Answer:
1.Factors affecting include oxygen diffusion capacity of the lungs, cardiac output, oxygen transport capacity of the blood, capillary density of the muscles, and muscular mitochondria mass [3]. further depends on sex, age, genetics, body fat, medical conditions, and smoking [4–6].
2.When you exercise, heart rate increases to circulate more oxygen (via the blood) at a quicker pace. The more you exercise, the more efficient the heart becomes at this process, so you can work out harder and longer. Eventually, this lowers resting heart rate in fit people.
3.The best method to measure cardiorespiratory fitness is by measuring VO2Max, which is a calculation of how efficiently your body can transport and uitlize oxygen. To get an accurate measurement, expensive and extensive equipment is needed.
i hope this helps...
