Laughing promotes the release of endorphins and suppresses stress hormone such as cortisol. A physiology Faith is known for, unlike Lonel Messi, who seldomly laugh hence could not contain stressor pressure in 2018 Russia Fifa World Cup, thus performed below expectations.
“I was under a lot of pressure because the world, my fans and my country were waiting for gold medal from me,” said Chepng’etich of Tokyo Olympic pressure-stressors that could activated production of cortisol hormone.
There immediate response that is activated when one encounter adversary; in Tokyo Olympic, Faith adversary was Sifan Hassan, Dutchwoman-which leads to the release of adrenaline that trigger your heart rate and blood pressure to go up, breathe faster, your body releases more glucose, your muscles tense, and there is increased blood and oxygen supply to brain and muscles all in readiness for “fight or flight” where for Faith was later and she broke Tokyo Olympic 1,500 meters record.
This my interpretation as my human anatomy class.