"this is my oc, Placeholder. he's a superhero, a speedster.
he has two abilities:

1. Super speed. Placeholder can run in short bursts at a maximum speed of 1400 mph (2253.08 kph), this is mostly meant for combat, dodging attacks, travelling short distances, etc, as moving this fast is not sustainable and will cause discomfort.
Alternatively, Placeholder can run long distances at 600-800 mph (965.60-1287.47 kph).

2. Scale healing. Placeholder's body heals differently than the average person. when he's not moving, his body cannot heal at all, whether that be from his natural healing factor, medication, or other. however when moving his healing will scale with how fast he is moving/how fast his heart is beating. the faster he is moving, the faster and more effective his self-healing becomes. any injury sustained will be healed perfectly."