Are Pre-, Intra-, and Post-Workout Carbohydrates Important for Powerlifters?

Hey all, hope everyone had a great July 4th!

Today is the day I write and publish my first official blog post.  In this, I'm going to talk about why pre-, intra-, and post-workout carbohydrates are popular topics, as well as go over what some old and recent literature suggests on the matter.  My goal here is to make some of the data regarding this topic as easy to understand as possible.  Hopefully by the end of this post, you will have a better idea of why this topic is of such a high order of importance, and whether it's something worth your time and energy as an athlete, coach, trainer, nutritionist, etc.

Summary of Points

• Glycogen is the preferred source of energy for the Krebs cycle
• Workout volume and intensity respectively affect degree and rate of glycogen depletion
• Resistance training heavily expends glycolytic energy
• Post-workout carbohydrates improve immediate recovery and performance
• Pre-workout (and possibly intra-workout) carbohydrates may benefit morning lifters, two-a-day lifters, and low-carb dieters

A Quick Anecdote

Something happened yesterday.  I forgot to eat a small meal 1-2hrs before my workout, I didn't have any Gatorade during my workout, and after my workout, I had another 2 hours to wait until my July 4th dinner was ready.  My workouts take 2 hours to complete, and they aren't easy.  I was in quite the predicament.

Sure, I was hungry during and after my workout, but then again, I always am.  But I was still able to hit every rep and set at the weight and RPE I was expecting to.  I just... didn't feel as good as usual while doing it.

So What's the Big Deal?

If exercise physiology has taught me anything, it's that the Krebs cycle is the mecca of energy production in the human body, and glycolysis is its lifeline... well... its preferred lifeline, at least... sorry to leave you out, oxidative phosphorylation.

As many of you may or may not know, glycolytic ATP production is much faster than oxidative ATP production.  In order for glycolysis to happen, we need glycogen, and glycogen comes from glucose, which comes from ingested carbohydrates.

So here's where pre-, intra-, and post-workout nutrition earn their heat.  As we exercise, we expend phosphagenic and glycolytic energy (along with oxidative energy, but that's not important here).  The degree to which this occurs depends on total workout volume, and the rate at which this occurs depends on the intensity of our bouts.  It's the same as measuring gas expenditure from driving a car.  Drive for longer, and you use more total gas.  Drive faster, and you use more gas per unit of time.

Let's apply this rambling to a hypothetical, but not unrealistic, athlete/scenario.

Powerlifters tend to train with a lot of volume, and they also tend to train at a fairly high intensity.  I'll paint a picture for us both to look at.

Allow me to introduce you to Brian, an imaginary national-level -105kg lifter.  Let's say Brian is 8 weeks out from his next meet.  He's currently running a program with DUP, and as a -105kg class lifter, he can squat 600lbs, bench 400lbs, and deadlift 600lbs.

Here's his high-intensity, moderate-volume workout for this Friday:

That's 60 total reps of compound barbell movements, at supra-80% intensity, followed by another compound movement for another 32 total reps, followed by one of the most dreadful exercises known to man.  This is a fairly typical scheme for a competitive powerlifter who works out 3-4 times per week.  So surely there is bound to be some serious glycogen depletion during this workout.  We'll come back to Brian in a bit.  Sit tight, Brian.

On Glycogen Depletion

Todd Astorino and Len Kravitz have an excellent analysis of older literature on glycogen depletion in strength training.  Research dating back to the 70s, 80s, and 90s has shown glycogen depletion to be more liberal than one may expect.  Here are what I found to be its most important points, though I encourage everyone to read the whole review:

• Robergs et al. (1991) showed a workout as simple as 6 sets of leg extensions can deplete up to 38-39% of one's stored glycogen
• Tesch et al. (1986) showed a 30 minute workout consisting of front squats, back squats, leg presses, and leg extensions to fatigue depleted 26% of total stored glycogen in its subjects
• A follow up study, by Essen-Gustavsson and Tesch (1990) found a 28% glycogen depletion accompanied by a 30% muscle triglyceride depletion after the same workout
• Haff et al. (1999) showed athletes who "supplemented" 250g of carbohydrates after their morning workouts experienced significantly better performance (more sets, more reps, and for 30 minutes longer) during their second workout, 4 hours later
• Glycogen depletion reduces work capacity

But now let's look at what a more recent study found regarding a similar topic (pre- and intra-workout carbohydrates).  Kulik et al. (2008) tested the effects of pre- and intra-workout carbohydrates supplementation on squat performance.  Here's a summary:

• Subjects performed sets of 5 with 85% of their 1-rep max
• One group was given .3g of carbohydrates per kg of body mass before the workout and after each set
• The other group was given a placebo of equal volume and frequency
• No difference in performance was found

The subjects in this study ate a controlled diet consisting of 55% carbohydrates, 20% protein, and 25% fat.  They went into their workouts "fresh" so to speak - rested, and with plenty of glycogen in their system already.

