Objective: To determine if basal metabolic rate (BMR) could be elevated in older women undertaking a program of progressive resistance exercise of up to 52-weeks duration.
Design: Randomized controlled trial with subjects assigned to either a control (CO), high-intensity (HI), or low-intensity (LO) training group for 15 weeks. BMR, body composition, energy intake and expenditure, and muscle strength were assessed at baseline and after 15 weeks. Subjects were encouraged to continue in their assigned exercise group for an additional 37 weeks, after which time they were reevaluated.
Setting: An exercise facility at a medical center.
Subjects: Thirty-six community-dwelling healthy women aged 65 to 79 years.
Intervention: Exercise groups performed three sets of 10 exercises, 3 days/week, at either 80% of one-repetition maximum (1-RM) for seven repetitions (HI) or 40% of 1-RM for 14 repetitions (LO).
Measures: BMR by indirect calorimetry, body composition by dual energy X-ray absorptiometry, energy intake and expenditure from 4-day dietary and activity records, and dynamic muscle strength by 1-RM.
Results: Muscle strength increased, on average (+/- SEM), by 40 +/- 6% and 36 +/- 7% in the HI and LO groups after 15 weeks, respectively, compared with 4 +/- 1% in the nonexercising subjects (P = .0001). Fat mass decreased after 15 weeks in LO exercisers by 1.0 kg (P < .05), whereas there was a trend for fat-free mass (FFM) to increase in the HI group by 0.7 kg (P = .08). No change occurred in any group for BMR. From weeks 15 to 52, muscle strength increased a further 9 +/- 2% and 11 +/- 2% in HI and LO groups, respectively, compared with 3 +/- 1% in nonexercisers (P < .005). There was no change in BMR or any body composition parameter during this time period.
Conclusions: Neither training program significantly altered BMR and both produced only minimal changes in body composition. However, both the HI and LO exercise regimens resulted in similar and substantial gains in upper and lower body muscle strength that persisted over the course of the year. This suggests that either exercise regimen may prove an effective strategy for preventing frailty and maintaining functional independence in older adults.