Table 1. . Body mass, muscle mass, grip strength, muscle force and myofiber size.

Characteristic	PBS (n = 9)	ActRIIB-mFc dose mg/kg			ANOVA p-value	Post-hoc p-value
		3.3 (n = 10)	6.6 (n = 9)	9.9 (n = 10)
Body mass (g)	28.06 ± 0.75	32.17 ± 0.77	32.74 ± 0.81	34.61 ± 0.76	0.0001	0.0035 0.0011 <0.0001
Absolute muscle mass (g)	0.191 ± 0.0070	0.220 ± 0.0055	0.224 ± 0.013	0.234 ± 0.0075	0.0065	ns ns 0.0059
Normalized muscle mass (g/g)	0.0069 ± 0.0003	0.0069 ± 0.0002	0.0068 ± 0.0003	0.0068 ± 0.0002	ns	ns ns ns
Fore limb grip strength (g)	146.6 ± 5.5	166.6 ± 7.8	159.6 ± 10.1	181.6 ± 8.0	0.0314	ns ns 0.0201
Hind limb grip strength (g)	34.0 ± 5.2	37.9 ± 9.2	32.9 ± 5.6	47.7 ± 6.5	ns	ns ns ns
Normalized fore limb grip strength (g/g)	5.234 ± 0.178	5.177 ± 0.215	4.883 ± 0.300	5.263 ± 0.239	ns	ns ns ns
Normalized hind limb grip strength (g/g)	1.235 ± 0.213	1.167 ± 0.266	1.004 ± 0.170	1.378 ± 0.194	ns	ns ns ns
Twitch force (mN)	767.2 ± 50.02	829.6 ± 33.97	905.4 ± 34.83	939.9 ± 42.35	0.0233	ns ns 0.0246
Tetanic force (mN)	2783 ± 163	2871 ± 123	3145 ± 153	3167 ± 238	ns	ns ns ns
Normalized twitch force (mN/g)	27.38 ± 1.67	25.94 ± 1.31	27.82 ± 1.36	27.29 ± 1.34	ns	ns ns ns
Normalized tetanic force (mN/g)	99.65 ± 6.18	89.80 ± 4.58	96.13 ± 4.62	92.15 ± 7.21	ns	ns ns ns
Mean fiber area (μm2)	1673 ± 65	2310 ± 131	2284 ± 167	2621 ± 124	0.001	0.0062 0.0114 <0.0001

For muscle fiber cross-sectional area: PBS (1680 fibers); ActRIIB-mFc @ 3.3 mg/kg (1486 fibers); ActRIIB-mFc @ 6.6 mg/kg (1299 fibers); ActRIIB-mFc @ 9.9 mg/kg (1255 fibers) were analyzed. Grip strength and muscle force were normalized to body mass. Data shown as mean ± standard error of the mean.

Post-hoc p-values are reported for the comparison between each individual ActRIIB-mFc dose versus the PBS control. None of the post-hoc p-values for the comparison between the various ActRIIB-mFc doses were significant.

ANOVA: Analysis of variance; ns: Not significant; PBS: Phosphate-buffered saline.