The Post-Workout Fuel Puzzle–Shake It Up…Or Not?

post-workout fuel

Plenty of articles have been written by experts in the fitness industry stressing the importance of post-workout “fuel” as a complement to rigorous training. We try to pass some of this information on to our clients, feeling remiss in our professionalism should we neglect to address this vital component of a healthy lifestyle. However, the type of fuel that we suggest is the subject of much scrutiny, and such action inevitably leads to a debate. What should we recommend to our personal training clients when it comes to shakes and post-workout fuel?

The Ubiquitous Protein Shake

You are probably familiar with the research indicating the need to replenish glycogen stores within a magical “window of opportunity” immediately following a workout, which lies somewhere between 45 minutes and 1 hour. During my years as a competitive bodybuilder, I strictly adhered to my Coach’s dogma of downing a protein shake and simple carbohydrates immediately after removing the workout gloves.

If you too are a member of this camp, you are keenly aware of the cost factor involved in living like this! I extolled the virtues of the highest quality whey protein powder, isolate derived through a cold-filtering process, to maximize its bioavailability. I also hydrated the powder shortly prior to consumption, so that the protein structures themselves would not have a chance to degrade. Does any of this sound familiar?

Liquid Or Solid?

Athletes and scientists have recently begun questioning whether post-workout fuel is necessarily optimized in the form of a whey protein shake. Former Academy of Nutrition and Dietetics Spokesperson Christine Gerbstadt, MD, MPH, RD, CSSD, is in favor of experimenting with both shakes and whole foods. However, her window is much smaller, suggesting the athlete refuel within 15 to 20 minutes of a workout’s final lift.

She advocates a 3:1 ratio of carbohydrate to protein at this time, followed by a regular whole food meal 3 to 4 hours later. This combination will help prevent the body from using its own hard-earned muscle tissue for energy and also encourages that all-important anabolic muscle synthesis. Dr. Gerbstadt makes the following suggestions for post-workout replenishment:

~A smoothie made with low-fat milk and fruit

~A serving of low-fat chocolate milk

~A whole-grain wrap containing lean turkey and vegetables

As you can see, she does not discriminate between liquid and solid food, stressing the timing and the proper ratios over the method of delivery to your system. As a scientist myself, I question the use of dairy products at this time. Casein, which is the protein found in dairy products, is a much slower-digesting protein than whey.

I would typically consume casein protein during the afternoons and before retiring for the night, so that muscles could be “fed” throughout the hours between workouts. However, many dietitians do suggest chocolate milk as an easy and inexpensive recovery drink.

And Then There’s The Science

A study published in the Journal of the International Society of Sports Nutrition poses the surprisingly potent question, “Do you really need a post-workout meal?” This inquiry seems to fly in the face of both liquid and whole food choices! The primary researchers delved deeply into the science behind this particular meal.

The purpose of post-exercise nutrition is to replenish depleted glycogen stores. As we know by this point, glycogen is one of the primary fuels needed for effective muscular contraction. Just 3 sets of 12 reps can reduce the body’s glycogen stores to almost half of what they were prior to entering the gym.

Most bodybuilding workouts encompass far more volume than a mere three sets, thereby depleting glycogen even more severely. Refueling lost glycogen is critical to the next training session; and since muscle tissue is in a prime anabolic state after resistance training, the post-workout fuel window of opportunity has traditionally been viewed as the critical time to commence this process. Countless studies have demonstrated that consuming a protein and carbohydrate mix post-workout is the optimal solution.

The authors of one such study found this to be a well-documented dogma, but only in cases when significant resistance training was repeated again within eight hours. Many elite athletes perform what are called “2-day’s”, expending considerable amounts of energy within a time frame of less than 12 hours.

Those who trained only once a day seemed to be garnering sufficient glycogen recovery, but the recovery was spread over many hours. The researchers, therefore, concluded that starting this process with post-workout fuel seemed to be irrelevant, as long as the daily total caloric needs were met during the next 24 hours.

Another study further corroborated these findings. When it comes to proper nutrition for muscle building, meeting your body’s individual overall calorie/macronutrient needs for the day is the most important component, and these macronutrients can just as simply be derived from clean whole foods sources or a protein shake.

A new study from the University of Texas Medical Branch finds that eating a mix of protein types—whey, casein, and soy—immediately post-workout may help athletes meet their desired muscularity even more effectively than ingesting a fast-acting protein alone.

Research indicates that the combination of the three proteins seems to prolong the body’s amino acid delivery to muscles, increasing the amount of time that the muscles remain in their anabolic “growth state.” Different forms of proteins are absorbed by the body at different rates.

Soy is largely considered an “intermediate” deliverer of amino acids, whey offers a “fast” protein and casein is “slow to digest”, taking a few hours to be effectively processed in the body. The longer the muscle tissue can be plied with amino acids, the building blocks of proteins, the better it is for growth and recovery, according to Mark Cope, Nutrition research scientist at Solae Global, the consumer goods company that backed the aforementioned study.

The Final Analysis

There is no denying the convenience and simplicity of a protein shake as post-workout fuel. I dispense the appropriate amount of protein powder in my shaker bottles for the entire week, toss one in my gym bag each day, and hydrate it prior to consumption. On most days I have a brief amount of time between the end of my workout and the arrival of my first client, so again, convenience wins out.

However, science has shown us that a whole food meal of the appropriate macronutrients and calories can be just as beneficial. If you find yourself with the luxury of time after the gym, you will most likely savor the food choices over the liquid supplement. A serving of lean chicken coupled with brown rice would be a perfectly adequate replenishing meal, as would a sweet potato and a piece of fish. Keeping in mind the protein-to-carbohydrate ratio that works best for you, preparing food-based post-workout meals often will satisfy a hungry athlete more readily than a shake.

The Role Of The Personal Trainer

As eager as we are to point our clients in the right direction when it comes to post-workout fuel and general nutrition, we must keep in mind the definition of our professional limits. Offer the information, but do not “assign” meal plans or nutritional directives

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Cathleen Kronemer is an NFPT CEC writer and a member of the NFPT Certification Council Board. Cathleen is an AFAA-Certified Group Exercise Instructor, NSCA-Certified Personal Trainer, ACE-Certified Health Coach, former competitive bodybuilder and freelance writer. She is employed at the Jewish Community Center in St. Louis, MO. Cathleen has been involved in the fitness industry for over three decades. Feel free to contact her at [email protected]. She welcomes your feedback and your comments!