Jan 29, 2015After-Workout Drinks
The latest research shows that milk-based beverages may help with exercise recovery, as well as with gaining muscle mass. Here’s a look at how and when to use them.
By Michelle Rockwell
Michelle Rockwell, MS, RD, is a nutrition consultant for several sports teams ranging from youth to professional. She recently co-launched RK Team Nutrition, at: www.rkteamnutrition.net, and can be reached at: [email protected]
When today’s athletes grab a beverage, many are choosing a new option: the milk-based sports nutrition drink. The number of these drinks on the market has increased rapidly in recent years. In fact, a quick perusal of my local health club’s supplement section revealed more than 20 different varieties, all with slightly different ingredients. That means more options, which is great, but it can also mean more confusion for athletes.
There are ready-to-drink formulas vs. powders, many different combinations of nutrients, varying amounts of milk protein, and a plethora of flavors. Some companies market their products as recovery drinks, while others call them meal replacements, and still others tout them as a way to boost calcium intake. And their nutrition labels are jam-packed with lots of fancy-sounding ingredients.
So how can you advise your athletes on the use of milk-based nutrition beverages? Let’s take a look at their nutritional composition, how and when they work best, and what type of athlete benefits most.
OPENING THE LID
Milk-based products all contain actual milk (and/or soy milk) or different combinations of modified milk proteins. One of the most popular milk proteins added is whey protein isolate.
Milk has two primary proteins, whey and casein. When milk is curdled (or made into cheese or cottage cheese), the solid portion is casein, while the remaining liquid is whey. Interestingly, for years and years, the whey liquid was discarded as a useless waste product during cheese-making. Now we know that whey protein is actually a high quality protein source–it is rich in branched-chain amino acids, which are important to exercising muscles. Whey protein isolate is produced by separating whey protein even further and eliminating non-protein compounds to make a pure protein product.
Most of the popular milk-based beverages are good sources of protein, containing 10 to 40 grams per serving. In addition to helping athletes achieve overall protein needs, the protein is significant because it has been found to enhance muscle synthesis after strength training, a concept I will detail in the next section of this article.
There may also be other benefits of protein, although they have not been confirmed with enough research. Some manufacturers claim that certain proteins or amino acid combinations can enhance immune function, but not all studies support this notion. Some of these beverages are also fortified with glutamine (in addition to the glutamine that occurs naturally in some of the ingredients) because it has been theorized to be involved with muscle recovery and synthesis. However, studies have not confirmed this. Some research has shown that consuming protein during the recovery period prevents muscle damage caused by exercise-induced circulating free radicals, but more research is needed in this area, too.
The carbohydrate content of milk-based beverages varies widely, from 10 to as much as 90 grams per serving. The source of carbohydrates is typically a combination of simple sugars (such as dextrose or sucrose) and starches. In some cases, lactose, the naturally occurring sugar in milk, has been mostly removed from the beverages. However, most still contain some lactose.
Fat content varies from about two to 15 grams per serving, sometimes derived from the milk ingredients but more often from added oils and fats. The fat enhances the product’s taste and texture, but obviously would be detrimental to athletes who are concerned with weight gain. At least two available products contain medium chain triglycerides. They are marketed as being better utilized during activity–although peer-reviewed research to support this claim is lacking.
In terms of vitamins and minerals, many milk-based beverages are naturally high in calcium, zinc, and vitamin D due to their milk base. Calcium content ranges from 300 to 600 mg per serving, which represents 20 to 50 percent of athletes’ daily needs, depending on age and gender. If the powdered beverages are mixed with milk, there is opportunity for even more calcium, protein, and carbohydrate. If they are mixed with juice, they may be good sources of vitamin C and contain additional carbohydrates.
Most products are also fortified with extra vitamins and minerals, which is a plus. There are a few products that contain creatine, caffeine, or other supplemental additives and thus should be used with caution. Additional ingredients found in some (but not all) of these beverages include stabilizers, thickeners, artificial flavoring, coloring, and sweeteners.
A growing body of research supports the notion that nutrients consumed after intense exercise can play a critical role in exercise recovery for activities ranging from weightlifting to stop-and-go sports to endurance training. More specifically, it has been shown that glycogen re-synthesis (replacing carbohydrate stores in the liver and muscle), muscle synthesis and breakdown, and overall adaptation to training may be influenced by consuming carbohydrates and protein in the post-exercise period.
In terms of carbohydrates, athletes should consume approximately one gram of carbohydrate per kg of body weight as soon as possible post-exercise for workouts that are intense and/or long. For example, a 150-pound athlete (who weighs 68 kg) should aim for 65 to 70 grams of carbohydrates, and a 250-pound athlete (who weighs 113 kg) should aim for 110 to 115 grams of carbohydrates as soon as possible post-workout. Athletes who are training in primarily anaerobic activities or for a shorter duration would need lower levels of carbohydrates.
