Glycerin GTS 21 vs ForeverRun Nitro 1

The Glycerin GTS 21 is Brooks' plush daily training shoe with a layer of gentle support built in. GTS stands for Go To Support, so this is the stability sibling of the neutral Glycerin 21: same soft, high-cushion ride, but with guide rails that quietly hold your stride together when your form starts to wobble. At 289g with a 10mm drop, it is a substantial, protective running shoe rather than a light or fast one. That weight is the price of the cushioning, and it is aimed squarely at runners who value comfort and a bit of guidance over speed. We rate it as a soft-riding stability daily trainer for easy miles, long runs and everyday base training. If you overpronate mildly, want a max-comfort shoe that keeps you aligned, and are not chasing pace, it is one of the easiest shoes in this class to just put on and run.

The ForeverRun Nitro is Puma's answer to the big, dependable stability trainer, and it lands squarely in that daily-mileage space rather than trying to be fast. This is a supportive road running shoe built for runners who want their legs held steady over long, repeated miles. At 274g it is a substantial shoe, and you feel that weight, but you also feel the reward: a stable, planted platform with a 10mm drop that suits heel and midfoot strikers alike. Puma leans on structure rather than a firm medial post you can feel, so the guidance is there without shouting. If you have bounced off aggressive stability shoes like the Asics Gel Kayano in the past, this is a gentler take on the same idea. We rate it as a genuine long-run workhorse for overpronators and heavier runners who value durability and calm underfoot over pace.