Students are stuck sitting in class for the majority of the day. Few of them get the opportunity to effectively move their body.
If they don't have a way to get exercise this can cause serious problems such as depression, exhaustion, obesity, high blood pressure, and high blood cholesterol.
This can cause obesity, heart diesese, lack of energy, exhaustion, and in some causes depression.
School-sanctioned sports allow students to move their bodies in an effective way that doesn't cost an enormous amount. Club sports often are expensive and travel often making it a poor option for many. However just because someone doesn't have an abundance of money shouldn't stop them from getting exercise in a fun competitive environment.