Fig. 4

Effects of long-term NMES training on skeletal muscle homeostasis. A Number of Pax7^pos cells per myofiber in control (n = 7) and NMES (n = 6) mice. B Number of myonuclei (i.e., PCM1^pos cells below the basal lamina) per myofiber in control (n = 7) and NMES (n = 6) mice. C-F Number of myonuclei per myofiber type I; IIA; IIX and IIB in control (n = 8) and NMES (n = 8) mice. G Gastrocnemius myofiber cross-sectional area distribution in control (n = 15) and NMES (n = 18) mice. H Whole gastrocnemius muscle section immunostained for laminin (grey), MyHC-I (blue), MyHC-IIA (green), MyHC-IIX (black), MyHC-IIB (red). Scale bar = 500 µm. I-L Myofiber cross-sectional area of myofiber type I; IIA; IIX and IIB in control (n = 7) and NMES (n = 11) mice. M Maximal isometric force production in control (n = 15) and NMES trained (n = 20) mice. N Proportion of myofibers positive for IgG in mice submitted either to the control procedure (n = 7) or to NMES (n = 6). O Proportion of myofibers positive for embryonic myosin heavy chain in control (n = 7) and NMES (n = 7) mice. P Proportion of myofibers with central nuclei in control (n = 6) and NMES (n = 7) mice. Significantly different from control: ^* P < 0.05; ^** P < 0.01; ^*** P < 0.001; ^# P = 0.076; ^£ P = 0.066. Values are reported as mean ± SD expect for myofiber cross-sectional area distribution where values are reported as mean ± SEM for the sake of clarity