Donovan UW-L Journal of Undergraduate Research VII (2004) Characteristics of Myosin Heavy Chain and Titin in Strength and Endurance Athletes

The purpose of this investigation was to identify differences in myosin heavy chain (MyHC) and titin (T) isoforms in different athletic populations with increased levels of muscular endurance or strength relative to non-athletes. Subjects consisted of three groups based on training status: (1) endurance trained athletes (ET; n=5), (2) strength trained athletes (ST; n=5); or (3) non-athletes (NA; n=5). From gel electrophoresis analysis of muscle samples, MyHC I, MyHC IIa, and MyHC IIb along with T1 and T2 protein bands were identified and quantified. The percentages [mean ± SD] of MyHC I isoforms in ET, ST, and NA were 40.2 ± 16.0, 38.0 ± 8.4, and 38.0 ± 6.6, respectively, while MyHC IIa isoform distribution among the samples was 51.8 ± 14.0, 53.6 ± 12.6, and 44.4 ± 13.2, and MyHC IIb isoform distribution was 7.8 ± 9.1, 8.4 ± 8.3, and 18.2 ± 17.1. Similarly, T1 distribution among ET, ST, and NA groups was found to be 95.4 ± 7.1, 91.1 ± 9.2, and 69.2 ± 20.2, respectively, and T2 distribution was 4.6 ± 7.1, 8.9 ± 9.2, and 30.8 ± 20.2. There was a significantly higher expression of T2 in the NA group. These results suggest that different modes of training may result in changes in MyHC and T isoform distribution among athletes