adidas Ultraboost 21 Prime Running FX7729

Built for neutral road runners

The adidas Ultraboost 21 Prime Running FX7729 is categorised as a men's neutral running shoe, suited to neutral gait and supination, with a 10 mm drop and a road-focused design. Runners who log medium to medium-slow paces and want a cushioned, comfortable ride will find the updated Boost midsole and supportive upper work together to keep the foot stable through the support phase and into toe-off.

Cushioning and energy return

The Boost midsole uses thousands of energy capsules to deliver soft, springy cushioning that stays responsive in varying temperatures. This version adds 6% more Boost compound, giving better control during the foot's support phase while maintaining the comfort Ultraboost is known for. The Linear Energy Push system, built into the sole with lateral flaps along the metatarsus, amplifies the propulsive effect during the thrust phase.

Fit, support and breathability

The revisited Primeknit+ upper is more elastic and shaped in specific areas to hold the foot securely while allowing airflow. An integrated lacing system with side inserts helps manage pressure across the foot, while TPU side inserts stabilise the foot inside the fit. A stiffer heel insert adds stability, and a higher collar around the Achilles tendon improves comfort during longer runs.

Outsole and sustainable materials

A Stretchweb outsole with Continental™ Rubber provides traction on both dry and wet surfaces, with a minimal rubber layer that preserves the midsole's dynamics. The Primeblue upper is a high-performance recycled material made in part with Parley Ocean Plastic, created from plastic waste recovered from islands, beaches and coastal communities before it reaches the ocean.

Confirmed details