STRENGTH TRAINING AND DIET: EFFECTS ON SKELETAL MUSCLE IN OLDER MEN (AGING, PROTEIN METABOLISM, MUSCLE HYPERTROPHY) by FRONTERA, WALTER ROBERTO ROURA, S.C.D.C., Boston University, 1987, 218 pages; AAT 8702128

Abstract (Summary)

The purpose of this study was the determination of the interaction between strength training and dietary supplementation on skeletal muscle structure and function in older men. Twelve healthy, untrained volunteers (age range = 60-72 years) were assigned at random to either a control (C) or experimental (E) group. The E group received a dietary supplement providing an additional 8 kcal and 0.33 g/kg/day of protein above the normal ad lib diet. Both groups participated in a 12 week strength training program (8 reps/set; 3 sets/day; 3 days/week) at 80% of the one repetition maximum (1 RM) for extensors and flexors of both knee joints. They were evaluated before the program and after 6 and 12 weeks of training. No significant differences between groups were noted in muscle structure and performance at any point during training. Weekly measurements of 1 RM showed a linear increase in strength in all muscle groups. By week 12, extensor and flexor strength had increased 102% (p = 0.0001) and 172% (p = 0.0001) respectively. Isokinetic strength measured on a Cybex dynamometer increased 7.8-14.5% (p < 0.05) at 60 deg/sec and 6.7-17% (p < 0.05) at 240 deg/sec in the various muscle groups. The in vivo torque-velocity relationship, obtained on the isokinetic dynamometer (speeds = 0, 30, 60, 120, 180, 240, 300 deg/sec), showed an upward displacement of the curve mainly in the slow-velocity, high-torque region (0-60 deg/sec). Mid-thigh composition from planimetric analysis of computerized tomographic scans (CT scans) showed significant increases (p < 0.01) in total thigh area (7.8%), total muscle area (9.8%), quadriceps area (10.4%) and non-extensors muscle area (9.2%). Muscle biopsy analysis revealed significant (p < 0.01) increases in type I fiber area (30.7%), type II fiber area (26.5%) and mean fiber area (26.9%). The E group consumed more energy and nutrients than the C group but this had no effect on body composition or function. The results of the present study suggest that strength gains in older men can be associated with significant muscle hypertrophy. Further, an increase in dietary protein in older men already consuming an average American diet does not enhance improvements in muscle performance nor changes in muscle size.

Indexing (document details)

School: Boston University

School Location: United States -- Massachusetts

Source: DAI-B 47/10, p. 4078, Apr 1987

Source type: Dissertation

Subjects: Anatomy & physiology, Animals