micro twist maintenance help!!!!

I need some helpful tips on keeping my micro twists look good longer.  I'm a month away from being 2yrs chemical free.  I'm in my third set of twist since July and I love the versatilty of them.  I workout 4-5 days weekly and between sweating & water aerobics my twist tend to frizz alot where my natural hair ends are in the twist.  So do anyone know of a way to keep these ends sealed inside the twists or some products that will help hold down the frizz, cause they start looking frizzy after about 3 weeks and I have been trying to get 2 months out of them?