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Static stretching, dynamic stretching, foam rolling, TheraGun, lacrosse balls... The list goes on and on for tools that help us improve our flexibility and range of motion. Based on recent research, there is one type of exercise that should always be included in this list: Eccentric strengthening.
What is eccentric strengthening?
Eccentric strengthening is when a muscle is lengthening while under tension or load. It is commonly referred to as the “negative” phase of a lift or exercise. Let’s take a bicep curl, for example. The eccentric phase of this exercise is when the weight is being lowered in a slow and controlled manner. During the lowering phase, the bicep muscle itself is lengthening, while resisting the load of the weight in your hand. Some common examples of eccentric-focused exercises are Nordic hamstring curls or tempo squats.
What Research Tells Us
The popular thought is that if our muscles are tight, we should stretch them, right? Well, this is not always the case. Although it feels like it is tight, it may not need stretching or foam rolling to solve this problem. Often, our muscles feel chronically “tight” due to an underlying weakness or strength deficit. When we have a weak muscle, our brain tells our body to increase tone in that muscle to provide it with a mechanical advantage to keep working to the best of its ability and provide our joints with additional stability. Does this mean stretching, foam rolling, or using a lacrosse ball or Theragun are a waste of time? Absolutely not! These methods can be very beneficial for pain relief and short-term improvements in flexibility. However, recent research has shown that eccentric strengthening not only increases joint range of motion and muscle fascicle length, but also has longer lasting effects [1]. There are also many other benefits to eccentric strengthening from a rehabilitation or injury prevention standpoint including pain relief, improving force production, and increasing power output, thus decreasing our risk for injury [2].
Most people assume that strengthening will further tighten their muscles. This train of thought is a common misconception. Strengthening the muscle will actually help improve the muscle’s ability to control movements through the full range of motion, resulting in less sensations of “tightness”. One study that has been performed on eccentric loading helps demonstrate this concept. The study looked at individuals with Achilles tendinopathy and split them into two groups: an eccentric exercise group and a control group. The eccentric exercise group was given a 6-week eccentric strengthening program for the calf muscles, while the control group did not perform any training at all. At the end of the 6-week program, the eccentric exercise group demonstrated improved ankle ROM and decreased passive resistive torque of the calf muscles. They also found that the stiffness of the Achilles tendon did not change with the addition of the eccentric strengthening program. The results of this study tell us that eccentric strengthening results in change of some mechanical properties of our muscles necessary for improving range of motion and flexibility, but, contrary to popular belief, does not increase stiffness [3].
Eccentric strengthening has been widely used in the rehab setting for many injuries, including overuse injuries and tendinopathies. Research tells us that eccentric training requires the lowest cost of energy production compared to other muscle contractions. It also creates the highest force production. A low-cost, high force producing exercise that also improves our flexibility, range of motion, power output, and reduces our risk for future injury? We would be severely amiss to not incorporate this into our programming. If you are one of those individuals that has been stretching and foam rolling every day with little improvement, try to incorporate strengthening, specifically eccentric training, to your program. Give it a try consistently for about 6 weeks and see if you notice the changes in your flexibility that you have been looking for!
If you need help adding in eccentric based activities, feel free to contact us at Precision Performance and Physical Therapy!
Resources:
1. Diong J, Carden PC, O'Sullivan K, Sherrington C, Reed DS. Eccentric exercise improves joint flexibility in adults: A systematic review update and meta-analysis. Musculoskelet Sci Pract. 2022 Aug;60:102556. doi: 10.1016/j.msksp.2022.102556. Epub 2022 Mar 25. PMID: 35390669.
2. O'Sullivan K, McAuliffe S, Deburca N. The effects of eccentric training on lower limb flexibility: a systematic review. Br J Sports Med. 2012 Sep;46(12):838-45. doi: 10.1136/bjsports-2011-090835. Epub 2012 Apr 20. PMID: 22522590.
3. Mahieu NN, McNair P, Cools A, D'Haen C, Vandermeulen K, Witvrouw E. Effect of eccentric training on the plantar flexor muscle-tendon tissue properties. Med Sci Sports Exerc. 2008 Jan;40(1):117-23. doi: 10.1249/mss.0b013e3181599254. PMID: 18091014.