The Adidas Adizero Blaze jacket borrows its build from emergency blankets, using a metallic coating that reflects body heat back instead of trapping it under bulk insulation. Ripstop material handles the wear of regular training miles, and bonded seams replace traditional stitching so nothing chafes mid-stride. What Our Gearhead(R) Experts Are Saying:"I wore this jacket through a 20-degree tempo run expecting to peel it off by mile two, and the heat stayed put instead of venting out with every stride. The metallic lining is doing real work here, not just catching the eye at the start line."