Understanding the importance of food intake to support clients’ workouts depends partly on science, and also on each one’s body unique response to the demands of physical exercise. In a society that tends to shun carbohydrates in general, how can we best guide them towards the optimal post-workout carbs as a recovery energy source?
Energy from Within
During exercise, hard-working muscles use glucose (readily available) and glycogen (stored sources) for energy. Glycogen stored in muscle cells pulls water inward to increase not only the cell volume but also the fullness within muscle fibers. Research suggests that a greater muscle cell volume can lead to long-term growth.
At some point during an intense lifting session, blood glucose levels and glycogen stores drop so precipitously low that exercise cannot continue. We refer to this state as “going to failure”, that overwhelming sensation of not having enough power/strength to complete another single repetition. Here, the body begins to secrete the “stress hormone” cortisol, a highly catabolic chemical. Cortisol eats up muscle tissue for protein, converting it into usable glucose. A process called gluconeogenesis ensues, producing glucose from these amino acids in the liver. This results in a loss of muscle tissue.
As we know, strength training causes micro-tears in the muscles’ fibers, and sweating causes the loss of fluids replete with electrolytes. Post-workout nutrients, therefore, take on a critical importance, essential for replenishing muscle glycogen depleted from physical demands. In addition, consuming an exercise recovery meal helps stimulate protein synthesis to repair and build new muscle tissue while restoring fluid and electrolyte balance.
Focus on Nutrient Timing
According to research, consuming the appropriate ratio of carbohydrates to protein can greatly impact the success of one’s recovery. When to eat post-workout depends upon the type of exercise in which the client has engaged.
Intense weight resistance workouts, with a goal of increasing muscle size, favor the consumption of 20-30 grams (g) of lean protein with 30-40 grams of clean simple carbohydrates, ideally within 30 minutes of completing training. Shakes work extremely well for such athletes. Following lighter aerobic workouts, with a goal of staying in shape, experts suggest eating a well-balanced whole-food meal within an hour of exercising. The protein/carb ratio remains the same.
Of course, these specific macronutrient amounts vary with the size of the individual, an important aspect to keep in mind. (Always consult a Registered Sports Dietitian for assistance with specific guidelines before counseling clients.)
Proper nutrient balance following training allows for the release of insulin, one of several anabolic or muscle-building hormones in the body. Clients who consistently train with heavy loads, especially in the absence of steroid supplementation, need to maximize the release of the body’s anabolic hormones through any naturally available method.
The Great Importance of the Glycemic Index
A working knowledge of glycemic index helps trainers convey information regarding post-workout food choices. Glycemic index, or GI, measures how quickly a food raises blood sugar and insulin levels. Typically, we coach our clients to eat lower glycemic foods throughout the day (complex, slow-digesting carbohydrates) so as not to initiate an insulin spike. Foods with an assigned GI rating of 55 and under rate as low. But post-workout, the body requires the exact opposite.
Following intense exercise, the body needs carbs and protein shuttled to the muscle cells as fast as possible. An elevated insulin levels facilitates the driving of nutrients into these hungry muscle cells. High-glycemic carbs (with a rating of 70 or above) work optimally for this purpose. Insulin attaches to receptors on muscle cells, allowing a greater uptake of carbs, creatine, carnitine and other amino acids, all of which serve critical processes in muscle repair and recovery.
Carbs consumed immediately post-workout can result in a beneficial “super-compensation” of glycogen. Research has found that delaying the ingestion of carbs by even 2 hours following training can reduce not only glycogen replenishing but also recovery by 50%.
Too Many Post-Workout Carbs to Choose From?
When it comes to high GI, post-workout carbs, you have to read labels. There are lots of unusual and unfamiliar options that you have to know to spot. Here are a few:
Dextrose/maltodextrin combo This rates as the old school bodybuilder post-workout mix of choice. The combo has a fast uptake and causes less bloat due to the combination of molecule sizes; however, some still suffer from that side effect. The downside to dextrose is that it can cause GI distress due to the low molecular weight and high osmolality – it draws water into the GI tract, leading to the “bloat”.
