To Stretch or Not To Stretch – That Is The Question (which I’m about to answer)
This blog is about to revolutionise your warmups. You’ve read it in magazines, heard it by physios, been informed the benefits of it by PT’s and certainly felt the guilt of not doing it… I’m talking about stretching before you train. But should you really be lengthening muscles before you powerlift?
To begin, I’ll explain my own experience with warmups. I’ve been lifting weights since I was 13, and being more impressionable than my current self I always stretched. I found that the more I stretched, the tighter I got and the more I needed to stretch. I was very good at stretching so I kept doing it, I later found out this is because I have diagnosable joint hypermobility. Realistically, stretching never helped me but I didn’t realise this until much later when a few good coaches and physios told me to stop warming-up with stretching and instead strengthen/shorten muscles around the “tight” joint. Only then did my mobility increase, injuries subside and strength really soar. This is now a more recognised approach for joint hypermobility– which is more common than you think. If you’re hypermobile stop stretching- NOW!!!
So we’ve covered the freaks and contortionists. But what about the rest of you? Lucky for you, I’m curious, obsessive and also enrolled in a science degree. So, armed with a video camera I recently went on a quest to find out.
My quest was a university assignment for my physiotherapy degree, where we had to use biomechanical analysis software to test a hypothesis. We examined which warmup method is better for deadlift power- lengthening or shortening.
Before experimenting, we already had a strong hypothesis.
Across a multitude of studies, static stretching has decreased power (1.) and force production (1.), strength work capacity and even 1RM strength (1.). In contrast, a correlation has been shown between a stiffer musculotendinous unit (muscle + tendon attachments) and increased force production.
So far all I’ve talked about is stiffness, and muscle length. There is another more complex system affected by warmups – the nervous system. The EMG results of a few studies (1. 2. 3.) show that static stretching might not only decrease force by lengthening the muscle (too loose or too tight and the muscle can’t contract properly), but also by dampening the nervous system. Again, in contrast to this, “tightening” or ”contraction” warmups have shown to prime the nervous system, and there is a large body of research to back up that this warmup type produces better performance (if you want to know more, this is referred to as Post Activation Potentiation).
In summary, your take home points are as follows; scientists think static stretching lengthens the muscles too much and dumbs your nervous system, which might just make it one of the worst warmups for strength movements. On the flip side, muscle activation or “shortening” movements literally get your nervous system in the mood to pick up heavy things.
We used bar speed in the conventional deadlift to test which warmup results in a more powerful movement. You can see the two different warmups in the table:
For anyone interested in our rationale for using bar speed to measure power, power can be defined as force multiplied by velocity. Keeping in mind that increased velocity leads to greater momentum for a given bar weight (momentum= mass x velocity), we figured velocity was the key player (and really easy to measure). Increased momentum can help overcome sticking points in the lift.
Our results were pretty significant. On average, the stretching trial made people perform 20% worse than the muscle activation/shortening trial. Just in case you missed that, STRETCHING MAKES YOU 20% SLOWER. This was unanimous- every single recording for each subject showed a better performance in muscle tightening compared to stretching.
And to answer the question on the tip of everyone’s tongue- our t-test result was 0.02.
The BORING BITS
I will touch briefly on the study limitations, because like many of you, I have OCD. Aside from the obvious, our sample population and design were the biggest limitations.
We only tested males, had a small sample size, and only looked at novice lifters. Not quite an athletic population.
Secondly, we did not have a control group and therefore cannot tell whether the difference between trials was caused by a positive effect from strengthening warmup, negative effect from stretching, or both.
All things considered, I believe our results are still significant as the differences between trials were so vast, and in line with previous literature.
For anyone who is interested, here is our very boring video that we submitted to the assessment board:
One study showed what’s taken my life until now to learn- muscle “shortening” warmups are extremely effective, and potentially the superior warmup method for strength movements. This is a point heavily advocated by champion lifter Chris Duffin. While powerlifters commonly use this warmup for weaker imbalanced muscles, a full body approach would have additional benefits.
I have completely overhauled my warmup routine so I only “shorten” and no longer stretch; with fantastic results. For my less mobile colleagues, you might find a combined approach is effective with targeted stretches and full body tightening. A good line in the sand is that if you can’t explain and justify the specific function of the stretch to your body and to the strength movement- then you shouldn’t be using that stretch (no, “I just need to loosen up” is not sufficient).
Don’t let the pictures of girls blissfully stretching fool you – that foolish grin will fade when you realise your deadlift sucks. Stretch LESS, contract MORE, warmup BETTER.