, squat jump (SJ) and countermovement jump (CMJ) height, and SJ:CMJ ratio between ballet dancers and resistance trained women. Fifteen resistance trained women and 12 ballet dancers were tested over five sessions. The first visit consisted of demographic measurements and instruction in testing protocols (no stretching), while the other four involved SS or BS in a counterbalanced order. At each of these sessions, six stretching exercises were performed, three focusing on quadriceps and three on hamstrings, in counterbalanced order. Two way repeated measures ANOVAs were used to compare interactions between conditions and groups for H:Q and SJ:CMJ ratios. Both groups demonstrated a significant decrease in H:Q ratio after SS, but there were no significant differences in SJ:CMJ ratio or jump height between conditions (p > 0.001). However, the ballet group had greater SJ:CMJ ratios and SJ heights than the resistance trained group. These findings suggest that both ballet dancers and resistance trained women decrease H:Q ratio similarly after BS and SS. Long-duration stretching negatively impacts H:Q ratio in the short term, which may lead to greater hamstring to quadriceps imbalance regardless of training background.
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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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 it