Rest Days – Do You Still Drink A Protein Shake?

The day to day routine doesn’t change much.  Wake up, work, train, eat, do it again.  Whether you’re a guy or girl reading this, you resistance train to gain strength, build some muscle and improve your body composition.  If you’re not, you should be!

You have likely read several times over that on the days you train a key step to promoting maximal recovery and stimulating increases in muscle strength and growth is to take a daily dose of the essential amino acids.  Studies have shown that around 6 – 12 grams of the key amino acids are what is needed to maximally stimulate growth (Borsheim 2002).  Other studies have shown that a high-quality protein source like whey protein isolate, which contains the highest concentration of the essential amino acids of all protein sources, does a great job at stimulating increases in protein growth (Tang 2009).

Remember that a typical 25 gram dose of whey protein isolate will provide the upper end of the required amount of essential amino acids and it might be better to deliver these amino acids in one large dose as opposed to many smaller doses  and that amino acid levels stay elevated for around 2-3 hours or so (West 2011).  In this regard, drinking a dose of amino acids quickly as opposed to slowly has also been shown to cause greater increases in the proteins that actually contract in muscle when examined three to five hours after a single bout of resistance training when compared to sipping on the protein shake for over a couple of hours (West 2011).  All of these recommendations and findings are key points for what to consume and how to consume it on days when you resistance train.  What do you do on the days when you don’t resistance train such as a rest day or a day when you’re too busy to get in a workout?  Do you take a shake on those days as well or just not worry about it?

For starters, you must remember that your body is in a constant state of flux between building and breaking down proteins all throughout your body.  Not just proteins in your muscles, but also proteins in your bones, liver, skin, tendons, ligaments, lungs, etc., etc.  For this reason, an adequate delivery of protein is important each day as is delivery of the essential amino acids, which you can get from eating protein sources which come from animals (e.g., beef, poultry, milk, eggs, etc.).  But let’s be honest, you’re not particularly concerned with optimally building and rebuilding protein in your liver or skin, you’re concerned about building protein in your muscles.

Now, this conversation holds equally true for men as it does for women.  Sure men typically want to get bigger and leaner, but many women also strive for a more firm, toned and lean look, which comes from building smaller amounts of muscle and having it replace their body fat.  As a result, this topic relates equally well to both genders.  A recent study had fifteen young college-aged men complete a study that helped shed some light on this question (Burd 2011).

In one condition they came in to the lab after fasting for several hours and then consumed a shake which contained 15 grams of whey protein isolate.  Measures of muscle protein synthesis were made to determine the extent to which the whey protein shake by itself stimulated increases in protein synthesis.  In the other condition, the subjects completed a standard resistance training bout with the lower body and then came in the next morning after working out (a rest day or non-workout day).  The following day the same measures were taken as in the previous condition.  When the authors examined their findings they determined that a single bout of resistance exercise provides a stimulatory effect on muscle proteins for up to 24 hours.  Previous studies had reported this effect for up to five hours after a weight lifting bout (Moore 2009) but discovering that increases are still present up to 24 hours after exercise holds great meaning.

In particular, the authors were able to isolate only those proteins which are responsible for the contracting and shortening of our muscle tissue.  They found that these proteins were stimulated to an ever greater degree suggesting that those proteins which are involved in the exercise process experience specific and favorable changes when compared to other proteins (Burd 2011).  Another key finding is one with practical implications and helps us answer the initial question which was posed.  Should you consider taking a protein shake on an off day or more specifically a day after a workout?  The answer from this research appears to be yes.  However, two additional points need to be discussed.  First, this research only suggests that a greater stimulatory ability of muscle proteins occurs after completion of a resistance training bout for up to 24 hours.  While these are exciting findings, it’s also possible these findings may be extended to even longer periods of time such as 36 or 48 hours after an exercise bout.

If revealed, this would lend to the possibility that taking a high-quality protein shake for a day or two after a workout may stimulate protein growth to a greater extent than if no workout occurred.  This could easily happen if you go on quick business trip or you end up missing a couple of days in a row and certainly can give you motivation to get to the gym.  Additionally, this research didn’t examine the impact of other protein sources so at the very least these findings highlight the importance of protein and essential amino acid ingestion the day after a workout.  While strong arguments could be made to suggest a whey protein isolate is a preferred source of protein because of its higher concentration of essential amino acids than other protein sources, these study findings should not lead someone to think they have to consume whey protein for this to work as its possible other protein sources may also have a similar impact

In conclusion, the benefits of resistance exercise inside your muscle tissue appear to be extended well past the three to five hours which are commonly discussed.  Recent scientific findings suggest that in the day after completing a single bout of resistance exercise, greater increases in muscle contractile protein growth occurs when a small dose of whey protein isolate is consumed the following day when compared to ingesting the protein source when no weight lifting exercise preceded its ingestion.  Again and again, studies show that the combination of regular resistance exercise and high-quality whey protein ingestion confers favorable advantages for individuals who hope to increase strength, lean muscle mass and improve their body composition.

This post was written by Chad Kerksick, an Assistant Professor of Exercise Science at Lindenwood University in St. Charles, MO. Dr. Kerksick is a nerd for exercise physiology and particularly enjoys discussing strategies to lose fat and enhance performance through diet, supplementation and exercise.

REFERENCES

Borsheim, E., K. D. Tipton, et al. (2002). “Essential amino acids and muscle protein recovery from resistance exercise.” Am J Physiol Endocrinol Metab 283(4): E648-657.

Burd, N. A., D. W. West, et al. (2011). “Enhanced amino acid sensitivity of myofibrillar protein synthesis persists for up to 24 h after resistance exercise in young men.” The Journal of nutrition 141(4): 568-573.

Moore, D. R., J. E. Tang, et al. (2009). “Differential stimulation of myofibrillar and sarcoplasmic protein synthesis with protein ingestion at rest and after resistance exercise.” J Physiol 587(Pt 4): 897-904.

Tang, J. E., D. R. Moore, et al. (2009). “Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men.” J Appl Physiol 107(3): 987-992.

West, D. W., N. A. Burd, et al. (2011). “Rapid aminoacidemia enhances myofibrillar protein synthesis and anabolic intramuscular signaling responses after resistance exercise.” The American journal of clinical nutrition 94(3): 795-803.

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