Mitochondrial-targeted catalase (MCAT) does not rescue contractile dysfunction induced by hindlimb unloading (HU). A: peak twitch force for soleus (SOL) muscle in wild-type (WT; open bars) and MCAT (filled bars) mice with or without HU. B: representative twitch force tracings in SOL muscles with or without HU. C: force frequency curves for SOL muscles with or without HU. D: representative tetanic force tracings (200 Hz) for SOL muscles with or without HU (WT non-HU, n = 4; MCAT non-HU, n = 5; WT HU, n = 5; MCAT HU, n = 8). E: peak twitch force for extensor digitorum longus (EDL) muscles with or without HU. F: representative twitch force tracings in EDL muscles with or without HU. G: force-frequency curves for EDL muscles with or without HU. H: representative tetanic force tracings (200 Hz) for EDL muscles with or without HU (WT non-HU, n = 5; MCAT non-HU, n = 4; WT HU, n = 6; MCAT HU, n = 8). *Main effect of HU (P < 0.05). Values are means ± SE.