Many of us have a preferred workout time – whether it’s an early jog before work or a late-evening gym session. New research suggests that when we exercise may actually influence cancer risk. In a large new study published in JAMA Network Open, scientists used wearable accelerometers to track people’s activity throughout the day and then followed them for several years. They found that more moderate-to-vigorous physical activity (MVPA) – think brisk walking, running, biking, or other heart-pumping exercise – was linked to lower cancer risk. Best of all, people who did a big chunk of their workouts in the morning hours saw the biggest benefits for certain cancers, especially prostate, breast, and endometrial (uterine) cancer.
The idea that timing matters makes sense when you consider our body clocks. For example, exercise late in the day can push back your melatonin cycle, whereas morning workouts don’t disrupt your natural night-time hormone surge. (Melatonin – the “sleep” hormone made at night – has been associated in studies with lower cancer risk .) In fact, the study team noted that body rhythms and hormone patterns are likely at play: “The timing of physical activity obviously has an effect upon the rhythm of sex hormones and melatonin… That might explain our results” . In other words, exercising at sunrise may help sync up our physiology in a cancer-protective way.
Key Insights from the Study:
Morning workouts pack extra punch. The study found that people who did most of their MVPA in the early morning (around 6–10 am) had the lowest rates of certain cancers. In particular, early-day exercise was most strongly protective against breast cancer in women . Men saw similar protection for prostate cancer – and interestingly, men who exercised in the evening still got a big benefit for prostate cancer risk . MVPA is important all the time. Whether morning or evening, getting moderate-to-vigorous exercise is key. There is convincing evidence that MVPA cuts the risk of breast and endometrial cancers (and also colon cancer) . The new study adds that fitting those active minutes early in the day may provide an extra edge for hormone-related cancers. Guidelines still apply: Adults should aim for at least 150 minutes per week of moderate activity (like brisk walking or easy cycling) or 75 minutes of vigorous exercise (running, aerobic classes, etc.) . That works out to about 30 minutes a day, five days a week – even short morning sessions count toward this goal. Lifestyle wins: Beyond timing, the big picture is that staying active is a powerful way to lower cancer risk. Even simple changes – taking a brisk walk on your morning break, swapping one extra TV show for an early jog – can add up. Morning exercise might give a bonus benefit, but any regular MVPA is a win for your long-term health.
Key Takeaways:
Doing regular moderate-to-vigorous exercise (brisk walking, running, swimming, etc.) is shown to cut cancer risk – especially for breast and endometrial cancers . A new large-scale study suggests early-morning workouts may give added protection. Participants who exercised around 6–10 am had significantly lower rates of breast and prostate cancer . Men in the study also benefited from evening workouts (on prostate cancer risk), but women saw the strongest benefit from morning activity . Aim for at least 150 minutes of MVPA per week (or 75 minutes of vigorous exercise) . Morning exercise routines – even just 10–20 minutes – count toward that goal and may boost your cancer-protection benefits. Bottom line: It’s not just exercise, but timing. If you can, try fitting workouts into the morning. Even going for a jog or doing yoga after breakfast a few times a week may help align your body clock for better health.
Making Morning Exercise a Habit
If you’re not already an early bird, there are simple ways to start: lay out your workout clothes the night before, set a gentle alarm, or begin with a quick walk around the block. You don’t need to jump straight into a long run; even a short morning workout counts. For example, a 10-minute brisk walk or a brief home exercise routine in the a.m. gets your heart pumping and adds to your weekly MVPA total.
Many people find that exercising first thing gives them energy and a mood boost that lasts all day. It also means you’ll have already “checked it off” before the day’s distractions kick in. You might try pairing exercise with another morning habit – like doing stretches while coffee brews, or parking farther from the office for a brisk walk. If you’re really pressed for time, even splitting your workout into two 10-minute morning and evening sessions works toward the goal. The important thing is consistency.
Remember, any activity is better than none: if you absolutely can’t swing a morning workout, exercising later is still great. But if you’re looking for extra benefits (and a peaceful, energetic start to the day), try waking up a little earlier for some movement. Over time, those morning minutes of activity may add up to a healthier you – and according to new research, a lower chance of hormone-related cancers. So set that alarm clock, enjoy the sunrise, and give your body an early-day boost toward cancer prevention!
Sources: The findings are based on a recent JAMA Network Open study of accelerometer-measured activity and cancer outcomes (using wearable fitness trackers). The results align with long-known evidence that MVPA reduces breast and endometrial cancer risk . For more details on physical activity and cancer prevention, see the World Cancer Research Fund recommendations and related research.