Activities are classified as **light, moderate, or heavy** according to the energy expended or the oxygen consumed while accomplishing them.

**Light work** for the average male (65 kg) requires 2.0 to 4.9 kcal/min, or 6.1 to 15.2 mL O2/kg per minute, or 1.6 to 3.9 METs. Strolling 1.6 km/hr, or 1.0 mph, is considered light work.

**Heavy work **for the average male (65 kg) requires 7.5 to 9.9 kcal/min, or 23.0 to 30.6 mL O2/kg per minute, or 6.0 to 7.9 METs. Jogging 8.0 km/hr, or 5.0 mph, requires 25 to 28 mL O2/kg per minute and is considered heavy work. The energy expended is equivalent to 8 to 10 kcal/min, or 7 to 8 METs.

The energy expenditure necessary for most industrial jobs requires more than three times the energy expenditure at rest. Energy expenditure of certain physical activities can vary, depending on factors such as skill, pace, and fitness level.

The average individual engaged in normal daily tasks expends 1800 to 3000 kcal per day. Athletes engaged in intense training can use more than 10,000 kcal per day.

## What is Energy Expenditure in Physiotherapy?

**oxygen**consumed. Units used to quantify energy expenditure are kilocalories and METs.

- A
**kilocalorie**is a Represents the energy value of food taken by person. It is the amount of heat necessary to raise 1 kilogram (kg) of water 1˚C. A kilocalorie (kcal) can be expressed in oxygen equivalents. Five kilocalories equal approximately 1 liter of oxygen consumed (5 kcal = 1 liter O2). - A
**MET**is defined as the oxygen consumed (milliliters) per kilogram of body weight per minute (mL/kg). It is equal to approximately 3.5 mL/kg per minute.

## What is Workout Efficiency? How its measures?

Percent efficiency = useful work output/energy expended or work input × 100