OBJECTIVES The purpose of this study was to investigate the effects of 20 days' bed rest on the viscoelastic properties of human tendon structures in knee extensor and plantar flexor muscles in vivo. METHODS Eight healthy men (age: 24+/-4 years, height: 172+/-9 m, body mass: 69+/-13 kg) carried out a 6 degrees head-down bed rest for 20 days. Before and after bed rest, elongation (L) of the te...

The effects of 2 and 4 mo of bed rest, with or without exercise countermeasures, on the contractile properties of slow fibers in the human soleus muscle were examined. Mean fiber diameters were 8 and 36% smaller after 2 and 4 mo of bed rest, respectively, than the pre-bed rest level. Maximum tetanic force (P(o)), maximum activated force (F(max)) per cross-sectional area (CSA), and the common-lo...

INTRODUCTION Dietary control and nutrient intake are critical aspects of any metabolic study, but this is especially true in the case of bed rest studies. We sought to define nutritional requirements, develop menus, and implement them during long-duration head-down bed rest studies. METHODS The dietary goals were to provide 100% of subjects' nutrient requirements and to maintain subjects' bod...

Few studies have addressed the interaction between energy balance and lean body mass in healthy subjects during spaceflight or its simulations. We used doubly labeled water to measure total energy expenditure (TEE) in nine healthy adult men during two 7-day periods, once before and once during a 10-day head-down bed-rest period. Mean TEE was 21% less during than before bed rest; however, neithe...

Immobilization in hospitalized medical patients or during simulation of spaceflight induced deconditioning has been shown to be associated with loss of muscle mass and bone. Resistance vibrating exercise (RVE) and/or high protein diet are countermeasures, which are capable of mitigating the adverse effects of immobilization. We investigated the effect of these countermeasures on the coagulation...

BACKGROUND Headache after cervical or lumbar puncture has long been attributed to early mobilization; however, there is little evidence for this. We performed a systematic literature review and meta-analysis of randomized controlled trials to assess whether longer bed rest is better than immediate mobilization or short bed rest in preventing headache. METHODS We searched EMBASE (1988 to March...

OBJECTIVE The aim of this study was to investigate the impact of 9 days of bed rest on insulin secretion, insulin action, and whole-body glucose and fat metabolism in first-degree relative (FDR) and matched control (CON) subjects. RESEARCH DESIGN AND METHODS A total of 13 FDR and 20 CON subjects participated in the study. All were studied before and after 9 days of bed rest using the clamp te...