Fast fiber is approximately 50 percent of muscle composition for most people, and it rarely gets used during traditional long - slow cardio exercise. (sprint8book.com)
By enhancing the function of a single protein, Howard Hughes Medical Institute researchers have produced a «marathon mouse» with altered muscle composition and enough physical endurance to run twice... (hhmi.org)
However Sids muscle composition accounted for I'm sure Radko Gudas would have helped him lift it if he was called upon. (sbnation.com)