The same training principles that improve athletic performance in competitive athletes also help to prevent heart attacks and prolong lives:
• The SUN Study on 18,737 middle-aged people showed that those who exercise intensely have half the rate of heart attacks as those who do the same amount of exercise less intensely (Am J of Cardiology, Sept 11, 2018)
• Vigorous exercise is associated with a much lower rate of metabolic syndrome and diabetes than low-intensity exercise (American J of Prev Med, April 2017;52(4):e95–e101)
• An extensive review of major articles shows that exercise helps to prevent heart attacks and strokes (J of Clinical and Preventive Cardiology, 2017;6(3):109-114)
• Even low doses of exercise, such as slow walking, are associated with reduced likelihood for heart attacks and strokes (Am J Lifestyle Med, Jul 1, 2009;3(1 Suppl):44S–49S)
• The amount of time teenagers spend exercising intensely predicts markers of arteriosclerosis and inflammation far more than how much time they spend sitting still (PLoS Medicine, Sept 2018;15(9):e1002649)
• A Mediterranean diet and regular exercise, individually and combined, are associated with reduced risk for heart attacks and strokes (Eur J of Prev, June 26, 2018)

How Intense Exercise Helps to Prevent Heart Attacks
Intense exercise makes muscles stronger, including your heart muscle. All people lose heart muscle as they age, which increases risk for frailty and heart failure. Strengthening your heart muscle helps you to live a more vigorous lifestyle and to protect you from heart failure. Intense exercise also helps to stabilize plaques in arteries and widens heart arteries to help protect you from a heart attack.

Stress and Recover
If you try to exercise intensely every day, you are at high risk for injuries. To become stronger and faster and have greater endurance, you need to exercise on one day intensely enough to damage your muscle fibers and feel short of breath. Then you will feel sore on the next day and are supposed to exercise at a reduced intensity for as many days as it takes for your muscles to heal and the soreness to lessen or disappear. Only then should you take your next intense workout.
• You can tell you are exercising intensely enough to damage your muscles by a feeling of burning in your muscles when you exercise.
• You will not improve your maximal ability to take in and use oxygen unless you exercise intensely enough to become short of breath.

Use Interval Training to Avoid Injuries
Adding interval workouts to an endurance training program specifically makes muscles stronger than continuous endurance training (Med & Sci in Sprts & Exe, June 2017;49(6):1126–1136). To use intervals in your exercise program, first you warm up for 10 or more minutes by going at a slow pace. Then you pick up the pace in your sport (such as running, skiing or cycling) until you start to feel a burning in your muscles or start breathing hard, usually after about 5-30 seconds. Then slow down. When you have completely recovered your breath and your muscles feel fresh again, start your next interval. Alternate picking up the pace and slowing down for full recovery until your muscles start to feel stiff or heavy, and then cool down by exercising at a slow pace for about 10-15 minutes. Most people will be able to do 5-20 short intervals of less than 30 seconds each in their early workouts and increase the number slightly as they keep on doing intervals two or three times a week. You can avoid injuries as long as you listen to your body when it tells you to reduce the intensity or to stop your workout.

Recovery Days
Most athletes in endurance and strength sports exercise on their recovery days and do not plan to take many days off. However, on recovery days, they work at a markedly reduced intensity to put minimal pressure on their muscles. If you develop pain anywhere that gets worse as you continue exercising, or doesn’t go away when you slow down, you are supposed to stop exercising for that day. Active recoveries on easy days at low intensity make muscles tougher and more fibrous so your muscles can withstand harder workouts on your intense days.

My Recommendations
• Before you start a program of interval training to improve your endurance, you should have exercised regularly for many months, be in good shape and not have any health conditions that can harm you.
• Try to set up your exercise program so that you take a hard workout that damages your muscles so they feel sore on the next day. Then take easy workouts until the soreness goes away, and then take your next hard workout.
• Immediately after an intense workout, eat whatever source of carbohydrates and protein you like best. I eat oranges and nuts immediately after I finish an intense workout to help me recover faster for my next workout. See Why You Should Eat Within One Hour After an Intense Workout.
• When you are training properly, your muscles may feel sore every morning. If they don’t feel better after a 10 minute warm-up, take the day off. I do not recommend taking NSAIDs to Relieve Muscle Soreness; they can interfere with your strength gains.
• If you feel pain in one spot that does not go away after you slow down, stop that workout immediately. Otherwise you are headed for an injury.

CAUTION:  Intense exercise can cause a heart attack in a person who has blocked arteries or heart damage. Check with your doctor before you start a new exercise program or make a sudden increase in the intensity of your existing program.

Checked 6/22/23