The amount of things you can do with a kettlebell is unsurpassed by any other training equipment – dumbbells, resistance machines, free weights. The way they're constructed alone – with a weight and solid handle that can be swung – offers some interesting physics. They force you to control the swing, focus on balance, and marry cardio with weight training in a powerful and effective way. There's also a rhythmic element to the whole thing that does wonders for your balance and really jacks your heart rate, more than almost anything else. Plus, in 10 to 15 minutes with a kettlebell, you can tear yourself up. My advice is to use the kettlebell as part of a circuit – from weighted lunges to shoulder presses, all glued together with swings.
If you were looking for one desert-island exercise, the kettlebell swing is up there. It's a little bit like jumping rope, only with weights. Start with a lightweight bell (around 26 pounds). Take it by both hands and swing it between your legs, then up to eye level, and back between your legs. That movement is one of the single greatest muscle-building activities you can do in the gym. This isn't an upper-body exercise, though – if you're doing it right, you're working your hips (which press forward as the bell peaks), back legs, and core more than your arms. You can swing with both hands or alternate arms, switching hands in mid-swing.
Taking on the dead lift with a kettlebell is a great way to approach this common move with lower weight than you would with a barbell. Grab a 44-pound kettlebell and try to repeat dead lifts: Put the bell between your legs and, with a flat back, bent legs, and open chest, grab the bell and stand up straight, squeezing your glutes and abs. Once you build up some strength, try keeping your legs straight – but not locked – for a stiff-leg dead lift.
Doing presses with kettlebells is a great way to strengthen your upper body while also protecting your shoulders. Hold an 18-pound kettlebell in one hand, resting on your biceps with a bent elbow kept close to your body. Push up until your arm is straight above the head, controlling the weight as you lower, and repeat. Make sure you hold it in a tight grip and handle the bell so it doesn't slide or flop. This forces your shoulder to become a lot more dynamic than with a regular dumbbell. The agility your muscles develop from balancing things also makes you a lot stronger. For a seated variation that will further engage the core, get on a balance ball and do sets from there.
Adding kettlebells to lunges is an excellent way to work your legs and core. Hold an 18- to 26-pound kettlebell in each hand or try switched-hand lunges with a single bell. For these, hold the kettlebell in your left hand, step backward with your left leg, pass the kettlebell underneath to your right hand, and step forward again with your left leg. Reverse the motion and repeat for two minutes, smoothly and quickly switching the kettlebell back and forth.
Chest presses are the hardest movement the people I train have to do with the kettlebell. Here's how to do it: Take two matching kettlebells, lie on your back on a bench or balance ball (the ball makes it even harder), and hold a kettlebell in each hand like you're going to do a bench press. Now flip the bells in your hand so the weight faces the ceiling and control it there, balancing the bells as you repeatedly push the weights up and down. Take care with this move; it's definitely advanced, and you'll be surprised how hard it is to simultaneously balance each bell individually as you're pushing.