The Effects of Exercise Training versus Intensive Insulin Treatment on Skeletal Muscle Fibre Content in Type 1 Diabetes Mellitus Rodents
Abstract
In patients with Type I diabetes mellitus (T1DM) undergoing intensive insulin therapy, the development of insulin resistance (IR) is linked to the improper storage of intramyocellular lipid (IMCL) species. While both IR and IMCL are improved with combined aerobic and resistance training, it is unclear how these adaptations relate to individual fibre-type transitions and metabolic function. This study aimed to compare the effects of combined exercise training versus conventional and intensive insulin therapy on skeletal muscle fibres in T1DM rodents. Seventeen Sprague-Dawley rats were divided into groups: Control-Sedentary (CS; n=4), conventionally-treated T1DM sedentary (DCT; n=4), intensively-treated T1DM sedentary (DIT; n=5) and combined aerobic/resistance exercise-trained T1DM (DCE; n=4). After twelve weeks, muscle fibre type, IMCL, and muscle glycogen content were analyzed. Significant increases in IMCL storage solely in type I fibres implicate improvements in oxidative capacity rather than a shift towards more oxidative fibres as the primary mechanism for these improvements.