Start in a lunge - one leg back, back knee hovering above the floor, fists up. Drive through your front heel and rise all the way up onto that leg, swinging your back knee through and up to hip height in front of you, arms switching in running rhythm. Balance for a beat on one leg at the top, then step the raised leg back down into the lunge and go again. Finish the set, then switch sides: it's a lunge and a knee drive welded into one rep.

Works: quads, glutes, hamstrings, hip flexors, core

Breathing: Exhale as you drive up to the knee raise, inhale as you step back into the lunge.

Common Mistakes: Pushing off the back toes instead of the front heel, skipping the balance moment at the top, and letting the torso pitch forward through the drive.

Make Easier: Bring the back foot to a tap beside the standing leg instead of driving the knee high, and use a wall for balance - or build up with Lunges.

Make Harder: Add a hop at the top of the knee drive, or move on to Jumping Lunges or High Knees.