Eccentric vs Concentric - Which Contraction is King?
In most matters of fitness, it seems that any debate between different techniques or methodologies always boils down to some sort of oppositional dichotomy. Inevitably, two opposites come to the forefront of the argument. The examples are countless: Bulking vs. Cutting. Push vs. Pull. Upper vs. Lower. Full body vs. Body part splits. Low-intensity, steady state cardio vs. high-intensity interval training. Just as athletes are always striving to build the biggest, fastest, or strongest bodies they can, there is a constant push to find the most effective training methods to allow an efficient pursuit of one’s goals. But when you think about it, it makes sense - who wants to waste time with techniques that don’t work when there are better alternatives available? Certainly not me, and no one I can think of fits this description either.
One other popular debate that often arises involves the type of muscular contraction that is performed as the stimulus in strength training. Muscles in the body can be contracted in three ways: concentrically, eccentrically, and isometrically. In concentric contractions, the length of the prime mover muscle is shortened as it provides more force than the resistance, as in the lifting phase of a dumbbell curl. In eccentric contractions, the length of the prime mover lengthens, as it works to slow a resistance that has a larger force output, as in the lowering phase of the aforementioned dumbbell curl. And lastly, in an isometric contraction, the length of the muscle remains the same as it pushes against an immobile object.
While all three of these contractions stimulate muscle fibers, concentric and eccentric contraction are used more frequently than isometric contraction, and thus, a debate has emerged as to which method is more effective for strength training. In order to clear up the debate, the August 2009 issue of the British Journal of Sports Medicine investigated the advantages and disadvantages associated with concentric and eccentric exercises.
Because muscles have the ability to attain higher absolute force during an eccentric contraction then a concentric one, many believe that eccentric contractions are superior in terms of building strength, as such exercises would provide a larger stimulus to the working muscles. Despite this popular assumption, though, this new research indicated that when the intensity of training was comparable for eccentric and concentric contractions, the gains in total strength gained were not significantly different. According to the data, strength gains with eccentric training were only superior to concentric training when the intensity was higher during eccentric training.
However, when gains in muscular size were compared, eccentric training proved to be superior, both when intensity of training was the same in both groups and when the eccentric group worked at a higher intensity. Additionally, eccentric contraction adaptations seemed to be closely related to velocity.
Based on this research, eccentric contraction may be superior for building muscle size alone, but is not necessarily better for building strength. In any case, a combination of the methods seems worthwhile, if only for the sake of variety.
SOURCE:
1. Roig, M., et al. The effects of eccentric versus concentric resistance training on muscle strength and mass in healthy adults: a systematic review with meta-analysis. The British Journal of Sports Medicine, 2009; 43:556-568
Post by: BrianWillett