Sweating cleans out your pores.

Although sweating causes your pores to widen, it does not clean them out.  Even though working out is an important part of a healthy lifestyle, it can cause acne problems from some of us.  Exercising stimulates sebum oil production, which combines with heat, friction and scale (dead skin cells) to aggravate acne.  In addition anytime equipment or clothing interferes with the bodies ability for sebum and scale to exit the pores, acne can develop.  This may be the case with helmets of any kind, shoulder pads, or even heavy clingy uniforms.  It's possible to minimize acne irritation by wearing loose fitting cotton clothing and by showering immediately after exercise.