Physical activity, exercise, and physical fitness: definitions and distinctions for health-related research.

TLDR

Physical activity, exercise, and physical fitness are distinct concepts—physical activity is any skeletal‑muscle movement that expends energy (measured in kilocalories) and can be categorized by context; exercise is a planned, structured, repetitive subset aimed at improving fitness; fitness comprises health‑ or skill‑related attributes that can be quantified by specific tests—yet these terms are often used interchangeably. The paper proposes clear definitions to distinguish physical activity, exercise, and physical fitness. These definitions are offered as an interpretational framework for comparing studies that relate physical activity, exercise, and physical fitness to health.

Abstract

"Physical activity," "exercise," and "physical fitness" are terms that describe different concepts. However, they are often confused with one another, and the terms are sometimes used interchangeably. This paper proposes definitions to distinguish them. Physical activity is defined as any bodily movement produced by skeletal muscles that results in energy expenditure. The energy expenditure can be measured in kilocalories. Physical activity in daily life can be categorized into occupational, sports, conditioning, household, or other activities. Exercise is a subset of physical activity that is planned, structured, and repetitive and has as a final or an intermediate objective the improvement or maintenance of physical fitness. Physical fitness is a set of attributes that are either health- or skill-related. The degree to which people have these attributes can be measured with specific tests. These definitions are offered as an interpretational framework for comparing studies that relate physical activity, exercise, and physical fitness to health.