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Exercise and Metabolism Energy

Exercise and Metabolism Energy. Learning Objectives. Explain that food energy comes from lipids, proteins and carbohydrates Explain how the potential energy in food is used to synthesise ATP State that energy is measured in kilojoules (kJ)

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Exercise and Metabolism Energy

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  1. Exercise and MetabolismEnergy

  2. Learning Objectives • Explain that food energy comes from lipids, proteins and carbohydrates • Explain how the potential energy in food is used to synthesise ATP • State that energy is measured in kilojoules (kJ) • State that energy balance is considered as : energy in – energy out = change in energy stores • Explain the link between diet, coronary heart disease and obesity

  3. Learning Objectives • Describe basal metabolic rate (BMR) and its measurement. • Describe how physical activity and dietary-induced thermogenesis can affect energy expenditure • Describe factors affecting total energy expenditure to include: body size and composition, age,sex,nutritional status, pregnancy and lactation.

  4. Why do we need energy? • Movement – ie muscle contraction • Synthesis of enzymes and other cellular materials which allow growth and repair of body tissues • Basal Metabolic Rate – energy required for heart beat, breathing, maintaining body temp and all other vital processes.

  5. Energy from food • Carbohydrates • Lipids (fats) • Protein • Energy stored as chemical energy which is released during respiration to produce ATP (energy currency). • Energy content of food measured in either kilojoules (kJ) or kilocalories (kcal).

  6. Energy Balance • To have an energy balance: Energy from food = energy expended by the body • If energy in>energy out  weight gain • If energy in<energy out  weight loss • Energy required by an individual depends on basal metabolic rate, level of physical activity and thermic effect of food.

  7. Dietary recommendations for health • Obesity in increasing due to increase in energy intake from fat & inactivity. • Increased fat in diet  cholesterol & CVD. • Government recommends our energy intake should be from: fat (30%); protein (20%) and carbohydrate (50%).

  8. Energy Expenditure • Total amount of energy expended by the body is the sum of three components: - Basal Metabolic Rate - Thermic Effect of food - Physical activity

  9. Basal Metabolic Rate • The energy required to carry out essential body functions eg. heart beat, blood circulation. • 60-70% of an individual’s total energy output

  10. Basal Metabolic Rate • Very difficult to measure. Requires highly standardised conditions. • Usually measured in MJ/day or kcal/day. • There are a number of age-,weight-, sex adjusted equations for the prediction of BMR.

  11. Thermic Effect of Food • The body uses up energy to digest, metabolise and store ingested nutrients. • This energy is eventually released as heat • Energy expended varies with food type: - protein = 17% increase - carbohydrate = 9% increase - fat = 3% increase

  12. Physical Activity • Any activity, however gentle, uses up energy in addition to BMR. • Highly variable, depending on activity. • Energy expending for an activity is usually expressed as a multiple of BMR known as Physical Activity Ratio – PAR. • Exercising regularly will increase energy used and BMR.

  13. Factors affecting total expenditure • Body size and composition • Age • Sex • Nutritional status • Pregnancy/Lactation • Activity levels • Climate

  14. Typical Essay Question • Discuss the factors that influence the energy needs and energy expenditure of the body.

  15. Websites • http://www.brianmac.demon.co.uk/energyexp.htm • http://www.primusweb.com/fitnesspartner/library/weight/calsburned.htm • http://instruct1.cit.cornell.edu/courses/ns421/BMR.html • http://scholar.hw.ac.uk

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