There are two types of muscle contractions: isotonic and isometric. Isotonic is a muscle contraction where the muscle changes in length. An isotonic contraction can be either eccentric (lengthening of the muscle) or concentric (shortening of the muscle). In contrast, isometric exercises are those in which you hold a position for a certain period of time. During an isometric movement, the joint angle and muscle length don’t change throughout the exercise, unlike isotonic exercises where the muscle length changes as the muscle moves through the concentric and eccentric phases.
Most of the muscle contractions people do when they strength train are isotonic. In fact, you wouldn’t want isometric movements to make up the bulk of your workout. That’s because isometric exercises enhance strength at the particular muscle angle and length you’re working. In other words, if you hold a biceps curl at the midpoint with your arms bent at a 90-degree angle, your biceps will become stronger only at that angle, not through their full range-of-motion. That’s a significant limitation. That’s why dynamic, isotonic movements that work the muscle throughout its full range-of-motion are best for building strength and size. Still, some isometric exercises are a good addition to your training routine for variety and to stimulate the muscle fibers in a different way. Let’s look at some of them.
Isometric Exercises: Planks
If you were to include only one isometric exercise in your routine, planks should be it. Unlike many isometric exercises, holding a plank position develops strength in a variety of muscle groups because you’re forced to stabilize your core. In fact, planks are one of the best exercises for core development and they’re less stressful on your back than abdominal crunches. Plus, you build strength and endurance in your shoulders, arms, and glutes when doing a standard plank. Multiple muscles get in on the action, making it a time expedient exercise.
How can you get the benefits? Although you might feel like a hero holding a plank for a couple of minutes, your time might better be spent holding one for 30 seconds to one minute using excellent form. Once you can do that, try one of the more advanced plank variations or lift one arm or leg off the floor at a time for a balance challenge. Doing this works your stabilizing muscles as well.
Don’t forget about side planks, another isometric exercise. Side planks work a muscle in your posterior abdominal wall called the quadratus lumborum that, when this muscle is strong, helps protect against back pain and injury. Once you can do a side plank, try lifting your top leg off the floor and holding it for a balance challenge. There are many plank variations you can add to your workout to challenge your body in a different way.
Isometric Exercises: Wall Sits
Wall sits primarily target the quadriceps muscles in the front of your thighs. To do this exercise, place you back against a wall with your feet roughly shoulder-width apart and your knees about an inch from the wall. Now, lower your hips with your back still against the wall until your knees are at a right angle. Hold this position for 30 seconds and gradually work up to a minute. Although this is a good exercise for building quad endurance and strength at the angle you’re working them, it can be stressful on the knees. So, don’t do this exercise if you have knee issues. Although it’s normal to have some burning and fatigue when you hold a wall sit to fatigue, stop if you feel significant pain.
Isometric Exercises: Supermans
Supermans are an isometric exercise that you do on a mat on the floor. It’s named after, who else, Superman, and the way he looks when he flies through the air. Now, you can be Superman too! To do this exercise, lie face down on a mat and extend your arms out in front of you. Once in this position, lift your arms and legs off the mat to form a “U” and hold the position isometrically for 3 to 5 seconds before releasing. Supermans are a good exercise for strengthening your lower back and glutes. If you do crunches to work your abs, flip over and do a Superman for every set of crunches you do. This will help you avoid strength imbalances.
Isometric Exercises: Pauses
One of the easiest ways to add some isometric action to your routine is to include pauses during some sets. When you’re doing standard exercises, such as biceps curls or squats, pause and hold the position at the bottom of the movement for a few seconds. By doing this, you keep the muscles under tension longer. It also adds a whole, new level of challenge!
Isometric Exercises: Isometric Push-ups
This is a variation on the pause theme. To do an isometric push-up, get into standard push-up position. Lower your body toward the floor until your chest almost touches the ground. Now, hold this position for as long as you can. This move is a real arm scorcher! Repeat a few more times.
The Bottom Line
Isometrics offer benefits, but also some disadvantages. As mentioned, you’re not building strength through the full range-of-motion of a muscle. Secondly, strength gains will be limited if you’re only using your own body weight. Also, you restrict blood flow during isometric movements and this can cause a spike in blood pressure. So, use them judiciously in your routine and don’t do them without consulting your physician if you have hypertension or heart disease.
One of the big advantages of isometric exercises is you can do them when you don’t have equipment. If you’re on vacation, combine isometrics with bodyweight exercises to get a workout. You can also intersperse isometric exercises into your standard routine for variety. Enjoy challenging your muscles in a new way with isometrics!
References:
CoachMag.co.uk. “Side Plank: The Best Abs Move You’re (Probably) Not Doing”
J Sports Sci. 2005 Aug;23(8):817-24.
Scand J Rehabil Med. 11 (1): 33–6.
Journal of Sports Sciences, 23(8), 817-824. (2005)
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