World Health Organization has defined physical activity as “any bodily movement produced by skeletal muscles that requires energy expenditure”. Similar definitions have been used for guidelines in America, the United Kingdom and Australia, for example 2008 Physical Activity Guidelines for Americans refers physical activity to “any bodily movement produced by the contraction of skeletal muscle that increases energy expenditure above a basal level”.
World Health Organization also differentiates the term physical activity with the term exercise which is “planned, structured, repetitive, and aims to improve or maintain one or more components of physical fitness”.