Psoas Major Muscle In Elderly Female Rowers

Abstract

The psoas major muscle (PM), which is recruited for hip/lumber stabilization and during hip joint flexion, plays an important role in maintenance of upright posture and walking. The age-related wasting of PM size is more remarkable than quadriceps femoris muscle. Rowing exercise, which includes hip joint flexion, may be categorized as one of the exercise mode for maintaining PM size and functions. We showed that elderly rowing trained men had larger PM than age-matched untrained men (MSSE, 40(5)suppl.:371, 2008). However, little is known whether rowing exercise can prevent the wasting and weakness of PM in elderly women. b>PURPOSE: The purpose of this study was to evaluate the effects of regularly performed-rowing exercise on the morphology and function of PM in elderly women. METHODS: Participants were 8 elderly female rowers (ER: age 64.1±4.6 yrs, BMI 20.7±0.8 kg/m2, mean±SD), 14 age-matched female walkers as active control group (EC: 62.8±3.8 yrs, 21.6±2.3 kg/m2) and 6 young untrained women (YC: 21.5±1.0 yrs, 20.2±0.9 kg/m2). Elderly rowers and walkers performed rowing or walking exercise regularly twice a week and each session 60-120 min. Muscle cross-sectional area (CSA) of PM scanned by magnetic resonance imaging and bilateral leg extension power were measured. RESULTS: The CSA of PM in EC was 33% lower than that in YC (p<0.001). ER had 74% higher CSA of PM than EC (p<0.001), which was comparable to that of YC (YC: 9.4±1.3 cm2, EC: 6.2±1.0 cm2, ER: 8.7±1.7 cm2, mean±SD). The leg extension power in EC was 28% lower than that in YC (YC: 853±221 W vs EC: 616±148 W, p<0.05), whereas there was no significant difference between ER and YC (ER: 704±154 W). The CSAs of PM was strongly associated with leg extension power (r=0.914, p<0.001). Furthermore, partial correlation analysis revealed that PM is strong independent predictor of leg extension power(r=0.585, p<0.001). CONCLUSIONS: These results provide the possibility that PM plays an important role in the muscle function of leg extension, and that rowing exercise can prevent age-related decline in PM in women as well as men.