How muscle memory makes you stronger

Thursday, February 15, 2018. Author Dr Haran Sivapalan

How muscle memory makes you stronger

We all go through phases of inactivity. We may be consigned to rest through injury or illness, or life may simply get in the way, meaning we can’t make it to the gym for a while. Elite athletes may even deliberately take an ‘off-season’ break, performing little to no exercise over a period of days or weeks. Throughout these inactive phases, any muscle gains start to wane through disuse – just ask anyone who’s struggled to stand up after a prolonged stay in bed.

But does a layoff mean all our previous hard work at the gym has been in vain?  According to a new study of gene expression in muscle tissue, the answer is: no, our muscles may ‘remember’ their previous workouts, allowing them to grow in size when exercise is resumed.

How was the study conducted?

The study, published in the journal Scientific Reports, saw eight subjects undertake a three-phase resistance training program.  Each phase lasted seven weeks. The first phase, or ‘loading phase’, comprised a mixture of upper and lower limb strength exercises, with the greater focus on leg work-outs such as squats, leg presses, and weighted lunges. (The subjects were certainly not skipping leg day!).

The loading phase was followed by an ‘unloading phase’, in which subjects refrained from resistance exercise completely. Finally, in what was termed the ‘reloading phase’, subjects restarted their strength training exactly as before. At the end of each 7-week phase, samples (biopsies) of quadriceps muscle tissue were taken to look for any genetic changes. Researchers also scanned subjects’ legs using specialized X-rays (DEXA scan) to assess for changes in lean muscle mass.

What did the study find?

Unsurprisingly, the DEXA scans showed significant muscle gains during the 7-week loading period, with subjects boosting their lower limb lean muscle mass by 6.5% compared to baseline. In keeping with the ‘use it or lose it’ principle of muscle growth, however, these muscle gains soon regressed towards baseline during the 7-week ‘unloading phase,’ as leg muscles were under-exercised. 

By the end of the 7-week ‘reloading phase’ though, when strength training was resumed, subjects not only recouped their previous gains, but put on more muscle than before (12.4% compared to baseline).  So, what was underlying this rebound effect?

Muscle memory

The researchers suggest that our muscles have a type of ‘memory’ for previous exercise. As the analysis of the quadriceps tissue samples revealed, this memory is mediated not by brain cells, but by changes to genes. When we initially exercise (as in the loading phase of the study), certain genes become switched on. The DNA code within each gene is then used to produce a protein – a process called ‘gene expression.’

As we later become inactive (unloading phase), several genes switch back off again, but other genes remained switched on, as if to ‘remember’ our preceding bout of exercise. This happens despite the concomitant loss of muscle gains. When exercise is resumed (reloading phase), the switched-on genes become further activated, and this increased gene expression contributes to enhanced muscle growth.

It’s important not to get the above phenomenon confused with the other type of ‘muscle memory’. The latter describes your brain’s capacity to remember a motor skill and explains why you can still ride a bike as an adult, even though you may not have ridden a bike since childhood. 

By contrast, the ‘memory’ in this study, was not a property of gray matter, but of so-called ‘epigenetic changes’ in muscle tissue. Epigenetic changes refer to alterations in the way genes express themselves. As Dr. Sam Decombel has explained, your DNA sequence is fixed throughout life, but the body can tag marker molecules to the outside of genes, without changing the sequence. Adding and removing these markers may switch genes on and off, or regulate the level of proteins (e.g., enzymes, muscle fiber components) made from genes. This comes in handy for responding to changing environmental triggers. In this case, resistance training seems to switch genes on in anticipation of further demands on muscle.  

So, worry not: even if you can’t remember the last time you hit the weights, your muscles probably still can! And, if you fancy putting that ‘memory’ to use, try our Build Muscle System.

I hope you enjoyed this article.  Please read my other blogs: 

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The top 5 fitness trends of 2018

Nutrition tips for exercising in the snow

What do elite athletes think about DNA analysis

Health benefits of Christmas foods

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Air pollution and exercise:  Is it safe to train outside?

Is struggling with weight your destiny?

How Your Finger Length Influences Overall Strength

Just Say No to Upselling

Unravelling the Secrets of Our Circadian Rhythm

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