Physical activity refers to any bodily movement produced by skeletal muscles that increase energy expenditure above a basal level. It can be divided into two main categories. One is exercise that involves structured and repetitive bodily movements. The other is non-exercise physical activity, such as standing, commuting to and from school or work, or participating in household chores or occupational work. Both exercise and non-exercise physical activity can further be classified by the level of intensity: light, moderate and vigorous. While vigorous-intensity physical activity (e.g., jogging) can provide greater benefits for physical fitness and burn more calories per unit of time than moderate-intensity physical activity (such as brisk walking), engaging in low-intensity physical activity (such as light walking) is better than no physical activity at all.

Level of
intensity
Physical Activity
Exercise Non-exercise physical activity
Vigorous Examples:
jogging, fast swimming, fast dancing, jumping rope, tennis (singles), basket ball, soccer
Examples:
playing with children or dogs at a fast pace, heavy gardening (such as continuous digging or hoeing)
Moderate Examples:
brisk walking, water aeorbics, tennis (doubles), biking on level ground, sports involving catch and throw (such as volleyball and baseball)
Examples:
stair-climbing, carrying small children, mopping floor, scrubbing the bathtub, car washing, general gardening
Low Examples:
light walking, stretching, lifting hand weights, sit-ups, push-ups against the walls
Examples:
standing, washing dishes, doing laundry, cooking, playing piano

Besides, different types of physical activity confer different health benefits. Resistance exercise (such as weight lifting and resistance band workouts) can not only increase muscular strength and endurance but also maintain or increase muscle mass. Weight-bearing exercise can help increase bone mass during growth, maintain peak bone mass during adulthood and reduce the rate of bone loss during aging.

Flexibility activity (such as Tai Chi and yoga) keeps muscles relaxed and joints mobile.

Becoming more active is safe for most people. However, some people may need to get a medical clearance before they exercise. If you are in doubt, please see a doctor.

References

Exercise and Physical Activity Guide for Health Promotion 2006. Tokyo: Ministry of Health, Labour and Welfare of Japan; 2006.

Pacific Physical Activity Guidelines for Adults: Framework for Accelerating the Communication of Physical Activity Guidelines. Manila: World Health Organization Regional Office for the Western Pacific Region; 2009.