Rodent hindlimb suspension is widely used to induce inflammation and muscle impairment. In this study, we set out to define the role of mast cells in neutrophil and macrophage recruitment and in muscle recovery following unloading-reloading periods. We hypothesized that mechanical perturbation would stimulate the release of pro-inflammatory substances by mast cells, which would influence leukocyte recruitment and muscle function. Rats were thus suspended for 10 days and injected with a mast cell inhibitor or stimulator, or a placebo, before reloading. Leukocyte accumulation and muscle function were assessed using immunohistological staining and measurements of contractile properties in vitro. Our results showed that mechanical loading activated mast cells, thereby influencing leukocyte recruitment in the early reloading periods. Indeed, the inhibition of mast cell degranulation significantly reduced the number of neutrophil cell profiles in reloaded soleus muscle, while mast cell activation provoked a significant increase in the number of neutrophil cell profiles in uninjured muscle. However, the inhibition of mast cell degranulation also led to a significant increase in the number of ED1⁺ macrophage cell profiles. These perturbations in the inflammatory response caused by mast cell inhibition induced a short protective effect on the loss of muscle force during the first day of reloading, but delayed the return to the normal contractile properties of muscles after 14 days of reloading. These results indicate that mechanical loading can induce mast cell degranulation, which can influence leukocyte influx and also highlighted the possibility that leukocytes may play a dual role in skeletal muscles.