Prolonged immobilization of the human body results in functional impairments and musculoskeletal system deconditioning that may be attenuated by adequate muscle exercise.

In a 56-day horizontal bed rest campaign involving voluntary males we investigated the effects of vibration muscle exercise (RVE, 2x6 min daily) on the lower limb skeletal muscles using a newly designed foot plantar trainer (Galileo Space) for use at supine position during bed rest.

The maximally voluntary isometric plantar flexion force was maintained following regular RVE bouts during bed rest. At the start and end of bed rest muscle biopsies were taken from both mixed fast/slow-type vastus lateralis and mainly slow-type soleus muscle, each having n=10.

RVE group: the size of myofiber types I and II was largely unchanged in VL (vastus lateralis), and increased in SOL.

In the controlled group: the SOL depicted a disrupted pattern of myofibers I/II profiles suggesting a slow-to-fast muscle phenotype shift. RVE training increased the activity-dependent expression of nitric oxide synthase type 1 immunofluorescence at SOL and VL myofiber membranes.

These data provides evidence for the beneficial effects of RVE training on the deconditioned structure and function of the lower limb skeletal muscle. Daily short RVE should be employed as an effective atrophy countermeasure co-protocol preferentially addressing postural calf muscles during prolonged clinical immobilization or long-term human space missions.

Source: US National Library of Medicine National Institutes of Health