Ran a trail race this weekend, one mile loops of 500 feet climbing and crushing downhills, on repeat for 20 miles. About 18 loops in my quads began screaming, when I hit the bottom again I used the spray on both legs. Went on easily, and I was off. About halfway into the next loop, I noticed a buffering effect, the pain was dulled and I was able to focus on staying upright and making good time. Definitely worth adding to your run kit!