It's important that you do a dynamic warmup before you pick up a set of dumbbells. This helps you stretch and activate your muscles at the same time, and it doesn't have to be complicated. "My favourite warmup is walking backwards," Eric said. "It raises agility, increases balance, and teaches your body a new skill to be stored away for later in your muscle memory. It also forces the hip flexor, a muscle that spends most of its life moving forward, to shoot backwards, putting your body in a state of shock."
Eric recommends a six- to 12-minute warmup (choose one or more of these dynamic exercises) to get the most out of your strength-training circuit.