You don't always have to jump around doing cardio to burn major calories. Strength training builds metabolism-boosting muscle and burns even more calories [1] after your workout as your body recovers and repairs itself. This workout from trainer Autumn Calabrese [2] builds on this principal by adding isometric holds to strength-training moves. And it's challenging but quiet. So grab a pair of weights and get ready to build muscles in a whole new way (without disturbing your downstairs neighbors).

On Anna: Eden Activewear [3] tights & sports bra
On Autumn: Lorna Jane [4] tank