Sex-Based Differences in Lower Extremity Kinematics During Dynamic Jump Landing Tasks After Neuromuscular Fatigue of the Hip Extensors and Knee Flexors
Bibliographic record
Abstract
Background: Neuromuscular fatigue can increase the activation of antagonist muscles, thereby reducing the moment produced by the agonist. During the deceleration phase of landing, hip extensor and knee flexor muscles contract eccentrically to counteract the external hip flexion moment. Decreased hip flexion is associated with greater knee extensor moments and risk of injury. Purpose: To investigate sex-based differences in kinematics and muscle activity after neuromuscular fatigue of the hip extensors and knee flexors during dynamic single-leg tasks. Study Design: Controlled laboratory study. Methods: In this study, 9 female (age, 22.3 ± 3.4 years) and 7 male participants (age, 21.3 ± 2.6 years) completed the triple hop (THop) for distance and single-leg drop-jump (SJump) tasks before and after a fatigue protocol consisting of eccentric hip extension and knee flexion. Motion capture and electromyography were used to compare lower extremity kinematics and muscular activation between the sexes. Results: During the THop, neuromuscular fatigue resulted in significantly decreased maximum hip flexion angles ( P = .01), maximum knee flexion angles ( P = .039), and an effect of sex on all hip flexion angles, where both sexes saw decreased hip flexion postfatigue ( P = .033). A significant interaction of fatigue and sex on hip flexion angular velocity was observed during the SJump, indicating that men experienced an increase while women experienced a decrease in hip flexion angular velocities due to fatigue ( P = .03). Gluteus maximus activation was increased, and erector spinae activation was decreased postfatigue in women during the THop ( P = .053 and P = .023, respectively). Conclusion: Results indicate that men and women compensated differently after fatigue of the hip extensors and knee flexors. Clinical Relevance: Women more commonly assumed an erect landing posture associated with increased injury risk after fatigue of the hip extensors and knee flexors.
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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 | 0.000 | 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".