Skeletal muscle fiber type, cell size, and myonuclear content in an elite male powerlifter: a case study

Powerlifters are a population that is extensively exposed to both high intensity resistance training and anabolic androgenic steroids (AAS), however little is known about the physiological adaptations that occur in these athletes. We were presented with the unique opportunity to investigate muscle tissue of an elite level Powerlifter (EPL) and competitive Powerlifter (CPL) brother with a background of AAS use. Muscle biopsies were acquired from EPL and CPL, both of whom are currently engaged in Powerlifting training, as well as consistent AAS use. Single muscle fibers were analyzed for MHC content, cell size, and myonuclear parameters Therefore, the primary investigators aimed to determine 1) the MHC fiber type composition of previously acquired vastus lateralis muscle tissue via SDS-PAGE, 2) fiber type-specific size and MND using longitudinal imaging via confocal microscopy and immunofluorescence, and 3) how the above measures compare to reference subjects from prior literature. Analysis showed that EPL had a mean MHC Ila CSA and fiber volume that were similar to previous human data, but the mean MND was discernably smaller than comparable populations. Aside from MHC Ila isoforms, the current investigation produced insufficient MHC variability for analysis of cell size and myonuclear parameters. Fiber analysis of EPL displayed a profile of 9% MHC 1 ,12% MHC I/IIa, 79% MHC Ila (amongst the highest content reported utilizing similar methods to-date), and 0% of any other MHC isoform. Undeniably, EPL has a unique set of characteristics and circumstances, and the sport of Powerlifting is growing exponentially with concurrent AAS use. Only through continued analysis of elite subjects utilizing performance enhancing substances can we parse out the metaphorical ceiling of performance.