Practical Science on Movement and Pain

Stretching Increases Strength in Contralateral Muscle

I am too busy right now to do any in depth posts, so here’s a quick little review of an interesting study I just read.

I’ve written several times before on this blog about how unilateral exercise can have significant effects on the contralateral side. I find this interesting not just because it’s kind of cool but because it is an elegant way to prove the extent to which adaptations to exercise are central as opposed to local. I’ve also written about how stretching seems to suck. Well I recently read a study which shows that stretching is good for something, and that it can have cool effects on the opposite side of the body. Here’s a brief discussion of the study.

Researchers asked subjects to stretch their right calf muscle 3 times per week for 10 weeks. After this time, subjects experienced an 8% increase in range of motion at the ankle, as well as a 29% increase in the one repetition maximum strength at the ankle. They also gained 11% greater 1RM strength on the contralateral leg, which didn’t do any work at all.

Nice job stretching!

Interesting information to keep in mind next time you are trying to preserve strength and/or range of motion in an injured limb during a rehab period.

Update: There are some interesting discussions on Facebook about what this study means. Tony Ingram has offered his opinion here, most of which I agree with. Here is one of my comments:

To me this is just a curiosity, or a little hack or trick, not something I think will change the way people train. But I do think it illustrates a general principle that is very applicable – that strength and other qualities we assume to be local are in fact more centrally governed than we imagine, and the governor can be effected by a wide variety of factors, including simple sensory feedback.

I don’t have the full text of the paper but a summary prepared by Chris Beardsley and Bret Contreras states that one of the mechanisms for crossover in the case of unilateral strength training is thought to be modulation at the spinal cord level. For example, unilateral electrical stim has a crossover strength effect. So they wondered whether stretching would do the same as the stim. And it did. Cool, but it won’t get me stretching.

What do you think? Let me know in the comments below.

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5 Responses to Stretching Increases Strength in Contralateral Muscle

  1. Sadly this study lacks what happened after they stopped stretching.

  2. Mark Hollis says:

    While I agree that ‘i don’t think it’ll change the way people will train’ it could be used as a good initial step for people that are untrained and looking to change. Being able to say to the couch potato that hey as little as this amount of movement/activity change can produce this much strength/ROM change is possibly a little easier to initially accept/visualise/implement than trying to get a major lifestyle overhaul. A little like getting someone to stop putting a teaspoon of sugar in their coffee may be an initial more realisable concrete goal than getting them to radically change their diet/every single meal. Any step towards more activity or a healthy lifestyle, even if it is a 1 legged step, is what I imagine most therapists are after and for those at the more sedentary end of the lifestyle scale maybe this could be the necessary first step of that journey. Yes a change in ROM/strength doesn’t automatically translate to a change in improved movement/activity, yes a small study that doesn’t necessarily translate to a larger population, yes there isn’t reports of long term effects but for some the thought of being ‘29% stronger’ with only a little initial input may be an initially beneficial or empowering concept and an easy to take on board concept, when I think of myself being ‘29% stronger’ I automatically then get proceeding thoughts of ‘and then i could do this and this and this!’.

    Thanks as always for the blog, Todd.

    • Todd Hargrove says:

      Thanks for the comment Mark. One idea I like is that the best exercise is whatever gets the client to show up and move. If that is stretching so be it!

  3. Mark Hollis says:

    Precisely, I look at the obesity statistics and think anything that gets butts off seats, any metaphor/idea that is a more exciting sell than tv or xbox or (ahem) the internet. It won’t change the majority of people I work with as a physio but it’s a nugget to keep for the occassional one. To me the interesting/important thing is promoting how ‘little input is sometimes able to significantly change output’.

  4. Brian says:

    My anatomy instructor told us when the fibers cross over in the spinal cord it activates the opposite side of the one you are moving.

    He told us if you have an injury and can’t move a part, start moving the opposite side which will stimulate healing in the injured side.

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