This interval training workout proves that “high intensity” doesn't have to mean “high impact.” Instead, this low-impact program keeps you nearly breathless with fast, deep and wide-ranging exercises (plus lots of intensity-enhancing equipment). You'll start with traditional athletic moves like squats, lunges, pulses and lifts (done with and without dumbbells). Then Cathe adds the step platform — lifting your body up and down definitely boosts the challenge. Finally, she advances to the gliding disc section. It includes mountain climbers and non-impact “disc jacks” — moves that demand core strength and cardio endurance (they're tough!). Requires 2 to 10 lb. dumbbells, a step and gliding discs (but paper plates will work). ©2012.