Energy Expenditure

EE: Physical Activity (2005)


Aerobic (cardiorespiratory) fitness- developed through exercise that is designed to improve the ability of the heart and lungs to deliver oxygen to the working muscles for activity.  It includes observations of the heart rate, blood pressure, perceived exertion and a subjective response to exercise.  To improve aerobic fitness, beginners work at fairly low levels of intensity (55-65% of maximal heart rate) and work upwards to moderate levels (65-80% max heart rate).  This exercise is performed 3-5 days per week with 20-60 minutes of continuous or accumulated bouts (of at least 10 minutes for each bout).  The maximal heart rate can be estimated from the equation:  220 minus the subjects age.

Anaerobic (muscular) fitness- is developed by increasing the resistance to movement or the frequency or duration of activity levels above those normally experience and to perform a minimum of 8-10 different exercises that train the major muscle groups that lasts approximately one hour.  The exercise should involve lifting (concentric phases) and lowering (eccentric phases).

Excess post-exercise oxygen consumption (EPOC): see post-exercise recovery oxygen consumption

Exercise (Exercise training) – a planned structured and repetitive bodily movement done to promote or maintain one or more components of physical fitness and is more vigorous and leads to improvements in physical fitness (Institute of Medicine. Dietary reference intakes: Energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids.  Washington, DC: National Academy Press, 2002.  Internet access:  Accessed March 12, 2004 and June 16, 2004.)  For the two types of common exercise training see Aerobic (cardiorespiratory) fitness and Anaerobic (muscular) fitness.

Exercise Frequency – For individuals having moderate to higher levels of fitness, 3 to 5 sessions per week are recommended.  Those with lower levels of fitness benefit from multiple shorter daily exercise sessions.  The American College of Sports Medicine (ACSM) recommends minimal thresholds of 300 kcal per exercise session performed 3 days per week or 200 kcal per session completed 4 days per week.  A reasonable approach is to achieve a weekly exercise caloric expenditure of approximately 1000 kcal.

Exercise Intensity – The ACSM recommends exercise intensity be prescribed at 60-90% of maximum heart rate (HRmax).  However, very low initial levels of fitness working at a low exercise intensity (30-60% HRmax) can also benefit.  To estimate a training heart rate, multiple the maximal heart rate time 60%, 70% or 80%. 

Exercise Progression – The ACSM recommends progression of exercise to promote endurance.

Initial conditioning stage lasts for about 4 or 5 weeks with an exercise intensity beginning at ~40% of HRmax progressing to 70% with sessions lasting from 12 minutes up to ~20 minutes with a frequency 3 times per week.

Improvement stage lasts from 4 to 5 months, where intensity progresses to achieve 60-85% of HRmax with a duration of 20 minutes increasing to 30 minutes per exercise sessions; 3 to 5 sessions per week.

Maintenance stage begins after training for 6 months, involves exercise frequency of about 3 times/week; working at 70-85% HRmax and each session lasting 30-45 minutes.

Source:  David Geffen School of XXX.  Internet access: .  UCLA Nutrition Education.  Accessed May 31, 2004.

Maximal heart rate can be estimated from the equation:  220 minus the subjects age; individuals may have higher or lower Max HR and must be measured directly to know exactly]

Maximal oxygen uptake (VO2 max): traditionally accepted criterion measure of cardiorespiratory fitness.

METS- multiples of an individual’s resting oxygen uptake, defined as the rate of oxygen (O2) consumption of 3.5 mL of O2/min/kg body weight in adults. 

Non-exercise activity thermogenesis  (NEAT): energy related to activity that is not exercise such as minor movements and general ambulation (Levine JA, Non-exercise activity thermogenesis (NEAT).  Best Practice and Research Clinical Endocrinology and Metabolism.  2002;16:679-702).

Physical activity- bodily movement that is produced by the contraction of muscle and that substantially increases energy expenditure (Department of Health & Human Services. Centers for Disease Control & Prevention, National Center for Chronic Disease Prevention and Health Promotion, The President’s Council on Physical Fitness and Sports.  Physical activity and Health: A report of the Surgeon General.  Atlanta: GA, 1996)

Physical activity level (PAL)- The term used in the Dietary Recommended Intake (DRI) energy recommendations.  Physical activity level (PAL) coefficients are based on rates of energy expenditure during exercise reported in terms of METs, with an allowance for the post-exercise increase in energy expenditure (EPOC) induced by physical activities and the thermic effect of food that needs to be consumed to cover the overall cost of these activities.  Table 1 defines the various ranges.

