Which statement best describes how aging affects VO2 max and trainability?

Which statement best describes how aging affects VO2 max and trainability?

• A. VO2 max increases with age due to gains with training.
• B. VO2 max is unaffected by aging and training.
• C. VO2 max declines with age due to reduced cardiac output and mitochondrial density.
• D. VO2 max declines with age due to reduced cardiac output and mitochondrial density, but aerobic training can still elicit improvements, albeit smaller.

Answer: (D)

VO2 max is the maximum rate at which the body can take in, transport, and use oxygen during intense exercise, governed by central factors (like cardiac output) and peripheral factors (how well muscles use oxygen, tied to mitochondrial density and oxidative capacity). With aging, maximal heart rate and the ability to increase stroke volume at peak effort decline, and muscle mitochondria and capillary networks can become less dense and efficient. This combination leads to a natural drop in VO2 max. Yet aerobic training can still produce improvements by boosting both sides: it can enhance stroke volume and overall cardiac efficiency, and it increases mitochondrial density and oxidative enzymes in muscle, improving oxygen utilization. The gains tend to be smaller than in younger individuals, but they are real, making the description that VO2 max declines with age due to reduced cardiac output and mitochondrial density, while aerobic training can still elicit improvements, the best fit.