By diving into the most recent literature on protein intake for athletes, these authors shake up some misconceptions and offer up-to-date advice.
This article first appeared in the April 2016 issue of Training and Conditioning.
By Dr. Lonnie Lowery and Mary Catherine Powers
Lonnie Lowery, PhD, RD, LD, FISSN, is an Associate Professor in the Department of Human Performance and Sport Business at the University of Mount Union. He is the author of Dietary Protein & Resistance Exercise, co-hosts the Iron Radio podcast, and has completed numerous studies on dietary protein and health. He can be reached at: email@example.com.
Mary Catherine Powers, CSCS, is a Graduate Assistant Strength and Conditioning Coach at Kent State University.
Athletes need protein to maximize performance—that much we all know. But when it comes to the specific types to consume, how much to consume, and when to consume them, things are less clear-cut to athletes.
The use of dietary protein for performance gains has an interesting and controversial history. From early gym lore suggesting athletes take in as much as possible to the protein dissuasion that occasionally surfaced in the 1990s and early 2000s, few nutrients have been accompanied by such mixed messages.
The truth lies somewhere in the middle and evolves as we discover more about the role of protein. Research on the topic is constantly progressing, and athletes have to adapt to the latest findings. This may require letting some commonly held beliefs fall by the wayside, but doing so will help athletes optimize this vital nutrient.
To start, it’s important to understand the basics of what proteins are and how to incorporate them into athletes’ diets. Among the macronutrients, proteins are unique because they serve many roles in the body, such as boosting gains in muscle mass, enhancing exercise recovery, and regulating tissues and organs. In addition, unlike carbohydrates and fats, they are not a preferred fuel source.
Human proteins are made of 20 different amino acids. Nine of those amino acids are considered essential—our bodies cannot manufacture them, so we must consume them in our diets.
Complete protein sources like meat, eggs, and dairy include all the essential amino acids. Egg protein used to be considered the gold standard for increasing muscle mass, but that honor is now held by whey.
Derived from processing cows’ milk, whey is one of the most popular types of protein used in the strength world. Studies have shown that it increases post-workout muscle protein synthesis more than casein (another dairy protein) or soy. It is also sometimes (depending on use/intent) considered superior to casein because of its leucine content, solubility, and speed of absorption.
On the other hand, casein is a slower-releasing protein than whey, egg, or soy. For this reason, consuming it before bed may reduce muscle breakdown during the overnight fasting period. Furthermore, casein may enhance health in other ways, namely by reducing blood pressure or bolstering the immune system.
Incomplete proteins—those that don’t contain all the essential amino acids—include plant-based sources like legumes, nuts, and grains. Soybean protein is more complete than many plant proteins but still does not compare well with dairy for muscle gains.
Athletes who don’t consume animal proteins can combine complementary plant proteins (e.g., grains and beans) to meet their essential amino acid needs. Supplementation can also help. For example, a vegan athlete might take soy protein with a few grams of the amino acids methionine or pea protein with added leucine.
HOW THEY WORK
Many of the latest findings on protein have helped us better comprehend what’s happening “under the hood.” Protein synthesis is a complex orchestration of molecules that can be manipulated by resistance exercise, endurance training, anabolic hormones, and dietary intake. Traditionally, our understanding of the process has been that when a muscle cell synthesized a new protein, a messenger RNA left the nucleus and traveled to the “ribosome factory” in the cell. Here, it coded the exact sequence of amino acids needed for the protein to work effectively.
Yet there’s more to protein synthesis than many previously believed. Fifteen years ago, researchers discovered mTOR (also called mTORC), a particular portion of the cellular pathway that serves as a primary driver of muscle growth. More recent findings have shown that scientists’ understanding of mTOR has evolved—other systems are involved in building muscle, too.
For instance, a 2014 study from Tufts University published in The FASEB Journal suggests that part of the control of muscle growth may have been overlooked. Micro-RNAs—tiny RNA molecules that repress gene activity and muscle protein production—appear to be important in reducing “anabolic sensitivity,” a condition that determines how well athletes can drive new muscle gains with protein intake and strength training. Therefore, if anabolic sensitivity is interfered with, less muscle growth takes place.
“How much protein should I be eating?” It’s probably the most frequently asked question about protein, and the answer changes as research advances. Scientists in the 1980s and 1990s used nitrogen balance studies (comparing nitrogen “in” via diet minus nitrogen “out” in urine, sweat, etc.) and stable isotopes to suggest a daily intake of 1.2 to 1.8 grams per kilogram of bodyweight for resistance athletes and 1.0 g/kg for endurance athletes. However, the Recommended Dietary Allowance (RDA) for the general population has long been set at 0.8 g/kg.
Despite these relatively modest guidelines, some athletes still believe the myth that increasingly more protein equals greater strength gains. We now know that’s simply not true. Very large protein intakes (above 1.8 g/kg daily) are likely to be broken down and the nitrogen excreted. An endless linear increase in protein intake does not correlate to ever more muscle mass.
However, excessive intake by athletes in the past has led health educators to warn against the potentially harmful effects of high-protein diets, including renal stress, dehydration, gout, bone catabolism, and reduced diet quality. Very little data supports these claims, though. In fact, most of the evidence suggests that consuming large amounts of protein daily has no negative repercussions for healthy athletes. Investigations on resistance athletes specifically in the late 1990s and early 2000s found no adverse effects on renal or bone health while following a high-protein diet.
In addition, I worked on three separate studies in 2009, 2011, and 2012 that supported this conclusion. Our findings suggested that weight trainers who consumed well over 200 grams of protein daily for at least a decade did not experience kidney damage, bone loss, dehydration, or hampered dietary quality.
