Effect of age on muscle hypertrophy induced by resistance training. J Gerontol A Biol Sci Med Sci 51: M270–M275

Background. Previous research has shown that resistance training induces muscle hypertrophy in older subjects, but has not clarified whether the degree of hypertrophy is affected by age. The present study was done to test the hypothesis that men and women over 60 years old have a smaller hypertrophic response to resistance training than young adults. Methods. Cross-sectional areas (CSA) of muscle in the thigh and upper arm were determined before and after 3 months of progressive resistance training by magnetic resonance imaging (MRI) in 9 young (22-31 yr, 5 male and 4 female) and 8 old (62-72 yr, 4 male and 4 female) subjects. Strength was determined by 3-repetition-maximum (3RM) testing. The amount of weight lifted during the training program was proportional to baseline strength. Results. Mean pretraining 3RM strength, per cm2 CSA, was less in the older group for all muscle groups examined (1