The Brooks Glycerin was once the most comfortable running shoe available, with its stack of cushioning making it stand out. Now, however, many of the best cushioned running shoes have higher stacks and softer foams than the Glycerin—and the Brooks Glycerin 21 is relatively lightweight and low-stack for a cushioned shoe. This makes it a more versatile daily training option than many cushioned shoes, and I rate the Glycerin 21 among the best running shoes for those looking for a protective shoe that has pop for faster runs.
