BMR, VO2 max, Lactate Threshold

Applications of Metabolism & Respiration

Basal Metabolic Rate

• metabolic rate = the amount of energy consumed by an organism in a given time

• basal metabolic rate (BMR) = the minimum amount of energy on which an organism can survive

BMR and Age(Image from:http://www.vrp.com/neuroendocrine-support/)

Measuring BMR

• amount of thermal energy lost measured using a Benzinger calorimeter

• measurement of body surface area (BSA) by encasing person in wax mould

• …or using the equation: BSA = m0.425 x h0.725 x 0.007184

• …or just using a nomogram

Nomogram(Image from: http://www.manuelsweb.com/ped_dose_nomo.htm)

BMR questions (p.112)

1. Why is BSA used in the determination of BMR?

2a. Use the BSA equation to determine the body surface area of a teenager whose mass is 78kg and height is 1.70m. Use the nomogram in Figure 27 to check your answer.

2b. Calculate the teenager’s BMA as he dissipates 439 kJ of thermal energy in 1.5 hours.

BMR questions (p.115)

18a. Distinguish between metabolic rate and basal metabolic rate.

18b. Explain how and why metabolic rate changes as we grow older.

Exercise Physiology

• study of the body’s responses to exercise

• aerobic fitness = the measure of the ability of the heart, lungs, and bloodstream to supply oxygen to the cells of the body during physical exercise

VO2 max(Image from: http://nyvelocity.com/content/coachingfitness/2007/lactate-and-vo2-max-test-cadence)

• maximum oxygen consumption (VO2 max) = the maximum volume of oxygen in mL, that the cells of the body can removed from the bloodstream in one minute per kg of body mass while the body experiences maximal exertion

VO2 max(Image from: http://nyvelocity.com/content/coachingfitness/2007/lactate-and-vo2-max-test-cadence)

Lactate Threshold

• lactate threshold (LT) = the value of exercise intensity at which blood lactate concentration begins to increase sharply

• training improves blood circulation and oxygen delivery, which results in an increase in lactate threshold

Lactate Threshold(Image from: http://www.sport-fitness-advisor.com/lactate-threshold.html)

Homework (p.124)

10. Define maximum oxygen consumption, VO2 max.

11. How do VO2 max values vary with age? How do they vary with increases in body mass? Explain.

12. Why are VO2 max values not perfectly correlated with overall athletic performance?

Homework (p.124)

13a. Determine the value of the lactate threshold from Figure 9.

13b. What does this value mean?