Sandbag exercise for metabolic conditioning

Like a medicine ball, a sandbag helps improve the strength of both muscle and elastic connective tissues because you can move a sandbag in multiple directions as opposed to moving in only a single, linear path of motion. Additional benefits of sandbags include a pliable surface that helps develop grip strength and, unlike medicine balls, it won't roll away from you when you set it down. Select a weight that is approximately 5 to 7 percent of your body weight when starting a circuit. As you get stronger, you can gradually progress to ones that weigh 10 to 15 percent of your body weight.

"Your goal is to complete AMRAP during the work interval," says Pete McCall, author of Smarter Workouts. "As you feel yourself getting stronger, keep track of the number of reps you do during your first time through the circuit, and then try to meet or beat that number each additional time you do the exercise."