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Number and percentage of single-muscle fiber physiology experiments studied by MHC classification
| Young Exercisers |
Lifelong Exercisers |
Old Healthy Nonexercisers |
||||
|---|---|---|---|---|---|---|
| n | % | n | % | n | % | |
| MHC isoform | ||||||
| I | 114 | 49 | 83 | 49 | 110 | 46 |
| I/IIa | 13 | 6 | 5 | 3 | 4 | 2 |
| IIa | 87 | 38 | 65 | 38 | 99 | 41 |
| IIa/IIx | 16 | 7 | 16 | 9 | 27 | 11 |
| IIx | 1 | <1 | 2 | 1 | 1 | <1 |
| Total fibers | 231 | 171 | 241 | |||
MHC, myosin heavy chain.
