Maybe you noticed all those people wearing a weighted vest posting their Murph Challenge this past Memorial Day. Maybe you've seen trainers wearing the vest, which looks a little bit like battle armor. Either way, it's easy to write off this training tool as something that takes things a bit too far. But they're actually an effective and relatively simple way to boost most bodyweight exercises.

The additional load makes your moves more effective without altering your form—which is why they're so popular in cross-training. When it comes to exercises like squats or box jumps, the vest is key to building strength and explosive power.

As for cardio training, comparative studies suggest training with the added resistance can improve both your speed and oxygen consumption. To put it another way, since the vest's weight load is directly on your shoulders and upper body, it instantly engages your respiratory muscles. Nothing revs your heart rate faster than wearing all this weight while climbing on a treadmill or running stairs. Which means you get an added boost in calorie burn and a bump in metabolism without having to go quite as hard.

So if you're looking to switch up your workouts and get more from your movements, leave the dumbbells on the rack. For general fitness and toning, go with leaner and lighter vests in the 10 to 20 pound range. For muscle building, you'll want an adjustable model that allows you to add or remove bricks to dial in the weight you want. Then start supercharging your planks, push-ups and pull-ups.