Puma ForeverRun Nitro 2 vs Nike Structure 26:
Which to Choose

The spec sheets are strikingly close. Weights land within a hair of each other — roughly 291g for the ForeverRun Nitro 2 versus about 298g for the Structure 26 in a men's US 9 — and so do the stacks, at about 35mm heel / 26.5mm forefoot on the Puma against roughly 36mm / 26mm on the Nike, with both carrying a 10mm drop. Both corral the foot with sidewall-style guidance (Puma's RunGuide walls, Nike's dual guide rails) that quietly resists inward roll without feeling corrective, and neither uses a propulsion plate, so energy return comes from the foam alone. The one difference that actually decides it is that foam. Puma's nitrogen-infused Nitro midsole runs softer and livelier — cushioned but composed, with a touch more spring underfoot — while Nike's ReactX is firmer and more planted, delivering a controlled, locked-down ride that prioritizes a secure, straight-tracking feel over any bounce. In practice the Puma feels a shade more energetic and forgiving at steady effort, and the Nike feels more deliberately grounded and stable. Neither rewards hard acceleration; both are happiest in the easy-to-steady zone, roughly 4:45–6:00 min/km, and start to feel like a lot of shoe when pushed quicker.