Objective: To assess how dietary change affects gain in strength and muscle mass during heavy resistance training of elderly men.
Design: Randomized controlled trial.
Intervention: During 12 weeks of resistance training of knee extensors and flexors, a daily supplement of 560 +/- 16 kcal/day (17% energy from protein, 43% from carbohydrate, 40% from fat) was randomly assigned to six men (S) while five men (U) received no supplement. Food intake, strength, whole body composition, and midthigh composition by CT scan were assessed before training and at 6 and 12 weeks.
Setting: The men were outpatients but lived in a Metabolic Research Unit during the three assessments.
Participants: Eleven healthy men aged 61 to 72 years.
Results: Densitometry showed no change over time in fat or fat-free mass. However, the S men increased (P less than 0.05) weight, skinfold thickness at six sites, subcutaneous midthigh fat, and creatinine excretion; in all men, changes in these values and in midthigh muscle were proportional to changes in reported energy intake (P less than 0.05). There was midthigh muscle hypertrophy in both groups, but it was greater in S than U (P less than 0.01). Both groups gained strength (P less than 0.001) with no effect of diet.
Conclusions: During physical rehabilitation of the elderly, dietary intake may influence the increase in lean as well as adipose tissue without altering strength gain. These preliminary findings should be confirmed by a larger study with sedentary controls.