Any time is a good time to exercise on a treadmill. You can improve your health, especially your heart health and aerobic capacity, by regularly using a treadmill regardless of the time of day. However, certain times may be optimal for treadmill use. These times vary from one person to the next, but you can make generalisations about the best times of day for treadmill exercise.
The time when you are likely to perform treadmill exercise most effectively depends partly on your body's circadian rhythms. These rhythms originate in a region of your brain and regulate various conditions, including body temperature. When your body temperature peaks during a normal daily cycle, you are more likely to have a productive treadmill session. For most people, this point typically happens late in the afternoon. According to the American Council on Exercise, studies show that exercising at that time produces better performance.
On the other hand, according to the American College of Sports Medicine, research indicates that people who exercise in the morning have a better chance of sticking to their routines. The earlier you exercise, the less chance unforeseen daily events have of interrupting your workout plans.
Some people might be wary about exercising on a treadmill early in the day because they have heard that morning exercise may increase a person's risk of suffering a heart attack. Blood platelets, which trigger blood-clot formation, are stickiest early in the day, which is why fatal heart attacks have a statistically higher chance of occurring before noon. However, exercising in the morning does not increase the risk of having a heart attack. On the contrary, regular exercise reduces the risk of suffering a heart attack at any hour of the day.
If you have trouble sleeping, treadmill exercise may help you fall asleep more easily if you time it right. Exercise such as treadmill work triggers a rise in body temperature, followed by a subsequent drop. The drop in temperature makes falling asleep and remaining asleep easier. The best time to use treadmill exercise as a "sleep aid" is in the late afternoon or early evening. A treadmill routine late at night or just before bed may make it harder to fall asleep because of its stimulating effect and corresponding rise in body temperature. Treadmill exercise in general is an excellent choice for trying to fight sleeplessness because, as a form of aerobic exercise, it increases the amount of oxygen in your blood.
If you use treadmill exercise for performance training - for example, to prepare for a charity 5k walk or run - try to exercise each day at a time that mirrors the start of the event. If the race starts at 7 a.m., try to use the treadmill as close to 7 a.m. as possible most days. Such training allows your body to adapt its circadian rhythms to exercising at that time of day. Certainly your aerobic capacity will improve regardless of what time of day you exercise on a treadmill. But timing your exercise to correspond with the event's start time means you will be able to sustain a higher level of exertion during the race.
Fitness experts say the best time to exercise on a treadmill is the time that consistently works for you. You might be a "morning person" who can easily get up an hour or so ahead of schedule to exercise. You might prefer to wait until after work to use your treadmill session to relieve stress and tension that build during the day. You might want to use all or part of your lunch break for treadmill exercise. Whatever time is most convenient is the time you have the best chance of sticking to, and the time when your exercise will be most efficient, making that the ideal time for you.