QUESTION: I was training for a two-day, 187-mile bike ride when my coach said he felt a little short of breath. He ended up in the hospital getting a stent for a 95 percent blockage in an artery!

He’s one of the healthiest people I know. How is that possible? — Sonja G., Tacoma, Wash.

ANSWER: It’s true that running, biking and swimming convey enormous health benefits. People in their 70s who have been exercising regularly for a long time can maintain the heart, lung and muscle fitness of people at least 30 years younger.

However, endurance training puts a big strain on not just your respiratory and musculoskeletal systems, but your cardiovascular system too. A National Institutes of Health report that looked at eight runners who died from doing the London marathon found that only one of them had reported any cardiac symptoms to family or doctors.

But endurance athletes aren’t the only folks who get bushwhacked by potentially lethal cardiac events. About 47 percent of sudden cardiac deaths occur outside a hospital — possibly because many people, especially if they’re generally healthy and younger than 60, either don’t recognize or rationalize signs they’re on the road to problems. Those signs include dizziness, chest discomfort, shortness of breath, sweating, a rapid pulse or even heart palpitations.

That’s why everyone should have regular cardiovascular health screenings.

>> Check for high blood pressure: Monitor blood pressure every two years starting at age 20, if your blood pressure is below 120/80 mmHg. Higher? Ask your doc about more frequent checks and aim to get BP under 125/85.

>> Monitor cholesterol levels: Check levels every four to six years starting at age 20, younger if you have a family history of hypercholesteremia, are overweight or have Type 2 diabetes, and more frequently if your LDL is elevated or your HDL level is low.

>> Additional checks: Over age 50, get an evaluation of your diet and coronary calcium. Keep tabs on waist size and blood sugar levels.

Mehmet Oz, M.D., is host of “The Dr. Oz Show,” and Mike Roizen, M.D., is Chief Wellness Officer and Chair of Wellness Institute at Cleveland Clinic. Email questions to youdocsdaily@sharecare.com.