Wednesday, February 6, 2013

Chronic Resistance Training Reduces the Anabolic Signaling in Response to Exercise - 12 Days of Detraining Restore It

This rodent obviously knows about the value of detraining as a means to restore the signaling protein response that gets blunted over weeks of continuous training (photo from livescience.com)
Ah, some really good stuff in the news, or rather in the journals as of late (for the news version of the articles, you obviously got to come here, to the SuppVersity ;-). So, let's skip any lengthy preludes and let's start with a simple question pertaining to the topic of the day: "When was the last time you took 2 weeks or more off?" What? Last year, when you were down with the flu? No, that does not count. I am talking about detraining, here; so only voluntary off-times will be reckoned as off time... I thought so, you haven't taken off in years, right? Well, what if I told you that this may be the reason your gains have not taken off either? Interested? Yeah, that's what I thought.

Chronic resistance training reduces its own anabolic effect, detraining restores it

I guess in the end, all of us knew this instinctively: The unbelievable gains you make as a rookie vs. the slow and arduous road you will be walking later in your "career" as a trainee are too obvious for anyone not to suspect that the marginal utility of exercise declines.

Learn more about domain sizes, protein synthesis and  "muscle bulding" in Part II of the Intermittent Thoughts on Building muscle.
Now, one of the most common and certainly accurate hypothesis to explain this phenomenon is that the restructuring processes that starts when you hit the early domain size limit is more time consuming than just "pumping more protein into the muscle" - a process, which happens more or less automatically, a previously sedentary individual picks up a dumb- or barbell ;-)

With the impending publication of a study by researchers from the Ritsumeikan University, the University of Tokyo, the Nippon Sport Science University and the  University of Mississippi we do now have evidence for another, yet probably not unrelated reason to the exponential decline in marginal utility: The amelioration of the exercise induced phosphorylation of signaling proteins, due to which the marginal utility of your workouts decreases over time.

What did the scientists do?

In the experiment, the results of which Riki Ogasawara and his colleagues summarized an discussed in their latest paper, the researchers randomized a group of male Sprague-Dawley rats (10 weeks of age, 356.1 ± 4.4 g body weight) to four groups (+control) performing either continuous training (1S, 12S, 18S), in the form of 1 exercise session (1S), 12 exercise sessions (12S), or 18 exercise sessions (18S) every other day (Mo, Tue, Wed, Fr, Su, Tue, ...), or continuous training + detraining (DT), in the form of 12 sessions of exercise every followed by 12 days of detraining.
Figure 1: The "muscle builder" mTOR and the pertaining signaling cascade(s); remember that the line with the bar at the end indicates an antagonism → higher mTOR = higher phosphorylation of p70SK and it's downstream target rpS6, but lower 4E-BP1 (my orange markups; original from ebiotrade.com).
The exercise itself was mimicking a leg-training regimen, in the course of which, the gastrocnemius muscle was trained by stimulating 5 contractions, with a 5-s interval between contractions, per set for 5 sets (5-min rest intervals in-between the sets).
"The voltage (~30 V) and stimulation frequency (60 Hz) were adjusted to produce maximal isometric tension. Before every exercise session, peak twitch torque was measured. Torque signals were collected continuously at a sampling rate of 1024 Hz using a 16-bit analog-to-digital converter (PowerLab/16SP;AD Instruments, Japan) and analyzed using Power Lab Chart 5 software (AD Instruments, Japan). " (Ogasawara. 2013)
24h after the last exercise session, the rats were anesthetized and exsanguinated. The muscles were removed immediately after death and both muscle size, volume and weight, as well as the expression of the signaling proteins p70S6 kinase, p90RSK, 4E-BP1 and S6 ribosomal protein (rpS6) were measured.

So what's that all about? Did the rats become more muscular?

As you can see from  my plot of the protein responses on the left and the respective effects the different training (+detraining) protocols had on the muscle weight of the rodents on the right hand side of figure 2, the chronic resistance training protocols lead to statistically significant reductions in the post training p70S6K and rpS6 expression, which were restored in response to the detraining protocol.
Figure 2: Phosphorylation status of p70S6K (Thr389), p90RSK (Thr573), 4E-BP1 (total) an rpS6(Ser235/236) on the left and body weight, as well as muscle weight  in both exercised (RT ) and non-exercised (CON) rodents measured on the day after the last workout of the respective training group (Ogasawara. 2013).
Notwithstanding, the fact that the muscle gains were (expressed relative to the respective control group) statistically identical, shouldn't surprise you. After all, the growth benefits of the detraining protocol will show only in the weeks after your absence from the gym. The rodents in the study at hand, however, were subjected to only one training session after the detraining period and killed afterwards. Therefore, the main message the data on the increase in muscle weight in the DT compared to its control group is sending us is that short periods of detraining won't cost you precious muscle mass.

Don't hesitate, dare growing like a rookie again - dare taking a week off!

In a previous study, by Ogasawara et al. I have likewise discussed here at the SuppVersity, the researchers have already shown that a "6-weeks-on vs. 3-weeks off" training-detraining regimen produces identical gains in muscle growth as continuous training w/out  producing the logarithmic decline in marginal gains that brings skeletal muscle hypertrophy to a screetching halt over time (read more)
The novel information about the decline and restoration of the signaling proteins this study provides would support the longstanding hypothesis that continuous exercise blunts its own growth response. And what's more it's also supported by various human studies. In 2006, for example, Coffey et al. were able to show that the phosphorylation of p70S6K and rpS6 in response to resistance training was almost completely blunted in highly resistance-trained subjects (power lifters), while it did occur in the untrained controls (Coffey. 2006).Morever, Ogasawara et al. have shown last year already that an even longer detraining period of 3 weeks lead to much steeper inclines in muscle CSA in human subjects than continous training (see figure next to the paragraph below and read up all the details in the respective SuppVersity article from October 2012)

Collectively, these results clearly suggest that the notion of planned, regular detraining periods could have benefits that go way beyond the well-known ability to protect you from getting caught in the downward spiral of chronic overtraining, as it will also "reset" the anabolic response to a given workload.

