Midnight skating the university campus we cover miles in the desert summer air—roads, parking lots, pathways, circling the sports arena then hopping curbs, leaping stairs and riding concrete benches, flying off with the rehearsed grace of Olympians.

Rollerblades were an inevitable invention. Wheels on the feet. It couldn’t be simpler, a complete freedom that yields surprisingly exceptional posture and strength, promising you’ll bound flights of stairs with ease, prompted by hard glutes and solid hamstrings. The very basics of inline ensure it: Skater pushes off, extends leg back, pushes off with other leg, repeating thousands of rolling lunges in one evening. It’s why the racehorse-esque gluteal muscles of male figure skaters become armchair conversation. “Maybe I should take up ice skating,” someone finally says.

Wheels.