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CircadianI Rhythms And Sports Performance

If you are athletic, you must have already noticed that you are in better shape in the morning or afternoon. This phenomenon is linked to circadian rhythms, that is to say, the biological rhythms that follow one another every 24 hours. They are paramount in sports competitions when athletes seek maximum performance at a specific time.

The Rhythm Of Organs Depends On Several Biological Clocks

Circadian cycles are controlled by an internal clock in the brain at the level of the suprachiasmatic nuclei of the hypothalamus, which synchronizes the body to the rhythm of day/night alternation. There are also peripheral biological clocks in different organs, such as the muscles, the intestine, or the liver. The activity of these organs depends on various daily variations, linked in particular to diet and metabolism.

The central clock in the brain sends information to peripheral clocks via the nervous pathway (sympathetic system) or the hormonal pathway (glucocorticoids). Peripheral clocks, therefore, depend on both information related to brightness and other parameters such as diet, physical exercise, or even stress.

Circadian Rhythms And Epigenetics

At the cellular level, circadian rhythms are manifested by gene expression that follows 24 hours. These cyclical variations influence numerous physiological functions that evolve during the day, such as hunger, sleep, hormone production, or body temperature.

Cyclic gene expression in muscle

In skeletal muscles, the expression of more than 2,300 genes evolves according to a circadian rhythm, following instructions sent by the central clock and other signals, such as variations induced by diet. In addition, the rhythm of the muscle must be synchronized with that of other organs, such as the liver or adipose tissue, because all of these organs and tissues participate in concert in controlling blood sugar. These cyclical variations could explain why our muscles perform better at certain times of the day.

Sports Performance Varies Throughout The Day

Most studies show that sports performance is better after 4 p.m. when the expression of genes linked to muscle contraction and mitochondrial activity is maximal. This effect is observed in both adults and children. Variations in performance depending on the time of day could also be linked to variations in body temperature during the day. 

This is what two scientists from the University of Basse-Normandie put forward in a 2004 article on the cyclic performance of muscles in anaerobic conditions: “The increase in body temperature during the day can be compared to overheating. Nizar Souissi & Damien Davenne also mention other hypotheses: for example, the level of wakefulness is better in the afternoon than in the morning.

Climate Influences Sports Performance

Daily variations in sports performance vary depending on climatic conditions, namely humidity and heat. Temperature influences muscle activity since an increase of 1°C in muscle temperature improves muscle performance by 2% to 5%. A French study published in 2004 tested the performance of 11 young men and sports students. 

The researchers exposed them for one hour to a “neutral” environment (20.5°C, 67% humidity) or hot, humid conditions (29.5°C and 74% humidity). Then, the participants performed a knee extension exercise. The researchers observed increased muscle strength in the group exposed to the hot and humid environment. Other studies confirm these results.

Physical Preparation Adapted To Improve Performance For D-Day

In mice, researchers have shown that the cyclic activity of genes can be modified at the peripheral level without impact at the central level. In short, we can shift our peak performance of the day without changing our sleep schedule. To do this, the procedure is simple: as soon as you know your deadline (competition or other), change your training times so that they coincide with the time of the competition. To perform well in the morning, you need to train regularly. 

Thus, it has been observed that performance in a 200-meter swim in the morning is better in swimmers who are used to training in the morning than those who train in the evening. Conversely, if you train mainly in the evening, you will be even more efficient at the end of the day and accentuate the difference between morning and evening. The activity of the genes of your peripheral clock will thus adapt, and you will put all the chances on your side, particularly if your nutrition is well adapted to these new schedules.

The Influence Of Meal Times On Performance

Meal timing is another factor in modulating performance. Nutrients are more or less available depending on the time of day, but these molecules influence the peripheral clocks present in the organs. Thus, intermittent fasting is a way to smooth out performance over the day.

How To Eat To Adapt To The Time Of Maximum Performance

The Central Washington University website gives some meal tips, depending on when your competition occurs. These recommendations are inspired by the book by Nancy Clark, a dietitian specializing in athletes’ nutrition. For example, for intense exercise at:

  1. 10 a.m.: Eat a carbohydrate-rich meal the night before and a usual breakfast before 7 a.m.
  2. 2 p.m.: Have a high-carb breakfast, a light lunch, or a big brunch at 10 a.m.
  3. 8 p.m.: Opt for a carb-rich breakfast and lunch, eat dinner at 5 p.m., or have a light dinner between 6 p.m. and 7 p.m.

Read Also: The 20 Best Alkalizing Foods


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