Eccentric is a type of training that is defined as a muscle contraction that occurs when the muscle lengthens and is the opposite of the concentric contraction which occurs when the muscle shortens. An easy example of this would be the biceps curl movement when the bar or dumbbell is being lowered down after full flexion of the elbow, as the elbow extends the lifter should lower it slowly and this will be an eccentric contraction of the biceps. In general there are three phases of movement that are involved with muscle and tendon contraction:
Isometric (no movement)
p style="text-align: justify;"Eccentric training is when training concentrates on this lengthening stage, this challenged the muscles in a different way the concentric training does, and it has the potential to lead to more hypertrophic changes, faster muscle repair and an increase in metabolism. The eccentric phase is in general a braking stage of muscle contraction that protects joints, ligaments and tendons from damage after the concentric contraction, it has been touted to be good for nearly everyone from novice’s to experienced athletes and those who need to rehabilitate from injury. Many name this training as “negative training” or doing “negatives”, when the weight lifted is over the force developed by the muscle then the muscle absorbs this weight lowering the weight away from the concentric contraction of that muscles trajectory, this means that an eccentric contraction uses less energy but the force required to maintain the contraction is actually greater than that of a concentric contraction.
A small history of eccentric contractions, in 1882 a man named Adolf Fick discovered that contraction of the muscle whilst it is under stretch can produce more force than the shortening contraction of the muscle. This was followed up by half a century later by A.V. Hill that made the assumption that eccentric contraction of the muscle has lower energy demands than that of the concentric contractions. By the time 1953 came around Erling Asmussen introduced eccentric training but with the name “excentric” training, which if broken down means:
- Ex = away
- Centric = centre
So basically a term to explain the movement itself, away from the centre of the muscle, the true benefits of this form of training was not realised until a demonstration took place by Bud Abbott, Brenda Bigland, and Murdoch Ritchie. This demonstration used ergometers and cyclists with the ergometers placed back to back on a single chain, when one of cyclists peddled forward the other had to peddle backwards which would brake the forward movement on the peddles. The internal force within the device was low but it showed that the cyclists that was going against the forward force found it much easier, and that the force produced during the braking movement was much easier to produce than the forward movement.
So what does this all mean for those involved with exercise?
Eccentric Stress as a Superior Stimulus for Strength Improvements
Well to start it means that the negative part of the rep is responsible for greater strength gains than trying to overcome the force as with the concentric part of the rep. research has been conducted proving that training with a programme designed purely with eccentric movements in mind increased strength more so than a programme with only concentric movements, both programmes following a 6 week protocol. This study was in relation to maximal strength which is a sum or concentric, isometric and eccentric movements, and in those parameters it showed that the eccentric movement increased maximal strength by 85% whilst the concentric only increased strength by 78%. A separate study by Higbie et al. (1996) showed that there was an improvement of 43% of combined strength (both concentric & eccentric) when training is carried out using an eccentric programme and when a concentric programme is used a 31.3% increase is noted. One of the conclusions from a study by Hilliard-Robertson stated that:
“A resistance training protocol which includes eccentric as well as concentric exercise, particularly when the eccentric is emphasized, appears to result in greater strength gains than concentric exercise alone."
Earlier studies backed this conclusion such as Komi and Burskirk (1972) who showed larger strength increases after following an eccentric training regime against a concentric only training regime. Again backed by yet another study by Dudley at al. (1991) which showed that strength gains are seriously damaged by those who do not train utilising the eccentric part of the rep.
Not only is eccentric training a great way to boost strength but it has been shown to be an excellent method at increasing muscle growth. The Dudley et al. (1991) study discovered that those who trained using eccentric movements only showed an increase of 6.6% muscle size gain after 10 weeks compared with only 5% gains from a concentric programme alone, this difference could be a difference between a bodybuilder winning a show and a bodybuilder losing out, Farthing and Cilibeck (2003) discovered that eccentric training causes more hypertrophic changes than concentric training, LaStayo et al. (2003) found that that an accentuated eccentric programme could increase muscle hypertrophy by 19% compared to a classic training programme.
Eccentric training is therefore great at stimulating muscles strength and muscle hypertrophy, the methods it does this is by first of all increasing neural activity within the muscle, this is particularly important for those just starting out in lifting, as the neural improvements in muscle is the foundation of strength and contraction of muscle, it is also the reason why beginners get rapid strength increases. As eccentric loads allow for a greater weight or resistance it produces more maximal overload of the muscle which in general leads to greater adaptations within the muscle tissue.
Linnamo et al. (2002) found that eccentric training causes higher amounts of stress to be put through specific motor units, where in concentric contraction greater numbers are recruited, eccentric uses less and therefore brings on greater stimulation, this was backed by Grabiner & Owings (2002. It is known that the nervous system recruits less motor units during maximal contraction therefore it would be an easy link to assume that eccentric exercise would improve maximal contraction more so that concentric.
A big one would be the research done by Nardone et al. (1989), Hortobagyi et al. (1996) and Howell et al. (1995) who found that maximal eccentric contractions recruits more fast-twitch fibres which as you know are responsive to strengthening and hypertrophy of muscular tissue, it is also purported that eccentric training may lead to a faster twitch muscle fibre profile in evolution. The small tears that occur to our muscles during exercise occur during the eccentric phase of training, these tears are what are purported to be the main reason for muscle adaptation according to Clarke & Feedback, (1996). Eccentric training doesn’t just yield the positive effects as mentioned above, there is a multitude of other great reasons to get yourself training using eccentric lifts, there appears to be a greater cross-education system through the nervous system when utilising eccentric lifts, this means that those who train eccentrically get greater benefits on both sides of their bodies even if only one side is working this is due to neural activity, this is obviously beneficial if one limb is injured and/or immobilized. Again on the rehabilitation side of things eccentric training has been shown to be a more effective way of treating tendonitis than when it is treated using concentric only exercises. It has also been found by Collinder and Tesch (1992) that the gains made through eccentric training remain longer and are maintained better even without training compared with those concentrating on concentric movements alone, this is backed up by Housh et al (1996).
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References & Bibliography
Bahr, Roald, Fossan, Bjorn, Loken, Sverre, and Engebretsen, Lars, Surgical Treatment Compared with Eccentric Training for Patellar Tendinopathy (Jumpers Knee) A Randomized Controlled Trial, The Journal of Bone and Joint Surgery, Volume 88A, Number 8. August 2006.
Brown SJ., Child RB., Day SH., Donnelly AE., Indices of skeletal muscle damage and connective tissue breakdown following eccentric muscle contractions. Eur J Appl Physiol 75. 1997.
Clarke MS., Feeback DL., Mechanical load induces sarcoplasmic wounding and FGF release in differentiated human skeletal muscle cultures. FASEB J. 10(4):502-509 1996.
Colliander EB., Tesch PA., Effects of eccentric and concentric muscle actions in resistance training. Acta Physiol. Scand. 140:31-39, 1990.
Colliander EB., Tesch PA., Effects of detraining following short term resistance training on eccentric and concentric muscle strength. Acta Physiol. Scand. Jan;144(1), 1992.
Dudley GA., Tesch PA., Miller BJ., Buchanan P., Importance of eccentric actions in performance adaptations to resistance training. Aviat Space Environ Med 62. 1991.
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