Not all exercises involve repetitively hoisting weights, pushing and pulling or otherwise flailing your limbs. Isometric exercise is a way of putting muscles under tension without changing their length as you would with most other types of exercises.
Most of the exercises we do, such as weight lifting, push-ups and crunches, are isotonic, involving limb or trunk movements that cause the muscle to lengthen or shorten. Isometric exercise, by contrast, puts muscles in a state of contraction without repetitive movement by pitting them against each other or forcing them to work against gravity -- such as assuming a sitting-position against a wall.
While they're not the fast track to building chest muscle, isometric chest exercises will strengthen your pectorals. You can also use them to top off a workout with weights to squeeze out a little more muscle activation even after you can't lift anymore.
Isometrics are usually performed by holding a joint or muscle in a set position for six to eight seconds, doing five to 10 sets. With consistency, you may see noticeable results in six to eight weeks.
The isometric chest press can be done sitting or standing. Begin by pressing your hands in front of your chest in a prayer position. Keep your elbows at 90-degree angles. Apply as much pressure between your palms as you can generate. Hold for five seconds, then relax for 5 to 10 seconds. Do five reps, working your way up to holding the position for up to 15 seconds.
Standing in a doorway, place your hands at about chest level against either side of the door frame. Exert outward pressure as if you're trying to push the sides of the door frame farther apart. Use the pressure to pull your chest slightly forward into the doorway. Hold for 15 seconds then gently release. Rest for 30 seconds and repeat. Aim for five reps.
Place your hands against a wall at shoulder height with your body leaning inward at a slight hang. Your feet should be firmly planted into the floor. Gripping shoe soles may be necessary to avoid sliding. Apply pressure through your arms, chest and hands as if you are trying to push the wall away, pulling your shoulder blades down as you press. To make the exercise more challenging, lower your hands to near waist level.
To perform an isometric push-up, start out as you would with a normal push-up. When lowering your body, stop the motion half-way and hold rather than lowering yourself all the way down. Hold the position for a count of 10 or 15 seconds and release. You can activate different parts of your chest muscles by varying both the width of your hands and the point in your descent at which you freeze the motion.
One of the benefits of isometrics is that we spend much of our daily life in positions that require extended low-level isometric muscle activity -- standing in line, for example -- so isometrics reinforce our strength in ways that are important to general stamina. Another great thing about them is that they don't require equipment and you can do them anywhere -- even in confined spaces, such as a cubicle at work, They are also frequently recommended by physical therapists for people whose range of motion may be limited by arthritis or injury.