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In the women's single 10-meter diving platform final at the Paris Olympics, 17-year-old Chinese athlete Quan Hongchan won the gold medal with 425.6 points, becoming the youngest triple gold medalist in Chinese Olympic history.

Careful viewers may notice that after Quan Hongchan finishes her moves and swims out of the diving pool, the camera always follows her to the shower area, followed by a detailed score of the jump on the screen. This process runs through the entire competition like copy and paste.

This is so strange! Didn’t you just come out of the water? Why did you have to run to flush the water immediately?

Is it because they are afraid of getting dirty? After all, even Olympic athletes admit that they have urinated in almost every pool they swim in, and honestly say that everyone does the same[1].

Whether it is a public swimming pool used for entertainment or a competitive swimming pool designed specifically for sports competitions, disinfection products need to be added to the water to ensure the safety of users.The most common of these are chlorine-based disinfectants[2][3].

Exposure to high concentrations of chloramine is indeed harmful to the human body. In severe cases, symptoms such as difficulty breathing, rashes, and coughing may occur. For example, the United States and Russia have both experienced public health problems due to excessive chlorine levels in swimming pools[5][6].

Despite this, spectators do not need to worry too much about the swimming pool becoming a gathering place for toxic substances, with divers going straight to the hospital after swimming a lap.

World Health Organization (WHO) clearly stipulates that the combined chlorine content in swimming pools and open waters should not exceed 0.5 mg/L, which is also the standard for Olympic swimming pools[7][2]. More importantly, WHO points out thatIn swimming pools that meet standards and management practices, the risk of exposure to chlorination byproducts is minimal[7].

To what extent are the requirements for hosting large-scale sports events? The 19th Asian Games was held in Hangzhou. The swimming pool water in the swimming pool had to be processed through a water circulation system with seven "checkpoints" before it could be used for the competition. It was so clean that you could even scoop it up and drink it.[8]

The water, which has been strictly regulated and repeatedly tested, has basically ruled out safety issues caused by excessive chlorine content. Naturally, there is no need for athletes to use flushing to avoid risks.

To take a step back, if the athletes are really worried, they can of course go for a flush.But in practical terms, taking a few minutes in the shower (while wearing a bathing suit) to eliminate the negative effects of chlorine on the body is very limited.To achieve thorough cleansing, careful rinsing is necessary and the effects should be enhanced with an anti-chlorine shampoo and body wash containing sodium thiosulfate.[9][10]

Since the pool water is not as dirty as we think, and a brief rinse with clean water has little effect in removing dirt, why do divers insist on flushing after getting ashore?

Under the current Olympic diving rules, for example, in the women’s 10-meter platform final in which Quan Hongchan participated, the twelve athletes had to complete five dives in a round-by-round competition.[11] In other words, after each dive, Quan Hongchan had to wait for the other 11 athletes to finish before she could proceed to the next dive.

After the referee blows the whistle, the contestants must start their moves within one minute[11]. Including entering and leaving the stage, the total waiting time for each round is about 15 minutes.

According to FINA regulations, the temperature of the diving pool must not be lower than 28 degrees Celsius[12], while the average human body temperature is 37 degrees Celsius[13]. The finals are usually held at night, when the athletes return to shore from the water.The evaporation of water causes the body's heat to be lost quickly. If you don't keep warm in time, it will cause muscle stiffness and even colds.diarrheaand other diseases[14].In this case, athletes mostly choose to keep warm with hot water.

Diving coach Bremer of Ball State University in Indiana once explained this point: Diving is a sport that requires high precision and quick reaction. If the athletes are tense due to the cold, their flexibility will be greatly affected, making it impossible for them to complete complex diving movements.[15] Yu Fen, head coach of the Tsinghua diving team, also said,Hot showers are designed to keep athletes warm while waiting to dive and prevent muscle stiffness.[16][17]

According to the official facility rules issued by the International Swimming Federation, there is a hot tub next to the diving pool[12]. During the break in the women's synchronized 10-meter platform final, Quan Hongchan and Chen Yuxi even soaked in it and chatted. It's not that people treat the Olympic venues as a top-of-the-line bathhouse.Rather, bathing is a way to maintain body temperature and relax muscles[18].

So at the Paris Aquatics Centre, spectators could see the following scene: the divers, soaking wet, jogged out of the water and quickly dived into the hot water pool with happy smiles on their faces, such as the men’s doubles 3m springboard team of Wang Zongyuan and Long Daoyi[19].

A study from the UK found that compared with a group that relied entirely on natural recovery,Strength trainingThe group that soaked in 40°C hot water for 10 minutes was able to significantly increase its intramuscular temperature in a short period of time[20]. Researchers at the University of Maryland also observed that soaking in hot water (46°C) for 10 minutes can also promote the recovery of muscle strength[21].

On the playing field, everything is for good results.

The water temperature of the diving pool is much lower than the normal human body temperature. In the intervals between different rounds of competition, the contestants go to the poolside to shower or bathe, not only to maintain body temperature,It can also relieve muscle tension and soreness caused by old injuries and cold water stimulation to a certain extent.Minimize the impact of physical factors on on-field performance.

Quan Hongchan jumped into the water as lightly and flexibly as a small fish, but the process was far from as smooth and harmless as the audience saw. According to the analysis of professional orthopedic doctors, when the contestants touched the water surface,The body decelerates rapidly due to the impact, and the impact force is dispersed to the hands, wrists, elbows, shoulders and other parts, which is called the "kinetic chain".Athletes who use water splashes to improve their scores also put a lot of stress on the lower back muscles and hip flexors[22].

For this reason, the incidence of wrist pain among divers who train for the 10-meter diving platform is as high as 85.7%, and muscle strains and ligament sprains are also very common[23]. When American team member Loschiavo participated in the Tokyo Olympics, he still had screws left in his wrist from surgical repair[22].

Researchers at Auckland University of Technology analyzed the effects of soaking in water of different temperatures on exercise recovery. The results showed that soaking in cold water below 15°C for 15-20 minutes can cause local vasoconstriction, reduce the permeability of cells, lymphatic vessels and capillaries, and reduce the diffusion of fluid into the interstitial space, which can reduce acute inflammation caused by muscle damage. Soaking in hot water (above 36°C) will increase blood flow and promote cell recovery.metabolism, improving the efficiency of exercise recovery[25].

Because cold water and hot water each have their own effects, alternating between them has become an important method for athletes in different fields to relieve pain and relax muscles[26].

Even if the water temperature is not exact, simply soaking in any bathtub or pool at 16°C-25°C can help relieve muscle tension.This is because the effect of water immersion does not come from the water temperature, but from "hydrostatic pressure".This pressure causes fluid in the extremities to move toward the core of the body, facilitating the transport of substances within the muscles and, together with the anti-gravity effect of buoyancy, reducing fatigue[25].

The body can remain flexible and stretched, and muscle soreness caused by new and old injuries can be relieved, making showers and baths an indispensable part of the competition process for diving athletes.

After landing, take a bath and rinse with warm/hot water.It can reduce the activity of the sympathetic nervous system[27] and lower levels of the stress hormone cortisol[28].Perhaps it can help the players relieve tension and anxiety to a certain extent.

If the venue is not good, our athletes, who are both intelligent and brave, will "stand on their own feet". The 2024 Doha World Championships did not provide showers. The diving team brought buckets filled with hot water into the venue. Quan Hongchan tested the water temperature and said it was "very hot" [29]!