Domino is a cardio workout built on chain reactions: every big block of movement tips over into a small, explosive one, and the small one knocks the set forward again. High knees, scissor chops and jumping lunges are the tiles - 20-rep runs of continuous movement, each toppling into a 2-rep burst of jumping lunges before the next run begins. Once the first tile falls, the set carries itself.

The circuit runs without rest between exercises, and the ratio is what makes the design click. The 20-rep blocks are momentum: high knees keep the legs cycling and the heart rate up, while scissor chops sweep the arms horizontally across the chest, loading the shoulders and upper back without breaking the rhythm below. The 2 jumping lunges wedged between every pair of blocks are the falling tile - a maximal, coordinated explosion demanded from legs that are mid-flow, not fresh. Three times per set, the workout asks you to convert steady-state motion into instant power and back again, and that conversion - smooth to explosive, explosive to smooth - is precisely the quality the domino structure trains.

Drive knees to hip height with quick, light feet on high knees. Keep scissor chops at shoulder height with long arms, crossing and opening in full sweeps - the movement comes from the shoulders, not the elbows. On jumping lunges, switch legs in the air and land soft with the front knee tracking over the foot; two reps means two perfect ones.

One tile tips, the whole line goes. All you ever had to do was start the first rep.

Make it Harder: Double every jumping lunge block to 4 reps.

Make it Easier: Swap jumping lunges for alternating reverse lunges and march the high knees.