Interesting - I didn't know about forearm cooling!
I was dubious too. I'm a heat princess but before the Canadian Death Race in 2012, I started working on it since my poor life choices make heat unavoidable. My first "cooling" purchases were a Columbia Omni-Freeze Zero T-shirt and buff. I really don't notice much difference when I wear them - and if there is a difference, I'm not sure it is in the right direction. I carried the buff yesterday, thinking I might fill it with ice and put it around my neck but I don't think it would be better than any other piece of cloth filled with ice. It might have worked in the same way that my patent-pending Ziploc-Sponge method worked without the fuss of carrying the ziploc, but that's about it.
I've tried the Sugoi cooling sleeves on one or two previous runs and did notice a difference. It's not huge but everything helps on a really hot day. When they're wet or when there is even a small breeze, there is an obvious cooling sensation. If they dry out and the breeze dies, then they feel like an extra layer. It has something to do with making better use of evaporative cooling, I think. I was sweating enough that they always stayed at least damp so the sensation never got worse than neutral; the slightest breeze gave me a little jolt of cooling. Once in awhile, I squeezed the sponge on them, which felt awesome. They are very lightweight and silky compared to regular arm warmers.
The features of IceFil fabric are listed below. I wouldn't give the sleeves 10/10 and I've only tried them on mega-hot days, but they are the only cooling clothing that has done anything for me so far.
- High-performance IceFil fabric reduces your skin temperature and protects you at the maximum level from harmful UV rays. Comfort elastic bands stay put and won't slide down your arms.
- IceFil fabric with UPF 50 absorbs and disperses sweat
- Xylitol treatment process generates a cooling effect when it comes in contact with moisture
- Xylitol treatment effectively turns sweat into a micro-refrigerant for topical temperature control