Since rapid absorption of carbohydrates is desirable, high glycemic carbohydrates are recommended. The simple sugars used in most milk-based beverages fit this bill. In fact, athletes who are concerned about how much sugar the beverages contain are often surprised to learn that the sugar is justified when it comes to recovery.
In terms of protein, smaller amounts are needed. Researchers originally hypothesized that post-exercise protein enhances glycogen synthesis, but more recent studies have shown that as long as adequate carbohydrates are taken in, protein does not further enhance glycogen synthesis. Nevertheless, protein intake is believed to be valuable for reducing post-exercise muscle breakdown and stimulating muscle synthesis, allowing athletes to make the greatest muscular adaptations to strength training.
For most athletes, 15 to 20 grams of protein (or six to 10 grams of essential amino acids) is sufficient to promote these changes. Many milk-based products are within this range. Because less research has been conducted on post-workout protein needs as compared to carbohydrate needs, recommendations are based primarily on average-weight male exercisers. In the future, we may have more specific recommendations for different athletes.
If you want an easier formula for figuring out carb and protein post-workout needs, some researchers and sports nutrition professionals recommend a 4:1 ratio of carbohydrates to protein. For example, 60 grams of carbohydrate and 15 grams of protein would suffice.
HOW ABOUT CHOCOLATE MILK? Chocolate milk has recently been touted as an ideal recovery beverage. It is true that low-fat chocolate milk has an approximate 4:1 ratio of carbohydrates to protein, which gives it a higher concentration of carbohydrates compared to white milk. The cost can also be a fraction of the ready-to-drink milk-based beverages and the taste is well received by many.
On the other hand, athletes must consume more chocolate milk than almost any of the pre-made milk-based beverages to achieve the same amount of calories, protein, and carbohydrates. While low-fat chocolate milk has 220 calories in 11 ounces, many milk-based drinks (which often come in 11-ounce servings) have over 350 calories. Similarly, chocolate milk contains about one gram of protein per ounce while many milk-based beverages have three to five grams of protein per ounce. If not careful to chose low-fat or reduced-fat varieties, chocolate milk may contain more saturated fat than milk-based drinks.
Another consideration with chocolate milk is that it is rich in lactose which presents digestibility problems for some individuals. Although true lactose intolerance is rare, many athletes report negative side effects following milk consumption. Many of these same athletes tolerate milk-based beverages better, potentially because they have significantly less lactose.
A study published by the International Journal of Sport Nutrition and Exercise Metabolism in 2006 on chocolate milk gained a lot of media attention. Subjects in the study were provided with equal amounts of either chocolate milk, Gatorade, or Endurox R4 (a sports beverage containing carbs and protein) after an interval cycling workout and then again after two hours of recovery. In two more hours, they cycled to fatigue at 70 percent of VO2 max. Subjects who drank chocolate milk performed about as well as those who drank Gatorade and significantly better than those who drank Endurox R4. Researchers concluded that “chocolate milk is an effective recovery aid.”
But the media presented the study’s results vaguely, and in some cases inaccurately, by using such headlines as “Chocolate Milk Shown to be Better Than Gatorade for Athletes” and “Chocolate Milk, A Better Sports Drink for Athletes.” In truth, chocolate milk was found to be similar to Gatorade for recovery, not better.
It’s also difficult to interpret the study’s results because there was no placebo used (such as a group that consumed a calorie-free drink) to compare subjects’ performance if they hadn’t had any calories at all. Furthermore, because the amount of calories subjects received varied among groups, it’s possible that chocolate milk performed better than other beverages simply because it contained the most calories. Finally, it is unclear why both the chocolate milk and Gatorade out-performed the Endurox R4 since its nutritional composition is somewhat similar to chocolate milk. To make matters even more confusing, other published studies have not found a performance benefit of milk over sports drink or placebo during 10 weeks of strength training.
The results of the chocolate milk study are very interesting and provoke further research. Since athletes may have heard misleading conclusions based on this study, they might need guidance to separate the facts from the hype.
Along with aiding in athletes’ adaptation to training, the specific ingredients in milk-based beverages may also help them gain muscle mass. Some studies have shown that whey protein outperforms other protein sources in promoting gains in lean body mass and strength. Others have found whey plus casein protein supplementation to be more effective than whey protein alone. Finally, others have shown that the specific source of the protein supplement doesn’t matter–what matters is simply taking in extra protein and calories at the right time.
In my professional experience, this last factor seems to be the most important. Using milk-based sports nutrition beverages helps athletes achieve a positive energy balance (eating more calories than they are expending) and nitrogen balance (indicating adequate overall protein intake). It also helps them meet the recommendation of eating five or six times per day.