Table 1:  DRI physical activity levels (PALS) 






³1.0 to <1.4]

Includes BMR, TEF, & physical activity for independent living


³1.4 to <1.6]

Using 70 kg adult, walking 2 miles/d at 3-4 m/h or equivalent energy expenditure in other activities


³1.6 to <1.9

Using 70 kg adult, walking 7.3 miles/d or equivalent energy expenditure in other activities

Very Active                          

³1.9 to <2.5

Using 70 kg adult, walking 16.7 miles/d or equivalent energy expenditure in other activities

      *Note: These distances can vary with body weight and substantially reduced by walking faster or performing other  physical activities of various intensities.  Substantial fidgeting and other spontaneous activities may contribute to PAL but not produce health benefits of sustained exercise (5).

                SourceNational Institutes of Health, Health Canada, and the National Academy of Sciences Institute of Medicine (IOM) Food and     Nutrition Board

Physical fitness- A set of attributes that people have that relates to the ability to perform physical activity.

Post-exercise recovery oxygen consumption:  the time course of oxygen consumption during recovery from exercise; rate of decay typically completed in 10 – 90 minutes (Mole, 1990)

Cumulative net increase above pre-exercise RMR- Derived by determining the difference between the total oxygen consumption during postexercise trial values and the extrapolated oxygen consumption during an equal period of controlled, pre-exercise sitting RMR

Percent above pre-exercise RMR- Determined by subtracting the controlled sitting RMR from the postexercise trial at specific time points and multiplying by 100

Total volume group mean O2 consumption –Oxygen consumption during recovery from exercise that includes rest period oxygen consumption plus post-exercise oxygen consumption; and is reported at specific time points

Thermic effect of test meal (TEM):  includes the energy cost of total food intake and includes the energy cost of food absorption, metabolism, and storage within the body; usually measured from 30 mintues to up to 8 hours.

                Obligatory thermogenesis component:  the energy cost associated with absorption and transport of nutrients as well as the synthesis of protein, fat, and carbohydrate

                Facultative thermogenesis component:  Energy expended in excess of obligatory thermogenesis.

Thermic effect of feeding (TEF): includes the cumulative energy expenditure associated with the ingestion of food;, and constitutes approximately 10% of daily energy expenditure.

Thermic effect of activity (TEA):  Most variable energy expenditure component in humans and includes the additional energy expended above RMR and TEM due to physical activity, including shivering and fidgeting.  In sedentary persons, TEA may constitute approximately 15% of total daily energy expenditure, whereas individuals who regularly exercise may have phys ical activity increases up to 30% of daily energy.

Weight Classifications

The indirect calorimetry study integrated the BMI classification distinctions between Overweight and Obesity.  Healthy adults included healthy (i.e., “normal”) weights and overweight BMI classifications.  Obese adults included individuals with BMIs >/= 30 kg/m2

Classification of Overweight and Obesity by BMI



BMI (kg/m2)

Obesity Class








25.0 – 29.9



30.0 – 34.9



35.0 – 39.9


Extreme Obesity

>/= 40


SOURCE:  National Heart, Lung, and Blood Institute.  NHLBI Obesity Education Initiative Expert Panel. Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults.  The evidence report.  Bethesda, MD: National Institutes of Health, National Heart, Lung, and Blood Institute (NHLBI), June, 1998.

Classification of Overweight and Obesity by Percent Body Fat

Body Fat Guidelines from the American Dietetic Association and DRI Prepublication



American Dietetic Association

Institute of Medicine. Dietary Reference Intakes


(% Fat)

(% Fat)

(% Fat)

(% Fat)


(BMI 18.5 up to 25)






(BMI 25 up to 30)






(BMI 30 up to 35)

> 30

> 25



Clinically obese

(BMI 35 or >)





Sources:  Gallagher D, Heymsfield SB, Geo M, Jebb SA, Murgatroyd PR, Sakamoto Y.  Healthy percentage body fat ranges: an approach for developing guideline based on body mass index.  Am J Clin Nutr. 2000;72:694-701; Institute of Medicine.  Dietary reference intakes: energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids.  Washington, DC: National Academy Press. 2002; Internet access: , Accessed February 20, 2003.