In an effort to simulate the compromised function and @entity194 of lower limb muscles experienced by astronauts after spaceflight, 21 @entity1 and @entity1 age 30-56 yr were subjected to unilateral lower limb unloading for 5 wk. Whereas 10 of these subjects performed unilateral knee extensor resistance exercise (ULRE) two or three times weekly, 11 subjects (UL) refrained from training. The exercise regimen consisted of four sets of seven maximal actions, using an apparatus that offers concentric and eccentric resistance by utilizing the inertia of rotating flywheel(s). Knee extensor muscle strength was measured before and after UL and ULRE, and knee extensor and @entity121 were determined by means of magnetic resonance imaging. Surface electromyographic activity measured after UL inferred increased muscle use to perform a given motor task. UL induced an 8.8% decrease (P < 0.05) in knee extensor muscle volume. After ULRE and as a result of only approximately 16 min of maximal contractile activity over the 5-wk course, muscle volume increased 7.7% (P < 0.05). Muscle strength decreased 24-32% (P < 0.05) in response to UL. Group ULRE showed maintained (P > 0.05) strength. Ankle plantar flexor muscle volume of the unloaded limb decreased (P < 0.05) in both groups (UL 10.5%; ULRE 11.1%). In neither group did the right weight-bearing limb show any change (P > 0.05) in muscle volume or strength. The results of this study provide evidence that resistance exercise not only may offset @entity2057 but is in fact capable of promoting marked @entity1184 of chronically unloaded muscle.

XXXX of chronically unloaded muscle subjected to resistance exercise.

@entity1 :: ('9606', 'Species') :: ['men', 'women'] @entity1184 :: ('MESH:D006984', 'Disease') :: ['hypertrophy'] @entity194 :: ('MESH:D001284', 'Disease') :: ['atrophy'] @entity2057 :: ('MESH:D009133', 'Disease') :: ['muscle atrophy'] @entity121 :: ('MESH:D009135', 'Disease') :: ['ankle plantar flexor muscle volumes']
@entity1184 :: (MESH:D006984,Disease) :: ['Hypertrophy']
