Cardiorespiratory fitness is widely recognized as a major component of overall p
ID: 3240058 • Letter: C
Question
Cardiorespiratory fitness is widely recognized as a major component of overall physical well-being. Direct measurement of maximal oxygen uptake (VO_2max) is the single best measure of such fitness, but direct measurement is time-consuming and expensive. It is therefore desirable to have a prediction equation for VO_2max in terms of easily obtained quantities. Consider the variables y = VO_2max (L/min) x_1 = weight (kg) x_2 = age (yr) x3 time necessary to walk 1 mile (min) x_4 heart rate at the end of the walk (beats/min) Here is one possible model for male students, consistent with the information given in the article "Validation of the Rockport Fitness Walking Test in College Males and Females" +: y =5.0 + 0.01x_1 - 0.05x_2 - 0.13x_3 -0.01x_4 + sigma = 0.4 (a) Interpret beta_1. Holding all other variables constant, a 1 kg increase in weight will result in a 0.01 L/min decrease in VO_2max. Holding all other variables constant, a 0.01 kg increase in weight will result in a 1 L/min decrease in VO_2max. Holding all other variables constant, a 1 kg increase in weight will result in a 0.01 L/min increase in VO_2max. Holding all other variables constant, a 0.01 kg increase in weight will result in a 1 L/min increase in VO_2max. Interpret beta_3. Holding all other variables constant, a 1 min increase in walk time will result in a 0.13 L/min decrease in VO_2max. Holding all other variables constant, a 0.13 min increase in walk time will result in a 1 L/min increase in VO_2max. Holding all other variables constant, a 1 min increase in walk time will result in a 0.13 L/min increase in VO_2max. Holding all other variables constant, a 0.13 min increase in walk time will result in a 1 L/min decrease in VO_2max. (b) What is the expected value of VO_2max when weight is 75 kg, age is 24 yr, walk time is 11 min, and heart rate is 140 b/m? L/minExplanation / Answer
a) For B1: Option C is correct.
For B3: Option A is correct.
b) For x1 = 75, x2 = 24, x3 = 11, x4 = 140
y = 5 + 0.01(75) - 0.05(24) - 0.13(11) - 0.01(140)
y = 1.72