Eccentric Training

Eccentric training focuses on the lowering phase of a lift or exercise. It is widely used for prevention and the rehabilitation of muscle and tendon injuries. In terms of strength and conditioning, eccentric training is very exciting because eccentric training can produce bigger gains when measured against concentric training (1). For the record concentric training focuses on the upwards phase of the lift. 

The Basics of Eccentric Training

During the lowering phase (eccentric) of the lift the main muscles lengthen. Conversely, when you lift a weight upwards (concentric), the main muscles shorten.

The key principle to understand is that eccentric activation generates greater muscle force and allows muscle to resist a greater load. For example, you are 20-25% stronger during the eccentric phase of lift (1). This means that if you can squat 100kgs, then you can slowly lower the squat at 120-125kgs (with a spotter). For muscles to grow they need to be fully stressed and this happens during eccentric training. This causes micro-tears within the muscle tissue, these need repairing i.e. with a high protein and ample rest, and then new muscle tissue is created.  The greater the load the muscle endures, the greater the microdamage it sustains, and the greater its growth response.

 

The exact mechanism behind eccentric contraction greater force generation is poorly understood. Some authors believe muscle fibers contain “rubber band” like proteins that are only activated when they are stretched to their maximum length and in turn these “rubber bands” provide additional resistance and force generation capability.

 

Increase in Strength

The eccentric and concentric phases are different in how they create muscular force. There is less energy used during eccentric training. This means that you can exercise for longer periods during eccentric training without becoming fatigued. A study has shown that untrained males could perform an average of 5 concentric reps @ 90% 1RM (concentric) and an average of 8 eccentric reps @ 90% 1RM (eccentric) (1). These results indicated that we are more energy efficient during the eccentric phase, and we can pump more reps out at the same 1RM (same for both training methods). Basically, we can train harder with more weight, for longer periods of time and this improves your strength.

In addition, it has been shown that for optimal strength gains, a training program should use different resistances on the upwards and downwards phases. In terms of bicep curls, a study determined that for 3 sets of 10 reps; the optimum weight is 75% of 1RM on the upwards curl and 100% 1RM on the downwards curl when using a weights machine (4).

Increase in Hypertrophy (Size)

Muscle hypertrophy means increasing the size of the muscle. Numerous studies have compared eccentric and concentric training to determine their impacts on muscle hypertrophy and strength. One study used a combination of leg and knee extensions. It discovered that muscle contractions during the eccentric phase vastly increased muscle hypertrophy (3). Additionally, another study focused on the different speeds of the bicep curl and how the muscle contractions impacted its overall growth and development (4). The participants who lowered the weight to 180 degrees per seconds had bigger muscle gains and an increase in overall strength. The eccentric phase of this study lasted for 1 second, and this quick explosive bicep curl induced muscle growth and development.

 

Musculoskeletal Health Benefits of Eccentric Resistance Training

 

1. Promotes tendon health and accelerates tendon healing

The exact mechanisms as to why eccentric training seems to optimize the rehabilitation of  injured tendons are not completely understood. Some researchers suggest that eccentric exercises expose tendons to a greater load than concentric exercises and therefore induce a greater healing signal. Another possible mechanism is that eccentric loading generates high-frequency oscillations in the tendon that is an effective stimulus for the remodeling of scar tissue. Additionally, eccentric tendon activation may “choke off” newly formed blood vessels in the injured tendon. These new blood vessels have been associated with increased inflammation, pain, and tendon non-healing.

Swedish investigators examined the effect of eccentric training in chronic painful impingement syndrome of the shoulder.  The authors completed the in 9 subjects that were on the waiting list for surgery. All subjects had to perform painful eccentric training for the supraspinatus and deltoid muscles for 12 wk, 7 d a week, 3 sets of 15 repetitions, twice a day. Afterthis period of training and at 52-wk follow-up, 5 out of 9 subjects were satisfied with the result of the treatmentand withdrew from the waiting list for surgical treatment.(Jonsson P et al. Eccentric training in chronic painful impingement syndrome of the shoulder: results of a pilot study. Knee Surg Sports Traumatol Arthrosc. 2006 Jan;14(1):76-81.)

2. Protects Against Sarcopenia

Sarcopenia is a clinical condition described as a state of chronic muscle loss and strength reduction. Sarcopenia is associated with restricted function, disability, lack of independence, social isolation, and death. Eccentric resistance exercise has been shown to counteract sarcopenia by promoting muscle growth, increased strength, and improved idependent function.

Spanish researchers performed a systematic review of the scientific literature examining the role of eccentric exercise as preventive tool against sarcopenia. The authors concluded Eccentric training is an option to reduce and prevent sarcopenia. It decreases risk of falling, and improves mobility and quality of life. (Vásquez-Morales A et al. Eccentric exercise as preventive physical option in people over 65 years: a systematic review of the scientific literature. Enferm Clin. 2013 Mar-Apr;23(2):48-55.)

