Resistance training is quickly becoming one of the most desirable forms of exercise, appealing to both males and females of all ages. Resistance training can offer numerous health and fitness related benefits, including enhanced muscle mass percentages, size and strength to name but a few.
Variety within resistance training is often brought about through differentiating between body parts and exercises on any given training day. Further variation can be achieved through the resistance utilised, repetitions/sets completed and the actual action of the target muscle. It is the latter that this article will focus upon.
Muscle action itself makes reference to how a muscle works whilst under tension from an external load – of which there can be considered three: concentric where the muscle shortens, eccentric where the muscle lengthens and isometric where no change in the actual muscle length is observed (de Souza-Teixeira and de Paz. 2012).
Eccentric muscle action can be further described as the “development of tension during muscle lengthening” (Ryschon et al. 1997).
Before moving on and considering the potential benefits of working eccentrically, let us firstly put this into an exercise example. Utilising the biceps curl, the upward phase of this exercise involves the contraction and shortening of the biceps muscle group, which can be considered a concentric action. At the top of this movement, slowly reversing this action and, in a controlled manner, lowering the resistance would be considered an eccentric action, where your biceps muscle is lengthening whilst under tension.
Without trying to stereotype an entire population, many individuals will concentrate on the concentric phase of an exercise whilst omitting the eccentric phase. For example, if we again utilise the biceps curl, the resistance will be suitably moved during the upward phase but simply dropped on the downward phase, thereby omitting any eccentric element.
So why should consideration be given to this eccentric phase? Isn’t simply working concentrically enough? Hortobayi (2003) demonstrated greater force production during the eccentric phase of an exercise by up to five times when compared to its concentric equivalent. This is just one potential advantage eccentric actions can offer over its concentric counterpart.
The purpose of this article is to consider these potential benefits on offer and how best to apply them to your current training regime.
Previous research has also contemplated the difference between concentric and eccentric actions and maximal force generation. Colliander and Tesch (1990) demonstrated during their research investigation that maximal force for any given exercise was between 20-60% greater during eccentric actions. These findings have been echoed in numerous investigations although the hypothesis for such results is still widely debatable.
Training eccentrically can not only produce greater maximal forces, but it can do so at a lower metabolic cost. Horstmann et al (2001) demonstrated that during eccentric movements the utilisation of primary energy source ATP and the production of exercise waste products such as ammonia and lactate remained relatively low. This demonstrated an enhanced effectiveness and efficiency of working eccentrically compared to concentric movements and ultimately equalled decreased fatigue of the target muscle.
Not only are you able to produce greater maximal force when working eccentrically but you are able to maintain this enhanced strength for longer periods of time compared to the concentric equivocal.
Perhaps one of the most interesting subsections of this research is the ability of eccentric resistance training at bringing about hypertrophic changes within a muscle. Tesch et al, (2004) considered exactly this during their research investigation. Initially two experimental groups were required to undertake five weeks of resistance training, with and without eccentric exercise.
Final results demonstrated on average an 11% increase in strength levels and a 6% increase in mass levels of participants from the eccentric control group.
These findings have been echoed throughout numerous research investigations. It is hypothesised that the greater ability to achieve maximal force through eccentric muscle action leads to greater muscular hypertrophic changes than its concentric counterpart (Farthing and Chilibeck. 2003).
So far this article has considered numerous benefits of eccentric resistance training. This is by no means however an exhaustive list. You might be thinking at this stage; if eccentric resistance training is so good then why do people even bother with concentric movements?
This is a good question and one which needs addressing. There are numerous reasons for the continual use of concentric resistance training, the first of which focuses on muscular damage. Eccentric resistance training places increasing demands on the target muscle. Muscle fibres are taken to their limits during eccentric actions and despite its benefits it can take it toll of that particular body part. As a result, further rest and recovery periods are required compared to that during concentric movements.
Continuing from the above point, the increasing demands of eccentric resistance training make it an unsuitable exercise variation for both novices and those suffering with injuries. Concentric and isometric resistance training should instead be utilised until a base foundation of strength is developed in the target muscles.
The nature of eccentric resistance training and the significantly enhanced loads means that a second person or spotter is often required in order for your session to run smoothly and efficiently. If you train alone then traditional concentric movements might suit you more.
Lastly but by no means least, concentric resistance training and its associated actions, including pushing and pulling, offer benefits in their own right. Not only do these actions mimic many everyday activities, but they are also required to excel at your chosen sport or activity.
This article has considered the potential benefits on offer through eccentric resistance exercise. These advantages include but are by no means limited to: greater force production, greater maximal force, lower metabolic costs, decreased fatigue and enhanced hypertrophic changes when comparisons are drawn against the concentric equivalent.
These benefits are not without there shortfalls however. Eccentric resistance training requires longer rest and recovery periods, should not be undertaken by those carrying injuries or novices and often requires a training partner in order to be successful.
Why choose one over the other when you can successfully implement both into your training program? Provided the above contraindications do not apply to you, then why not experiment and experience both muscle action forms? Eccentric resistance training can allow you to burst through any previous plateaus or sticking points and achieve new personal bests.
Experienced athletes will sometimes undertake sessions that only feature eccentric actions. Although this will allow for further resistance to be added to any given exercise and will shock the target muscle, you don’t necessarily have to go to these extremes to make the most of this training principle variation. By simply concentrating on the downward phase of a bicep curl – rather than dropping it with gravity – you will start to reap the benefits and rewards of eccentric training.
With all this in mind, why not try adding it to your next scheduled session. Let me know in the comments section what your favourite exercises are to train eccentrically and how long you usually spend on the return section of any particular exercise…
We will leave you with a great video that explains why you should also be ‘focusing on the negative’ in your gym routine: