Morning Workouts Linked to Improved Cardiometabolic Health, Study Finds

If you typically work out in the morning, a new study suggests you may have a lower risk for high blood pressure, type 2 diabetes, obesity, and other contributors to heart disease compared with people who exercise later in the day. “This study suggests that when you exercise may matter, not just how much you exercise,” says senior study author Prashant Rao, MBBS, a sports cardiologist and physician-scientist at Beth Israel Deaconess Medical Center and Harvard Medical School in Boston.

Early Morning Workouts and Cardiometabolic Health

The research, which will be presented at the American College of Cardiology’s Annual Scientific Session, relied on minute-level heart rate data from nearly 15,000 adults. Dr. Rao explains this allowed his team to capture long-term, real-world exercise data with greater detail and accuracy.

Researchers analyzed health records and Fitbit heart rate data collected over a year. They identified periods when participants had an elevated heart rate for 15 minutes or more to track physical activity. Participants were then grouped based on the time of day their exercise occurred.

The study compared these timing groups with health data, including rates of high blood pressure, obesity, high cholesterol, atrial fibrillation, coronary artery disease, and other cardiovascular health problems. Findings were adjusted to account for differences in age, sex, income level, total activity level, sleep, alcohol use, and smoking status.

The results showed that, compared with adults who exercised later in the day, those who worked out in the morning had a reduced risk of these conditions. Adults who exercised between 7 and 8 a.m. Had the lowest odds of coronary artery disease.

Expert Commentary

Aubrey Grant, MD, a sports cardiologist at MedStar Health in Washington, D.C., who was not involved in the research, says the results suggest that “timing may be a previously underappreciated lever in cardiometabolic risk reduction.” He adds that wearable technology is providing scientists with more granular exercise data, which “opens a more nuanced conversation about how physical activity interacts with the body’s daily rhythms.”

Dr. Grant describes the link between exercise timing and health as a “new frontier in exercise science.” For decades, research has focused on “how much and how hard” people worked out—variables that still matter. However, more data on timing is emerging. A study published in January found that older adults who identified as “night people” had worse cardiovascular health compared with those who identified as “morning people.”

Why Timing May Matter

“The honest answer is that we do not fully realize yet” why this link is appearing, says Dr. Grant. He suggests that morning exercise may align better with circadian physiology, or how bodily functions naturally correspond to the time of day. “Cortisol peaks early in the day and can prime the body for physical exertion, potentially enhancing metabolic efficiency,” he adds.

Exercise is similarly a natural stimulant. Working out early revs up bodily systems and energizes you for the day, says Andrew Freeman, MD, director of cardiovascular prevention and wellness at National Jewish Health in Denver, who was not involved in the new study.

Alex Rothstein, EdD, assistant professor of exercise science at the New York Institute of Technology in Old Westbury, notes that people who work out earlier may also have healthier lifestyle habits overall. “If you work out earlier in the day, you tend to have fewer excuses to not work out,” and you may exercise more consistently.

Should You Change Your Workout Time?

Dr. Freeman recommends getting 30 minutes a day of “breathless physical activity,” including a combination of cardio and strength training. However, if you prefer to work out in the afternoons or have responsibilities preventing morning exercise, don’t worry.

“It does not mean people should feel guilty about evening workouts,” says Dr. Grant. “It means that when we counsel patients on optimizing their health, exercise timing is now a legitimate part of that conversation, alongside sleep, nutrition, and stress management.”

If you have flexibility, Rothstein suggests exercising in the morning, as it’s less likely that something will interfere with your workout later on, and it may offer extra heart health benefits.

“The most important message is still: Exercise consistently, regardless of timing,” says Dr. Rao. However, “Timing may represent a simple, low-cost way to potentially optimize health.”