Physical activity in an inpatient setting is often limited to brief periods of walking. For healthy adults, public health agencies recommend a minimum of 150 min/week of moderate-intensity exercise. The authors sought to determine if meeting this activity threshold, in the absence of incidental activities of daily living, could protect skeletal muscle health during bed rest. Healthy older adults (68 ± 2 years) were randomized to 7-day bed rest with (STEP, n = 7) or without (CON, n = 10) a 2,000 steps/day intervention. Performing 2018 ± 4 steps/day did not prevent the loss of lean leg mass and had no beneficial effect on aerobic capacity, strength, or muscle fiber volume. However, the insulin response to an oral glucose challenge was preserved. Performing a block of 2,000 steps/day, in the absence of incidental activities of daily living, was insufficient to fully counter the catabolic effects of bed rest in healthy older adults.
Arentson-Lantz, Galvan, Fry, and Paddon-Jones are with the Dept. of Nutrition and Metabolism, The University of Texas Medical Branch, Galveston, TX. Wacher is with the Dept. of Anesthesiology, The University of Texas Medical Branch, Galveston, TX.