GLOSSARY

Sedentary Time is the duration spent in sedentary behavior during a specified interval. A person may train regularly while still accumulating substantial sedentary time elsewhere in the day.

Physical activity varies in intensity, duration and frequency. A hard training session may coexist with little movement during the rest of the day, and people can change nonexercise activity when training or food intake changes. A device's calorie estimate is not a direct measurement of total daily expenditure. Record the activity context and assess intake, recovery and longer-term body-mass trends together before changing a nutrition plan in response to one reported exercise value.

MET values describe an activity's energy demand relative to a reference resting rate. Standard MET tables are useful for comparing or classifying activities, but the reference may differ from an individual's actual resting metabolism. Multiplying a MET value by duration produces a volume indicator, not a direct measurement of energy expenditure in every athlete. Mechanical efficiency, body size, fitness and conditions can alter actual cost, particularly when values are transferred between different sports or individuals.

Total expenditure includes energy needed at rest, the thermic effect of food and physical activity. Planned exercise is only part of activity expenditure. Work, walking and spontaneous movement can also matter. When an estimate already includes a component, adding it again double counts energy. Establish whether an exercise value is gross or net of resting expenditure, and use the same convention when comparing days or combining wearable estimates with a daily energy model.