Ask Dr. K: Exercise is the best feel-good step you can take

There are at least four ways that regular exercise makes you feel more energetic.

For starters, when you exercise, more energy-producing mitochondria form in your muscle cells. Mitochrondria are the cellular powerhouses that convert glucose, fat and oxygen into the substance that cells use for energy. So while exercise burns energy, it also enables muscle cells to produce more energy.

Any type of regular exercise also creates more tiny blood vessels. Those vessels bring more oxygen (and glucose and fat) to every one of your cells. Aerobic exercise, which makes you breathe deeply and increases your heart rate, gets the most oxygen circulating.

Exercise also affects levels of hormones and chemical messengers. When you work out, your body releases epinephrine and norepinephrine. In large amounts, these stress hormones cause the energy-draining fight-or-flight response. But in the modest amounts induced by exercise, they make you feel energized. Exercise also boosts levels of compounds called endorphins. These are the “feel-good” chemicals that lift your mood. An elevated mood in itself can be an energy booster.

Finally, regular aerobic exercise almost guarantees that you will sleep more soundly — and good sleep is essential for feeling refreshed. Exercise is the only proven way to increase the amount of time you spend in deep sleep, the type that particularly restores energy. The more deep sleep you get, the less likely you are to awaken in the middle of the night, and the more rested you’ll feel the next day.

So it does sound paradoxical, but it’s true: Regular exercise can improve your energy even if you don’t feel you have the energy to exercise. But be smart about it.

I’m an early riser. I feel a lot more like exercising when I wake up than I do at the end of the day. For many of my friends and patients, it’s just the opposite. They’re late risers who have to be at work by 9 a.m., but don’t feel they’re really awake until later in the morning. (They don’t mention this observation to their boss.) They exercise at the end of the day.

But I hope you won’t think of exercise as a tedious routine. Instead, look at exercise as a surefire energy enhancer you can tap into at will.

You’ve heard repeatedly in this column (and elsewhere) that regular exercise is good for your health. It lowers your risk of many serious diseases. But, frankly, most of us find it easier to take action to achieve some benefit now, not 30 years from now. Regular exercise will make you feel better now.

(Dr. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.)