MUSCLE STRENGTH AND MYOSIN HEAVY CHAIN mRNA EXPRESSION IN THE ELDERLY AFTER WEIGHT TRAINING

Abstract

1099 The purpose of this study was to determine the effects of 12 weeks of low-(LIEX) and high-intensity (HIEX) weight training on the muscular strength and myosin heavy chain (MHC) mRNA isoform expression of 16 elderly men and women using RT-PCR. Subjects were randomly assigned to either a control group (CON), or training groups of either LIEX or HIEX. Training sessions occurred 3 days/week and involved 3 sets of 12-15 repetitions at 65% 1-RM for LIEX and 3 sets of 8-10 repetitions at 85% 1-RM for HIEX. For upper-body strength, results showed increases of 6.56% for CON, and significant increases of 46.09% and 52.83%, respectively, for LIEX and HIEX. There were also increases in lower-body strength of 3.48% for CON, and significant increases of 38.18% and 55.84% for LIEX and HIEX, respectively. There were significant increases in Type IIa MHC mRNA expression for LIEX and Type I and IIa for HIEX that were significantly correlated with the respective increases in lower-body strength while the Type IIx MHC isoform in LIEX and HIEX was significantly less than CON. This study suggests that both low- and high-intensity weight training produces similar increases in strength which seem to be related to respective increases in the expression of Type I and IIa MHC mRNA isoforms in elderly men and women.