| Desmin is an important cytoskeletal protein of striated muscle. Little is known regarding its response to resistance exercise in humans. In order to expand our understanding, we measured desmin protein and other cellular constituents in muscle biopsies obtained 1 week before and 1, 2, 4, and 8 weeks following a single bout of exercise, and at similar time points during an 8 week resistance training regimen. Desmin and actin protein levels were determined with immunoblotting and MHC isoform distribution was determined using SDS PAGE at each time point for each group. We also measured maximal strength (1 RM) at weeks 0, 1, 2, 4, and 8 for the training group, and at weeks 0 and 8 for the single bout group. Desmin protein did not change at any time point for the single bout group. In the training group, desmin protein significantly increased at weeks 4 and 8 (89 +/- 26% and 77 +/- 13%, respectively, P < 0.0001). Actin protein content was unchanged in both groups at all time points. There were no changes in MHC isoforms in the single bout group. The percentage of MHC type IIa increased and MHC type IIx decreased at week 8 in the training group. Strength was significantly increased by week 2 (knee extension) and week 4 (leg press), and further increased at week 8 for both these exercises in the training group only. These data suggest a time course for desmin cyt{09}oskeleton modifications in response to resistance training that occurs shortly after strength gains, and precedes adaptations in MHC isoforms. |