And while you can hardly expect the results to be anywhere similar to those you've hopefully experienced, when you were still a scrawny beginner, the data from the study at hand does suggest that there will be an increase in the marginal utility of your workouts after one or two weeks of detraining. Moreover, there is no reason to be afraid that you could lose muscle within this short time period. Based on the absolute numbers in the study at hand (cf. figure 2), you could rather expect to see a non-significant increase in muscle mass that will occur during shorter (1-2 weeks) detraining phases.

If you have no idea what macro- and micro-cycles are or are clueless about how to incorporate phases of detraining and - as a possible alternative with potentially similar effects - tapering into your routine, I suggest you go back to part VI of the Step by Step Guide to Your Own Workout
Just don't forget, that just as it was the case in the previously mentioned 2012 human study by Ogasawara et al., you will see and feel the beneficial effects of the detraining period, not before you are back on the grind for 1-2 weeks. If you look back at the protocol, Ogasawara et al. used, the fact that the gains were "just" identical (even that would be a huge plus: after all you get the added bonus of reduced risk of injury, overtraining, etc. without missing out on a single additional mm on your arms, chest, shoulders, quads, hams, and what not) would actually support my gut feeling that a detraining period (= no training at all) of three weeks after "only" 6 weeks, could be a little too long. In the study at hand, which is obviously not a human stud and did not involve a regular full-body split routine, it did after all take no more than 12 days, i.e. 9 days less for the signaling responses to return to baseline.

Further speculations about optimal off-times and respective increases in muscle gains would be mere speculation, so that I would suggest, we will postpone more concrete suggestions until the next paper from Ogosawara's group at the Research Organization of Science and Technology to be published. If we assume that it will take another 3 months, which happens to be the interval between the aforementioned human study and the study at hand, you better mark the first two weeks of April 2013 in your calendar, if you don't want to miss the respective SuppVersity post on the matter ;-)



Regular periods of detraining are not the only thing you should keep in mind, when you lay out your workout routine. A study I wrote about in June 2012, for example showed that appropriate periodization can help you "Cut 12% Body Fat in 12 Weeks, Get Stronger, Bigger and Better Conditioned" (read more)
In short, what is it, this paper brings to the table and what are the implications? The "new" information this paper has to offer pertains to the restorative effects of detraining n the exercise induced protein signaling cascade that will eventually result in skeletal muscle hypertrophy (=muscle gains). The differential protein expression in the different training groups tell us, that the 12 days of detraining effectively restored the p70S6K an  rpS96 that declines with each and every workout during periods of continuous training.

The practical implications of these findings, should actually be obvious: Incorporating regular periods of detraining in your macrocycles and most importantly sticking to the plan, will not just help you to avoid overtraining with all it's negative side effects, it will also prevent the hypertrophy response to your workouts from diminishing and thus propel your lean mass gains.
Update: Steven Acerra called my attention to an older study by Kadi et al. who report distinct effects of detraining on the satellite cell response to heavy resistance training (Kadi. 2004). According to the results of their study, the often overlooked contribution of the satellite cells to the structural underpinnings of skelatal muscle appears to peak early in the detraining phase with the maximal number of satellite cells per muscle fiber being achieved after 10 days of detraining and a return to pre-training levels after 90 days. Despite the fact that a straight forward extrapolation of practical recommendations based on these observations alone is not feasible, the researchers observations do confirm that there is a multilayered benefit to short (~14 day) detraining periods.
Whether 12 days is the "optimal" length for a detraining period, if this "optimum" depends on the length, intensity and type of the previous training period, whether it's body part specific (like stop training arms for two weeks to restore your growth response in the biceps and triceps) and whether or not the training status of an individual has any impact on the time that's necessary for the "reset" to take place, will have to be elucidated in previous studies. That the SuppVersity is going to be the place, where you will read about these first, is something I probably don't have to tell you, right?

References: 
  • Coffey VG, Zhong Z, Shield A, Canny BJ, Chibalin AV, Zierath JR, and Hawley JA. Early signaling responses to divergent exercisestimuli in skeletal muscle from well-trained humans. FASEB J. 2006; 20: 190-192. 
  • Kadi F, Schjerling P, Andersen LL, Charifi N, Madsen JL, Christensen LR, Andersen JL. The effects of heavy resistance training and detraining on satellite cells in human skeletal muscles. J Physiol. 2004 Aug 1;558(Pt 3):1005-12. Epub 2004 Jun 24.
  • Ogasawara R, Yasuda T, Sakamaki M, Ozaki H, Abe T. Effects of periodic and continued resistance training on muscle CSA and strength in previously untrained men. Clin Physiol Funct Imaging. 2011 Sep;31(5):399-404.
  • Ogasawara R, Kobayashi K, Tsutaki A, Lee K, Abe T, Fujita S, Nakazato K, Ishii N. mTOR signaling response to resistance exercise is altered by chronic resistance training and detraining in skeletal muscle. J Appl Physiol. 2013 Jan 31. [Epub ahead of print]