Jump for Joy
A jump squat is excactly as it sounds. Start in a squat position, knees bent and thighs parallel to the floor. It helps to start with your arms folded out in front of you, for balance and stability. Jump up as high as you can toward the ceiling, and throw your hands up as though you are going to touch the ceiling. Some trainers suggest doing these as long as you can, stopping only when you can do no more. Work out the best system for yourself, whether all-or-nothing or in a series of low-volume reps.
Thighs and Butts and Calves, Oh My!
This exercise is ideal for the quadriceps (muscles in the front of the thigh), hamstrings (those behind the thigh), buttocks, gluteus maximum and the calves. Be careful to do this exercise in concert with others that work the same and surrounding sets of muscles, and to properly stretch the muscle groups during warm up. Quick snapping of inflexible muscles, tendons and ligaments can cause pain during and following a workout, and such pain is not a necessary condition of a good workout, as many like to think. Tension tells you you're doing something right; outright sharp pain tells you that you need to change your activity.
Modify the Exercise
You can do this exercise with dumbbells in each hand, which, of course, adds to your ability to achieve greater muscle tone and definition. The added weight is beneficial to the muscle groups affected by the jump squats. With the dumbbells in each hand, start from a typical crouching squat position, thighs parallel to the floor. Keep your arms straight down on either side of you throughout this exercise. When ready, jump straight up with as much explosive force as you can muster. At the apex of your jump, tuck your knees up toward your chest as much as you can, then bring your legs back down as you get ready for contact with the ground. Repeat for as many reps as you can.
Any time you do an exercise that takes you off the ground or in some way has the potential for you to be off balance when weights are involved, it's always safe and wise to have someone spot you. In this case, have the person stand behind you and watch for correct form. Of course, the spotter should also be ready to steady you, should you land off balance.
Watch Out for Your Spine
Your spine can only take so much pressure and tension before it is unable to function adequately. With jump squats, especially if you do the modified version with dumbbells, remember to keep your legs flexible and to bend at the knees when you make contact with the floor.