Fig. 3. (A) Mean daily integrated EMG (IEMG), (B) mean EMG burst amplitude, and (C) mean daily duration of EMG over an entire 24 h period for six rats. The dark and light portions of the bars in (A) and (C) represent the dark and light periods. (D) Mean daily EMG amplitude over the entire 24 h period, i.e. including all periods of inactivity. Values are means ± 1 S.D. Abbreviations as in Fig. 1. s, m, t and v, significantly different from soleus, MG, TA and VL, respectively.