Geschatte leestijd: 8 minutenThe Stretch Shortening Cycle is a principle dependent on the elasticity (or stiffness) of the muscle and its attachment. A muscle that is first eccentrically stretched and then concentrically shortened can generate more force than when contracted concentrically directly. Eccentric stretching is when the muscle lengthens while being contracted.
Men make more use of the elasticity of attachments than women in strength training. For this reason, men have relatively more ease with combined movements than isolated eccentric or concentric exercises. This is one of the outcomes of a study published in December in the online version of The Journal of Strength & Conditioning Research (1).
Concentric, Eccentric, and Stretch Shortening Cycle
In the article on eccentric training, I extensively discuss the concepts of eccentric, concentric, and isometric. In the article on strength training for martial arts, I already discussed the Stretch Shortening Cycle (SSC). Here, I will briefly mention the concepts of eccentric, concentric, and isometric again using squats as an example exercise. This will make it easier to understand the more extensive explanation of the Stretch Shortening Cycle.
[Read more about eccentric training](https://www.fitsociety.nl/excentrisch-trainen/)Eccentric, Concentric, and Isometric
Starting from a straight position when squatting, you first bend your knees. During this process, the quadriceps muscles are elongated to bend at the knee joint. The quadriceps muscles are kept under tension because otherwise, you would simply collapse with the barbell on your neck. This lengthening of muscle fibers under tension is the eccentric part of a movement. When you push yourself back up, the muscle fibers are shortened under tension. This is the concentric part of a movement.
Between these movements, there is the transitional situation. Here, you can hold the tension while the muscle fibers neither shorten nor lengthen. This is the isometric part that we will not delve into today.
Stretch Shortening Cycle
If you make the transition in one go, from eccentric to concentric, you benefit (among other things) from the elasticity of the muscle attachments. The attachment is the tendon where the muscle ends and “attaches to” the bone that the muscle must be able to move.
Attachments are elastic. I extensively discuss this in the article about stretching. In short, you can imagine the attachment as an elastic between the bone and the muscle. When the muscle is lengthened under tension (eccentric part), the attachment is also stretched like an elastic. When the muscle is then shortened by contracting it (concentric part), the elasticity causes the stretched attachment to “snap back” and become shorter again, reducing the energy required to contract the muscle (2).
The elastic attachment thus absorbs some of the energy from the eccentric part, which is then reused during the concentric part. This principle is called the Stretch Shortening Cycle and ensures more efficient use of energy during the use of muscle strength (2,3,4,5).
Attachment, aponeurosis, or potentiation?
Just like with an elastic, the length of the attachment should also influence the amount of energy that can be stored. However, some researchers found that shortening the attachment did not affect muscle performance (6). Following another study three years later, the same researchers suspected that the aponeurosis also plays a role here (7).
The aponeurosis consists of layers of flat attachments resembling a membrane. This membrane can serve as a connection between the attachment and muscle, as with the gastrocnemius, between the attachment and bone, or it can also serve to bundle muscle fibers together. For example, the biceps have two attachments to the forearm, one normal and one that extends into an aponeurosis that bundles the muscles of the forearms together (this can sometimes cause painful tension in the forearms during certain bicep exercises, such as curls with a straight bar). In cases where the aponeurosis connects the attachment to the muscle or bone, researchers suspected that its elasticity also plays a role in the Stretch Shortening Cycle.
Postactivation Potentiation
Coincidentally, I wrote an article about Postactivation Potentiation yesterday. This principle assumes that if you do strength exercises first, the respective muscles perform better afterward. For example, squatting first to jump higher afterward. The idea is that the muscles are “activated” by the strength exercise. Some researchers suspected that in a similar way, the muscles are activated during the eccentric part of a movement, leading to better performance during the concentric part (8). In my article on “potentiation,” I wrote that researchers found it very difficult to demonstrate this principle, partly because some people seem to benefit from it while others do not. However, the Stretch Shortening Cycle offers benefits for everyone. Other researchers therefore think that potentiation cannot be responsible for the added energy of the Stretch Shortening Cycle (9,10,11).
Utilizing the Stretch Shortening Cycle: Cheating or Efficient Movement?
Whatever the exact mechanism is, the Stretch Shortening Cycle allows for more efficient use of muscle strength, allowing you to use less energy for the same performance or perform better with the same energy. For “all activities where performance can be expressed in what you have achieved outside your body with the effort made,” the Stretch Shortening Cycle is therefore of added value. Jumping higher, running longer, running faster, etc.
You frequently utilize the stretch shortening cycle during running and jumping, but also when you’re simply walking.
Suppose you want to make a vertical jump. You can do it in two ways:
- From a standstill, sitting in a chair, first tense your muscles and then jump,
- From a standing position, first lower until your knees have the same angle as when sitting in the chair, and then jump.
In both cases, the position before you jump is exactly the same. However, in the second situation, you will be able to jump higher because some of the energy from lowering through the legs is absorbed by the attachment and utilized during the jump.
Cheating: Men vs. Women
Athletes consciously or unconsciously make regular use of this. But what if it’s not about performance by the body, but about the load on the body? What if it’s not about how many times you can bench press a certain weight, but about how heavy you’re stressing your muscles?
If you train to increase your muscle mass or strength, you want to stress your muscles heavily. However, the Stretch Shortening Cycle is aimed at saving energy. Nevertheless, many people who train for muscle mass consciously use the Stretch Shortening Cycle to move more weight.
