Muscle Memory

[WarLobo]

Scientists May Have Unwittingly Uncovered Its Mystery

By Bryan Haycock

Anyone who has lifted weights, on and off, for several years is familiar with the concept of "muscle memory". Muscle memory in this context refers to the observation that when a person begins lifting weights after a prolonged lay off, it is much easier to return to their previous levels of size and strength than it was to get there the first time around. Even when significant atrophy (muscle shrinking) has taken place during the layoff, previously hypertrophied muscle returns to its previous size more quickly than usual. A recent study looking at fiber type conversions during muscle hypertrophy may have uncovered a possible mechanism for this fenomenon. For those of you not crazy about scientific lingo bear with me. Towards the end you
will see what I'm getting at with this study. In this study the distribution of myosin heavy chain (MHC) isoforms, fiber type composition, and fiber size of the vastus lateralis muscle were analyzed in a group of adult sedentary men before and after 3 months of resistance training and then again, after 3 months of detraining. Following the period of resistance training, MHC IIX content decreased from just over 9% to 2.0%,
with a corresponding increase in MHC IIA (42% to 49%). Following detraining the amount of MHC IIX reached values that were higher than before and during resistance training, over 17%! As expected, significant hypertrophy was observed for the type II fibers after resistance training,
and even remained larger than baseline after 3 months of detraining.

Myosin heavy chain isoforms, or MHCs, refer to the types of contractile protein you see in a given muscle fiber. MHCs determine how the muscle
fiber functions. MHCs are what make a fiber "fast twitch", "slow twitch", or something in-between. Certain MHCs are known to undergo a change in
response to resistance exercise. In this case, fibers that contain MHC IIX are fibers that aren't really sure what kind of fiber they are until they are called to action. Once recruited, they become MHC IIAs. So, fibers containg MHC IIX proteins serve as a reservoir of sorts for muscle
hypertrophy because the can transform themselves into fibers containing MHC IIX which grow easily in response to training. Like any great study, these researchers found what they expected as well
as a little extra that they didn't. I think this study caught my attention because it showed a long-term alteration in skeletal muscle following
resistance training. It has been this long-term change that has been the focus of my own training philosophy, which incorporates what I call
"strategic deconditioning". This study showed that resistance training decreases the amount of MHC IIX while reciprocally increasing MHC IIA
content. This was expected and has previously observed with changes in fiber type after resistance training. What they didn't expect was that detraining following heavy-load resistance training seems to cause what they refer to as an "overshoot" or doubling in the percentage of MHC IIX isoforms, significantly higher than that measured at baseline. What does this mean? It could mean that there are more fibers available for hypertrophy (growth) after a lay off from training than there are before you start training. This could very well explain the "muscle memory" effect many of us have experienced ourselves. It may also have
implications for natural bodybuilders looking to overcome long-standing plateaus.

There are a few questions that this study did not answer. For instance, they waited until 3 months after they stopped training before they took
final measurements. It would have been nice if they had taken measurements regularly so that the optimal period of detraining could be identified
corresponding to peak MHC IIX levels. Because it takes 3-4 weeks for these contractile muscle proteins to turn over, it would take longer than one month and probably less time than 6 months (previous research). Still the optimal time remains to be elucidated. Also, how would these guys respond to the same training regimen after the detraining period? Would their quads grow to their previous trained size, or even further? How long would it take? These questions, if answered, may add a new twist to typical training regimens. It may very well be that extended breaks from training may actually allow greater growth over a
12-month period than if training is uninterrupted. For serious athletes and bodybuilders, this would be important information and could significantly extend their competitive careers.

LAte

Lobo

[new@gettinbig1]

So your saying I should take a break eh?? Few weeks of loungin on the couch watchin soaps and eating bon bons!! Then I will come back bigger and stronger than ever Wow..... I need to try this, u can experiment with me!!

[WarLobo]

It's just re-inforcing the the argument that recovery time is very mportant.

Although I know you know that our friend knows how importaint it is not to over train. LOL, that was a good sentence huh....

LAte

Lobo

[WarLobo]

Oh, and BTW. I'll have the bon-bons sitting right in the middle of the two recliners directly front of my big screen. HOWEVER, soaps are out... But I'm sure a few dozen good movies might work!

LAte

Lobo

[W6]

MHC IIx gene expression is dependent on activity and is the default gene in fast muscle. During periods of inactivity, MHC IIx expression is up-regulated. Any type of exercise will turn off MHC IIx gene expression and up-regulate MHC IIa expression. One will also see (from a histochemical perspective) a decrease in IIb percent fiber area and type with exercise (aerobic or resistance) and an increase in type IIa % fiber area and type. Thus, these two changes parallel each other. The results of this study are consistent with this. The overshoot of MHC IIx is probably due to the abrupt decrease in activity. I'd bet if the detraining were tapered gradually, there wouldn't be an overshoot. In addition, the turnover of MHC protein take 3-4 weeks, therefore changes in these proteins take time to return to baseline. My guess is that if the study were extended to 120+ days, there wouldn't have been any difference. Overall, I'd say that this means little in terms of how to train and is simply a function of training/detraining. The study is published in Muscle and Nerve 23: 1095-1104, 2000. Also see RS Staron's work from 1990 and 1991 regarding heavy resistance training/detraining in women and the effects on fiber type and area. It's also important to note that only type II fibers hypertrophied in this study, so if you're doing one of those light-weight, high-rep cockroach routines, forget about hypertrophy.

W6

[retropump]

I've tried this. In fact I take 6-8 straight weeks off training every year. And I get bigger every year [img]/infopop/emoticons/icon_wink.gif[/img] Bon Bons are a good idea at this time. Make sure that couch is ergonomically correct.