Sucrose/high fructose corn syrup The debate surrounding whether high fructose corn syrup functions the same as naturally occurring sucrose continues to swirl. Some chemists concur, while others cite the creation of damaging reactive carbonyls, which occurs when the bond between the glucose and fructose is broken. Around 49% of the sugar found in fruits is fructose which, upon consumption, travels to the liver before being converted to glucose. This, in turn, further delays absorption to the critical areas of the body following a workout.
Waxy maize starch This sugar has a low osmolality and high molecular weight, which translates to larger molecules of starch. Thus far, the only proven claims about waxy maize show that its higher molecular weight classifies it as a long-chain complex (redundant) carbohydrate. Studies show that the greater the molecular weight of a carbohydrate, the more chains of glucose it contains and therefore takes longer to break down, delaying absorption. Waxy maize may prove beneficial for the endurance client, who out of necessity favors a steady supply and release of energy over time, compared to the rapidly digesting maltodextrin.
Side-by-side comparative research indicates that the bloodstream absorbs maltodextrin better and faster than any other simple carbohydrate sources. In order to “refuel” glycogen to the muscles, glucose must be delivered to the bloodstream, traveling on to the liver and muscles for conversion to and storage as glycogen. Maltodextrin provides an insulin spike far superior to any other source. Upon ingesting a carbohydrate food source, absorption occurs through the intestines, the majority taking place in the duodenum. Maltodextrin begins to degrade in the mouth and stomach, the work of salivary amylase, which easily breaks the weak hydrogen bonds holding the chemical together.
A Fun New Option
Many lifters I know have abandoned the “real food” simple carbs post-workout in favor of seizing the opportunity to satisfy a sweet tooth. Of all things, they gravitate toward gummy bears! I immediately dismissed this as empty calories. However, surprisingly, the research advocating and supporting this choice really exists! It turns out that playfully enjoying 15-20 of the ever-popular Haribo Gummi Bears provides 30-40 grams of simple carbs! (And if you choose not to eat them, at least read the reviews and questions on the Amazon listing for a good laught)
Do Not Rush to Shake Off the Whey Shake
The whey protein shake, often touted as the ideal source of immediate post-workout supplementation, still offers tremendous muscle-recovery potential. With so much talk regarding the importance of simple carbohydrates, where might the shake fit in? A 2011 study published in Medicine and Science in Sports and Exercise investigated this very question.
Researchers compared the effects of consuming 25 grams of whey protein against 25 grams of whey protein plus 50 grams of carbohydrates, to note whether the carbs played a significant role in raising insulin levels. They did not. The concurrent ingestion of 50 g of CHO with 25 g of protein did not stimulate mixed muscle protein synthesis or inhibit muscle protein breakdown any more than 25 g of protein alone, either at rest or after resistance exercise.
In another study, 12 healthy volunteers were served drinks consisting of either pure glucose (reference drink) or glucose supplemented with free amino acids or whey proteins. The beverage containing the branched-chain amino acids isoleucine, leucine, valine, and threonine (BCAA’s) elicited a significantly higher insulin response than the glucose drink alone. In fact, the insulin peak mimicked the glycemic and insulinemic responses observed following consumption of a high-quality whey protein shake.
Where should we go with these seemingly controversial results? It remains my strong conviction that, for starters, whey protein sources vary in quality, depending upon processing. I always counsel clients to take the time necessary to seek out the highest quality product they can comfortably afford. The BCAA’s typically found in such products also lend a significant hand in facilitating muscle recovery and rebuilding.
Regarding the simple carbohydrates post-workout, I continue to support the necessity of this macronutrient, and especially the timing of its ingestion. Learn as much as you can about the different types available, in addition to those presented here. Remember, what happens “in the kitchen”, so to speak, often exerts an even more dramatic effect than the workout upon the long-term success of a bodybuilder.