Slide 1Slide 2Physical Work Capacity (Å&R, Ch.7,8,11)Slide 4Energy Sources & Duration of WorkIntermittent Work (Work/Rest Cycles)Individual Differences in Physical Work CapacityPhysical Fitness (Males 20-29, in ml/min/kg)Measurement of Energy ExpenditureRespiratory Quotient RQ = VC02 / V02Measurement of Aerobic CapacityIE 5531IE 553 Engineering of Human WorkDr. Andris FreivaldsClass #26IE 5532IE 553 Engineering of Human WorkDr. Andris FreivaldsClass #26IE 5533Physical Work Capacity (Å&R, Ch.7,8,11)Work Capacities (Demands) •Aerobic (with oxygen) –C6H12O6 + 6O2 6CO⇒2 + 6H2O + 38ATP•Anaerobic (no oxygen)–C6H12O6 2C⇒3H6O3 + 2ATPAnaerobicAerobic(Myoglobin)IE 5534Intensity of WorkSubmaximal tasks, as measured by:• VO2 • LactateIE 5535Energy Sources & Duration of WorkMyoglobin = quick, replenishable supplier of O2IE 5536Intermittent Work (Work/Rest Cycles)• Short, frequent W/R cycles are best• Self-paced work with spontaneous pauses• For prolonged work, VO2 should be at steady state412 WIE 5537Individual Differences in Physical Work Capacity • Peaks at 25 then ↓• Males > females• Due to body sizeIE 5538Physical Fitness (Males 20-29, in ml/min/kg) Low Fair Average Good High<25 25-33 34-42 43-52 >53Average = 3 l/minIE 5539Measurement of Energy Expenditure1) Direct calorimetry2) Indirect calorimetry3) Predict from oxygen uptakeV02 (l/min) = VE [I02 - EO2]VC02 (l/min) = VE ECO2E (kcal/min) = 3.94 V02 + 1.106 VC02 - 2.17 Neq E (kcal/min) = 3.9 V02 + 1.1 VC02 E (kcal/min) = 4.9 V02 (if RQ = 0.9)RQ = VC02 / V02IE 55310Respiratory Quotient RQ = VC02 / V02 RQ kcal/O2Type of Diet1.0 5.05 Pure carbohydrates0.9 4.92 Normal (12% protein, 33% fat, 55% carbs)0.7 4.70 All fat0.0 (noCO2)4.5 All proteinIE 55311Measurement of Aerobic Capacity •Direct – supramax-imal task•Submaximal task, extrapolate with HR 1) Step levels of 5 min2) Reproducible workload3) Large muscle groups, 4) Not too much
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