Introduction: There is a notable scarcity of In vivo studies on the muscles of the posterior abdominal wall, and the psoas major muscle, which is important in occupation-related lumbopelvic mechanics, is not an exception. Hence, we determined the psoas major muscle thickness (PMMT) in an adult Nigerian population of different occupational groups with the aim of assessing the effect of unregulated occupation-related physical activity on the muscle while identifying its relationships with known anthropometric variables.
Material and methods: Eighty apparently healthy males between the ages of 18 and 30 were recruited for the study and divided into two groups: a control group of 40 relatively inactive subjects who were students and an age-matched quasi-experimental group of 40 artisans (manual labourers). B-mode ultrasound was used to measure the thickness of the psoas major muscle at the point of maximum thickness.
Results: The mean PMMT for the control group was 31.74 ±7.91 mm and did not significantly correlate with body mass index (r = –0.151, p < 0.05), body surface area (r = –0.255, p > 0.05), height (r = –0.186, p > 0.05), weight
(r = –0.244, p > 0.05), or age (r = 0.159, p > 0.05). However, PMMT was significantly greater in the artisan group (40.10 ±4.89 mm) than in the control group (31.74 ±7.91 mm) at p < 0.05.
Conclusions: This result is an obvious indication of the effect of unregulated occupation-related physical activity on the muscle, which may lead to a gradual alteration of normal lumbopelvic mechanics in these individuals.