Concentric action is when a muscle shortens/contracts, during lifting load as in the up motion of a squat or biceps curl. Eccentric action is when a muscle lengthens/extends during a controlled lowering of the load, as in the downward motion of a squat or biceps curl.
If you are experienced in strength training and looking for strength gains outside of your regular program, you may consider accentuated eccentric strength training.
Accentuated eccentric strength training is where you add extra weight/resistance for the eccentric action of an exercise but not for the concentric action. It takes advantage of the fact that you are stronger in the eccentric action of a movement. An example of this is during a barbell squat lowering 100kg during the eccentric action, releasing 20kg and lifting back up 80kg for the upward concentric action of the squat.
There is research attempting to illuminate how accentuated eccentric training works. And although it isn’t yet clear why it works, it does bring about more significant strength gains.
A natural form of eccentric exercise is walking downhill or down stairs.
THE APPLICATION OF ECCENTRIC TRAINING
The ideal application of accentuated eccentric training is unclear, and each muscle group responds differently. Curiously, in one study the benefits over traditional strength training didn’t take significant effect until after the first training block of 5 weeks. It was during the second training block that accentuated eccentric training had significant strength gains over traditional training.
How much you can increase the weight/resistance of the eccentric action depends on the muscle group. And the easiest way to apply accentuated eccentric training is to use two limbs for the concentric component and one limb for the eccentric part of a single limb lift. It appears that high intensity is significant and that for more effect aim for a load higher than your single limb concentric #RM load. For safety reasons I would start at or below my single limb concentric #RM, and very carefully work up from there.
Some weight training machines allow accentuated eccentric training. There are also devices of old such as weight release hooks used with free weights. However, we aren’t aware of these being available for purchase anymore. The safest way to train with heavy loads is to use experienced spotters to help you with the concentric portion of the lift. Alternatively, you can get them to put on and take off any overloading, and be readily available if you get into trouble.
Use caution when doing accentuated eccentric strength training and avoid the temptation to go beyond a load that you can safely manage. Legend has it that in the past plenty of people have injured themselves doing it. It is advisable only for people experienced in strength training. It often comes with increased muscle soreness, especially when beginning, and requires quality recovery. For this reason, it is not something you want to be doing before an event.
What is also unclear is whether continued long term accentuated eccentric training leads to continued gains or overreach.
ONE WAY ONLY
Eccentric only and concentric only training is where you perform only that action of an exercise with external weight/resistance and the opposing action with no external weight/resistance. It will increase strength. However, given the lack of evidence of any significant benefit over traditional strength training, there is little reason to apply it to most weight lifting exercises. If you are going to lower a weight, then why not get the benefit of lifting it as well?
Despite that, I do find using eccentric only training beneficial for extending a set of bodyweight exercises so that I can hit my target #RM. I also use it for unilateral work to strengthen my weaker left side.
When I can’t complete a full 10 reps for all of the sets doing pull-ups and triceps dips I finish off each set with eccentrics. I do these slowly with control at 3-4 seconds going down. The same principle can apply to strengthen my weaker left side by doing single arm dumbbell bench presses. I lift a heavy dumbbell with both arms and lower it with the left arm only. This is at the end of a set of doing both arms and puts a little more high intensity volume at the end to build up lefty.
Like the research study mentioned above, I have found that doing eccentric only pull-ups and triceps dips appeared to have no immediate effect. It was only after 2-3 months that suddenly the extra work kicked into effect.
There are many opportunities to miss the eccentric portion benefits of a lift by merely letting weight freefall. The most apparent exercise for this is the deadlift. Watch people deadlift, and you will most likely see them drop the weight, bouncing it off the ground. For all the effort to do the exercise, doing this you are missing a massive opportunity for further gains. If you lower the weight slowly with control, you will activate the eccentric portion of the lift. Sure you won’t be able to punch out as many reps, but if you park your ego aside, see how much you improve in 2-3 months.
Eccentric exercise can be useful for injury prevention. This use is due to the muscle’s ability to quickly adapt to the muscle fiber disruption from eccentric exercise and prevent further muscle damage. Therefore it may be beneficial for sporting applications and rehabilitation.
Either form of eccentric only or concentric only training may also have specific applications outside of the realm of this discussion.
1. Myofibrillar disruption following acute concentric and eccentric resistance exercise in strength-trained men. Gibala MJ, Interisano SA, Tarnopolsky MA, Roy BD, MacDonald JR, Yarasheski KE, MacDougall JD. Can J Physiol Pharmacol. 2000 Aug;78(8):656-61. www.ncbi.nlm.nih.gov/pubmed/10958167
2. Greater strength gains after training with accentuated eccentric than traditional isoinertial loads in already strength-trained men. Walker S, et al. Front Physiol. 2016; 7: 149. www.ncbi.nlm.nih.gov/pubmed/27199764
3. Muscle damage from eccentric exercise: mechanism, mechanical signs, adaptation and clinical applications. Proske U, Morgan DL. J Physiol. 2001 Dec 1; 537(Pt 2): 333-345. www.ncbi.nlm.nih.gov/pubmed/11731568