The Stretch Effect – Does Stretch Overload Produce More Muscle Gains

The stretch effect is when one emphasizes the “stretch” of the muscle fibers, creating more muscle tension, micro tears and possibly: more growth.

It is speculated that the muscle undergoes a state of actually multiplying the number of its fibers (hyperplasia) instead of just getting larger (hypertrophy) with the application of muscle stretch overload in lifting weights. This phenomenon is not yet proven by research; since it would require someone to volunteer to conduct a stretch emphasis exercise and then agree to have his limbs amputated so that the scientists could count the number of muscle fibers.

There are already some animal experiments  (like this one: Sola, O. M., D. L. Christensen, and A. W. Martin. Hypertrophy and hyperplasia of adult chicken anterior latissimus dorsi muscles following stretch with and without denervation. Exp. Neurol. 41: 76-100, 1973) and also some indirect evidences, but although there is no actual proof..YET, it makes sense to think that proper resistance exercise, especially stretch overload can induce a muscle fiber-multiplying adaptation.

So they used chickens in the research, what happened? They became big, muscular birds. No pun intended:

large musclar birds

Do or Die:

So why does this make sense? Basically you’re giving your muscles no choice upon stretch overload – either it splits or it strengthens and multiplies. We don’t even need to go into deep scientific jargons about this. We can summarize all o these into this equation:

Stretch overload plus recovery and nourishment equals muscle growth


It basically goes that way. That is the reason why methods such as X reps (which focus on stretch position partials), FST by Broser (which utilizes pumps before doing stretch emphasis exercises), doing heavy isolations, stretching AFTER working out, etc have been very effective thus far.  Al of these techniques and practices give importance to the “stretch factor” in resistance training.

So let’s say you are skeptic about the whole “stretch produces hyperplasia” thing since there is no evidence to it; well hyperplasia or not one thing is for sure:

Stretch overload produce muscle GROWTH

And that is backed by science! I would also suggest that you read Dr. Jose Antonio’s views about this. You can view Antonio’s treatise here.

Excerpt from Antonio’s article:


This animal model was first used by Sola et al. in 1973. In essence, you put a weight on one wing of a bird (usually a chicken or quail) and leave the other wing alone. By putting a weight on one wing (usually equal to 10% of the bird’s weight), a weight-induced stretch is imposed on the back muscles. The muscle which is usually examined is the anterior latissimus dorsi or ALD (unlike humans, birds have an anterior and posterior latissimus dorsi). Besides the expected observation that the individual fibers grew under this stress, Sola et al. found that this method of overload resulted in a 16% increase in ALD muscle fiber number. Since the work of Sola, numerous investigators have used this model. For example, Alway et al. showed that 30 days of chronic stretch (i.e., 30 days with the weight on with NO REST) resulted in a 172% increase in ALD muscle mass and a 52-75% increase in muscle fiber number! Imagine if humans could grow that fast!

More recently, I performed a study using the same stretch model. In addition, I used a progressive overload scheme whereby the bird was initally loaded with a weight equal to 10% of the its weight followed by increments of 15%, 20%, 25%, and 35% of its weight . Each weight increment was interspersed with a 2 day rest. The total number of stretch days was 28. Using this approach produced the greatest gains in muscle mass EVER recorded in an animal or human model of tension-induced overload, up to a 334% increase in muscle mass with up to a 90% increase in fiber number! That is pretty impressive training responsiveness for our feathered descendants of dinosaurs.

But you might ask yourself, what does hanging a weight on a bird have to do with humans who lift weights? So who cares if birds can increase muscle mass by over 300% and fiber number by 90%. Well, you’ve got a good point. Certainly, nobody out there (that I know of), hangs weights on their arms for 30 days straight or even 30 minutes for that matter. Maybe you should try it and see what happens. This could be a different albeit painful way to “train.” But actually the physiologically interesting point is that if presented with an appropriate stimulus, a muscle can produce more fibers! What is an appropriate stimulus? I think it is one that involves subjecting muscle fibers to high tension overload (enough to induce injury) followed by a regenerative period… (Read more)

In the next coming posts (updated check out the stretch overload regimen here) we will discuss ways on how to apply the stretch overload to your training regimen. Keep in mind that I do those techniques myself and so far I am seeing positive results. By the way if anyone here has an experience with Stretch overload please let us know by commenting below. Eat you eggs, people!

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