I'm sorry @GoodFaith, but sweat does not coagulate like butter, it's mostly water. Sebum + Dead Skin Cells + Bacteria produce acne. Reduce the effect of these, and you get less acne. Sebum can be affected by diet, dead skin cells by washing and exfoliating, bacteria by washing also. Sweat may increase the rate at which acne will form (as will heat), but is not itself the cause. The usual common sense, wash off after exercise is good advice, just exfoliate more vigorously with a loofah or similar for a deeper clean if your back gives you trouble.

You need to rinse the sweat off immediately, or it coaggulates in the pores like butter. I would suggest a luke warm shower-if you don't have access to a shower, you need to bring some wipes with you & wipe yourself as best as you can. Try to find some with tea tree oil in them. Also, take a zinc supplement. They sell it at GNC for about $3.

Get a back loofah. You can get one at Target and it comes with a handle, but use an exfoliating body wash. Also, it's helpful to wear breathable fabrics when being active so the bacteria and sweat don't get so trapped.

Check out Faith's article under the "Trend" section on back acne, you will get some fabulous tips!

I am a Licensed Esthetician and I have written a really extensive article on Bacne. Look for it under TRENDS. I am sure it will help you tremendously.