Swimming in cool water won’t give you a cold—it actually has plenty of benefits!

Why does it feel better to swim in cooler water? That’s because when the pool water is warm, stepping in feels pleasantly lukewarm at first—but after just a few strokes, it becomes uncomfortably hot. At high temperatures, you simply can’t swim comfortably! It’s much more enjoyable—and sustainable—to stick with cooler water instead. But why exactly?

According to the standards of the China Engineering Construction Standardization Association,

The temperature of the indoor swimming pool is:
Competition pool: 24–26°C
Training pool: 25–27°C
Diving pool: 26–28°C
Children's swimming pool: 24-29°C

About 10 degrees lower than the normal human body temperature of 37 degrees.

The constant-temperature pool maintains a slightly lower water temperature because:

1. Heat Dissipation
We all feel warm after exercising for a while. If it’s an activity like running on the ground, we can directly cool down by sweating—evaporation draws heat away from the body (and many people actually find this sweaty, intense state incredibly appealing!).

However, sweating in water doesn’t help cool you down by evaporative cooling—it actually leads to dehydration! That’s why swimming comfortably requires using cooler water to aid in temperature regulation.

2. Enable muscles to generate force
Every tiny movement of the human body is accomplished through muscle contraction. Only after muscles contract can they unleash their full power.

Water that’s too hot can leave your muscles feeling weak! Think about taking a hot bath—while the warm water relaxes and stretches your skin’s pores, it also makes you feel limp and unable to move. On the other hand, cold water actually helps contract your blood vessels and muscles, giving them the strength needed to perform even the most energetic movements.

3. Safety
Swimming in warm water is inherently more tiring, as it requires greater energy expenditure. And since the extra heat generated isn’t effectively dissipated by the warm water, it causes a person’s body temperature to steadily rise instead.

To dissipate heat, skin blood vessels dilate further, leading to insufficient blood supply to vital organs within the body.

Meanwhile, to cool down, the body tends to sweat heavily—but swimming in warm water not only fails to accomplish this task, it actually leads to dehydration.

This ultimately leads to: abnormal heart function, confusion, and difficulty breathing. If you’re concerned about the cool water in autumn and winter making it uncomfortable to enter, consider doing some warm-up exercises beforehand. Before getting into the water, splash yourself with lukewarm or slightly cooler water to gradually acclimate your body to the temperature.