Relationship between muscle echo intensity on ultrasound and isokinetic strength of the three superficial quadriceps femoris muscles in healthy young adults.
Tomoyuki Yamauchi, Takumi Yamada, Yoshinao Satoh
PMID 33935357WHAT IT FOUND
In healthy young adults, only vastus medialis echo intensity correlated with knee extension strength.
Rectus femoris and vastus lateralis showed no significant relationship. Measuring vastus medialis alone may be sufficient for assessing muscle quality related to strength in this population.
Key findings
01Echo intensity of the vastus medialis, but not the rectus femoris or vastus lateralis, correlated negatively with isokinetic knee extension strength in both males and females.
02The average echo intensity of all three superficial quadriceps muscles did not correlate significantly with strength in either gender.
03The authors suggest that measuring only the vastus medialis may be sufficient to clarify the relationship between echo intensity and maximum isokinetic force in the quadriceps.
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 young adults, so results may not apply to elderly, frail, or clinical populations. Absolute echo intensity values vary between different ultrasound devices and settings, limiting comparability with other studies. The sample size was small (25 participants), which may affect the stability of the correlation estimates. The study design is cross-sectional, so it cannot establish causality between muscle quality and strength.
Declared interests
The authors have no conflicts of interest to disclose.
The easy way to misread this
Do not assume that measuring all three quadriceps muscles or their average provides a better indicator of strength than measuring the vastus medialis alone. The average echo intensity did not correlate significantly with strength in this study, whereas the vastus medialis did.