Pectoralis minor index range of healthy 18-24-year-old students from a Kenyan public university.
Eugene C Agweyu, Joseph M Matheri, Benita Olivier and 1 others
PMID 40061854WHAT IT FOUND
Healthy Kenyan students aged 18-24 show lower pectoralis minor index values on their dominant side than on their non-dominant side.
Gender differences in these values were significant in some postures but not others, suggesting that habitual use and sex both influence resting muscle length.
Key findings
01The mean pectoralis minor index was significantly lower on the dominant side (10.6) than on the non-dominant side (11.22) in a standing relaxed position.
02In supine lying, males had significantly higher mean pectoralis minor index values than females in relaxed and passively lengthened positions, but not in the actively lengthened position.
03Most participants (83%) used a backpack to carry learning materials, and the right shoulder was the dominant carrying side for 79.2% of them.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTsWhat it means for SLPs
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What it does not show
The study only included healthy students aged 18-24, so the baseline ranges may not apply to older adults, clinical populations, or those with shoulder pathology. The cross-sectional design cannot determine if the lower PMI on the dominant side causes dysfunction or is simply an adaptation to use. Self-reported dominant shoulder and carrying habits may introduce recall bias. The study did not assess pain or functional outcomes, so it is unclear if the measured muscle length differences are clinically meaningful for this population.
Declared interests
The authors declared no funding from any public, commercial, or not-for-profit agency.
The easy way to misread this
Do not assume that a lower PMI on the dominant side is pathological. The study measured healthy students, so this difference may be a normal adaptation to habitual use rather than a sign of dysfunction requiring treatment.