Ex.physiology 6,7

Course Information

• Course name: Exercise Physiology
• Course code: DPT-213

Learning Outcomes

• Identify concepts of total daily energy expenditure (TDEE)
• Explain effect of body weight on energy cost of physical activity

Total Daily Energy Expenditure (TDEE)

• Determined by three factors:
  • Resting metabolic rate (RMR)
  • Thermogenic influence of consumed food
  • Energy expended during physical activity

Energy Expenditure During Physical Activity

• Total energy expenditure = Basal Metabolism + Digestion (thermic effect of food) + Physical Activity

Basal Metabolic Rate (BMR)

• Minimum energy needed to sustain body functions in waking state
• Oxygen consumption values for BMR usually range between 160 and 290 mL/min (0.8 to 1.43 kCal/min)

Resting Daily Energy Expenditure (RDEE)

• Can be predicted using models
• Models include body mass (BM), stature (S), and age (A)
• Equations exist to calculate RDEE for women and men
• Harris-Benedict Equation used for calculations during 24 hours

Activity Examples

• BM = 62.7 kg, S = 172.5 cm, A = 22.4 years

Estimation of RDEE Based on Fat-Free Body Mass (FFM)

• Generalized equation applicable to males and females: RDEE (kCal) = 370 + 21.6 (FFM, kg)
• Example: A male weighing 90.9 kg at 21% body fat has an estimated FFM of 71.7 kg.

Dietary-induced Thermogenesis

• Total energy expenditure = Basal Metabolism + Digestion (thermic effect of food) + Physical Activity

Thermic Effect of a Meal

• Two components:
  • Obligatory thermogenesis (digestion and absorption; synthesis of protein, fat, and carbohydrate)
  • Facultative thermogenesis (peaks in 30-90 minutes; depends on size and content of meal, attributed to sympathetic nervous system activity)

Estimation of Caloric Expenditure

• Caloric equivalent: kilocalories produced per liter of oxygen consumed
• Caloric cost: energy expenditure of an activity for a specified period of time
• Expressed as total calories (kcal), calories or kilojoules per minute (kcal·min-¹ or kJ-min-¹), relative to body weight (kcal-kg-1·min-1 or kJ-kg-1·min-¹)

Five-Level Classification of Physical Activity Based on Energy Expenditure

• Table showing energy expenditure levels in kcal/min-1,L/min-1, mLkg-1·min-1 and METS for both men and women

Estimation of Caloric Expenditure

• Carbohydrates are most efficient in oxygen use for energy production, followed by fat, then protein

Estimation of Caloric Expenditure

• Factors determining the caloric cost of activity include the amount of oxygen consumed, and the caloric equivalent.
• Calculation example to determine the energy expenditure of activity.

Cardiovascular Responses: Integration of Exercise Response

• Complex, fast, and finely tuned
• First priority: maintenance of blood pressure
• Blood flow maintained only as long as BP is stable

Cardiovascular variables

• HR (Heart Rate)
• SV (Stroke Volume)
• BP (Blood Pressure - SBP & DBP)
• TPR (Total Peripheral Resistance)
• Q (Cardiac output)
• RPP (Rate Pressure product)

Exercise Physiology for Health, Fitness, and Performance

• Written by Sharon A. Plowman and Denise L. Smith
• Published in the 3rd edition - Chapter 4 (pp. 105-108)
• Published in the 3rd edition - Chapter 12

Exercise Physiology: Nutrition, Energy, and Human Performance

• Written by William D. McArdle, Frank I. Katch, and Victor L. Katch
• Pages in the book, Chapter 8 and 9

Measurement of energy expenditure during exertion

• Calculating the energy expenditure of physical activity

Gross versus Net Energy Expenditure

• Gross expenditure or total values include resting energy requirement during the activity phase
• Net expenditure reflects the energy cost of the activity, excluding resting metabolism, over an equivalent time period

Field Estimates of gross Energy Expenditure during Exercise

• Calculation example for walking at a 20 min mi-1 pace (3 mi hr-1) - velocity is 80.4 m·min-1
• Walking oxygen consumption is 11.54 mL-kg-1-min-1

Problem solving examples

• Determining the number of kilocalories expended for various exercises

The Metabolic Equivalent (MET)

• Acronym for Metabolic Equivalent
• Represents the average seated rest energy cost for adults
• Set at 3.5 ml·kg-¹.min-1 of oxygen, or 1 kcal.kg-1.hr-1
• Used by exercise physiologists and physicians for metabolic equivalent values

Cardiac Output (Q)

• Q = HR x SV
• Increases with intensity, plateaus near VO2 max
• Normal values:
  • Resting Q ~5 L/min
  • Untrained Q max ~20 L/min
  • Trained Q max ~40 L/min

Cardiovascular responses to prolonged, moderately intense exercise

• Measurement of cardiovascular variables over time during activity
• Cardiovascular drift is associated with rising body temperature

Upper-Body versus Lower-Body Aerobic Exercise

• Comparisons of cardiovascular responses during upper-body versus lower-body aerobic exercise

Arm versus Leg Exercise

• Comparison of metabolic responses during arm versus leg exercise

Cardiovascular Responses to Exercise

• Classification of exercise types
• Short-term, light to moderate submaximal aerobic exercise
• Long-term, moderate to heavy submaximal aerobic exercise
• Incremental aerobic exercise to maximum

Recovery of heart rate and blood pressure.

• Recovery from exercise depends on factors such as fitness level, temperature, and humidity, as well as duration and intensity of exercise

Pressure rate product (RPP)

• Index of myocardial oxygen consumption
• Used to assess myocardial workload
• Calculation of RPP (RPP = HR * SBP)

Pregnancy Effects on Cardiovascular Function.

• Pregnancy does not compromise absolute aerobic capacity
• Body weight increases, decreasing economy of movement
• Pulmonary ventilation increases during later stages of pregnancy, with a greater response to the submaximal exercise intensity
• The hormones increase the sensitivity of the respiratory center to carbon dioxide, which leads to increased maternal hyperventilation in response to exercise