Here's the principle.
People's fatigue and drowsiness come from one substance and receptor-adenosine and adenosine receptor.
In human body, when adenosine binds to adenosine receptor, it will send out the signal of "drowsiness", and people will feel tired. The more adenosine, the stronger the sense of fatigue.
Caffeine is a substance with similar structure to adenosine, which can be disguised as adenosine and combine with its receptor to some extent without releasing fatigue signals.
Once a large amount of caffeine is ingested in a short time, a large number of adenosine receptors will be occupied by caffeine, resulting in adenosine not working normally, and people will not feel tired. This is the principle of coffee refreshing. By the same logic, if a person is already in a state of fatigue, it means that a large number of adenosine receptors in his body have combined with adenosine. Caffeine can't replace adenosine when drinking coffee at this time, because adenosine has already worked, which is why coffee can't pull people out of fatigue.
The prolonged waking time after drinking coffee also needs corresponding sleep, that is, should I sleep 8 hours a day or must I sleep 8 hours?
Here's the principle.
Although caffeine can be disguised as adenosine, it can combine with the receptor and make people feel tired temporarily, but adenosine that is blocked from the door will not disappear, but it is still accumulating. Once caffeine is exhausted, adenosine that is blocked from the door will recombine with the receptor. Because I have accumulated adenosine before, I may be more sleepy, and I still need enough sleep to eliminate fatigue.
Caffeine is completely absorbed by the stomach and small intestine within 45 minutes after ingestion, and will be distributed to all organs of the whole body after absorption [1]. Based on this principle, the best time to drink coffee should be around 1 hour before deciding to extend the waking time.
Caffeine metabolism is related to age, liver function, pregnancy, intake of other drugs and the content of caffeine metabolizing enzymes in liver. The slower caffeine metabolism, the longer caffeine lasts (which is not necessarily a good thing).
Caffeine is metabolized in the body to produce paraxanthine, theobromine and theophylline.
Paraxanthine can accelerate lipolysis, leading to the increase of glycerol and free fatty acids in plasma; Theobromine can dilate blood vessels and increase urine output; Theophylline soothes bronchial smooth muscle and is used to treat asthma, but the dose used for treatment is much greater than that produced by caffeine metabolism. (This article cannot be used for medical treatment or medication guidance, please follow the doctor's advice. )
In this way, caffeine diuresis, the amount of a cup of coffee, may discharge more than one cup of urine, further leading to water shortage in the human body, and the concentration of certain substances in the blood will rise, which may increase the burden on the heart.
So drink coffee and replenish water in time.
Caffeine can improve physical function and brain power to some extent. A study of 1979 shows that compared with the control group, the performance of athletes who take caffeine in long-distance cycling has improved by 7%[ 1].
Other studies have achieved more remarkable results: an experiment on trained runners showed that after taking 9 mg/kg caffeine, the endurance of straight running increased by 44% and that of circular running increased by 55%. [2]
Such remarkable improvement is not an isolated case, and some subsequent studies have obtained similar results. Another study shows that the duration of cycling can be increased by 29% after taking 5.5 mg of caffeine per kilogram of body weight [3].
Generally speaking, black coffee has the best refreshing effect. After getting up early, you can have a cup of American and iced coffee before work and study. At the same time, a cup of black coffee in the morning can also eliminate some edema, which is very helpful to both appearance and interior.
Mixed coffee, such as mocha, latte, caramel macchiato and other coffee-based mixed drinks, milk and sugar can stimulate dopamine and enhance happiness, which is suitable for daily scenes, but coffee is not the focus here.
Lemon coffee is very common in Hong Kong. Add lemon slices to black coffee and mix the two flavors. Lemon coffee is more suitable for after-work scenes. After a hard day's work, the unique sour taste of lemon coffee and the bitter taste of black coffee can play a certain role in eliminating fatigue.
refer to
[1]: Newton, r; Broughton LJ, Linde MJ, Morrison PJ, Rogers HJ, Brad Brook ID card. ? Pharmacokinetics of caffeine in human plasma and saliva. European Journal of Clinical Pharmacology. 198 1,? 2 1 ? ( 1): 45–52.？ PMID 7333346
[2]: Ivy, JL; Costel DL, Fink WJ, get off RW. Effects of caffeine and carbohydrates on endurance performance. Medical science and physical education. 1979 spring, 1 1 ? ( 1): 6– 1 1.？ PMID 48 1 158
[3]: Graham, te; Sprite, Illinois. ? Performance and metabolic response to high-dose caffeine during long-term exercise. Journal of applied physiology. 199 1 Dec，？ 7 1 ? (6): 2292–8.？ PMID 1778925
[4]:Trice，I； Amy hymes. Effect of caffeine intake on exercise-induced changes during high-intensity intermittent exercise. International journal of sports nutrition. Mar 1995？ 5 ? ( 1): 37–44.？ PMID 7749424