Fig. 5. (A) A survey of normal daily muscle activity from rat, cat, monkey and human muscles and (B) the percentage of type I (slow) muscle fibers. (C) The relationship between muscle fiber type and the duration of daily activity. The species are identified by the color of the bars and symbols and the muscles are denoted by symbol shape. The phenotype data are from the following sources: rats (Ariano et al., 1973; Armstrong and Phelps, 1984; Delp and Duan, 1996), cats (Ariano et al., 1973; Braund et al., 1995; Talmadge et al., 1996), Rhesus monkeys (Grichko et al., 1999; Roy et al., 1991a) and humans (Saltin and Gollnick, 1983). Additional EMG data are taken from the following sources: rats (Alford et al., 1987; Blewett and Elder, 1993), cats (Alaimo et al., 1984; Hensbergen and Kernell, 1997, 1998), Rhesus monkey (Hodgson et al., 2001) and humans (Edgerton et al., 2001; Kern et al., 2001). Abbreviations as in Fig. 1.