ARE POST-WORKOUT CARBS AFTER TRAINING VITAL?

It's a question that never goes away.

Do you need carbs postworkout? Are they a must or nothing to be concerned about?

The post-workout drink topic pops up frequently, but as you'll discover, it really depends on the type of training you're doing. 

The notion that they're important seems to stem from some studies into endurance athletes in the 80's, that found carbohydrates immediately after training were beneficial for recovery and the restoration of muscle glycogen.

As often happens, some people take what's applicable in one area (endurance athletes) and assume it applies to others (bodybuilders/resistance trainers).

This is how fitness myths are created! 

The example here is carbs after training are a must for the restoration of muscle glycogen and to kick start muscle protein synthesis, via the action of insulin. 

Now whilst aspects of this are correct as you'll discover, it still isn't as black and white as this. 

To date there's a fair amount of data out there that we can draw from to make a conclusion - so let's dive into it!

THE RESEARCH 

A very recent study tested the idea that consuming carbohydrates and protein together would increase muscle protein synthesis and inhibit muscle protein breakdown at rest and after resistance training (1).

9 men performed leg extension workouts (4 x 8-12 reps to failure) then gulped down either 25 grams of whey protein, or the same amount of whey combined with 50 g of maltodextrin.

And the results?

The added carbohydrates weren't found to stimulate muscle protein synthesis or stop muscle protein breakdown more than just the whey protein alone.

To quote from the paper's conclusion:

"Our data suggest that insulin is not additive or synergistic to rates of muscle protein synthesis or muscle protein breakdown when carbohydrate is coingested with a dose of protein that maximally stimulates rates of muscle protein synthesis."

 

To my knowledge, there are currently only four studies that have examined this; the above cited one and three others that conclude the same thing; additional carbohydrates are NOT needed (2,3,4).

So carbs after training certainly don't appear to be super vital for the bodybuilder/resistance trainer, at least as far as these four papers are concerned.

Furthermore, other research found that 100 grams of carbohydrates alone after resistance training bolsters net muscle protein balance (5).

BUT - this was achieved by REDUCING protein degradation rates as opposed to INCREASING protein synthesis.

To inject an analogy, it's kind of like building a wind barrier around your house of cards indoors where there's no wind - you prevent it from falling but there's really no need. You're also not adding any extra cards to help it grow - so it becomes a pointless exercise.  

You can slam 100 grams of carbs post workout to prevent protein breakdown, but why would you when taking whey protein alone is enough to decrease protein breakdown AND increase protein synthesis?

Put simply - you wouldn't.

But it's easy to see how the importance of carbohydrates after training can be taken out of context following observations of studies like this.

WHERE ELSE DID THIS THEORY COME FROM?

Additional carbohydrates were long thought to drive nutrients (notably leucine, a key regulator of protein synthesis) into muscle cells via the action of insulin.

For those of you who aren't aware, leucine in one of the three BCAAS and is contained in all the protein you eat.

It sounds like the perfect plan, insulin to drive leucine into muscle cells? Right?

Correct....but carbohydrates are NOT needed.

Leucine ingestion ALONE (eg, taking whey protein) has the ability to secrete insulin! (6,7). 

So there's no real need to have carbohydrates too, especially when you also consider the 2-3 fold increase in circulating insulin concentrations above fasting levels that've been observed in the bulk of protein supplementation studies (8,9).

SO DOES THIS PUT THE ISSUE TO BED ONCE AND FOR ALL?

Well, that all depends on who you ask.

Certainly SHORT TERM - carbs after training don't appear to be a nessecity.

For now, they don't appear to be one of the useful bodybuilding supplements. 

But in terms of LONG TERMS designs, there's not much data to go off and this remains to be seen before we can make any definitive conclusions.

Whilst one study did examine a protein/carbohydrate supplement pre and post workout V's morning and evening for ten weeks (impressive), it didn't examine carbohydrate intake alone (10).

WHAT ABOUT GLYCOGEN REPLENISHMENT?  

When we train with weights, we lose our stored muscle glycogen - that's no secret.

Glycogen is chains of glucose molecules together that store in our muscles for energy.

Studies show that 3 sets of a 12 rep max on leg extensions results in a 26.1% reduction of glycogen, whilst 6 sets of the identical intensity results in a 38% increase (11).

So the other justification for carbs post-workout is: they'll help restore muscle glycogen quickly.

Data shows that this is definetly the case; when carbs are consumed right after training there's a supercompensation of stored glycogen, but wait 2 hours and muscle glycogen re-synthesis is hindered by up to 50% (12).

But there's no need for alarm and to start smashing carbs post-workout for the restoration of muscle glycogen. 

If you're a resistance trainer who trains one muscle group per day, then replenishing muscle glycogen in time for your next workout really is almost as simple as breathing - providing you're getting stuck into some carbohydrate meals in the meantime.

Also, glucose transporter type 4 (otherwise known as GLUT4) can uptake glucose in the absence of insulin and there's lots of work done by GLUT4 during glycogen depletion (13).

So carbs or no carbs immediately after pumping iron - glycogen resynthesis is still going to occur.

And this is when we return to the idea of replenishing glycogen for endurance athletes - they need to consume a protein and carbohydrate shake immediately after training, especially when their events that put a huge dent in glycogen stores are less than 8 hours apart (14).

But for the male/female who finishes work, heads to the gym and pumps iron and then does the same thing 24 hours but for a different muscle group (as most people do), then racing to consume a carbohydrate shake after training is really not going to be vital to replenishing muscle glycogen.

