Physical activity refers to any bodilymovement that is produced by the skeletal muscles and results in energyexpenditure that aims to maintain and improve physical fitness (Daskalopoulou, 2017).Physical activity can be classified as structured or incidental. Structuredphysical activity is planned, purposeful activity undertaken to promote healthand fitness benefits while incidental physical activity is not planned andusually is the result of daily activities at work, at home, or during transport(Strath et al., 2017).
Based on recentstudies, physical activity is associated with a reduction in obesity, weightgain, coronary heart diseases (CHD), type II diabetes mellitus and the age-relateddiseases of dementia and Alzheimer’s disease (Reiner et al., 2013). This maylead to a good quality of life because of the lower risk of getting diseases. Physicalactivity can be defines further into three dimensions which is frequency,duration, and intensity. These three dimensions together constitute the amountor the dose of physical activity performed (5).
Frequency refersto how often the activity occurs and duration refers to time. For example howlong the activity lasts. According to World Health Organization (2010), theintensity of physical activity refers to the rate at which the activity isperformed or the magnitude of the effort that is required to perform theactivity and is therefore important in relation to physical fitness. Hence,moderate-intensity of physical activity requires a moderate amount of effortand noticeably accelerates the heart rate such as brisk walking.
Meanwhilephysical activity of vigorous-intensity requires a large amount of effort andcauses rapid breathing and a substantial increase in heart rate like running(WHO, 2010).Beside,intensity is defined as relation to the metabolic rate of the body whereas onemetabolic equivalent (MET) is defined as the amount of oxygen consumed whilesitting at rest (Jette et al., 1990). Furthermore, relative intensity refers tothe level of effort required to do an activity while absolute intensity is theamount of energy expended per minute of activity.
According to (Physical Activity GuidelinesAdvisory Committee, 2008), absolute intensity has been defined intothree intervals of metabolic rate which is <3 METs is for light-intensityphysical activity, 3-5.9 METs for moderate-intensity physical activity and ?6 METsis equal to vigorous-intensity physical activity. In relation to public healthguidelines for physical activity, the intensity is an important factor.