The SOL but not the EDL of motor-impaired mice shows the same deficit in peak tetanic force after 3 days of T treatment. Tetanic force in the slow-twitch SOL from T Tg mice was significantly decreased after 3 days of T treatment (A), comparable to the magnitude of the effect of 5 days of treatment (Fig 2). A subtle, but not significant difference was seen in EDL from the same motor-impaired mice (T Tg versus T WT mice, p = 0.07). However, peak twitch force in both muscles was significantly reduced in T Tg mice compared to T WT mice (B). Twitch kinetics were largely unaffected in T-treated Tg mice after 3 days of treatment (C, D) except that relaxation time was significantly slowed in EDL, consonant with the effect of T on this parameter after 5 days of treatment (Fig 4). N = 5–7/group. *p<0.05.