Whether a shoe can hold up through quick stops and directional changes while also withstanding the impact of heavy lifting was a key focus Christian McCaffrey tested repeatedly throughout the design process. The signature shoe, named CMC after the San Francisco 49ers running back's own initials, was developed in partnership with athletic brand While On Earth. McCaffrey personally took part in testing throughout the shoe's development, translating the demands of his own "explosive training" and high-intensity hybrid workouts directly into the shoe's specifications.
McCaffrey said: "In developing the CMC, I wanted to create a shoe that reflects how I train now—one that can handle explosive, powerful movements while delivering stability, durability, and lasting comfort across different types of training. The specs speak to that, including the TPU midfoot plate and external heel counter." His NFL training regimen involves a heavy dose of explosive power and lateral movement, cutting, and force production—all of which served as reference points in the CMC's design.
Other details on the CMC include a forefoot flexibility design, a multi-directional rubber outsole for enhanced ground traction, rubber-reinforced toe and forefoot areas, and an angled heel tab designed to reduce pressure on the Achilles tendon. McCaffrey joined While On Earth as a co-founder and investor starting in August 2025, and the CMC marks his third shoe collaboration with the brand.
Before the CMC, While On Earth had already released two shoes: the Move Trainer, a hybrid training shoe designed to transition between weightlifting and HIIT-style workouts with a 6mm heel-to-toe drop; and the Rhythm Runner, the brand's first-ever running shoe launched this past summer, featuring a breathable upper and a rugged tread outsole. McCaffrey described it as suited for "everything from easy recovery runs to long distances, treadmill mileage, even the track—while also holding up for high-intensity hybrid training moves."
While On Earth was co-founded in fall 2024 by former Nobull CMO Todd Meleney alongside CrossFit athletes Brooke Wells and Mat Fraser, with Wells currently also serving as the brand's Creative Director of women's apparel. The CMC, along with the brand's existing Move Trainer and Rhythm Runner, are all available in men's and women's sizing. Detailed pricing and release timing were not mentioned in the materials.
