Physical Activity Definition

Physical activity and exercise are often used interchangeably, but these terms are not similar. "Physical activity is defined as any bodily movement produced by the contraction of skeletal muscles that result in a substantial increases over resting energy expenditure" (ACSM, 2009 and WHO, 2010). Physical activity, exercise and related terms have been defined somewhat inconsistency over the last decade ( USDHHS, 1996 and Caspersen, 1985). It is therefor important to differentiate betwen a numbers of related terms which have different meaning. Physical activity is defined as any bodily movement resulted by the contraction of skeletal muscle that increase energy expenditure above a basal level (PAGAC, 2008)

2.1.1 Types of Physical Activity

However, exercise is a subcategory of physical activity and has been defined as “planned, structured, and repetitive and purposive in the sense that the improvement or maintenance of one or more components of fitness is the objective”, and in some studies sports participation is assessed and analyzed separately from other leisure‐time activities (ACSM 2009, PAGAC, 2008, Caspersen et al. 1985,). Physical activity is sometimes defined synonymously with fitness. The fitness concept includes aerobic capacity, strength, flexibility, speed and power (Riddoch, 2005). Physical fitness has been defined in different ways. See for example the WHO’s definition, where fitness refers the ability to perform muscular work satisfactorily (PAGAC, 2008). Physical fitness has typically been defined as a set of attributes or characteristics that people have or achieve that relates to the ability to perform physical activity. These characteristics are usually categorized into either health related or skill related fitness components (Caspersen et al. 1985, ACSM

It is defined as “activities that do not increase energy expenditure significant above the resting level” (1.0-1.5 metabolic equivalent units) and includes activities such as sleeping, sitting and lying down (Pate RR et al, 2008).

2.1.2 Assessment of Physical Activity

There is no universal agreed definition or measure of physical activity (WHO, 2002). Measuring physical activity is very difficult, and the “accurate” assessment of individual physical activity levels remains a difficult area (Riddoch, 2005). For measurement or assessment at the population level, feasibility must be balanced with measurement accuracy (Hagströmer, 2007). An individual’s physical activity level is a complex, dynamic process that encompasses various phases of physical activity participation during life.

Physical activity can be measured or assessed in terms of energy consumption or behaviour. The components of activity which contribute to health status are activity intensity, duration and frequency. Most of our weekly consumption of energy is the result of physical activity that is not related to sport. Instead, it is due to the everyday physical activities such as walking or cycling to work, using the stairs instead of the elevator, working in the garden, the physical demands of the workplace or playing with the children. For non athletes, such activities are the largest component of total energy consumption in