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Patients with medical, orthopaedic and surgical conditions are often assigned to bed-rest and/or immobilised in orthopaedic devices. Although such conditions lead to muscle atrophy, no studies have yet considered differential atrophy of the lower-limb musculature during inactivity to enable the development of rehabilitative exercise programmes. Bed-rest is a model used to simulate the effects of spaceflight and physical inactivity. Ten male subjects underwent 56-days of bed-rest. Magnetic resonance imaging of the lower-limbs was performed at 2-weekly intervals during bed-rest. Volume of individual muscles of the lower-limb and subsequently, rates of atrophy were calculated. Rates of atrophy differed (F = 7.4, p < 0.0001) between the muscles with the greatest rates of atrophy seen in the medial gastrocnemius, soleus and vastii (p < 0.00000002). The hamstring muscles were also affected (p < 0.00015). Atrophy was less in the ankle dorsiflexors and anteromedial hip muscles (p > 0.081). Differential rates of atrophy were seen in synergistic muscles (e.g. adductor magnus > adductor longus, p = 0.009; medial gastrocnemius > lateral gastrocnemius, p = 0.002; vastii > rectus femoris, p = 0.0002). These results demonstrate that muscle imbalances can occur after extended periods of reduced postural muscle activity, potentially hampering recovery on return to full upright body position. Such deconditioned patients should be prescribed "closed-chain" simulated resistance exercises, which target the lower-limb antigravity extensor muscles which were most affected in bed-rest. [ABSTRACT FROM AUTHOR]

This study was performed to assess the effect of resistive vibration exercise during bed rest deconditioning on venous vascular dimension and function, as measured with ultrasound in the popliteal vein. Sixteen men were assigned to bed rest (BR-Ctrl) or bed rest with resistive vibration exercise (BR-RVE). Before and at 25 and 52 days of bed rest, popliteal vein diameter was measured at increasing cuff pressures. Venous capacitance and compliance were calculated from the pressure-volume curve. After 52 days of bed rest, BR-Ctrl showed no change in baseline popliteal vein diameter or compliance, while venous capacitance decreased. Resistive vibration exercise had no effect on the response in venous diameter, capacitance or compliance to 52 days of bed rest. The decline in venous capacitance due to long-term bed rest is not effectively counteracted by resistive vibration exercise, indicating that an alternative factor during bed rest deconditioning is responsible for venous changes. [ABSTRACT FROM AUTHOR]