Table 1.

Morphometric values in rats subjected to a 9 days time course hindlimb unloading

	Hindlimb unloading duration (days)
	0	1	3	5	7	9
Mean body weight (g)	197 ± 4	203 ± 3	190 ± 6	190 ± 5	197 ± 4	195 ± 2
Soleus weight (mg)/body weight (g)	0.40 ± 0.01	0.41 ± 0.01	0.38 ± 0.02	0.36 ± 0.02	0.31 ± 0.01***,¶¶¶,††	0.31 ± 0.02***,¶¶¶,††
Soleus mean FCSA (μm2)	2532 ± 75	2437 ± 122	2397 ± 142	1833 ± 68***,¶¶,††	1621 ± 86***,¶¶¶,†††	1879 ± 105***,¶¶,††
Plantaris weight (mg)/body weight (g)	0.98 ± 0.03	0.85 ± 0.04**	0.87 ± 0.02**	0.85 ± 0.03*	0.84 ± 0.02**	0.78 ± 0.02***
Plantaris mean FCSA (μm2)	2027 ± 86	2169 ± 236	1933 ± 71	1518 ± 50**,¶,†	1578 ± 118**,¶,†	1496 ± 58**,¶,†

Both soleus and plantaris muscles atrophied to a similar extent after 9 days of hindlimb unloading. Based on relative muscle weight, the plantaris muscle was atrophied as early as day 1 (P ≤ 0.01). Atrophy was delayed in soleus, significantly occurring only at day 7 (P ≤ 0.001). Based on the mean fibre cross-sectional area (FCSA), atrophy presented similar kinetics and amplitude in both muscles. Significantly different from day 0:

^*P ≤ 0.05

^**P ≤ 0.01

^***P ≤ 0.001.

Significantly different from day 1

^¶P ≤ 0.05

^¶¶P ≤ 0.01

^¶¶¶P ≤ 0.001.

Significantly different from day 3

^†P ≤ 0.05

^††P ≤ 0.01

^†††P ≤ 0.001.

Data are expressed as means ± s.e.m. (n = 6 rats/group).