Natural and artificially induced vibrations are common in the environment and studies on their long term effects on skeletal muscles have shown enhancements of power and force as well as debilitating outcomes such as Hand-Arm Vibration Syndrome. Little is known, however, of the contractile response of skeletal muscles during vibration. Adult C57BL6 male (n=6) and female (n=6) mice (32±0.4wk old; mean±SEM) were anaesthetized (pentobarbitone IP; 80mg/kg), killed by cervical dislocation and the soleus and extensor digitorum longus (EDL) muscles dissected. The muscles were subjected to longitudinal vibrations at 70, 40, 30, 20 and 10Hz with a displacement of 0.5mm, during which they were stimulated by 5, 1ms pulses at 0.1Hz. The peak forces (PF), time to peak-tensions (TPT) and half-relaxation times (HRT) of the contractile responses were measured. The Friedman’s and post-hoc Dunn’s tests were used to determine statistical significance (p values for the latter are shown). In the soleus, PF was reduced significantly during 70, 40, 20 and 10Hz vibration compared to control (1.94±0.35, 2.62±0.55, 2.15±0.54, 2.13±0.58 and 4.98±1.03mN, respectively; p<0.01), while in the EDL, PF was lower during 40, 30 and 20Hz vibration than during the control (0.70±0.15, 0.75±0.15, 0.73±0.15 and 3.61±0.73mN, respectively; p<0.0001). The TPTs of both muscles during 70Hz vibration were significantly shorter than controls (Soleus – 23.26±0.20 and 30.24±0.73ms, respectively, p=0.034; EDL – 20.38±0.37 and 22.54±0.21ms, respectively, p=0.023). Only the soleus, however, showed significantly faster HRTs during 30 and 20Hz vibration compared to control (17.09±0.22, 16.24±0.22 and 19.34±0.44ms, respectively; p<0.05). Furthermore, both muscles also showed a dependency on the phase of the vibration and the twitch-inducing stimuli. The changes in the contractile dynamics of the soleus and EDL muscles during vibration are likely to be due to a disturbance of the contractile machinery, causing a disassembly of actin-myosin cross-bridges and the resultant deactivation of force generating process’. The inter-muscle variations, however, may be due to differences in the stiffness of the muscles as well as the myosin heavy chain isoform content. These results suggest that the ability of skeletal muscles to respond appropriately to motor signals may be compromised during vibration.