Slide 1Why is measurement important?Why are we interested in energy expenditure?What is energy expenditureEnergy BalanceTotal daily energy expenditureSlide 7Resting energy expenditureMeasurement of Energy ExpenditureDirect CalorimetryIndirect CalorimetryStrengths/WeaknessesDoubly labeled waterDoubly labeled waterWhat is the Metabolic Equivalent (MET)?METs and physical activityMETs during physical activityMETs during physical activity (con’t)Compendium of Physical ActivitiesSlide 20Slide 21Slide 22Case Study: Application of METsCase Study: Energy StatusCase Study: Exercise prescriptionSlide 26Problems with METsSubject CharacteristicsImpact of reference baseline during activityResults: Average METs by ActivitySummaryConcepts and Methods 2: Measurement of exposure Energy ExpenditureFall 2017Why is measurement important? •Determine “dose” of physical activity that is important for health•Determine population levels of physical activity and how they are changing over time•Determine if interventions to increase physical activity improve healthWhy are we interested in energy expenditure?1) Understand metabolic requirements for rest and exercise2) Energy balance–What is meant by energy balance?3) Physical activity assessment4) Monitor energy expenditureWhat is energy expenditure•Energy expenditure –amount of energy a person uses daily to complete all bodily activities What makes us expend energy???Energy BalanceENERGY INTAKEENERGY EXPENDITURETotal daily energy expenditure•Total energy expenditure–Total number of kcals expended in a day•What determines TDEE?1)Thermic effect of feeding 2)Resting metabolic rate 3)Thermic effect of PAResting energy expenditure•Baseline energy expenditure•Energy expenditure that only includes what is required at rest•Influenced by–Body Surface area (BSA)–Growth and development–Sex–Stress–Hormones –Age •Typical range fromMeasurement of Energy Expenditure•95% of energy expenditure is from reactions with oxygenFoodstuff + O2  ATP + Heat + CO2 + H2O–Therefore, by measuring oxygen consumption, or heat you can measure energy expenditure1) Direct calorimetry - Measures body heat loss 2) Indirect calorimetry – Measures O2 consumption3) Doubly-labeled water- Measures free-living metabolic rateDirect CalorimetryMelanson et.al, 2010Indirect Calorimetry–Measurement of oxygen consumption as an estimate of metabolic rateFoodstuff + O2  Heat + CO2 + H2OStrengths/WeaknessesDirect CalorimetryStrengthsVery accurateWeaknessesExpensive! Limited “free-living” applicationsUsed up to 24 hoursIndirect CalorimetryStrengthsVery accurateWeaknessesLimited “free-living” applicationsRestricted to laboratoryDoubly labeled waterDoubly labeled water•Drink water (H2O) that contains labeled isotopes…so really it’s 2H218O•As energy is expended, CO2 and H2O are produced•2H2 leaves the body in urine, sweat and vapor (water loss)•18O leaves the body as water and carbon dioxide•Calculate difference between rate of loss of O and H–Oxygen consumption calculated from carbon dioxide production–EE calculated using stoichometry•Strengths: really accurate measure of energy expenditure and not invasive•Weakness: EXPENSIVE!!, gives total EE over a week but not a rate (per day, per hour)What is the Metabolic Equivalent (MET)?One MET is defined as:Energy expenditure at restRatio of working/resting metabolic rate MET factorial system–Expresses activity as multiples of resting metabolic rate (RMR)–e.g. 7 ml kg∙-1min∙-1 / 3.5ml kg∙-1∙min-1 = 2 METs –Oxygen consumption and Energy expenditure are directly relatedMETs and physical activitySweeping = 12 ml kg∙-1min∙-1 1 MET: 3.5 ml kg∙-1min∙-1 12/3.5=3.4 METsOrThree and a half times greater than restRunning = 30 ml kg∙-1min∙-1 1 MET: 3.5 ml kg∙-1min∙-1 30/3.5= 8.6 standard METsOr Nearly 9 times greater than restMET-hours = METS X # hours you perform the taskMET-minutes = METS X # minutes you perform the taskMETs during physical activity•Oxygen consumption during walking at a constant pace is 10 ml/kg/min–Resting oxygen consumption = 3.5 ml/kg/min•2.9 METs (10 ml/kg/min/3.5 ml/kg/min) or 2.9 times resting energy expenditure•If Bob weighs 60 kg, and it is known that 1 MET = 1.0 kcal/kg/hr, then the energy expenditure at 2.9 METs = 174 kcals per hr (2.9 METs * 60 kg)METs during physical activity (con’t)•Oxygen consumption during running at a constant pace is 35 ml/kg/min–Resting oxygen consumption = 3.5 ml/kg/min•10 METs (35 ml/kg/min/3.5 ml/kg/min) or 10 times resting energy expenditure•If Sally runs at this pace for 30 min, she will expend 300 kcalsCompendium of Physical Activities •Provides the energy cost of individual physical activities •First published in 1993, updated in 2000 and most recent version published in 2011–Useful for coding physical activity questionnairesAssigned MET value for 605 activities (Ainsworth et al. 1993, 2000)Divide measured VO2 by reference baseline (3.5 ml∙kg-1∙min-1)–http://sites.google.com/site/compendiumofphysicalactivities/Case Study: Application of METs •A client comes to you and wants to lose weight: goal - to lose 12 pounds in the next 6 weeks.•She currently weighs 80 Kg • You recognize she should pace herself and lose 2lbs/week. –It takes 3500kcals to lose one pound so she needs to have energy deficit of 7000kcals/week or 1000/day. •Energy Intake–Current eats 2200 kcals/day–Agrees to cut calories by 300/day•Energy expenditure–RMR is 1500 kcal/day–TEF is 300 kcal/day–PA is 300 kcal/dayCase Study: Energy Status•Intake before = 2200 kcal/day•Expenditure before = 2100 kcal /day•She is in energy __________ of ___________ kcal/day•Intake after 1900 kcal/day•Expenditure without exercise: 2100/day•She is in energy __________ of ___________ kcal/day•To get to energy deficit of 1000 kcal/day she needs to expend an extra ______________ kcal/day from exerciseCase Study: Exercise prescription•Need to expend _____ kcals/day from exercise to create an energy deficit of 1000kcals/day•What activities can she do to achieve this? 1. 30 minutes of running = 10 METs1. 10 kcal/Kg/hr2. 10 * 80 * 0.5 = 400kcals2. Walk dog for 30 minutes = 4 METs1. 4 kcal/kg/hr2. 4*80*0.5 = 160 kcals3. Do housework for an hour = 3 METs1. 3kcal/kg/hr2. 3*80*1 = 240 kcalPhysical Activity Intensity Classification according to MET level–Determined by a