For example, Sara is a 17-year-old Olympic-level swimmer who has a goal of increasing her strength and power and gaining six to eight pounds of lean mass. Her caloric expenditure was calculated as 4,200 calories per day during her heavy training period. Even after increasing the size of breakfast and lunch and adding a snack in the evening, Sara was still only consuming 3,500 calories per day and maintaining her weight (rather than gaining) despite feeling quite full.
Adding a milk-based beverage after her morning swim, a time when she hadn’t been eating anything, and another mid-afternoon, was an easy way for Sara to increase her caloric intake by 700 calories per day and better meet her protein needs. She also enjoyed these drinks–she chose a chocolate flavor and said it tasted like a special treat. Sara stated it was the first time she had eaten guilt-free chocolate in a long, long time.
From the opposite perspective, athletes who do not wish to gain weight may find drinking milk-based sports nutrition beverages provides them with extra, unwanted pounds. At approximately 200 to 400 calories per serving, athletes who don’t want to gain weight must adjust their intake of other food and beverages appropriately if they intend to use these products during the day or post-workout.
For example, an athlete who goes from an 11 a.m. lunch to 4 p.m. training without eating is likely to benefit from an energy standpoint by consuming a milk-based product mid-afternoon. However, if this athlete (who was already in energy balance) does not decrease his or her calorie intake at other times during the day, he or she could gain undesired weight.
WHEN TO USE
In general, the American Dietetic Association recommends that individuals strive to achieve their nutritional goals through actual food and beverage products rather than through supplements. The most important reason for this recommendation is that there are many components of food known to be beneficial that cannot be extracted and inserted into a supplement. For this reason, I advise athletes to avoid thinking of milk-based sports nutrition beverages as “meal replacements” even though they may be marketed as such. Instead, athletes should strive to take in well-balanced foods and beverages at least three or four times per day.
However, I do feel there is an important place for milk-based products in many athletes’ diets, as long as they are regarded as a dietary supplement rather than food replacement. Here are the factors to keep in mind:
Post-workout: It is important to note that, in addition to supplements, there are many actual food and beverage sources well-suited for post-exercise recovery. In keeping with the guidelines of high glycemic carbohydrates, appropriate selections would be bagels, rice cakes, potatoes, sugary candy such as jelly beans or Skittles, and traditional sports drinks. To obtain 15 to 20 grams of protein, athletes can combine one of these with two tablespoons of peanut butter, two ounces of cheese, two cups of milk or yogurt, or three ounces of meat. Of course, athletes should also be rehydrating after a workout.
However, if an athlete won’t take the time to prepare a post-workout snack with the correct amount of carbohydrates and protein, a milk-based recovery drink is an easy alternative. In addition, since many athletes complete exercise in a dehydrated state, a milk-based recovery drink doubles as a hydration source.
The ease of having quality nutrients packaged in an easily transported form is also quite beneficial for many athletes. Despite being milk-based, most products do not require refrigeration and can be stored in gym bags, locker rooms, and other readily available locations for athletes. For those who have a strong taste preference for these beverages chilled, some extra planning is needed–but not much. I have worked with athletes who place their beverage in an ice bag before their workout and then use the ice bag for treatment or rehab while they drink their beverage post-workout. Of course, you can also have a cooler or refrigerator in the locker room stocked with these beverages.
Pregame snack: Consuming enough calories before a game or meet to provide long-lasting energy can be a problem for athletes with “nervous” stomachs. Many athletes find they cannot tolerate (or are unwilling to try) solid foods before their contests. Since liquids are often absorbed from the stomach more quickly, athletes may feel more comfortable competing after liquid nutrients than solids, making milk-based products a good option.
Time demands: While milk-based products should not be viewed as a good excuse for skipping breakfast or lunch, replacing meals on an occasional basis due to time demands is fine. For athletes who simply can’t find time for lunch on days when they have classes, lab, and practice without a break, definitely suggest they pack milk-based beverages in their knapsacks. Getting some nutrients–even if not perfect in composition–is better than getting none at all.
Calcium: More and more studies are finding that athletes, both male and female, fail to meet their daily needs for calcium. Most male athletes need at least 1,000 to 1,200 mg of calcium per day while female athletes need at least 1,200 to 1,500 mg. Sufficient calcium intake is required for optimal bone mineralization and proper muscle function and may even play a role in minimizing body fat. Calcium deficiency, especially when it exists over time, can predispose athletes to stress fractures, osteoporosis as they age, and even muscle cramping.
We are in an era when young people do a poor job of meeting calcium needs through diet, no matter how much we preach to them the importance of it. Milk-based beverages can provide a good method for improvement.
