Muscle Mass/strength Gaining In Endurance-trained Post-menopausal Women Is Related To Igf-1 Changes

Abstract

The importance of maintaining muscle mass and functions in post-menopausal women is well recognized and the strength-physical exercise is the most physiological aid. PURPOSE: To associate changes of body composition, muscle strength and plasma hormones to strength training protocol in post-menopausal sedentary women. METHODS: Fifty, 45–70yrs old, post-menopausal (over 12 mo. of last menses, plasma FSH> 40 mIU/ml), non smoker, non alcoholic, non HRT, non DM2, non uncontrolled hypertension, without history of cardio failure or stroke, able for physical exercises were selected after they have accomplished medical and ethical criteria. They were assigned in two groups control not trained (G1 = 27) and trained (G2=23) on supervisioned sessions of 2–3 exercise for larger (thigh, chest and back) and one exercise for smaller (biceps and triceps) groups in 3 series of 8–12 repetitions from individualized loads (60%-80% 1RM) for each exercise. The training period lasted 16 wks and was preceded by a low-load exercises (40%-50% 1RM) adaptation period of 4 wks (3 times/wk). Body weight, height and composition (BIA) along with fast-plasma hormone (FSH, LH, estradiol, cortisol, IGF-1 and testosterone) were assessed before (M0) and after (M2) the 16wk period with the muscle strength (1RM) determined also at 8 wk (M 1). The variable values were correlated by Person's test and the means compared by Student's t test. RESULTS: At baseline (M0) both groups were similar in age, time of post-menopause, body composition, muscle strength and hormonal profiles. However after 16wks, G2 presented higher BMI (2,1%), IGF-1(80,9%) and muscle mass gain (1,8±0,8kg) than G1. Muscle mass correlated positively with IGF-1 (r=0,39, p<0,05) and the muscle strength progressively increased in all exercises with greater magnitude in pectoral than legs and upper arms. CONCLUSION: Former sedentary post-menopausal women submitted to strength training gained muscle mass and strength irrespectively of fat mass changes but significantly associated with IGF-1 increasing. Supported by FAPESP/CAPES/CNPq.