Concurrent Exercise on a Gravity-Independent Device
In conclusion, the current study is a proof-of-principle study that examined the effectiveness of a countermeasure device allowing for both AE and RE training in mitigating the deconditioning effects of microgravity as simulated by a 10-d lower limb unloading protocol. This study produced four key findings. First, we found that a high-intensity, low-volume concurrent exercise program was able to show favorable changes in musculoskeletal and cardiovascular conditioning. Second, unloading provided typical slow-to-fast shifts in MHC mRNA expression that was mitigated by training in the vastus lateralis but not the soleus. Third, both atrogin and myostatin, molecular markers for the regulation of muscle atrophy, were positively manipulated with exercise training in the vastus lateralis but not the soleus. These results help explain the final key point that the soleus and the ankle plantar flexors are more sensitive to ULLS than the vastus lateralis and the knee extensors. The favorable results presented here show that a high-intensity concurrent exercise training program can have a positive effect on musculoskeletal and cardiovascular conditioning. Nevertheless, the heightened sensitivity of the soleus to unloading interferes with the effects of exercise training and highlights the need for further examination for optimal exercise prescription to affect the plantar flexor muscle group. These results show that a concurrent high-intensity resistance and aerobic interval training program using a single exercise device can positively affect the musculoskeletal and cardiovascular systems with short-term ULLS. This provides the groundwork necessary to pursue future research examining the effectiveness of this device with longer duration unloading as might occur during extended space missions.
Summary
In conclusion, the current study is a proof-of-principle study that examined the effectiveness of a countermeasure device allowing for both AE and RE training in mitigating the deconditioning effects of microgravity as simulated by a 10-d lower limb unloading protocol. This study produced four key findings. First, we found that a high-intensity, low-volume concurrent exercise program was able to show favorable changes in musculoskeletal and cardiovascular conditioning. Second, unloading provided typical slow-to-fast shifts in MHC mRNA expression that was mitigated by training in the vastus lateralis but not the soleus. Third, both atrogin and myostatin, molecular markers for the regulation of muscle atrophy, were positively manipulated with exercise training in the vastus lateralis but not the soleus. These results help explain the final key point that the soleus and the ankle plantar flexors are more sensitive to ULLS than the vastus lateralis and the knee extensors. The favorable results presented here show that a high-intensity concurrent exercise training program can have a positive effect on musculoskeletal and cardiovascular conditioning. Nevertheless, the heightened sensitivity of the soleus to unloading interferes with the effects of exercise training and highlights the need for further examination for optimal exercise prescription to affect the plantar flexor muscle group. These results show that a concurrent high-intensity resistance and aerobic interval training program using a single exercise device can positively affect the musculoskeletal and cardiovascular systems with short-term ULLS. This provides the groundwork necessary to pursue future research examining the effectiveness of this device with longer duration unloading as might occur during extended space missions.