Fig. 2.

Skeletal muscle type II fiber proportion shifted away from type IIa to type IIx, and fiber size was increased by resistance training. Nine men with the metabolic syndrome had muscle fiber type proportions and fiber cross-sectional areas assessed after 8 and 16 wk of progressive resistance training. A: as shown graphically, the proportion of type IIa fibers was lower than baseline at 8 (P = 0.007) and 16 wk (P = 0.021), and the %type IIx fibers was significantly higher at 8 (P = 0.002) and 16 wk (P < 0.001). The type I fiber proportion did not change at the 8- or 16-wk times. B: the 9 men showed progressive increases in type II fiber areas that were statistically significant at 16 wk of training.