Needing more calories: Athletes looking to gain weight often report that adding in another meal, eating more calories at meals, or finding time to prepare meals is too cumbersome. However, many find it less time-consuming to increase their consumption of beverages. For them, drinking milk-based products is an easy way to add calories to their diet. In addition, when an athlete feels too full to eat more solid food, they often may be able to tolerate liquids. And when exercise and heat have curtailed an athlete’s appetite, liquids may still be appealing, especially right after training.
Watching calories: For athletes who don’t need to gain weight, milk-based drinks may not be a good idea. Many weight-conscious athletes tell me they skip recovery beverages in order to consume calories at a more preferred time. For athletes trying to avoid weight gain, this rationale may be on-target and I don’t advise them differently.
However, some athletes simply need to be educated that quality calories consumed post-exercise may be much more important than calories consumed at other times of day, because they benefit performance and recovery. If I feel athletes can cut calories elsewhere, I talk to them about prioritizing their nutrient intake so there is room for the calories in milk-based recovery products after their workouts.
Nutrition deficiencies: Many of these beverages have extra vitamins and minerals, which can help athletes who have a poor quality diet or are on a limited budget. However, some athletes have specific micronutrient deficiencies that are better met by foods. For example, an iron deficient athlete would get substantially more iron from a roast beef sub and sports drink or fruit/nut trail mix and orange juice than from most milk-based beverages. Ideally, an athlete with nutrition deficiencies should see a sports dietitian.
Allergies: Athletes who have an allergy to milk should avoid milk-based products or select a beverage that is based exclusively on soy milk. Casein and whey (milk proteins that are the allergen substance) sometimes exist in higher quantities in milk-based beverages than in regular milk.
NCAA rules: If you are providing these drinks to athletes at an NCAA Division I or II institution, be careful to avoid violating NCAA bylaw 16.5.2.g (Division I) or bylaw 16.5.1.h (Division II), which outlines which supplements athletic departments are permitted to provide to athletes. This rule disallows athletic department staff members from distributing any product in which more than 30 percent of calories come from protein or any product with added protein from artificial, non-whole-food sources (often referred to on a label as a “protein blend” or “proprietary protein.”) Products that contain added amino acids or amino acid chelates are also impermissible.
In a few cases, companies have modified some of their products to meet the NCAA requirement of less than 30 percent protein. These products are higher in carbohydrates than some of the traditional or “light” milk-based products on the market.
Clearly, there are many considerations athletes and those advising them should make when evaluating the ever-growing milk-based beverage options. In all cases, keep in mind that they may be a beneficial component of a well-designed training plan and diet. But they should always be thought of as supplements to hard work and healthy eating, not as replacements.
References for this article can be found here.
Sidebar: LABEL LINGO
The nutrition information listed on supplements can be confusing for athletes. Below are some brief tips for becoming label-savvy when evaluating milk-based sports nutrition beverages.
Protein isolates are produced by removing non-protein compounds (such as fat, carbohydrates, lactose, and sodium) to form a product that is at least 90 percent protein. Milk protein isolates (which contain both casein and whey) and whey protein isolates are common in milk-based beverages.
Protein concentrates are produced similarly to isolates, but through a less expensive process that produces a product that is at least 75 percent protein. Whey protein concentrate and soy protein concentrate (among others) are common in milk-based beverages.
Amino acids are the building blocks for protein. Some are involved in muscle synthesis and energy production more than others, but research on whether high levels of any specific amino acid is beneficial is still ongoing. Any of the following on an ingredient list indicate the presence of an amino acid that has been added individually: alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, and valine. Some people theorize that the branched-chain amino acids (leucine, isoleucine, and valine) may be beneficial for reducing fatigue, that glutamine may help with recovery, and that arginine may promote muscle gain.
Sugars are recommended for recovery after intense exercise, particularly those that have a high glycemic index. Any of the following listed in the ingredients section on a label would indicate the presence of carbohydrates in the form of sugar: dextrose (glucose), sucrose, fructose, lactose, maltose, sucrose syrup, high fructose corn syrup, and fruit juice concentrate. Athletes doing shorter or more anaerobic-based exercise may want to select lower sugar milk-based beverages.
Sugar alcohols are much sweeter than regular sugar and are used to sweeten many low carbohydrate and low sugar products. Any of the following listed in the ingredients section on a label would indicate the presence of sugar alcohols: sorbitol, xylitol, and mannitol. Note that products containing sugar alcohols may be labeled as “low carb” or “low sugar” even if they are not low in calories. Some athletes experience gastrointestinal side effects when consuming significant amounts of sugar alcohols.
The Daily Value (DV) established for calcium is 1,000 mg for a 2,000 calorie diet. Most athletes need 1,200 to 1,500 mg of calcium a day, or even more. It’s important to know the 1,000 mg number because vitamin and mineral content is expressed as a percent of DV on food labels. So, a milk-based product that lists 30 percent DV for calcium contains 300 mg, and is only one quarter (or less) of what an athlete would need.