Unlike normal strength-training exercises that involve contracting your muscles through a range of motion, an isometric exercise is one in which you hold your muscle in one contracted position for a given amount of time. Martial arts cinema icon Bruce Lee incorporated many isometric exercises into his routine, and much of the strength-training exercises gymnasts do are isometrics. They are great for developing core strength.
The front plank strengthens your abs, arms, back and chest. Lie down on your stomach with your legs straight and your arms bent at your sides. With your palms pressed flat against the ground, lift your body until you are supported only by your forearms and toes. Keep your legs and torso rigid and straight, and keep your shoulders directly over your elbows with your head up, rather than allowing your shoulders to hunch up to your ears. Hold the position for 30 seconds and repeat three times.
This exercise will strengthen your lower abs and glutes. It can be done on the ground or on a stability ball. Lie down on your back and bend your knees to a 45-degree angle. Press your heels firmly against the ground and lift your hips up, keeping your torso in a firm, locked position. Do not arch your back, pushing your stomach toward the ceiling, but keep it level. Hold the pose for 30 seconds and repeat it three times.
Six-Inch Leg Raise
This is a great exercise for strengthening your abs, especially your lower abs. According to Chad Zimmerman in "How Michael Became His 'Airness'," leg raises are one of the exercises that helped Michael Jordan achieve his athletic greatness. To do leg raises, lie down flat on your back with your legs straight and your arms at your side. Slowly raise your heels 6 inches off the ground, keeping your legs straight and your abs contracted. Hold the pose for 30 seconds. Repeat the lift three times. Perform leg raises twice a week.
The L-sit is a gymnastic exercise that will strengthen your abs, shoulders and triceps. It's a challenging exercise, so you may have to work your way up to it. You can do it on parallettes or on the ground. Sit down with your legs extended straight out and your back straight. Place your palms flat on the ground and lift your whole body up and keep your legs straight. If you have trouble keeping your legs straight, do it with your knees bent and your legs tucked until you get stronger. Hold the pose for 30 seconds and repeat it three times.