Have you ever heard the term “circadian cycle” and how it influences our life? If you already have started thinking that this “circadian cycle” might be related to planets and stars that influence our signs of the zodiac and horoscopes, you are completely wrong. The term circadian comes from the Latin term circa, meaning “around”, and diem or dies, meaning “day”, and it is related to our internal biological clock. Circadian cycle or rhythm describes human sleep and wake patterns following the 24-hours daily cycle, and it’s strongly linked to daylight. Mainly, it’s the cycle that regulates our nervous system, hormones, body temperature, and metabolism, among other physiological functions. The cycle is not fixed though and may be reset based upon some environmental cues. One of the cues influencing our circadian cycle is our exercise routine, namely the time we exercise during the day.
There are lots of people believing that morning exercise increases our metabolism, burns more calories and helps us in reducing the body weight, but unfortunately, that is not the case. However, based on a very recent study, there are still some good news for individuals who love to start their day with an early morning exercise. Based on this study, it was found that women who took a 45 min morning walk were less attracted to photos of food, as their brains showed less attention to food than in non-exercise mornings. In other words, there was an appetite decline in women who took a 45 min morning walk compare to non-exercise mornings. However, the most important findings were that women didn’t eat any more calories on the morning exercise day, and were more active the rest of the day than on the day they didn’t do morning exercise. Therefore, morning exercise might help us reduce or control our appetite, and therefore assist us to reduce our body weight when is needed. Morning exercisers often question themselves whether to eat before or after their workout. According to a 2006 article in the “New York Times”, morning exercisers who hit the gym before eating tend to work out for shorter time and burn fewer calories. Indeed, having a light breakfast before you start exercising can provide you with a much-needed fuel for the extra kilometer. More on the benefits of breakfast you can read from one of our previous articles.
Some other individuals though, prefer or have the chance to exercise only at the afternoon or early at night. Based on the American council of exercise it is the influence of circadian rhythms on body temperature that seems to yield the most control over the quality of a workout. When body temperature is at its highest (for most people is 4 p.m. to 5 p.m.) our workouts are likely be more productive. Instead, when our body temperature is low our exercise sessions may be less than optimal. A study from the late 90’s suggested why athletes were able to perform better at certain times of the day. More specific, blood samples taken from all the participants showed that levels of two endocrine hormones – cortisol and thyrotropin – increased far more in those, who exercised either in the evening or late at night. Scientists also found that glucose levels decreased far more in the same subjects, as compared to morning exercisers. Overall, it was concluded that these are signs that our metabolism is adapting well to regular exercise and suggested that it might be better to train after work rather than first thing in the morning.
Circadian cycle is also influenced by our sleeping habits. Scientists at the University of Alberta found that there are significant differences in the way our brains function depending on whether we are early risers or night owls. Specifically, they identified that morning individuals’ brains were most excitable at 9 a.m. This slowly decreased throughout the day. It was the polar opposite for evening people, whose brains were most excitable at 9 p.m. In addition, it was found that evening people became physically stronger throughout the day, but the maximum amount of force morning people could produce remained the same. These findings showed that nervous system functions are different between early risers or night owls and have implications for maximizing human performance.
The bottom line is that we can decide the best time for us to exercise based upon our schedule and lifestyle. We should not worry since it is well documented that exercise could be beneficial irrespective of whether we train in the morning or late in the evening. However, we should always be aware and respect our internal biological clock. We should always listen to our circadian cycle, and by doing that we improve our sleeping quality and boost our mental and physical performance.