Heat, humidity pose challenges in Olympic marathon swimming
Florian Wellbrock, of Germany, swims in the men's 1500-meter freestyle final at the 2020 Summer Olympics, Sunday, Aug. 1, 2021, in Tokyo, Japan. (AP Photo/Jae C. Hong)

Florian Wellbrock, of Germany, swims in the men's 1500-meter freestyle final at the 2020 Summer Olympics, Sunday, Aug. 1, 2021, in Tokyo, Japan. (AP Photo/Jae C. Hong)

Jul. 31, 2021 10:27 PM EDT
Gregorio Paltrinieri of Italy poses with his silver medal for the men's 800-meters freestyle final at the 2020 Summer Olympics, Thursday, July 29, 2021, in Tokyo, Japan. (AP Photo/Matthias Schrader)

Gregorio Paltrinieri of Italy poses with his silver medal for the men's 800-meters freestyle final at the 2020 Summer Olympics, Thursday, July 29, 2021, in Tokyo, Japan. (AP Photo/Matthias Schrader)

Jul. 28, 2021 11:24 PM EDT
Gregorio Paltrinieri of Italy swims in the men's 800-meters freestyle final at the 2020 Summer Olympics, Thursday, July 29, 2021, in Tokyo, Japan. (AP Photo/Matthias Schrader)

Gregorio Paltrinieri of Italy swims in the men's 800-meters freestyle final at the 2020 Summer Olympics, Thursday, July 29, 2021, in Tokyo, Japan. (AP Photo/Matthias Schrader)

Jul. 28, 2021 09:45 PM EDT
Florian Wellbrock, of Germany, celebrates after winning the bronze medal in a men's 1500-meter freestyle final at the 2020 Summer Olympics, Sunday, Aug. 1, 2021, in Tokyo, Japan. (AP Photo/Gregory Bull)

Florian Wellbrock, of Germany, celebrates after winning the bronze medal in a men's 1500-meter freestyle final at the 2020 Summer Olympics, Sunday, Aug. 1, 2021, in Tokyo, Japan. (AP Photo/Gregory Bull)

Aug. 01, 2021 12:04 AM EDT