Although the current chapter deals with the physiology of exercise, it does not aim to be a treatise on sports physiology, for which excellent books a

. Classification of exercise The grading of seventy of exercise is made on the basis of: (1) energy expenditure/mm, (ii) power, that is, the rate of doing work, which is expressed in Watt (W) and (in) the pulse rate. The energy expenditure is expressed as the volume of oxygen utilized (also called 'O2 uptake') per minute. [Recall, energy, expenditure is usually measured, indirectly, by noting the 02 consumed, as 02 consumption is proportional to energy expenditure. Direct measurement of energy expenditure is cumbersome. In short, from measurement of the 02 consumptions, one can know the energy expenditure.] In colder climates, e.g. as that in Europe, these three parameters are often in harmony, as shown in table 9.3.1. able 93.1 Gradation of Exercise (based according to Ghristensen) Glass of O2 uptake Power Pulse rate exercise (liters/mm) (W) (per mm) Maximal > 2. 5850 or more > 175 Very heavy 2 to 2. 5 680 to 850 150-175 Heavy 1.5 to 2 510 to 680 120-150 Moderate 1.0 to 1.5340 to 510 100-120 Light Upto 1.0 170 to 340 above resting but upto 100. In tropical countries like India, the gradations according to the different parameters will not tally as in table 9.3.1. This is