Table 1.

Rate of force development is unchanged by pH 6.2 + 30 mM P_i

	15°C			30°C
	n	pH 7	pH 6.2 + 30 mM Pi	n	pH 7	pH 6.2 + 30 mM Pi
Type I	11	3.8 ± 0.5	3.1 ± 0.4	10	41.2 ± 5.4	23.6 ± 7.6
Type IIa	11	6.2 ± 1.0*	5.8 ± 1.8	7	66.9 ± 12.3*	50.3 ± 13.2
Type IIx	11	23.1 ± 4.4*†	30.7 ± 10.1*†	6	128.4 ± 5.5*†	122.3 ± 16.0*†
Type II combined	22	16.1 ± 3.2*	20.5 ± 6.5*	13	95.3 ± 11.2*	83.5 ± 14.2*

Values are means ± SE; n, number of fibers studied where type I and type II fibers were isolated from 3 and 6 rats, respectively. Rate of force development (k_tr) is a rate constant with units s⁻¹. The k_tr values at 30°C were all significantly higher than at 15°C (P < 0.05). There were no significant differences between pH 7 and pH 6.2 + 30 mM P_i conditions in any fiber type.

^*Significantly different from type I fibers, P < 0.05.

^†Significantly different from type IIa fibers, P < 0.05.