May bed rest cause greater muscle loss than limb immobilization?

Bed rest, as often occurs following surgery or during (critical) illness, may result in greater muscle loss than local muscle disuse, not only because of the amount of muscle tissue that is subjected to disuse, but also because of various systemic factors that may accelerate muscle atrophy. These factors could include hormonal changes or (low-grade) systemic inflammation. In medical research, experimental (whole-body) bed rest and (local) limb immobilization are typically applied in healthy volunteers to investigate the impact of disuse on the loss of muscle mass and strength. Previous work, based on combined results of separate studies, has suggested that immobilization leads to more pronounced muscle loss than bed rest due to the greater degree of restriction imposed (Clark 2009). However, a direct comparison of the loss of muscle mass and strength between both models is currently lacking