When is the Best Time to Exercise?

When it comes to convenience and practicality, any time that you can stick to regularly is the right time to exercise. If you are currently exercising in the morning, afternoon, or evening, and this schedule works for you and you feel you have enough energy and enthusiasm for your workouts, don't change anything.

However, if you have been dragging yourself to exercise and you are wondering if switching to another time of the day would make you feel better, here are the latest studies on the best time to exercise. Now, mind you, experts do not always agree with each other because this field of exercise science is still developing.

Circadian rhythms
According to the American Council on Exercise (ACE), our bodies follow a daily cycle called the circadian rhythms, which regulate everything from body temperature and metabolism to blood pressure. ACE explains that these rhythms have conformed to our 24-hour light-to-dark cycle, and may be regulated and re-regulated each day according to the environment.

Dr. David Hill of the University of North Texas says, "Our bodies' rhythms are inborn, but we reset them every day when our alarm goes off, when we eat our meals, and when we exercise." Whenever you change one of those things, your body reacts like it is undergoing jet lag. He says that your body learns to be fittest at whatever time of day you usually put it to work. So, if you're off schedule, take it easy because your stamina may be a bit lower.

This can make a lot of difference during a competitive athletic event so ACE recommends that you should train for an upcoming event at the same time that you will be competing in it. ACE mentions research that shows that the ability to maintain sustained exercise is adaptive to circadian rhythms. In other words, ACE says that consistently training in the morning will allow you to sustain exercise during a morning marathon longer than if you train in the evening.

Are you a lark or an owl?
If you wake up instantly in the morning with a cheerful attitude to boot but fade away quickly early in the evening, you are definitely a lark. If you have a hard time waking up and can't even talk for the next hour but are alive and energetic at night, you are an owl. For obvious reasons, larks feel better with morning exercise and owls work out better in the late afternoon or early evening.

But what if you are a lark who has to beat the traffic rush to get to work and you can only workout in the afternoon? Or what if you are an owl who comes home too late at night and can only exercise in the morning?

If this is your situation, don't despair. Your body can adapt to almost any condition if you give it enough time. Hill recommends giving yourself at least one month to adjust if you have to switch exercise schedules from morning to afternoon or vice-versa. I know this is possible because I am not a morning person but for reasons of convenience, I have taught a 7 a.m. exercise class for more than ten years.

Research shows people are stronger in the afternoon.
Your workout is affected the most by the influence of circadian rhythms on body temperature, says ACE. You get the best workout when your body temperature is at its highest and you get a slightly less than optimal workout when your temperature is low. ACE says that for most people, body temperature is at its lowest about one to three hours before waking up in the morning and it is at its highest in the late afternoon.

In his research, Hill found that strength is about 5 percent greater around noon. Aerobic capacity, meanwhile, increases by about 4 percent in the afternoon. Anaerobic performance (rapid intense activities like sprinting or jumping for a basketball) also improves by 5 percent in the afternoon. This may not make much of a difference for a recreational athlete but may spell the difference between winning a gold or silver medal in a competitive event. Researchers theorize that the body temperature peak between 4:00 and 5:00 p.m. may help facilitate anaerobic metabolism processes.

Neurologist Phyllis Zee of Northwestern University also believes that the best time to work out is in the late afternoon. She explained to CNN, "The reason for that is your muscle strength is at its peak, its highest. You're going to be less likely to injure yourself. It's also a time when people are most awake and alert". Zee further explained that body temperature in the afternoon is between one and two degrees warmer than in the morning, making muscles in the body more supple and lowering the risk of injury.

A study by the Research Institute for Sport and Exercise Science in England found that cyclists who considered themselves larks performed consistently better at 5:30 p.m. than at 7:30 a.m. However, according to the researchers, the difference cannot be explained by the increased body temperature in the afternoon because they made the cyclists do warm-up exercises to raise morning body temperature to the same level as that in the afternoon. Clearly, more research needs to be done to find the exact reasons why athletic performance is better in the afternoon.

