[Elizabeth Criner is a senior at NC State, currently working towards her bachelor’s degree in sport management while also minoring in business administration, business entrepreneurship, and psychology. She is currently participating in the Athletic Lab Internship Program.]
While exercising, your muscles go through different types of contractions. Contractions are when the muscles either shorten or lengthen. These contractions can be categorized into two overarching categories: isometric and isotonic. Isotonic contractions consist of two individual types: concentric and eccentric. Concentric contractions are when the tension in the muscle increases and the fibers shorten and contract. While isometric contractions are when you are making sure the angle of your joints do not change during the exercise, and the muscle does not shorten or lengthen. The final contraction is eccentric. This is when your muscles are lengthened. All of these contraction types can be useful when working out, and all can provide you with their own individual benefits.
The middle ground for the three contraction categories would be isometric. This is because unlike concentric or eccentric contractions, the muscles are neither lengthening nor shortening. Isometric movements are when you hold a key position with little to no movement happening at all. These movements help generate force without changing the length of the muscles. They are exercises in which you stay in one position without movement, so this means strength will be improved in only one specific area. Some examples of isometric exercises include; handstand holds, holding a wall sit, hollow body hold, side bridge, holding at the top of a pull up, front rack kettlebell hold, and high plank. If you want to use isometric exercises to help strengthen your body, you will have to use multiple exercises to hit all of the particular muscles you are trying to work on. One of the biggest benefits to isometric exercises is what it can do for your core. When performing these exercises, you must remain very still, which requires you to brace your core. This helps engage many muscles in your core and makes them work harder than they normally would. Isometrics also can be very helpful when working on body control and balance. Another benefit to isometric exercises is what they can provide for someone who has an injury, where movement could be too painful. Since you are not lengthening or shortening a muscle, you can use isometrics to help contract a muscle while working around the surgical incision or scar tissue. This also means that your muscles can be strengthened in a very specific range of motion around a specific joint (Moore, 2020). Sitting at the bottom of a squat with a weighted barbell on your back serves as an example. When squatting, many people struggle at the very bottom of the squat. By using and practicing this isometric holds, it can help to develop the strength needed to stand back up with the weight when performing squats. Almost any exercise or movement can have an isometric portion to it by simply adding a pause in the middle of the movement being performed. One example of an exercise that uses isometric, eccentric, and concentric movements is the bicep curl. If curling the biceps to 90 degrees, so that the forearm becomes parallel to the floor, when you hold the weight in that position for ten seconds, it is isometric training (Kassel, 2019). This can be beneficial because you are forced to engage your bicep muscles, so in turn they are getting stronger. When working out, you cannot only use isometrics and expect to get stronger. However, they are great for individuals trying to improve mobility or break through a strength plateau (Kassel, 2019.)
Eccentric contractions can be the most damaging movements to your muscles, because you are lengthening them. But this does not mean they are bad for your body. You have to create microtears in the muscles, so that your body can repair and build stronger muscles than before (Moore, 2020). During this process, muscles absorb energy developed by an external load, which is why eccentric contractions are also called “negative work” (Hody et al., 2019). Eccentric contractions put more of a demand on your muscles and nervous systems than the other contractions, which leads to recovery time being longer (Moore, 2020). An example of an eccentric movement would be when lowering from a pull-up bar as slowly as possible. This is an eccentric movement because when you are lowering your body from the pull-up bar, you are slowly lengthening the muscles in your arms. “On average you can lift 30-40 percent more weight eccentrically than you can concentrically” (Lin, 2017). Let’s go back to the pull up bar example. A concentric contraction is made during the upward motion of the pull up, which is usually the hardest part for an athlete, because you are pulling up your entire bodyweight. The eccentric contraction of a pull up is the portion when you are slowly lowering your body back to the ground. Some people might not be able to do the concentric pull up, but if you can jump up to the top of a pull up or use a box to get there, most people will be able to slowly lower themselves down and still get a good exercise in. Some examples of eccentric exercises include lowering the barbell toward your chest in a bench press, lowering into a parallel position in a squat, bringing the barbell back to the ground during a deadlift, lowering your body back to the ground during a sit up, and lowering into the bottom of a pushup (Bortenschlager, 2020). The downside to eccentric movements is that they cause the most damage to muscle fibers and are one of the big reasons why many people experience DOMS, which is delayed onset muscle soreness (Hody et al., 2019).
Concentric is the exact opposite of eccentric contractions, because the muscles are shortening instead of lengthening. If eccentric movements are called “negative work,” that means concentric movements are considered “positive work.” This contraction is considered positive work because you are making the body overcome gravity and either rise or accelerate. Concentric movements are when two endpoints move closer together. One of the most common concentric exercises is the bicep curl. The bicep curl can use all three types of muscle contractions, isometric, eccentric, and concentric. When doing this exercise, you are bringing the dumbbell from around hip height up to your shoulder. When the weight gets closer to the shoulder, the bicep muscle is shortening and there is much more tension in the muscle (Kassel, 2019). The eccentric movement in this exercise would be when you are lowering the weight from the shoulder height back down to hip level. Another example of a concentric movement would be the upward pull during a pull up, because the muscle is shortening as you get closer towards the pull up bar. Some examples of concentric movements would be: pushing up in a bench press, the beginning portion of a deadlift when you lift the barbell off the ground, sitting up in a sit up, pushing up from a lowered push up, and standing up in a back squat (Bortenschlager, 2020). One of the drawbacks to concentric contractions is that it can lead to wear and tear on your joints, because of the shortening process. This means it can increase your risk of injury and overuse as well. If you repeatedly perform concentric movements, you can cause yourself soreness and strain your muscles. It is important to make sure you are incorporating all contraction types into your workout so that you do not overuse individual muscles.
All of these movement types, isometric, eccentric, and concentric can create a very diverse and impactful workout. Mixing up and combining all of these different styles can help you get the most out of your daily workout. When working out in the gym, it is very common, if not inevitable, to use all three types of muscle contractions. Using all of these movements can be very beneficial, but you still need to train the movements in full. Practicing and performing the different contraction types should be how you build up to the full movement. After performing any or all of these movements, it is critical to stretch after. This will help loosen up the muscles and help reduce strain.
References
Bortenschlager, M. (2020, October 29). Concentric vs. Eccentric Exercises: How They Affect Your Muscles. 4legsfitness.com. https://4legsfitness.com/blogs/articles/concentric-vs-eccentric.
Hody, S., Croisier, J.-L., Bury, T., Rogister, B., & Leprince, P. (2019). Eccentric Muscle Contractions: Risks and Benefits. Frontiers in Physiology, 10. https://doi.org/10.3389/fphys.2019.00536
Kassel, G. (2019, November 26). What You Should Know About Eccentric, Concentric, and Isometric Exercises. Shape. https://www.shape.com/fitness/tips/eccentric-vs-concentric-isometric-exercises.
Lin, G. (2017, April 15). Muscle Contractions 101. CrossFit Central Houston. http://crossfitcentralhouston.com/blog/2017/4/15/muscle-contractions-101.
Moore, T. (2020, October 29). The 3 Categories of Exercise – Isometric, Concentric & Eccentric. Invictus Fitness. https://www.crossfitinvictus.com/blog/isometric-concentric-eccentric/.
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