ELEVEN WEEKS OF STRENGTH TRAINING DECREASED THE EXPRESSION OF IMMUNE-RELATED GENES IN OLDER SUBJECTS INDEPENDENT OF PROTEIN SUPPLEMENT TYPE; A RANDOMIZED CONTROLLED TRIAL

Abstract

Objective: To investigate the effects of eleven weeks of strength training combined with two isocaloric protein supplements on mRNA expression levels in skeletal muscle and peripheral blood mononuclear blood cells (PBMCs). Design: A double blind randomized controlled study. Setting: The Norwegian School of Sports Sciences, Norway. Participants: Untrained, but otherwise healthy, men and women (n=20, ≥ 70 yrs). Intervention: Participants were randomly allocated to receive either milk protein or a native whey protein supplement (20 g protein, morning and afternoon) combined with a standardized strength training protocol (6-10 RM, 1-3 sets, 3 times/week) for eleven weeks. Measurements: The mRNA expression levels of immune-related genes were measured before and after the intervention period, using RT-qPCR. Cytokines were measured using ELISA. Results: PBMC mRNA expression of interleukin (IL) 6, IL8, chemokine (C-C motif) ligand (CCL) 3, and nuclear receptor subfamily (NR) 1 group H (H) member 3 decreased significantly after the intervention period, whereas the mRNA expression of toll-like receptor (TLR2) increased. In skeletal muscle, the mRNA expression of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PPARGC1A) and PPARGC1B decreased significantly, whereas the mRNA expression of CCL2, CCL5, TLR2, TLR4 and hypoxia inducible factor 1 alpha subunit (HIF1A) increased significantly after the intervention. We found no significant differences in circulating C-reactive protein and IL6 after the intervention period. The consumption of whey and milk proteins had similar effects on mRNA expression levels after strength training in skeletal muscle as well as PBMCs. Conclusion: Eleven weeks of strength training and protein supplementation reduced the PBMC expression levels of genes involved in the immune system as well as in metabolism, underlining the close interaction between these processes. The upregulation of other immune-related genes observed in PBMCs as well as in skeletal muscle needs further investigations, but may be related to protein supplementation and training adaptations. Different protein supplementation (milk or native whey) did not differentially modulate mRNA expression after the intervention period.