3.  Promotes New Bone Growth

During resistance training the force generated at the area where muscle attaches to bone induces a pro bone growth stimulus that promotes new bone formation. This mechanism helps bone resist the stresses created at the bone-muscle interface. Additionally, adjacent areas experience an increase in bone mineral density, and a decrease bone resorption .

Researchers from Maryland reviewed the effect of weighted exercises on bone mineral density in post menopausal women. The authors concluded a resistance training program of moderate to high intensity (70 to 90% of one maximum repetition-1RM), including 3 to 4 bouts of 8 to 12 repetitions of each exercise, performed 2 or 3 times a week, is able to maintain or improve the BMD of hip and femur in postmenopausal women when performed over one year duration (Zehnacker CH et al. Effect of weighted exercises on bone mineral density in post menopausal women. A systematic review. J Geriatr Phys Ther. 2007;30(2):79-88.)

4. Counteracts Symptoms of  Osteoarthritis

Muscle strengthening through resistance exercise increases physical function, decreases pain and reduces self-reported disability. Resistance training helps correct abnormal muscle firing patterns that contribute to joint deterioration, promotes the release of natural pain killers, and reduces local low grade inflammation.

Turkish researchers examined the effects of eccentric resistance training on functional capacity and symptoms in patients with osteoarthrosis of the knee. The investigators found concentric training showed marked decreases in pain scores, increased functional capacity, and increased cross sectional areas of knee muscles. (Gür H et al. Concentric versus combined concentric-eccentric isokinetic training: effects on functional capacity and symptoms in patients with osteoarthrosis of the knee. Arch Phys Med Rehabil. 2002 Mar;83(3):308-16.)

5. Decreases Belly Fat

Belly fat is an important risk factor for low grade inflammation. Low grade inflammation is associated with chronic musculoskeletal diseases such as osteoarthritis, osteoporosis, and sarcopenia(muscle loss). Additionally, unwanted belly fat overloads lower extremity joints accelerating their degeneration.

Researchers at TCU examined the influence of moderate- to high-intensity resistance training on inflammatory markers in elderly women. The investigators concluded that hat 10 wk of moderate- to high-intensity resistance training reduced the systemic inflammatory milieu. (Phillips MD et al. Resistance training at eight repetition maximum reduces the inflammatory milieu in elderlywomen. Med Sci Sports Exerc. 2010 Feb;42(2):314-25. )

6. Promotes Healthy Blood Sugar Levels

Skeletal muscle is the primary site for glucose storage. Resistance training improves muscle uptake and storage of glucose.  In the absence of adequate glucose muscle storage,  excessive free sugar reacts with vital structures in joints and bones altering their structure and biomechanical properties. This leads to premature aging and dysfunction.

Australian investigators systematically reviewed the effect of resistance training on glycemic control and insulin sensitivity in adults with type 2 diabetes. The researchers reported clinically relevant reductions in glycosylated haemoglobin, a marker of blood glucose control. (Gordon BA et al. Resistance training improves metabolic health in type 2 diabetes: a systematic review. Diabetes Res Clin Pract. 2009 Feb;83(2):157-75. )

7. Boosts Mitochondrial Health

Mitochondria are the power generates of  the cell and play a key role in cell vitality. Mitochondrial dysfunction has been linked to multiple chronic musculoskeletal diseases including: osteoporosis, osteoarthritis, and sarcopenia.  Research suggests resistance exercise has the power to improve mitochondrial function and stimulate mitochondrial production.

Researchers in Florida examined the influence of resistance training on markers of mitochondrial health. The investigators found resistance increased mitochondrial content and enzyme activity. (Sparks LM et al. Nine months of combined training improves ex vivo skeletal muscle metabolism in individuals with type 2 diabetes. J Clin Endocrinol Metab. 2013 Apr;98(4):1694-702.)

 

Introduce Eccentric Training into your Regime

1. Add to the end of a set

Using the same resistance, and focus on lowering the weight slowly and under control. Aim for between 3-5 seconds and use a spotter.

2. Overload

Use a weight about 10% higher than your 1RM. The majority of 1RM tests only focus on the upwards part of the lift. Focus on negative reps, after you have warmed up, control the weight downwards for between 4-8 reps. Have a spotter to help you to lift the weight upwards.

3. Strict Form

Use very strict form when lowering the weights, as this prevents injuries and ensures the proper mechanics. You can also perform bodyweight eccentric exercises e.g. push ups by lowering and holding yourself in position for 2-5 seconds and then pushing your bodyweight back to the starting position.

4. Varying the Limbs

Use both limbs when you lift the weight, and use only one limb to lower the weight. For example when using the knee extension machine, use both legs to lift and then change to one leg to lower. Always remember to alternate both legs and to train your weaker muscles by using this strategy. You will start to see some quicker pay back, and controlling the weight downwards is better than relying on gravity to do all of the work for you.

References

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Blazevich, A. J., Cannavan, D., Coleman, D. R., & Horne, S. (2007). Influence of concentric and eccentric resistance training on architectural adaptation in human quadriceps muscles. Journal of Applied Physiology, 103(5), 1565-1575

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