Combining Amino Acid and Vitamin D Supplementation with Exercise Training Increases Skeletal Muscle Mass and Prevent Bone Mineral Density Loss in Participants with Low Muscle Mass

This study evaluated the impact of exercise training with amino acid and vitamin D supplementation on muscle and bone mass in participants with low muscle volume. Twenty-nine Japanese participants (56-84 years old) were enrolled and assigned into the supplement (n=15) and non-supplement (n=14) groups. All participants underwent a 6-month exercise program. Supplements and nutrition support were provided to the participants in the supplement group for 12 weeks. Body composition and whole bone mineral density (BMD) were measured using dual energy x-ray absorptiometry. The outcomes, including body composition, whole BMD, and skeletal muscle mass index (SMI), were evaluated twice- pre- and post-intervention. The SMI was 6.51(6.28; 7.14) and 5.58 (5.24; 6.05) (kg/m2) in men and women, respectively. The average SMI change was 0.13% (-0.05%; 0.31%) and 2.33% (-0.88%; 5.48%); [mean (lower; upper quartile)]. The average BMD loss in the non-supplement group was -2.78%, and the BMD increased in the supplement group by 4.34%; there was an absolute difference between the two groups (p<0.05). After the intervention, serum myostatin was changed (p=0.001, non-supplement>supplement), serum vitamin D was increased (p=0.03; supplement>non-supplement), and BMD was maintained (p=0.03, supplement>non-supplement). There was a significant difference in the serum myostatin level at baseline and at 6-month in the non-supplement group, with a mean difference of 0.48 ng/ml (p=0.01). There was no significant improvement in the total lean mass, and handgrip strength. Resistance exercise combined with an amino acid supplement affects muscle and bone mass in the short-term intervention.