8 min readConcept sheetOften a 5- or 10-mark answer; MET sums come as short problems

Physical activity: types, determinants, benefits and METs

Physical activity is any body movement by skeletal muscles that uses energy. Its intensity is measured in METs: kcal = MET × weight (kg) × hours.

Definition (WHO)Any bodily movement produced by skeletal muscles that requires energy expenditure

1 METResting energy use: 3.5 mL O2 per kg per minute, about 1 kcal per kg per hour

Intensity bandsLight below 3 MET; moderate 3-5.9 MET; vigorous 6 MET or more

WHO 2020, adults150-300 min moderate or 75-150 min vigorous a week, plus muscle strengthening on 2 or more days

Types of physical activity

Basis	Types	Indian examples
Domain (where it happens)	Occupational, household, transport, leisure and sport	Farm work or construction; sweeping and washing clothes by hand; cycling to college; cricket, dance, yoga
Kind of activity	Aerobic, muscle-strengthening, bone-strengthening, balance and flexibility	Brisk walking; push-ups; skipping and jumping; yoga asanas
Intensity (MET)	Light (below 3), moderate (3-5.9), vigorous (6 and above)	Slow walking, cooking; brisk walking, doubles badminton; running, a full kabaddi match

Determinants of physical activity (socio-ecological model)

Level	Determinants	Example
Individual: biological	Age, sex, health, body weight, fitness	Activity drops in the late teens, more among girls
Individual: psychological	Motivation, enjoyment, confidence (self-efficacy), time, knowledge	A student who enjoys dance stays active
Social	Family support, friends, coach, gender norms, culture	Parents who stop girls playing outdoors after school
Environmental	Parks, safe roads, street lights, weather, pollution	Summer heat or monsoon rain cuts outdoor play
Policy and programmes	School PE periods, sports quotas, workplace and national schemes	Fit India Movement, Khelo India, college sports days

Benefits of regular physical activity

Heart and blood vessels: lower resting heart rate and blood pressure, higher HDL cholesterol.
Metabolism: better insulin sensitivity and blood glucose control; lower risk of type 2 diabetes.
Body weight: more energy used, less body fat, muscle kept.
Bones and muscles: weight-bearing activity builds bone density and lowers osteoporosis risk.
Mind: better mood, sleep and concentration; less stress, anxiety and depression.
Lower disease risk: heart disease, stroke, some cancers (colon, breast); fewer falls in old age.
Children and teens: healthy growth, motor skills, social skills and school performance.

Energy cost of a training day using METs

Problem

Priya, a 55 kg hockey player, does 1.5 hours of hockey practice and 30 minutes of jogging. Take hockey as 8 MET (the Compendium of Physical Activities lists field hockey at 7.8; rounded to 8 here) and jogging as 7 MET (the 2011 Compendium value; the 2024 update lists 7.5). Find the energy used in these two activities.

Working

Formula: kcal = MET × body weight (kg) × time (hours).
Hockey: 8 × 55 × 1.5 = 440 × 1.5 = 660 kcal.
Jogging: 30 minutes = 0.5 hour, so 7 × 55 × 0.5 = 385 × 0.5 = 192.5 kcal.
Total = 660 + 192.5 = 852.5 kcal, rounded to 853 kcal.
Check: 8 × 55 = 440 and 440 × 1.5 = 660; 7 × 55 = 385 and 385 ÷ 2 = 192.5.

Answer

About 853 kcal for the two activities (rounded to the nearest kcal). This is added to her energy for the rest of the day.

Activity: heart rate, blood pressure and METs

1
Sit quietly for 5 minutes before any reading.
2
Resting pulse: feel the radial artery at the wrist, count for 30 seconds and double it. Normal adults: 60-100 beats/min; trained endurance athletes are often lower.
3
Blood pressure: cuff on the bare upper arm at heart level, arm supported; take two readings 1-2 minutes apart and average them. A normal adult reading is below 120/80 mm Hg.
4
Maximum heart rate ≈ 220 − age. American Heart Association target zones: moderate 50-70%, vigorous 70-85% of maximum. For a 20-year-old: maximum 200, moderate zone 100-140 beats/min.
5
Keep a 24-hour activity diary, give each activity a MET value from the Compendium of Physical Activities, and use kcal = MET × kg × hours.
6
Add up the day's energy and compare with the diet record.

For the athlete

MET sums let a sports dietitian add training energy to an athlete's basic needs. A kabaddi player who trains twice a day may need much more than the ICMR-NIN 2020 figure for a moderately active reference man (about 2710 kcal), so the plan is built from his own activity log.

Exam angle

2 marks: “What is a MET?” Metabolic equivalent: the energy used at rest, 3.5 mL O2/kg/min or about 1 kcal/kg/h. A 6 MET activity uses six times the resting energy.

5 marks: “Explain the determinants of physical activity.” Individual (biological, psychological), social, environmental and policy determinants, each with an Indian example.

10 marks: “Describe the types, determinants and benefits of physical activity.” Definition, types by domain, kind and MET intensity, determinants at each level, benefits by body system, WHO 2020 dose, and a closing line.

Remember it

MET sum: Multiply Everything Together: MET × kg × hours = kcal.