Morning exercisers more consistent.
Exercise physiologist Richard Cotton of ACE told CNN that afternoon exercise might be a good way to prevent injury and get maximum performance, but he said that the most important thing is a consistent exercise regimen.

Studies have shown that morning exercisers are more likely to stick with their exercise programs than people who exercise in the afternoon or evening. This is probably because as the day goes on, it is too easy to start making excuses why you can't exercise - your last meeting ran overtime, you feel too tired after a long day in the office, there is too much traffic, etc.

Other health experts interviewed by CNN said that if people prefer to exercise in the morning, they just need to spend a few more minutes warming up to prevent injury.

Can morning exercise make you sick?
Dr. Lygeri Dimitriou of Brunel University in London caused a bit of controversy in the athletic world when he suggested that morning exercise can make athletes more prone to infection. Dimitriou studied 14 professional swimmers and he found that the stress hormone cortisol is at its highest level in the morning while the chemical IgA is at its lowest. Cortisol lowers the immune system while IgA helps to destroy infections in the air so Dimitriou concluded that people could be at a higher risk of infection if they exercised in the morning. However, other experts disagree.

Dr. Brian English, chief medical officer of UK Athletics, told BBC News, "Athletes exercise when they feel their bodies are ready. And these are professional athletes, they know their bodies extremely well. They will know when their mental and physical circadian rhythms are at their highest." English also said that the average person can choose whatever time they want to exercise. He explained, "People tend to find their own times for exercising, when they feel best."

BBC also spoke to David Sparkes of the Amateur Swimming Association who said, "The research is very interesting, we shouldn't however leap to conclusions, it is a very small group that has been looked at. And we need much more work before we can accept this type of research. Our opinion is you do your exercise when you feel comfortable. Professional swimmers train in the morning as they have a big volume to get through. And any exercise is better than none."

Greater risk of heart attacks in the morning?
Although it is true that there is an increased incidence of heart attacks during the hours of 6:00 a.m. to noon, this should not discourage morning exercisers. Morning exercise does not increase the risk of heart attack in the morning, according to Dr. Paul Thompson, M.D., director of preventive cardiology at Miriam Hospital in Rhode Island. In his study of 15,000 joggers, Thompson found only one death from cardiac arrest per year.

If you have a history of heart disease or you have several risk factors, talk to your cardiologist if it is appropriate for you to exercise early in the morning.

Sleep problems and exercise timing.
Studies have shown that exercise can help people who have sleep problems. But there have been conflicting results as to whether morning or afternoon exercise is better.

Dr. Shelley Tworoger of the Fred Hutchison Cancer Research Center in Seattle found that menopausal women between the ages of 50 and 75 years old did better with aerobic exercise at 10:30 a.m. compared to 6:00 p.m. Study participants who did a stretching routine had fewer sleep improvements than the aerobic exercise group but it did not matter whether they did their workout in the morning or evening.

Meanwhile, the Stanford University School of Medicine found that sedentary insomniacs between the ages of 55 to 75 experienced improvements in sleep by doing aerobic exercise in the afternoon. They were able to increase their sleep time by one hour and they reduced by half the time required to fall asleep.

Scientists believe that exercise improves sleep because it produces a rise in body temperature, which is then followed by a drop a few hours later. It is the drop in temperature which apparently makes you sleepy.

So the traditional advice has been to exercise at least three to fours before your bedtime to give your body time to cool down and avoid having a hard time falling asleep. Now, sleep expert Shawn Youngstedt of the University of California of San Diego says that vigorous exercise half an hour before bedtime does not always affect sleep.

This is good news because people often ask me if they can exercise late at night or if they can exercise when they come home from night shift work early in the morning and go to bed afterwards. My advice has always been to experiment and find your own personal gap between exercise and bedtime because I do know a number of people who can exercise and go right to bed but I also know people who are so sensitive they can't sleep if they exercise after 5:00 p.m.

Youngstedt, who is also known as the "sleep guru" told Prevention Magazine that people should try doing some nighttime exercise for several weeks and observe how they respond.

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