Journal Article

Noninvasive Monitoring of Training Induced Muscle Adaptation with -MRS: Fibre Type Shifts Correlate with Metabolic Changes

Brechtel, Lars, Perka, Carsten, Stoltenburg-Didinger, Gisela, Hoff, Eike, Putzier, Michael, Konstanczak, Paul, Strube, Patrick

2013

Overview

Purpose . To evaluate training induced metabolic changes noninvasively with magnetic resonance spectroscopy (-MRS) for measuring muscle fibre type adaptation. Methods . Eleven volunteers underwent a 24-week training, consisting of speed-strength, endurance, and detraining (each 8 weeks). Prior to and following each training period, needle biopsies and -MRS of the resting gastrocnemius muscle were performed. Fibre type distribution was analyzed histologically and tested for correlation with the ratios of high energy phosphates ([PCr]/[], [PCr]/[ β ATP] and [PCr + ]/[ β ATP]). The correlation between the changes of the -MRS parameters during training and the resulting changes in fibre composition were also analysed. Results . We observed an increased type-II-fibre proportion after speed-strength and detraining. After endurance training the percentage of fast-twitch fibres was reduced. The progression of the [PCr]/[]-ratio was similar to that of the fast-twitch fibres during the training. We found a correlation between the type-II-fibre proportion and [PCr]/[] (, ) or [PCr]/[ β ATP] (, ); the correlations between its changes (delta) and the fibre-shift were significant as well (delta[PCr]/[] , delta[PCr]/[ β ATP] , ). Conclusion . Shifts in fibre type composition and high energy phosphate metabolite content covary in human gastrocnemius muscle. Therefore -MRS might be a feasible method for noninvasive monitoring of exercise-induced fibre type transformation.