Small, quick jumps on the balls of the feet with almost straight legs. They make the ankles and Achilles tendons stiffer and springier, which makes every running step cheaper.
Dose
3 × 20 jumps
Rest
60 s
How to do it
Stand tall with the feet hip-width apart and the knees almost straight.
Bounce up and down using only the ankles, spending as little time on the ground as you can.
Keep the heels just off the ground and the arms relaxed or swinging lightly.