Eccentric contractions are defined by a muscle or group of muscles producing force whilst increasing in length. Picture yourself performing a pull up. After completing a rep, I'd like to hope that you lower yourself under some level of control rather than dropping off of the bar. That there, is a simple example of you demonstrating an eccentric contraction. The musculature of your back, shoulders and arms are producing force whilst lengthening in order to lower yourself slowly and under control.
Now, in terms of training, true eccentrics are typically done with a greater load than what you can lift. More specifically, eccentrics should be performed with between 120-150% of your 1 Rep Max.
How is that even possible?!
Well, your muscles are capable of producing greater forces eccentrically than they are concentrically (muscles shortening). Meaning that in a squat, for example, you are capable of lowering a much greater load than you are lifting it.
Say you can squat 100kg for 1 rep. That is your current maximum. You have the potential to lower up to 150kg with some degree of control.
Of course, this needs to be trained. Multiple factors including neural efficiency and tendon strength plays a huge role so don't expect to be able to do this right away, however, you do have the potential.
What's the point?
I really like eccentrics, as those that work with me here at Cheshire Barbell will tell you. I try to integrate them into as many warm-ups as possible.
Asside from the physiological and neurological adaptations, eccentrics help lifters develop confidence in their ability to lower a bar safely and under control. Of course, you'll never stand up with 120% of your 1RM, so it also gives the lifter an opportunity to practise bailing from underneath a bar safely. This helps remove the fear element and therefore allows lifters to train outside of their comfort zone knowing that if the s*** hits the fan, they know how to do deal with it.
Eccentrics are also great for developing skill. The slow tempo nature of such lifting allows the trainee to focus their attention on their movement and execution of the exercise, meaning that they can work on improving their position and mechanics to become more proficient at the exercise and less likely to experience injury.
What about the physiological benefits to training eccentrics?
Muscle growth (hypertrophy) is associated with many factors. Too many, in fact, to go into any particular detail without me straying away from the main topic in this post.
One factor that is related, however, is that optimal muscle growth is associated with greater mechanical loading and muscle damage. Exactly what eccentric training offers...
Above maximal loads performed very slowly whilst attempting to maximally contract muscle tissue.
*For those interested, the increased joint-torque and torque time integral associated with true eccentric training are linked with greater anabolic signalling and muscle hypertrophy.
In practise, however, it is very very difficult to apply.
True eccentrics require you to dump or bail from the weight, re-rack it, and repeat multiple times until the necessary number of repetitions have been performed.
In addition, it is very very difficult to achieve maximal voluntary contraction / activation during eccentrics. You're under that much load it is a challenge to ensure you're squeezing and contracting your muscles as hard as possible, rather, you tend to focus so much on not collapsing under the weight.
Eccentrics are also difficult to recover from due to higher levels of muscle damage, the extent of which means you cannot do them all that frequently.
Since the torque-time-integral is also associated with increased muscle growth, lengthening the eccentric phase (using a slower lowering tempo) may be the best way to maximise muscle growth (Ashida et al., 2017).
For those of you who interested in Olympic Weightlifting or general strength training, it may be wise to programme slow tempo squats, for example, on a seperate day to that of your higher intensity / heavy days.
Front Squat 7x4 @ 80-85%
Slow/Tempo Back Squats 5x8 @ 65%
It'll give you chance to work on the technical aspects of the lift, and you may even develop some decent muscle tissue as a byproduct!
Karl Page MSc BSc Hons
Further reading: Effects of contraction mode and stimulation frequency on electrical stimulation-induced skeletal muscle hypertrophy, 2017. Ashida, Y., Himori, K., Tatebayashi, D., Yamada, R., Ogasawara, R. and Yamada, T. Journal of Applied Physiology, 7 (8).