Muscle activation and energy expenditure of sedentary behavior alternatives in young and old adults.

The physiological mechanisms that underlie the metabolic benefits of breaking up sedentary behavior (SB) have yet to be determined. The purpose of this study is to compare energy expenditure (EE) and muscle activation (MA) responses to sitting and four SB alternatives in younger and older adults. Twenty-two adults, grouped by age (21-35 and 62-76 years), completed five randomly ordered 20 min tasks: (1) continuous sitting (Sit), (2) sitting on a stability ball (Ball), (3) continuous standing (Stand), (4) sitting interrupted by walking (S/W), and (5) sitting interrupted by standing (S/S).