At one point or another, we all face those unexpected life events that force us to take time off from the gym for a while longer than we’d like. But just how much of a concern this is, if any, to physique competitors and fitness enthusiasts alike? This article goes in for a closer look at the research behind maintaining your hard-earned muscle when training isn’t an option.

MUSCLE: USE IT OR LOSE IT!
An oft-debated topic in exercise science and fitness culture is how reduced use of skeletal muscles induces atrophy/degeneration over time. Many individuals will advocate a protocol whereby they take a periodic “deload” week from resistance exercise by training with significantly lower volume and/or intensity.

Theoretically this allows the user to recuperate mentally and physically from chronic, intense training without subsequent skeletal muscle loss (atrophy) and/or reduction in physical performance. But what about situations where we just don’t train at all for a “longish” period of time, say 1-2 weeks or more? Naturally, I presume most people will be concerned with how long they can get away with not training a muscle before experiencing noticeable muscular atrophy and performance decrements.

Granted most people don’t advocate taking lengthy amounts of time completely off from training (except in extreme circumstances), at one point or another we all face those unexpected occurrences that pull us away from the gym for a while longer than we’d like. So let’s take a look at just how much of a concern this is, if any, to physique competitors and fitness enthusiasts alike.

EXTENDED REST & INACTIVITY
Several studies have corroborated that extended periods of inactivity (e.g. bed rest) may in fact attenuate the muscle protein synthesis (MPS) response to a bolus of essential amino acids (EAAs).[1,2] Essentially, once you’ve quit utilizing certain muscles, there appears to be an “anabolic resistance” mechanism enacted (as Breen et. al put it).

Figure 1: Mixed-MPS in skeletal muscle of older adults (n = 6) in the post-absorptive state and during the EAA ingestion period

One of the interesting notes from the Drummond et. al study was that their period of bed rest was rather short, relatively speaking (7 days).[1] Prior to this study, most experiments had noted similar physiological adaptations in longer periods of inactivity, such as 2-3 weeks.[3,4] Therefore it appears that maintaining some sort of physical activity is imperative, even in the interim when you aren’t training full-bore.

The main conundrum with the studies cited herein is that they analyzed individuals who were undergoing complete “bed rest” and essentially immobilized. This rarely occurs under someone’s (especially an athlete) own volition, unless you’re the epitome of human sloth; I would surmise that most people don’t fantasize over vacations where they’re glued to a bed for 7 days straight.

NUTRITION & ACTIVE REST
It may sound like a mutually exclusive concept to remain active during periods of rest (e.g. no training), but it’s prudent to continue doing some sort of physical activity even when you’re taking time off from the gym. Thus, deloads are in fact a useful tool to retain the MPS response to ingestion of protein/EAAs (and thus maintain lean tissue). Moreover, some people will aggressively lower calorie intake during their time away from the gym which only compounds the catabolic effect of inactivity. While there may indeed be an “anabolic resistance” mechanism in individuals who are chronically at rest, it’s still useful to maintain sufficient protein/EAA intake and a eucaloric diet.[5]

CONCLUSION
Again, the main point to consider here is that spurts of complete inactivity do in fact appear to increase the rate of lean tissue degeneration, especially in elderly individuals. Furthermore, it is wise to maintain physical activity even in your time away from training and keep eating properly (with emphasis on the latter). Now, don’t get in a tizzy thinking that going on vacation for a week or two is going to cause you to wither away to skin and bones, because even simple physical activity like walking appears to help maintain the MPS response to proteins/EAAs.[6] The point of rest/deloads/time off from the gym is to recuperate yourself, so obviously training intensely would negate that benefit.

For future considerations it would be interesting to see just how short of a time lapse there is between periods of bed rest and attenuated MPS response to nominal doses of protein/EAAs. I’d believe the effect increases somewhat precipitously, but in reality the muscle loss in short periods of inactivity (e.g. 4-6 days of rest) is likely trivial at best, assuming you’re eating adequately.

References:1.Drummond MJ, Dickinson JM, Fry CS, Walker DK, Gundermann DM, Reidy PT, Timmerman KL, Markofski MM, Paddon-Jones D, Rasmussen BB, Volpi E. Am J Physiol Endocrinol Metab. (2012). DzBed rest impairs skeletal muscle amino acid transporter expression, mTORC1 signaling, and protein synthesis in response to essential amino acids in older adults.DzMay 15;302(9):E1113-22.  2.Breen L, Stokes KA, Churchward-Venne TA, Moore DR, Baker SK, Smith K, Atherton PJ, Phillips SM. (2013). DzTwo weeks of reduced activity decreases leg lean mass and induces Dzanabolic resistancedz of myofibrillar protein synthesis in healthy elderly.dzJ Clin Endocrinol Metab. Jun;98(6):2604-12.3.Glover, E. I., Phillips, S. M., Oates, B. R., Tang, J. E., Tarnopolsky, M. A., Selby, A., … & Rennie, M. J. (2008). DzImmobilization induces anabolic resistance in human myofibrillar protein synthesis with low and high dose amino acid infusion.dzThe Journal of physiology, 586(24), 6049-6061. 4.Kortebein, P., Symons, T. B., Ferrando, A., Paddon-Jones, D., Ronsen, O., Protas, E., … & Evans, W. J. (2008). DzFunctional impact of 10 days of bed rest in healthy older adults.dzThe Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 63(10), 1076-1081. 5.Paddon-Jones D, Sheffield-Moore M, Zhang XJ, et al. (2004). DzAmino acid ingestion improves muscle protein synthesis in the young and elderly.dzAm J Physiol Endocrinol Metab;286:E321–328.6.Symons TB, Sheffield-Moore M, Chinkes DL, et al. (2009). DzArtificial gravity maintains skeletal muscle protein synthesis during 21 days of simulated microgravity.dzJ Appl Physiology;107:34–38