This Might Be the Best Time to Exercise For Better Heart and Lung Health

Exercising in the morning may uniquely benefit heart and lung functioning in older adults, according to new research. The study, published in Medicine & Science in Sports & Exercise, also linked a steady physical activity schedule to health benefits.

“The study suggests that getting earlier, consistent, and more physical activity during the day may help you maintain physical fitness as you get older,” said Cheng-Han Chen, MD, an interventional cardiologist at the MemorialCare Saddleback Medical Center in Laguna Hills, CA. 

Here’s a closer look at the research—and whether you should switch to morning workouts in light of the results.

To understand how the timing of our workouts impacts overall fitness and health, the scientists looked at the health data of 799 older adults with an average age of 76 who had participated in research known as the Study of Muscle, Mobility, and Aging.

Participants were instructed to wear wrist devices that continuously monitored their activity levels over seven days. They also underwent cardiopulmonary exercise testing (CPET) to evaluate their heart and lung health and participated in regular medical visits.

Researchers discovered that:

• Peak morning activity—a term used to describe the time of day when people are most active—was linked to better cardiorespiratory fitness and walking efficiency, which is how well the body utilizes energy while walking.
• Consistently exercising at the same time each day was associated with better health outcomes. 
• People who followed rhythmic patterns of rest and activity throughout the day had superior cardiorespiratory fitness and walking efficiency.

There’s still a lot to learn about how the timing of movement impacts overall health and the development of chronic diseases. “Much more research is necessary to better understand the relationship between timing of physical activity and health outcomes,” Chen said.

But according to senior study author Karyn Esser, PhD, chair of the University of Florida College of Medicine’s Department of Physiology and Aging, it’s the close link between exercise and our intrinsic circadian clock—the physical, mental, and behavioral changes the body experiences over 24 hours—that could explain why exercise timing might matter for health.

Because this clock regulates bodily functions like core temperature and hormone release, the time of day you’re most active could actually impact how well you perform and even how your muscles respond on a molecular level, according to Esser. Depending on the timing, working out could also either shift your internal clock or keep it consistent, which appears to support muscle cell function and metabolic health.

Finally, it’s important to note that every person has a chronotype, or a biological tendency to be more alert in the morning, afternoon, or evening. Scientists believe that knowing your chronotype—and timing your activities accordingly—could significantly impact various aspects of your health and fitness.

The study did not prove that morning physical activity directly improved heart and lung health. Rather, it found an association between the two.

However, this isn’t the first study to show that morning exercise may be best, at least when it comes to heart health. A report from 2023 found that morning physical activity was associated with a lower risk of cardiovascular disease. In fact, being most active between 8 a.m. and 11 a.m. was linked to the lowest risks of heart disease and stroke, particularly in women, that study found.

But other studies have found that afternoon and evening workouts provide their own benefits. One report discovered that afternoon and evening exercise go hand-in-hand with lower insulin resistance, and another paper determined that evening workouts were linked to lower rates of all-cause mortality. New research has also found that afternoon exercise may improve blood glucose response in people with type 2 diabetes, Esser added.

Other data suggest that people are strongest in the afternoon compared to the morning. And some studies have shown that the mitochondria in our muscles, which are structures in our cells that help generate energy, have a greater capacity in the afternoon. That could lead to better endurance and performance later in the day, Esser said.

The American Heart Association recommends 150 minutes a week of moderate-intensity exercise or 75 minutes of vigorous activity. But growing evidence suggests short bursts of movement—even 20 minutes of it a week—may offer significant cardiovascular benefits.

While these recommendations may seem overwhelming, Matthew Sedgley, MD, a sports medicine physician with MedStar Health, said that any amount of exercise can make a meaningful difference. He is less concerned about when you exercise than if you exercise. 

Chen echoed his advice, emphasizing that a steady schedule matters, too. “The timing of the activity is not as important as just having a consistent pattern,” he said. The new study and other research show that doing so offers a range of benefits, from preventing chronic diseases to improving survival rates with cancer.

But if your schedule is flexible? “You may want to exercise in the morning” based on this new data, Sedgley told Health.