When it comes to staying healthy, we’ve long been told that any exercise is good exercise. But does it matter what time of day you break a sweat? According to a new study published in Diabetes Care, for people who are overweight, squeezing in some evening activity may pack an extra punch against cardiovascular disease and early death.

Researchers from the University of Sydney and other institutions analyzed data from nearly 30,000 participants in the UK Biobank study to see how the timing of moderate-to-vigorous physical activity impacted health outcomes over an 8-year period. Moderate-to-vigorous activity included things like brisk walking, cycling, gardening, and sports that get your heart pumping.

 

What The Study Found

The study focused specifically on individuals who were obese, with a body mass index (BMI) over 30. Obesity and its common companion, Type 2 diabetes, can throw off the body’s metabolic rhythms, so researchers wanted to see if strategically timing exercise could help counteract some of these imbalances.

The participants were divided into four groups based on when they typically got moving:

• No “aerobic bouts” (less than 1 bout of moderate-to-vigorous activity lasting 3+ minutes per day on average)
• Morning movers (6 a.m.-noon)
• Afternoon athletes (noon-6 p.m.)
• Evening exercisers (6 p.m.-midnight)

Over the 8-year follow-up period, the researchers tracked deaths from any cause, as well as new diagnoses of cardiovascular disease (like heart attack and stroke) and microvascular disease (conditions like kidney disease, nerve damage, and vision problems that are common in people with diabetes).

The results showed a clear pattern – those who devoted time to evening exercise seemed to fare the best. Compared to the sedentary group, the evening crowd had a:

• 61% lower risk of death from any cause
• 36% lower risk of cardiovascular disease
• 24% lower risk of microvascular disease

While morning and afternoon exercise also showed health benefits compared to sedentary folks, the effects weren’t as robust as evening activity. For all-cause mortality, morning exercisers had a 33% lower risk and afternoon exercisers had a 40% lower risk compared to the sedentary group – still significant, but not as impressive as the 61% reduction for evening movers. Similarly, for cardiovascular disease, morning activity was linked to a 17% risk reduction and afternoon a 16% reduction – about half the impact of evening exercise. When it came to microvascular disease, the benefit was more evenly distributed across the time slots, with a 21% lower risk for morning, 16% for afternoon, and 24% for evening.

Interestingly, the frequency of exercise bouts (how often you move) seemed to matter more for health than the total duration.

When the researchers focused on the 3,000 or so participants who also had Type 2 diabetes, they found the same trend – evening exercisers showed the lowest rates of death and disease. In fact, the perks of nighttime activity were even more striking in this group.

Why Is Exercise At Night Better?

So what’s the magic behind an evening workout? The researchers point to a few potential explanations:

Our bodies are primed to handle blood sugar better later in the day. Because obesity and diabetes can exaggerate these natural fluctuations, adding some activity when insulin resistance is at its peak may provide a stronger counter-effect.

The evening is when blood sugar tends to creep up the most, especially for people with diabetes. Exercise helps shuttle that excess glucose out of the bloodstream and into the muscles. Tackling high blood sugar at this critical juncture may stave off more damage over time.

Squeezing in some steps later in the day might lower blood pressure throughout the night and into the next morning. Previous research has shown evening exercise has an edge on morning when it comes to round-the-clock blood pressure control.

Any Exercise Counts

The researchers stress these findings are still preliminary and need to be confirmed with more rigorous clinical trials. But the results suggest people with obesity and diabetes may want to consider shifting some of their activity later in the day as a simple, no-cost way to maximize health benefits.

That said, the researchers emphasize that any bout of movement, no matter when it happens, is better than staying sedentary. If schedules only allow for a morning jog or lunchtime walk, those are still surefire ways to reduce the risks that come with carrying extra weight.

“We didn’t discriminate on the kind of activity we tracked, it could be anything from power walking to climbing the stairs, but could also include structured exercise such as running, occupational labor or even vigorously cleaning the house,” said Dr Ahmadi, National Heart Foundation postdoctoral research fellow at the Charles Perkins Centre, University of Sydney, in a press release.

The bottom line? Don’t sweat the small stuff when it comes to exercise timing. What matters most is finding a consistent routine that works for your life. But if you have the flexibility, adding an evening stroll to your repertoire may give you a bit more bang for your buck.

As the study states: “The timing of physical activity may be an important consideration in the future of obesity and (diabetes) management.” With more research, we may discover the ideal “exercise prescription” isn’t just about how much you move – but when.

Researchers found that people who exercised in the evening (after 6 p.m.) had a 61% lower risk of death from any cause.