In many sports, the harder the hit, the louder the fans yell, but sometimes the outcome of a big blow isn't something to cheer about, like a concussion.
The Centers for Disease Control and Prevention says that one out of every ten athletes in a contact sport will get a concussion each season.
They also estimate that 3.8 million concussions happen each year in the United States with around 70% of them going undiagnosed.
When many people think of concussions, football automatically comes to mind, but women's soccer is the second leading sport for the brain injury.
When the brain moves around inside your head and hits the walls of your skull, that's when a concussion can happen.
It doesn't always take a big blow to do the trick either. Purdue University researchers found that a series of smaller hits can have the same result.
And most happen without the athlete ever losing consciousness.