US RDA. Physiological and Metabolic Bases for Energy Expenditures. Physical activity: HjE. 1 MET = 1 metabolic equivalent

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1 Physiological and Metabolic Bases for Energy Ependitures Physical activity: HjE Nutrition 202 Animal Energetics R. D. Sainz Lecture 11 Cathy by Cathy Guisewhite US RDA 1 MET = 1 metabolic equivalent ~ resting VO 2 ~ 3.5 ml kg-1 min-1 1 MET = kcal kg-1 min-1 = kj kg-1 min-1 1

2 work output Net efficiency = 100 energy used above rest E.g., gasoline engine: efficiency ~ 20-25% Humans: efficiency ~ 15-27%, depending upon work rate type of activity fitness skill From: Schmidt-Nielsen, K Animal Physiology. Adaptation and Environment. Cambridge University Press, Cambridge. 2

3 From: Schmidt-Nielsen, K Animal Physiology. Adaptation and Environment. Cambridge University Press, Cambridge. From: Schmidt-Nielsen, K Animal Physiology. Adaptation and Environment. Cambridge University Press, Cambridge. From: Schmidt-Nielsen, K Animal Physiology. Adaptation and Environment. Cambridge University Press, Cambridge. 3

4 From: Schmidt-Nielsen, K Animal Physiology. Adaptation and Environment. Cambridge University Press, Cambridge. kcal/hr Work rate, W Energy output Heat production Heat loss Evaporative heat loss From: Nelson, M (1938) Die Regulation der Kortemperatur bei Muskelarbeit. Scand. Arch. Psysiol. 79:138. Net energy cost of walking Miles/hr m/min kcal kg -1 min kcal kg -1 km From: Howley, ET and Franks, BD Health/Fitness Instructor s Handbook. Human Kinetics Publishers, Inc., Champaign, IL 4

5 Figure 1. The power required to walk and to run at various speeds. Note that below a speed of about 2 m/s, it is more efficient to walk than to run, but above that speed, it is more efficient to run. From: accessed May17, *PTS = preferred transition speed From: accessed May 17,

6 Relationship between work-output output and O 2 consumption Eample - bicycle ergometer fly wheel of 6 m pedaling rate of 50 RPM 1 kg resistance 300 kg.meter work are performed per min 1 kg.meter corresponds to kcal 300 kg.meter = 0.7 kcal of work-output Assuming 25% efficiency, the total energy ependiture per minute is = 2.8 kcal 2.8 kcal 4.8 kcal/l O 2 = 0.58-liter O 2 consumption (Note the following terms: work = force distance; force = mass acceleration; power = work per unit of time; energy = the capacity of performing work). From: accessed May 17, Energy costs of various activities Category Resting Very light Light Moderate Heavy Activity Sleeping Sitting quietly Laboratory work Raking lawn Shoveling snow Basketball, soccer Running, 9 mph MET So: Apply the appropriate MET factor multiplied by the time spent on each activity to arrive at the scalar for REE, as in Activity factors: TEE = REE activity factor Men Women Very light Light Moderate Heavy Eceptional

7 E.g., long-term active women (mean 8.6 h/week aerobic eercise): PAL 2.48 vs. non-eercisers: PAL 1.87 Question: How much energy does eercise burn? Answer: E.g. 82 kg woman Sitting: 2.4 kcal/min 45 min = 108 kcal Cooking: 3.7 kcal/min 45 min = 167 kcal Walking: 4.8 kcal/min 45 min = 216 kcal But: she may also eat more From: Pariskova, J Age-dependent changes in dietary intake related to work output, physical fitness, and body composition. Am. J. Clin. Nutr. 49:962. 7

8 Question: Is fat-burning eercise better than other kinds? Answer: Low-moderate intensity (50% of VO 2ma ): RQ = 0.85, fat:ch 2 O = 50:50 Moderate-high intensity (60% VO 2ma ): RQ = 0.88, fat:ch 2 O = 40:60 But: more intense eercise uses more total calories, therefore burns more fat Question: Does a person continue to epend more energy after eercise? Answer: 1. Sedentary s. highly active men Sedentary day Active day MJ/d S A * kj/kg LBM S A From: Horton, TJ & Geissler, CA Habitual eercise patterns and daily energy ependiture. Proc. Nutr. Soc. 49:119A. 2. Effects of fitness: VO 2 ma = rate of oygen uptake by a person while eercising heavily; varies with level of cardiovascular fitness VO 2 ma (ml/min) = Heart rate (beats/min) Stroke volume (L/beat) (A-V) O 2 (ml O 2 /L) Athletes 6,250 = Normally-active 3,500 = From: Rowell, LB Human Circulation Regulation During Physical Stress. Oford University Press, NY. 8

9 3. Other metabolic adaptations: From: Kasperek, GJ, Conway, GR, Krayeski, DS, and Lohne, JJ A reeamination of the effects of eercise on rate of muscle protein degradation. Am. J. Physiol. 263:E1144. From: Kasperek, GJ, Conway, GR, Krayeski, DS, and Lohne, JJ A reeamination of the effects of eercise on rate of muscle protein degradation. Am. J. Physiol. 263:E Ecess post-eercise energy consumption (EPOC)??? Effects on energy balance, weight loss??? 9

10 ALSO: the often-ignored value of fidgeting: Condition EE (%) Supine 100 Sitting Motionless Fidgeting Standing Motionless Fidgeting ANIMALS beef cattle where NEma = [(0.006*DMI*(0.9-D)) + (0.05*T/GF + 3))]*W NEma is the NEm for activity (MJ/d) DMI is dry matter intake from pasture (kg/d) D is digestibility of dry matter (decimal fraction) T is terrain (level=1.0, undulating=1.5, hilly=2.0) GF is green forage availability (ton/ha) W is body weight (kg) From: NRC,