Table 3.

Relationship between muscle atrophy and countermovement jump performance at the end of bed-rest and after 180 days of recovery

Muscle	End of bed-rest	180 days after bed-rest
Anterior tibial muscles	0.47a	−0.08
Flexor digitorum with tibialis posterior	0.53a	−0.38
Flexor hallucis longus	0.50a	−0.54b,*
Lateral gastrocnemius	0.64b,*	−0.01
Medial gastrocnemius	0.72c,**	−0.03
Peroneals	0.22	−0.16
Soleus	0.71c,**	0.15
Vasti	0.77c,***	−0.09
Rectus femoris	0.33	−0.42a
Adductor brevis	−0.04	−0.17
Adductor longus	0.28	−0.38
Adductor magnus	0.57b,*	0.14
Gracilis	−0.04	0.23
Sartorius	0.00	−0.38
Lower glut max	−0.05	0.23
Biceps femoris long head	0.03	−0.13
Biceps femoris short head	−0.22	−0.39
Semimembranosus	−0.10	−0.10
Semitendinosus	0.32	−0.27
Popliteus	0.29	0.17
Obturator externus	−0.06	−0.35
Obturator internus	−0.07	−0.02
Quadratus femoris	0.26	−0.27
Iliopsoas	0.02	−0.23

Values are Pearson’s correlation coefficient. *: p<0.05; **:p<0.01; ***: p<0.001 and indicate significance of correlation with p value adjusted for false positives via the ‘false discovery rate’ method. a: p<0.05; b: p<0.01; c: p<0.001 indicate significance of correlation with raw p values. Percentage change in muscle volume versus baseline was correlated with percentage change in countermovement jump power versus baseline. A positive (or negative) correlation implies greater (or less) muscle atrophy is associated with greater (or less) loss of countermovement jump power. Strong positive correlations between calf and thigh muscle atrophy were seen at the end of bed-rest, implying a dependence of jump performance loss on atrophy in these muscles. Since no positive correlations were seen 180 days after bed-rest, this implies that increased muscle volume seen in the inactive control group long-term after bed-rest (figure 2; tables 1 and 2) was not associated with functional benefits.