Passive stretching and explosive effort countermovement jumps both acutely reduce spinal reflex excitability and increase sit-to-stand vertical stiffness, with females showing lower spinal reflex excitability than males following explosive jumps.
Key Findings
Results
Spinal reflex excitability decreased following both passive stretching and explosive effort countermovement jumps compared to pre-condition measures.
Decrease in spinal reflex excitability was statistically significant in both post-PS and post-EE conditions (p < 0.001) compared to pre-condition measures.
No overall sex effect was found for spinal reflex excitability (p = 0.115).
Study used a randomised within-participant crossover design with 20 active adults (10 males, 10 females).
Measures were taken at three timepoints: pre-intervention, post-passive stretching, and post-explosive effort jumps.
Results
A condition × sex interaction revealed that females exhibited lower spinal reflex excitability than males following explosive effort countermovement jumps.
The condition × sex interaction for spinal reflex excitability post-EE was statistically significant (p = 0.002).
This sex difference was specific to the post-explosive effort condition.
The authors suggest this finding may relate to known sex-based differences in lower limb injury risk.
The explosive effort condition involved five sets of 20 countermovement jumps (100 total jumps).
Results
Sit-to-stand vertical stiffness increased following both passive stretching and explosive effort countermovement jumps.
Increases in sit-to-stand vertical stiffness were statistically significant in both post-PS and post-EE conditions (p < 0.001) compared to pre-condition.
Passive stretching involved three sets of 60-seconds duration.
The simultaneous decrease in spinal reflex excitability alongside an increase in vertical stiffness represents a neurophysiological-biomechanical link identified by the authors.
Results
Electromyography patterns during sit-to-stand were influenced by both condition and sex.
The effect of condition and sex on EMG patterns reached statistical significance (p ≤ 0.047).
EMG was measured during sit-to-stand tasks as part of a broader assessment of movement biomechanics.
Both intervention type (passive stretching vs. explosive jumps) and participant sex contributed to observed differences in muscle activation patterns.
Methods
The study design employed a randomised within-participant crossover approach with active adults completing two separate sessions.
Twenty participants (10 males and 10 females) completed two separate experimental sessions.
Each session included three sets of 60-second passive stretching followed by five sets of 20 explosive effort countermovement jumps.
Outcome measures included spinal reflex excitability, sit-to-stand vertical stiffness, and sit-to-stand electromyography patterns.
Measurements were taken at three timepoints: pre-intervention, post-passive stretching, and post-explosive effort.
What This Means
This research suggests that two common exercise activities — passive stretching and explosive jumping — both rapidly change how the nervous system controls muscle reflexes and how the body moves during a basic everyday task (sitting to standing). Specifically, both activities reduced spinal reflex excitability (meaning the nervous system's automatic muscle responses became less reactive) and increased the stiffness of movement during sit-to-stand tasks. Interestingly, after explosive jumping, women showed a greater reduction in spinal reflex excitability than men, which the researchers propose may be relevant to understanding why women are at higher risk for certain lower limb injuries.
The study involved 20 physically active adults (equal numbers of men and women) who completed stretching and jumping protocols in separate lab sessions, with measurements taken before and after each activity. The finding that both stretching and high-intensity jumping produced similar directional changes in reflex excitability — despite being very different types of activity — points to a shared neurological effect worth exploring further. The simultaneous increase in movement stiffness alongside reduced reflex activity suggests a complex relationship between the nervous system and mechanical movement that is not yet fully understood.
This research suggests that the acute neurological and biomechanical effects of warm-up activities like stretching and explosive jumps may differ between males and females in ways that could be relevant to injury prevention and rehabilitation program design. The findings add to scientific understanding of how different types of exercise preparation affect the nervous system and movement mechanics, though further research is needed to determine how these short-term laboratory findings translate to real-world athletic or clinical settings.
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McCauley S, Mann K, Cannon J, Chang M, Mgbemena N, Rassafiani M, et al.. (2026). Passive Stretching and Explosive Jumps Acutely Reduce Spinal Reflex Excitability and Alter Sit-To-Stand Biomechanics in Active Adults.. Journal of musculoskeletal & neuronal interactions. https://pubmed.ncbi.nlm.nih.gov/42675942/