How does age affect cardiorespiratory fitness according to the material?

• A. Aerobic capacity decreases about 10% per decade
• B. Aerobic capacity increases with age
• C. Age has no effect on heart elasticity
• D. Red blood cell volume increases with age

Answer: (A)

The main idea is that age tends to lower cardiorespiratory fitness, with a typical decline of about 10% per decade. As people get older, several physiological systems involved in aerobic performance become less capable: maximum heart rate tends to fall, cardiac output at peak effort can decrease, and skeletal muscles lose mitochondrial function and capillary density, all of which reduce the body's ability to take in and use oxygen during intense exercise. Regular endurance training can slow this decline, so physically active older adults often retain higher aerobic capacity than sedentary peers of the same age. The other statements don’t fit because age does affect heart and vascular function (so saying there’s no effect is inaccurate), aerobic capacity does not generally increase with age, and red blood cell volume isn’t the primary driver of the age-related change in aerobic fitness.