Effect of explosive resistance training on titin and myosin heavy chain isoforms in trained subjects

The purpose of this investigation was to evaluate changes in myosin heavy chain (MyHC) and titin isoforms after using various loads during explosive jump squat training. Twenty-four male athletic subjects were recruited for this study. Two experimental groups performed 8-weeks of jump squats using either 30% (n = 9) or 80% (n = 9) of their previously determined 1 repetition maximum. A third group served as controls (n = 6). Muscle biopsies were obtained before and after 8 weeks from vastus lateralis. The analysis of titin within these subjects confirmed that human skeletal muscle contains 2 isoforms of titin. There was no significant group x time interaction for MyHC or titin isoform expression. The data from this investigation indicates that a relatively short period of explosive resistance training results in negligible changes in the expression of MyHC or titin isoforms.