A challenging interval program with a unique blend of pure cardio, cardio/core and pure core exercises. It's all exceptionally well-cued and well-designed (with natural transitions and effective sequencing). Most intervals are classic Cathe-style fat-burning — high-intensity plyometrics like air jacks, lateral jumps and squat jumps. But some of Cathe's aerobic sections also integrate fast-paced ab toning (e.g. mountain climbers and squat thrusts that really work your core). The pure core intervals only last a couple minutes, but they're tough too (e.g one-leg push-ups and “triangle choke holds”). ©2009.