Does exercise give you energy?

Adapted from  Boosting Your Energy, Medical Editor: Anthony L. Komaroff, MD, Simcox-Clifford-Higby Professor of Medicine, Harvard Medical School; Senior Physician, Brigham & Women’s Hospital, Boston.

The benefits of exercise are truly profound. Exercise helps you feel better, think more clearly, and look your best. It also helps to control appetite, boost mood, improve sleep, and reduce your risk of heart disease, stroke, diabetes, dementia, depression, and many cancers.

Add to that long list of benefits that exercising regularly remains one of the most powerful ways to boost your energy. In fact, nothing medicine has ever invented or discovered rivals regular exercise when it comes to protecting your health and sustaining your energy.

Exercise boosts your energy

Think of your energy level as a rechargeable battery. Being active is like plugging in the battery and recharging it, while sitting idle causes the energy to drain away.

When you’re inactive, you are losing muscle cells. The cells that remain have fewer mitochondria, which lowers their ability to produce energy. It’s remarkable how little time it takes to see the effects of this.

People who have a limb immobilized because of an injury or illness begin losing muscle cells within just six hours. With weaker muscles, everything you ask your muscles to do requires more effort, leaving less energy for other activities.

It’s particularly important to keep exercising as you age because muscle mass tends to decline over the years. Sarcopenia, the gradual decrease in muscle tissue, starts earlier than you may realize — around age 30.

The average 30-year-old can expect to lose about 25% or more of his or her muscle mass and strength by age 70, and another 25% by age 90. The result is not only a decrease in energy, but also an increase in risk for a host of other diseases.

Lack of exercise also causes changes in your heart and lungs. These organs become less efficient at oxygenating your blood and pumping that blood (along with nutrients) to the different parts of your body.

That in turn affects your energy level, most noticeably during periods of physical exertion. Compared with an active person, a sedentary person experiences more fatigue when carrying out a physically demanding task and has both a higher heart rate and lower oxygen consumption.

Inactivity also has psychological effects. The less active you are, the less active you want to be. People who don’t exercise have a greater perception of fatigue than people who do.

The benefits of exercise: protecting your health

Regular physical activity not only increases your day-to-day vitality, but also helps prevent the kinds of illnesses that drain your energy over time. Strong evidence from thousands of studies shows that regular exercise delivers wide-ranging benefits, including

• reducing your risks of heart disease, stroke, high blood pressure, and high cholesterol
• lowering blood sugar levels and reducing your risk for type 2 diabetes and metabolic syndrome
• reducing the risk of certain cancers, including breast and colon cancers
• easing mild to moderate depression
• reducing your risk for osteoporosis (provided you do weight-bearing exercise, meaning exercise where you work against gravity)
• helping prevent or ease low back pain
• relieving arthritis pain and expanding a limited range of motion
• helping maintain muscle mass and prevent falls
• boosting mental sharpness in older adults
• strengthening your muscles, lungs, and heart
• improving functional abilities in older adults, such as being able to walk up stairs or through a store, heft groceries, rise from a chair without help, and perform a multitude of other activities that allow independence
• helping prevent weight gain, and possibly aid weight loss when combined with the proper diet
• lowering the risk for hip fractures.

The bottom line: move more, feel more energetic

Regular exercise doesn’t just build strength and fitness; it keeps your internal “battery” charged by preserving muscle, boosting heart and lung function, and keeping diseases at bay. Even small, consistent steps — like walking, stretching, or light strength training — can make a big difference in your daily energy and long-term health.