A curved treadmill uses a concave slatted deck powered by the runner rather than electricity. Pushing through the balls of the feet moves the belt, so speed is controlled by effort and there is no motor-imposed top speed.
The design can engage the glutes and hamstrings early, suit high-intensity intervals and provide a grippy surface that may reduce impact compared with hard outdoor ground. Start conservatively: the self-powered deck can feel more demanding than a motorised treadmill.