Red Alert is a cardio circuit that sounds the klaxon and keeps it blaring: 10 high knees, 10 punches, 10 high knees, 10 punches, 6 jumping lunges, 10 punches, 10 high knees. All hands to stations - the whole thing is designed to spike your heart rate fast and hold it there.

The structure alternates between legs-driven cardio and upper body striking so your heart never gets a quiet moment. High knees and punches trade off in rapid succession, shifting the demand between lower and upper body while your cardiovascular system pays for both. Right at the center of the circuit - where an emergency drill would place its hardest test - sit the 6 jumping lunges, the most explosive movement here and the one that hits when you are already breathing hard. Landing from a jump into a lunge demands control under fatigue, which is exactly what any alert condition trains for: performing precisely when everything is loud.

Drive your knees to hip height on high knees and stay light on the balls of your feet - the ground is lava, not a mattress. Punch from a guard with your hands returning to your face after every extension, rotating through the hips so the shoulders don't do all the work alone. In jumping lunges, land soft with your front knee tracking over your toes, absorb the landing through a full lunge, then switch. Six reps is few enough to make every landing count.

Shields up, heart rate to maximum. You can stand down when the set is done.

Make it Harder: Double the jumping lunges to 12.

Make it Easier: Swap jumping lunges for alternating stepping lunges at the same fast pace.