Functional improvements to 6 months of physical activity are not related to changes in size or density of multiple lower-extremity muscles in mobility-limited older individuals.

Older adults are encouraged to engage in multicomponent physical activity, which includes aerobic and muscle-strengthening activities. The current work is an extension of the Vitality, Independence, and Vigor in the Elderly 2 (VIVE2) study - a 6-month multicenter, randomized, placebo-controlled trial of physical activity and nutritional supplementation in community dwelling 70-year-old seniors. Here, we examined whether the magnitude of changes in muscle size and quality differed between major lower-extremity muscle groups and related these changes to functional outcomes. We also examined whether daily vitamin-D-enriched protein supplementation could augment the response to structured physical activity. Forty-nine men and women (77 ± 5 yrs) performed brisk walking, muscle-strengthening exercises for the lower limbs, and balance training 3 times weekly for 6 months. Participants were randomized to daily intake of a nutritional supplement (20 g whey protein + 800 IU vitamin D), or a placebo. Muscle cross-sectional area (CSA) and radiological attenuation (RA) were assessed in 8 different muscle groups using single-slice CT scans of the hip, thigh, and calf at baseline and after the intervention. Walking speed and performance in the Short Physical Performance Battery (SPPB) were also measured. For both CSA and RA, there were muscle group × time interactions (P < 0.01). Significant increases in CSA were observed in 2 of the 8 muscles studied, namely the knee extensors (1.9%) and the hip adductors (2.8%). For RA, increases were observed in 4 of 8 muscle groups, namely the hip flexors (1.1 HU), hip adductors (0.9 HU), knee extensors (1.2 HU), and ankle dorsiflexors (0.8 HU). No additive effect of nutritional supplementation was observed. While walking speed (13%) and SPPB performance (38%) improved markedly, multivariate analysis showed that these changes were not associated with the changes in muscle CSA and RA after the intervention. We conclude that this type of multicomponent physical activity program results in significant improvements in physical function despite relatively small changes in muscle size and quality of some, but not all, of the measured lower extremity muscles involved in locomotion.

Nutritional Supplementation With Physical Activity Improves Muscle Composition in Mobility-Limited Older Adults, The VIVE2 Study: A Randomized, Double-Blind, Placebo-Controlled Trial.

BACKGROUND: Nutritional supplementation and physical activity have been shown to positively influence muscle mass and strength in older adults. The efficacy of long-term nutritional supplementation in combination with physical activity in older adults remains unclear. METHODS: Mobility-limited (short physical performance battery [SPPB] ≤9) and vitamin D insufficient (serum 25(OH) D 9-24 ng/mL) older adults were recruited for this study. All subjects participated in a physical activity program. Subjects were randomized to consume a daily nutritional supplement (150 kcal, 20 g whey protein, 800 IU vitamin D, 119 mL beverage) or placebo (30 kcal, nonnutritive, 119 mL). In a prespecified secondary analysis, we examined total-body composition (dual energy X-ray absorptiometry), thigh composition (computed tomography), and muscle strength, power, and quality before and after the 6-month intervention. RESULTS: One hundred and forty-nine subjects were randomized into the study [mean (standard deviation, SD) age 78.5 (5.4) years; 46.3% female; mean (SD) short physical performance battery 7.9 (1.2); mean (SD) vitamin D 18.7 (6.4) ng/mL]. After the intervention period both groups demonstrated improvements in muscle strength, body composition, and thigh composition. Nutritional supplementation lead to further losses of intermuscular fat (p = .049) and increased normal muscle density (p = .018). CONCLUSIONS: Six months of physical activity resulted in improvements in body composition, subcutaneous fat, intermuscular fat, and strength measures. The addition of nutritional supplementation resulted in further declines in intermuscular fat and improved muscle density compared to placebo. These results suggest nutritional supplementation provides additional benefits to mobility-limited older adults undergoing exercise training. ClinicalTrials.gov Identifier: NCT01542892.