Expert: John Locke - 2/23/2008

Question
How might the result of a cardiovasualr exam differ for an athlete in top condition and a sedentary, overweight individual?

Answer
Thanks for using AllExperts, Nichole. There are a variety of beneficial cardiac adaptations that occur when people exercise regularly; detecting these changes, however, may be complicated. I'm not sure what tests might be included in a "cardiovascular exam"--some of the changes I'll mention below can only be detected with sophisticated equipment--but I will suggest some reliable cardiac adaptations from exercise. Individuals who are in good physical condition tend to have lower resting heart rates, for one. With this comes an increase in end-stroke volume, meaning that more blood will be ejected from the heart with each beat; it's more efficient for the heart to pump more blood with fewer strokes, and this increases when you exercise regularly. Lower respiration rates--fewer breaths per minute--are also associated with good physical condition.

Blood pressure also decreases for people in good cardiovascular shape. The density of muscle capillaries tends to be higher for athletes because of the greater muscle demand for oxygen (capillaries are extremely thin blood vessels in which oxygen, nutrients, and wastes are exchanged with body tissues). There's another quantity known as VO2 max, the maximum oxygen consumption by body tissues per minute, that increases for people who have well-conditioned cardiovascular systems. Two enzymes associated with aerobic respiration, succinate dehydrogenase and phosphofructokinase, increase their activity levels in athletes. All of these quantities have more information readily available about them online; below I've included the reference to a paper that describes some of these changes experimentally. If you have more questions, I'd be happy to answer them for you. Good luck.

Gollnick PD, Armstrong RB, Saubert CW, Piehl K, and Saltin B. Enzyme activity and fiber composition in skeletal muscle of untrained and trained men. Journal of Applied Physiology 33: 312–319, 1972. You can find this paper free online from PubMed (http://www.ncbi.nlm.nih.gov/PubMed/) or the Journal of Applied Physiology website (jap.physiology.org).