You'll achieve this simply by eating carbohydrates before your next workout.

For example, one study examined the consumption of 5 high-glycemic meals either during the first 4 hours right after exercise and from 2-6 hours onwards (15).

They were obviously seeing what effect this had on glycogen levels.

So what did they find? A word from the authors:

"These data indicate that delayed feeding of a HGI meal by 2 h has no effect on the rate of muscle glycogen resynthesis at 8 and 24 h post-exercise, providing that sufficient carbohydrate is ingested during the recovery period."

CONCLUSION

There's certainly no SOLID data to suggest carbs immediately after exercise are going to bring superior muscle growth results in comparison to not having any at all.

Although, this hasn't been examined long term and remains to be seen in a chronic study design.

But at this stage the general consensus is that carbs after training are NOT vital.

For the endurance athlete with back to back events - carbohydrate replenishment is paramount.

However for the bodybuilder, again, immediate post-workout carbs are not a must for the replenishment of muscle glycogen, if their next training bout is 24 hours later.

So in terms of muscle supplements, carbohydrates for the bodybuilder are not essential. 

So if you're someone who's looking to primarily increase your muscle mass and who trains once a day, forget your carbohydrate supplements until further notice.

 

"Stay Fit, Stay Flexed!"

 

REFERENCES 

(1) Staples AW, Burd NA, West DW, Currie KD, Atherton PJ, Moore DR, Rennie MJ, Macdonald MJ, Baker SK, Phillips SM. Carbohydrate does not augment exercise-induced protein accretion versus protein alone. Medi Sci Spots Exerc. 2011 Jul;43(7):1154-61. doi: 10.1249/MSS.0b013e31820751cb.

(2) Koopman R, Beelen M, Stellingwerff T, Pennings B, Saris WH, Kies AK, Kuipers H, Van Loon LJ:Coingestion of carbohydrate with protein does not further augment postexercise muscle protein synthesis. Am J Physiol Endocrinol Metab 2007, 293(3):E833-842. 

(3) Glynn EL, Fry CS, Timmerman KL, Drummond MJ, Volpi E, Rasmussen BB: Addition of carbohydrate or alanine to an essential amino acid mixture does not enhance human skeletal muscle protein anabolism. J Nutr 2013, 143(3):307-314. 

(4) Gorissen SH, Burd NA, Hamer HM, Gijsen AP, Groen BB, van Loon LJ. Carbohydrate coingestion delays dietary protein digestion and absorption but does not modulate postprandial muscle protein accretion.J Clin Endocrinol Metab. 2014 Jun;99(6):2250-8. doi: 10.1210/jc.2013-3970. Epub 2014 Mar 14.

(5) Børsheim E, Cree MG, Tipton KD, Elliott TA, Aarsland A, Wolfe RR: Effect of carbohydrate intake on net muscle protein synthesis during recovery from resistance exercise. J Appl Physiol 2004, 96(2):674-678.

(6) Floyd JC Jr, Fajans SS, Knopf RF, Conn JW: Evidence that insulin release is the mechanism for experimentally induced leucine hypoglycemia in man. J Clin Invest 1963, 42:1714-1719. 

(7) Anthony JC, Lang CH, Crozier SJ, Anthony TG, MacLean DA, Kimball SR, Jefferson LS:Contribution of insulin to the translational control of protein synthesis in skeletal muscle by leucine. Am J Physiol Endocrinol Metab 2002, 282(5):E1092-1101. 

(8) Akhavan T, Luhovyy BL, Brown PH, Cho CE, Anderson GH: Effect of premeal consumption of whey protein and its hydrolysate on food intake and postmeal glycemia and insulin responses in young adults. Am J Clin Nutr 2010, 91(4):966-975. 

(9) Morifuji M, Ishizaka M, Baba S, Fukuda K, Matsumoto H, Koga J, Kanegae M, Higuchi M:Comparison of different sources and degrees of hydrolysis of dietary protein: effect on plasma amino acids, dipeptides, and insulin responses in human subjects. J Agric Food Chem 2010, 58(15):8788-8797.

(10) Cribb PJ, Hayes A. Effects of supplement timing and resistance exercise on skeletal muscle hypertrophy. Med Sci Sports Exerc. 2006 Nov;38(11):1918-25. 

(11) Robergs RA, Pearson DR, Costill DL, Fink WJ, Pascoe DD, Benedict MA, Lambert CP, Zachweija JJ: Muscle glycogenolysis during differing intensities of weight-resistance exercise. J Appl Physiol 1991, 70(4):1700-6.

(12) Ivy JL: Glycogen resynthesis after exercise: effect of carbohydrate intake. Int J Sports Med. 1998, 19(Suppl 2):S142-5.

(13) Derave W, Lund S, Holman GD, Wojtaszewski J, Pedersen O, Richter EA: Contraction-stimulated muscle glucose transport and GLUT-4 surface content are dependent on glycogen content. Am J Physiol 1999, 277(6 Pt 1):E1103-10.

(14) Jentjens R, Jeukendrup A: Determinants of post-exercise glycogen synthesis during short-term recovery. Sports Med. 2003, 33(2):117-44.

(15) Parkin JA, Carey MF, Martin IK, Stojanovska L, Febbraio MA. Muscle glycogen storage following prolonged exercise: effect of timing of ingestion of high glycemic index food. Med Sci Sports Exerc. 1997 Feb;29(2):220-4.