Check out below the ways that sweat can damage your natural hair if you aren't careful. Clean your scalp after exercising especially if you perspire a lot. Leaving bacteria and salt on your scalp is a recipe for disaster.
References:
Sweating: Medline Plus ---https://medlineplus.gov/ency/article/003218.htm
Sweat: Medline Plus ---https://medlineplus.gov/sweat.html