Beyond accounting for athlete type, total calorie intake is a critical consideration when determining daily protein needs. Research done in the 1980s showed that protein needs increased as calorie intake declined. Later, the reverse was also found true—the more calories consumed, the less protein needed. Recent data from a 2006 study in Applied Physiology, Nutrition, and Metabolism highlighted this relationship by showing that a group of well-fed resistance athletes had adapted to actually need less protein.
Being cognizant of daily protein intake is necessary, but athletes should also be aware of how much they consume at each sitting. Research-backed per-meal protein dosing information has only been explored relatively recently—for years, sports nutritionists could only speculate.
A 2000 study in the Journal of Applied Physiology finally suggested that as little as six grams of essential amino acids added to 35 grams of sugar were effective at stimulating protein synthesis. This provided a rough minimum needed for muscular growth.
Many then wondered if we could optimize the protein synthetic machinery with a higher intake. This was later clarified by a 2009 study in the American Journal of Clinical Nutrition, which showed maximal protein synthesis in young resistance athletes after consuming 20 grams of egg protein.
Just when it felt like we had a per-meal dosing standard figured out, new research seemed to turn everything upside down again. At the 2015 International Society of Sports Nutrition conference, protein expert Robert Wolfe, PhD, Director of the Center for Translational Research in Aging and Longevity at the University of Arkansas for Medical Sciences, suggested that a huge protein intake of 70 grams per meal may enhance net protein retention in the body—not by stimulating more growth but by suppressing natural losses. Although there are issues when measuring whole-body versus muscle-specific protein balance, Wolfe argued that by looking at synthesis-versus-breakdown with isotopes, we could get a more complete picture of what athletes should be consuming. The breakdown side of the equation had been overlooked before, as synthesis was always considered more important in typical six- to 20-gram portions. Wolfe’s data will likely reignite the debate about what makes an optimal dose, as 70 grams is larger than the entire RDA for some athletes.
So what are athletes to do with this conflicting data? One way to find an individual’s ideal dose is to have him or her consume 20 grams of egg, whey, or casein after workouts for two to three months. Then, follow that up with another two- or three-month block of taking 70 grams post-training. The athlete should monitor his or her body composition and performance for both protein doses to see if fat-free mass or strength are gained. (See “Just Right” below for a sample athlete who followed this protocol.)
TIME TO EAT
By now, almost all athletes have been told to consume protein immediately following a workout. This practice stems from two studies in the mid-1990s that reported an elevation in protein synthesis for 24 to 48 hours after resistance exercises. Speculation began about the need to consume protein as soon as possible post-workout, and now it’s a common part of training for many athletes.
Yet, like many issues surrounding protein, this theory has drawn critical attention. A 2012 chapter in Dietary Protein and Resistance Exercise titled, “Dietary Protein Efficacy: Dose and Peri-Exercise Timing,” called into question the need for post-workout protein. The authors pointed out there is nothing magical about the immediate post-exercise period other than a stimulation of lingering protein synthesis that continues during a time in which protein is likely to be consumed anyway. In partial support of this stance, a 2015 study in Applied Physiology, Nutrition, and Metabolism reported that supplemental protein consumed after resistance exercise did not augment gains over four weeks of training in novice lifters.
What does this mean for athletes? They no longer have to worry about downing a protein shake immediately after a workout. Although helpful, it’s not a make-or-break proposition. Instead, their focus should be on eating a protein-rich meal or snack every two to four hours over the 24 hours. A scoop (about 20 grams) of whey or a whey-casein blend or 20 grams of egg protein within a couple hours of exercise should suffice to get the ball rolling. Other meal examples include two eggs with two to four pieces of toast or a potato, several pieces of turkey on one or two sandwiches, or a tuna wrap and milk.
The available research shows that using dietary protein as a tool for athletes is complicated. Understanding what proteins are, how they are metabolized, and what to realistically expect from their ingestion can make things easier. And although the dose and timing recommendations are in flux, the key is doing what works best for each athlete.
To view the references for this article, go to: Training-Conditioning.com/References.
RAISE THE BAR
Protein supplements come in a variety of products: functional foods (regular groceries with added protein), powders, and bars being the most popular. Of the three, protein bars rank the highest in terms of convenience, as they are portable sources of nutrition that are unlikely to spoil.
Since protein bars are often marketed to athletes, many believe they are a healthy, effective way to get protein. This is partially true. Unfortunately, some protein bars may not be all that they’re marketed to be.
Looking beyond the basic Nutrition Facts panel is essential. A bar could list 20 grams of protein on its label, but this could mostly consist of incomplete proteins like gelatin and collagen, which won’t assist with muscle growth or repair. Since an ingredients list is created in order of quantity, seeing one of these poor proteins toward the top doesn’t bode well for muscle protein synthesis. If athletes are going to utilize protein bars, look for those that include quality protein sources like whey, casein, or soy.
Jim, a 22-year-old football player, is interested in seeing how anabolically sensitive he is—whether he experiences sufficient muscle growth consuming a single scoop of whey after his four lifting sessions each week or if he needs two to three scoops. He jots down a typical day dietary log, undergoes skinfold testing at the local university, and settles on a 12-week fixed training regimen to put his protein plan to the test.
Jim starts his cycle by taking a single scoop of whey protein after each workout. He records a diet log to make sure his food intake remains consistent and carefully documents his training. At the end of 12 weeks, Jim’s skinfold testing suggests he’s gained 4.4 pounds of fat-free mass. He’s also added about five percent to his bench press and squat.
After resting for one week, Jim switches to taking three scoops of whey protein post-workout. He does his best to follow his previously recorded diet and training logs.
Twelve weeks later, Jim has gained an additional 4.0 pounds of fat-free mass using the high-protein doses and put another five percent on his bench and squat. He concludes that he’s anabolically sensitive and only needs one scoop of whey after workouts to see gains.