Increasing cardiorespiratory fitness levels is difficult for experienced athletes because
a. they are not motivated to increase their levels of cardiorespiratory fitnessb. they cannot commit the training time to increase their cardiorespiratory fitnessc. they have already achieved high levels of cardiorespiratory fitnessd. none of the above

Life expectancy in the united states is (76.4 for men and 81.1 for women). life expectancy is not the same as healthy life expectancy. healthy life expectancy is the number of years a person is expected to live in this number is obtained by subtracting years spent in poor health from overall life expectancy. the world health organization (who) calculates healthy life expectancy in 194 countries. the united states ranks twenty-ninth in the world using this measurement, with an average of of healthy life expectancy. singapore ranks number one (76 years), and japan is number two (75 years).