It doesn’t surprise me, then, that according to a recently published study, men make more use of the Stretch Shortening Cycle than women (1). The researchers looked at different executions of the squat and the bench press. These exercises had to be done both as separate eccentric and concentric exercises and combined (“dynamic”). The separate eccentric and concentric exercise makes use of the Stretch Shortening Cycle impossible because the combination of both movements is needed to store energy. The researchers observed that women could do proportionally more repetitions on the bench press with the eccentric and concentric exercise, while men had less difficulty with the combined exercise. They therefore concluded that men apparently make more use of the Stretch Shortening Cycle than women. For bench pressing, for example, you do this by pushing the barbell up immediately after lowering it. Instead of doing this, if you hold the barbell just above the chest before pushing it up, you make much less use of the Stretch Shortening Cycle.
They did not observe this difference in squats, however.
…women performed significantly more repetitions on the ECC and CON muscle actions of the bench press. Men performed more combined repetitions however, indicating a greater reliance on the stretch shortening cycle. Different muscle actions contribute uniquely to the successful performance of a lift and fatigue. These contributions appear to differ in men and women.
S.D. Flanagan, University of Connecticut
Men and Ego Lifting
This is called “ego lifting.” Adjusting your technique at the expense of the effect on muscle growth to be able to move more weight with the idea of impressing others.
A while ago, someone helped me during bench pressing. At the end, he said, “Nice job, but if you briefly tap the bar to your chest and push it up immediately instead of waiting, you can lift more weight.” To which my response was, “It’s not about the weight for me; it’s about how heavy I make it for myself. That’s the art!”
It’s illustrative of how often people don’t think properly about why they train and how they should do it. If I were a powerlifter participating in bench press competitions, I would welcome every tip to get that bar up. However, when it comes to creating muscle mass, it’s about muscle stress. The last thing you want then is to use tricks to make it easier for yourself.
The man in the image next to this, for example, lifts his lower back so high that the “flat bench press” becomes a “decline bench press” which is easier (in the sense that you can move more weight). Another example is the man below who has gathered all the weights from the gym. He probably spent more than half an hour doing this, only to show the worst “leg presses” (can’t even call them that) I’ve ever seen. I was waiting the whole time for him to start, then I realized he was already done. You wonder if he really thinks he’s impressing anyone with this:
It’s therefore not surprising that mainly men have a knack for this. When was the last time you saw women bench pressing in the gym like men? Screaming, “Yeah, Buddy” and “light weight” because they’ve just discovered Ronnie Coleman’s DVDs. Groaning from the first repetition as they go on to do 12 repetitions, and the first one really couldn’t have been heavy enough for the groaning to attract the attention of the entire gym. Throwing 20-kilo dumbbells so hard on the ground that they seem heavier (“Ronnie also throws them on the ground”). Or sliding plates hard onto the barbell so that 5 kilos sound like 20 because they happened to hear Schwarzenegger make a joke about it in Pumping Iron and take it seriously.
Technique for Stretch Shortening Cycle
The researchers believed that the difference couldn’t be due to technique because both men and women were experienced in strength training. This mainly tells me that the men are experienced enough to know they can cheat to press more weight while this isn’t a reason for women to adjust their technique.
You can ensure that the Stretch Shortening Cycle contributes as little as possible or not at all in various ways:
- Isolated concentric exercises
- Rest during the isometric phase before the concentric phase begins.
Isolated concentric exercises
Have you ever tried bench pressing in the smith machine or in the squat rack in such a way that the barbell lies just above your chest on supports? Instead of lowering the bar first, you now have to push it up from a standstill. This means you miss out on the energy of the Stretch Shortening Cycle because it hasn’t been “stored” during the eccentric movement. This exercise is surprisingly heavy if you’re not used to it, and you’ll have to perform it with less weight than you’re used to with bench pressing.
Rest during the isometric phase before the concentric phase begins
Another way is to perform the exercise “normally” with the difference that you now hold the barbell still (for about one full second) just above the chest (the isometric phase). This allows less use of stored energy (12).
I’ve taken bench pressing as an example now, but the above methods work for almost any exercise.
Conclusion
The conclusion is therefore short and simple. The Stretch Shortening Cycle is one of those countless “efficiency systems” of the body. A tool for the muscles to save energy. If it’s about what you achieve with muscle strength, then you should make sure this system works in your favor. However, if you’re training with muscle strength and/or mass as the goal, then you should try to eliminate this principle as much as possible.
References
- Flanagan, Shawn D. et al. The Relationship between Muscle Action and Repetition Maximum on the Squat and Bench Press in Men and Women. Journal of Strength and Conditioning Research Publish Ahead of Print. DOI: 10.1519/JSC.0000000000000337A.
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- Paavo V. Komi, Masaki Ishikawa and Vesa Linnamo. IDENTIFICATION OF STRETCH-SHORTENING CYCLES IN DIFFERENT SPORTS. Portuguese Journal of Sport Sciences 11 (Suppl. 2), 2011
- Thomas J. Roberts, Richard L. Marsh, Peter G. Weyand and C. Richard Taylor (1997). “Muscular Force in Running Turkeys: The Economy of Minimizing Work”. Science 275 (5303): 1113–1115.
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