Let's cross-pollinate this information.  The subjects from Haff et al.'s study underwent back to back workouts, separated by 4 hours of rest.  Account for the glycogen depletion reported from Robergs et al and Tesch et al.  Post- and pre-workout (and possibly intra-workout) carbohydrate sourcing is particularly important for those with already-depleted glycogen stores.  This is important for:

• Morning lifters
• Eat a moderately high-carb breakfast before working out
• 2-a-day lifters
• Eat plenty of carbohydrates immediately after the first workout
• Low-carb dieters
• Consume majority of carbs directly before and after working out

But What About Brian?

Brian works out at 4:00pm every day after he is done training and coaching clients.  His 7:00am breakfast consists of 2 cups of milk-cooked oats with a scoop of whey protein mixed in.  His 12:00pm lunch is 8oz of chicken thigh and a cup of cooked brown rice.  He eats an apple as a snack at 2:00pm, and he always makes a Chipotle run on his way home from the gym (extra rice and beans, triple chicken).  He doesn't need to worry about pre- and intra-workout nutrition, because his diet already provides him with sufficient glucose to keep his glycogen stores filled.  Plus, by the time it's 4:00pm, he's already had 2 full meals and a snack.

Remember my anecdote?  Well, my diet is pretty darn close to Brian's, so even though I forgot to eat lunch, my weeks of consistently sufficient dietary habits kept my glycogen stores at levels that were more than capable of getting me through my workout.  Now, if this were something I did every day, there'd be more to say.  But I guess the moral of the story is that if you're eating enough total calories and carbohydrates, peri-workout nutrition isn't something you should be losing sleep over.

However, when carbs are tight, such as when cutting weight for a meet, timing your carbohydrates around your workout is important and will significantly affect your performance and recovery.

Do you have specific peri-workout carb sources or meals?  If so, what are they, and do you think they help you?

References

Astorino, Todd & Kravitz, Len (n.d.). Glycogen and Resistance Training. Retrieved from https://www.unm.edu/~lkravitz/Article%20folder/glycogen.html.

Essen-Gustavsson, B. & Tesch, P. A. 1990. Glycogen and Triglyceride Utilization in Relation to Muscle Metabolic Characteristics in Men Performing Heavy-Resistance Exercise. European Journal of Applied Physiology, 61, 5-10.

Haff, G. G., et al. 1999. The Effect of Carbohydrate Supplementation on Multiple Sessions and Bouts of Resistance Exercise. Journal of Strength and Conditioning Research, 13(2), 111-7.

Kulik, J. R., Touchberry, C. D., Kawamori, N., Blumert, P. A., Crum, A. J., & Haff, G. G. (2008). Supplemental Carbohydrate Ingestion Does Not Improve Performance of High-Intensity Resistance Exercise. Journal Of Strength & Conditioning Research (Lippincott Williams & Wilkins), 22(4), 1101-1107.

Pöchmüller, M., Schwingshackl, L., Colombani, P. C., & Hoffmann, G. (2016). A Systematic Review and Meta-Analysis of Carbohydrate Benefits Associated with Randomized Controlled Competition-Based Performance Trials. Journal Of The International Society Of Sports Nutrition, 13, 1-12.

Robergs, R. A., Pearson, D. R., Costil, D. L., Fink, D. D., Pascoe, M. A., Benedict, C. P., Lambert, C. P., and Zachweija, J. J. (1991). Muscle Glycogenolysis During Differing Intensities of Weight-Resistance Exercise. Journal of Applied Physiology, 70, 1700-1706.

Tesch, P. A., Colliander, E. B., & Kaiser, P. 1986. Muscle Metabolism During Intensity, Heavy- Resistance Exercise. European Journal of Applied Physiology, 55, 362-6.