Your muscles, fat, and other cells respond differently to exercise depending on the time of day
Panoramic images/Alay
Usain Bolt He broke the 100m sprint record at the 2009 World Athletics Championships in Berlin, in an illuminated stadium under the night sky.
This article is part of a series on fitness that answers eight questions about exercise and how it affects our bodies and minds. Read more here.
This was no accident: when it comes to sportsmanship, timing is of the essence. For activities that rely purely on muscle power and endurance, most world records have been set in the afternoon or evening, likely aided by peaks in the daily rhythms of some of the body’s key physiological outputs.
But what about daily physical exercises? Is there an optimal time of day or month? get the most out of your workouts and reduce the risk of injury?
“Whether you’re looking at any aspect of sports — whether it’s sports medicine or exercise response — the time of day is important,” he says. Qing-Jun Meng at the University of Manchester, UK. Later in the afternoon or evening our body temperature peaks, resulting in faster metabolic reactions and nerve signal transmission compared to early morning. Connective tissue is also more flexible in the eveningour glycogen reserves, on the other hand, are the biochemical energy source used by our muscles during moderate or intense exercise – they had time to fill it.
Circadian rhythms
Other physiological parameters also change within 24 hourswhich may be important for exercise: testosterone secretion peaks around 9:00 a.m.; coordination is usually best around 2:30 p.m.; reaction times are fastest around 3.30pm; cardiovascular efficiency, peak muscle and grip strength from 5:00 to 5:30 p.m.
“Circadian rhythms are present in almost all cells it regulates key processes in the body and related to exercise and metabolism,” says Meng. “Depending on how long you exercise, your muscles, fat and other cells will also be in a different state, and will respond differently to exercise.”
In fact, a recent study Clear Lok at Stanford University in California and his colleagues found that, on average, Olympic swimmers are more than a third of a second faster if they compete in the afternoon rather than the morning. “In 40 percent of (swimming) races, the effect of time of day is greater than the difference between finishing first or second,” they wrote.
In sports that involve more technical skills, such as tennis or soccer, peak performance comes a little earlier, possibly because our cognitive abilities are at their peak in the morning or early afternoon. Soccer players juggle and chip the ball with the utmost precision around 4:00 p.m.; Tennis players serve faster in the eveningbut more specific in the morning. Of course, these times are based on averages, in fact, “Lakotchas” who tend to wake up early. and being more active in the mornings will be at its best earlier, and the “owls”, while living naturally in the evenings, will rise later.
What are all of these for the rest of us how to time our exercise? last year, Fabienne Bruggisser at the University of Basel in Switzerland and with his colleagues analyzed evidence from 26 previous studies and found little to support or disprove the idea that training at a specific time leads to better performance or improved health outcomes.
However, they found some evidence to improve physical performance at the same time of day to support training for a race or competition. In other words, morning training improves morning performance more than afternoon training, and vice versa. However, given that the studies included only young male participants, it remains to be seen whether these findings apply to the general population, the authors said.
Monthly cycles
Women may have another layer of complexity to consider. In recent years, several women’s soccer teams, including Chelsea FC Women, have begun tailoring their players’ training programs to their menstrual cycle, which they claim improves performance and reduces the risk of injury.
“The theory is that when estrogen is high and progesterone is low … that’s an anabolic environment; it’s a good (time) to work hard,” he says Stuart Phillips at McMaster University in Canada. However he and his colleagues recently review the evidence Because of the effect of menstrual phase on exercise performance, they found her to be “incredibly lean.” “The available evidence suggests there is no merit,” says Phillips.
However, he does not rule out recording symptoms and using them as a guide for scheduling workouts. “I know some women are really vulnerable at certain stages of their cycle with menstrual related symptoms: cramps, back pain, lack of motivation, fatigue, etc. And for female athletes who experience symptoms, they try to manage them and create on their own. It’s a big thing for the coaches to be aware of them,” he says.
“But when it comes to a blanket, ‘this is the way things are done’ approach, there is no consistent pattern of performance when analyzed systematically, and we know that gold medals and world records have been set at various (menstrual) phases, and birth control pills are on and off.”
Meng believes there may be other factors to consider. He generally advocates exercising in the morning, especially outdoors, as it exposes people to bright light, which helps synchronize our biological clocks with the time of day. Our bodies work best when the clocks in all our cells and tissues are aligned with each other and the time of day.
And even if there is no best time of day to work out, there may be times to avoid exercise. Recent research by Meng and his colleagues has suggested that a key mechanism for keeping the biological clocks in our bones and joints in sync with those in other tissues is exercise, and if mice are encouraged to exercise when they would normally be sleeping, it does so. bone clocks to they become desynchronized from their brain clocks – The phenomenon that Meng has called “skeletal jet lag”.
Although the effects of injury and physical performance in humans are unclear, further experiments in mice suggest that continuous exercise for the equivalent of one night activates genes associated with osteoarthritis. “We suspect that if you’ve been doing this for a long time, it can be really harmful,” says Meng.
This article is part of a special series investigating key questions about exercise.
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