MHC Fiber Typing
MHC fiber typing is laboratory analysis of muscle fiber composition, quantifying the percentage of slow-twitch (Type I) and fast-twitch (Type II) fibers in a muscle sample. Based on myosin heavy chain (MHC) isoform expression, fibers are classified into Type I (slow-twitch, oxidative), Type IIa (fast-twitch, oxidative-glycolytic), and Type IIx/IId (fast-twitch, glycolytic). Introduced by Bottinelli and colleagues (1994), MHC typing requires muscle biopsy and biochemical analysis. Fiber type composition is partially genetic but trainable; endurance training promotes Type II-to-IIa conversion, while power training promotes Type I-to-IIa transitions in some contexts. Understanding fiber composition informs training prescription and explains performance predispositions.
Source record
Citations copied verbatim from the method’s source record. No claim-level verification is inferred from them.
- Bottinelli, R., & Reggiani, C. (2000). Human skeletal muscle fibres: acting role of fibre type in resistance training. Journal of Sports Medicine and Physical Fitness, 40(2), 166-177. · URL
- Schiaffino, S., Reggiani, C., Akimoto, T., & Blaauw, B. (2013). Fiber type specification during muscle development: growth factor signaling versus transcriptional control. Advances in Experimental Medicine and Biology, 682, 199-218. · URL
- Staron, R. S., Hagerman, F. C., Hikida, R. S., Murray, T. F., Hostler, D. P., Crill, M. T., & Ragg, K. E. (2000). Fiber type composition of the vastus lateralis muscle of young men and women. Journal of Histochemistry & Cytochemistry, 48(5), 623-629. · DOI 10.1177/002215540004800506
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