The effect of stretching exercises on the fibre angle of the vastus lateralis and vastus medialis oblique: an ultrasound study.
Jordan Bethel, Alban Killingback, Claire Robertson and 1 others
PMID 35221521WHAT IT FOUND
A seven-week stretching program significantly reduced muscle fibre angles in both the vastus medialis and vastus lateralis.
Because both muscles changed by a similar amount, stretching may reduce overall quadriceps tone without correcting an existing imbalance between them.
Key findings
01The stretching program caused a statistically significant decrease in the fibre angle of both the vastus medialis oblique and vastus lateralis.
02There was no significant difference in the magnitude of change between the two muscles on the same limb, suggesting stretching reduces tone in both equally.
03The change in muscle fibre angle was not significantly correlated with participant compliance, and the study relied on self-reported adherence which averaged over 100%.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study included only healthy, athletic males, so results may not apply to females or symptomatic patients with patellofemoral pain. Compliance was self-reported and averaged over 100%, which is clinically unrealistic and suggests potential reporting bias. Participants continued their usual sports training during the study, which was not monitored and could have influenced muscle architecture. The study measured fibre angle as a proxy for muscle tone or function, but did not measure pain or functional outcomes.
Declared interests
The study was funded internally by St George’s, University of London. The authors declared no conflicts of interest.
The easy way to misread this
Do not assume that stretching selectively targets the vastus lateralis to fix patellar tracking. The data shows the vastus medialis also loses fibre angle, meaning the imbalance between the two muscles may persist even if both become more flexible.