Different continuous training modalities result in distinctive effects on muscle structure, plasticity and function

The effects of training on muscle structure are dependent on adaptive changes induced by different intensities of physical exercise. Evidence has shown that aerobic training is able to induce adaptive changes to muscle structure based on intensity. The aim of the present study was to investigate the effects of different methods of continuous aerobic training in mice using functional, morphological and biomolecular approaches. The continuous aerobic training methods used in the present study were uniform continuous training (UC), varying continuous training (VC) and progressive continuous training (PC). Mice were made to run 3 times a week for 12 weeks on a motorized RotaRod, following one of the three different training methods at different speeds. The results of the present study demonstrated that the various training methods had different effects on sarcomere length. Ultrastructural analysis demonstrated that UC training resulted in a shortening of sarcomere length, PC training resulted in an elongation of sarcomere length and VC training showed similar sarcomere length when compared with the control sedentary group. Additionally, succinate dehydrogenase complex flavoprotein subunit A levels in muscle tissue following VC training were higher compared with UC and PC training. Overall, the present study showed that varying exercise methods resulted in different types of muscle plasticity, and that the VC protocol resulted in increased coordination and strength endurance in the functional tests, in agreement with the ultrastructural and biochemical profile. These observations support the view that VC training may be more efficient in increasing performance and may thus form the basis of training regimens when an improvement of motor efficiency is required.