Hello doctor, I am a healthy 36-year-old. I run several times a week, often sprinting up hills for two to three minutes. In the past three years, I have had a few minor cardio-related symptoms, which I had checked out because I am motivated to stay in top physical condition. These include:  Dizziness (drop in blood pressure) when standing up suddenly. Feeling of shortness of breath during minor physical exertion (for example climbing stairs). That seemed out of character for my general level of fitness. A minor episode of palpitations that resolved in a week or so (last year).  I have had two thorough cardio workups in the past five years to look into these issues, including a 24 hour Holter monitor, EKGs, and two cardio treadmill stress tests. Two cardiologists have told me my cardiovascular system is in excellent shape and they cannot find anything wrong. They seemed quite impressed I made the full 21 m on the treadmill. I have no current cardio issues. My question is this: what are the risks of intense cardio exercise? Basically, what are the risks if I try to sprint up a mountain? I have read about the dangers of long periods of running, one hour or more, but do not really see anything about the risks of dropping dead from sprinting too hard too long.
Hello. Exercising regularly is a good thing to keep ourselves healthy. If you are a trained athlete and exercising under the guidance of an expert for intense cardio, exercise risk will be minimal. Your expert will design a workup that will suit you, like duration of the session, the frequency of the session, and adequate rest periods between workup. So, the risk of intense cardio exercise will be minimal if it is planned properly according to your fitness levels. Coming to your second question, if you sprint up a mountain with an adequate recovery period in between, the risk will be less. If you do not allow adequate recovery period, you may get symptoms related to muscular fatigue and dehydration. If you go high up the mountain (at 5000 to 8000 feet), there will be less oxygen availability and if you are not accustomed to such conditions of low levels of oxygen you may develop acute mountain sickness and then exercising will be harmful. If you are accustomed to low levels of oxygen, moderate-intensity exercise may be advisable under expert guidance.Hope this helps. For more information consult a cardiologist online -->