from lyle macdonalds site.


Milk: The New Sports Drink? A Review
Title
Roy BD. Milk: the new sports drink? A Review. J Int Soc Sports Nutr. 2008 Oct 2;5:15

ABSTRACT
There has been growing interest in the potential use of bovine milk as an exercise beverage, especially during recovery from resistance training and endurance sports. Based on the limited research, milk appears to be an effective post-resistance exercise beverage that results in favourable acute alterations in protein metabolism. Milk consumption acutely increases muscle protein synthesis, leading to an improved net muscle protein balance. Furthermore, when post-exercise milk consumption is combined with resistance training (12 weeks minimum), greater increases in muscle hypertrophy and lean mass have been observed. Although research with milk is limited, there is some evidence to suggest that milk may be an effective post-exercise beverage for endurance activities. Low-fat milk has been shown to be as effective, if not more effective, than commercially available sports drinks as a rehydration beverage. Milk represents a more nutrient dense beverage choice for individuals who partake in strength and endurance activities, compared to traditional sports drinks. Bovine low-fat fluid milk is a safe and effective post exercise beverage for most individuals, except for those who are lactose intolerant. Further research is warranted to better delineate the possible applications and efficacy of bovine milk in the field of sports nutrition.
My Comments
Milk, like all aspects of nutrition is often surrounded by controversy. From the nutjob tinfoil on the head anti-milk zealots to bodybuilders who say that milk makes you smooth, milk is often thought of as a terrible food for adult humans to eat.

Yet, objectively milk is an excellent source of high quality protein (a mix of casein and whey), carbohydrates (lactose, which admittedly some people have problems digesting) along with providing fluids, highly bio-available calcium, and electrolytes. Old time lifters often built large amounts of muscle mass with a program of squats and a gallon of milk per day; the idea is still around in various incarnations. In contrast to the anti-milk zealots, milk has been shown to have a number of potential health benefits beyond any sporting applications that may exist.
I’m not going to address the controversy regarding milk here, sufficed to say I’m on the side of milk (and dairy foods in general) being excellent for athletes and folks trying to improve body recomposition. The combination of both fast whey and slow casein is excellent for a lot of sporting and athletic applications, dairy calcium improves body composition, etc. And while dairy does contain quite a bit of sodium (which is what I suspect causes the issues with ’smoothness’ for contest bodybuilders), this is only an issue on the day of the contest. Dropping milk out 16 weeks out can only hurt fat loss, not help it.
You can read more about that in Contest Dieting Part 1. As well I discuss dairy proteins (both supplemental and whole food) in detail in The Protein book.

Which brings me in a roundabout way to today’s article which examines recent research examining the potential of milk as a sports drink.
The paper first examines much of what I talked about above, the overall macronutrient profile of milk. In that the recent area of research for sports nutrition revolves around carbohydrate, protein/amino acid intake, along with fluids and electrolytes, milk ends up covering all of those nutritional bases.
As noted above, milk contains a combination of both casein (a slow digesting protein) and whey (fast acting), along with a large proportion of the branched chain amino acids (BCAA). It also contains carbohydrates (lactose, see my note at the end of this piece), along with minerals, both sodium and potassium. Of course, milk automatically contains fluid and hydration/fluid balance is also important for optimal performance and recovery.
Moving on the paper first examines research on milk and resistance training adaptations. A number of studies have been performed from acute (single drink) studies to longer work looking at lean body mass gain. In one acute study, both fat free and whole milk were shown to improve protein synthesis following training; the whole milk worked better although the researchers weren’t sure why.
Of more interest, milk was shown to be superior to a soy based drink (both drinks contained identical protein, carbs and calories) in terms of lean body mass gains over 3-8 weeks. In addition, not only did the milk group gain more lean body mass, they lost a bit of fat. Of some interest, it was thought that the superiority of the milk was due to its slower digestion compared to the soy (a fast protein). As I detail in The Protein Book, in contrast to recurring beliefs that whey is superior post-workout, research shows that a slow or combination slow and fast protein following training appears to be superior in terms of lean body mass gains.
Quoting from the paper’s conclusion:

“Consumption of low-fat milk appears to create an anabolic environment following resistance training and over the long term with training, it appears that greater gains in lean mass and muscle hypertrophy can be obtained. Furthermore, milk may also lead to greater losses of body fat when it is consumed following resistance training.”

Now, moving onto endurance training, it’s first important to note that endurance athletes have a couple of issues to deal with (in terms of both performance and recovery) that strength trainers don’t necessarily have to deal with. This includes hydration and performance during training/competition as well as glycogen re-synthesis and re-hydration following training. While those certainly can be an issue following very voluminous strength training, they tend to be a bigger issue for endurance type training.
Now, about a zillion studies (give or take a couple hundred thousand) have looked at the impact of carb intake on endurance performance. The research is mixed and whether or not carbs help depends on the duration and intensity of training. Of more relevance here, some research has examined whether adding small amounts of protein during endurance competition can help performance. Some of it finds a benefit, some of it doesn’t; there is still some controversy over this issue.
In this vein, some work has examine the impact of milk during endurance training. While some potential benefits (such as increased blood amino acid levels) were seen, no performance benefits were seen and the subjects reported a fuller stomach due to the milk; this was likely due to the milk more slowly emptying from the stomach. This isn’t a good thing and what research has found a benefit of protein during endurance training invariably used faster proteins (whey or casein hydrolysate). I would not recommend milk during training.
However, as a post-workout drink, milk appears to be a good choice for endurance athletes. Some work has found that the combination of protein and carbs leads to better glycogen re-synthesis, however no research has directly examined milk in this context. One study compared chocolate milk to a commercial carbohydrate drink and found that the chocolate milk was at least as good at promoting performance as the carb drink.
With regards to hydration, a previous research review I did examined Milk as an Effective Post-Exercise Rehydration Drink, finding that milk was superior to water or commercial carbohydrate drinks for re-hydration following endurance exercise, presumably due to the sodium and potassium content.
Quoting again from the paper itself, the researchers conclude that

“The limited literature that does exist suggests that milk is as effective as commercially available sports drinks at facilitating recovery for additional performance…Furthermore, milk is also a very effective beverage at promoting fluid recovery following dehydrating exercise in the heat.”

The bottom link is that milk can be an effective post-workout drink for both resistance trainers and endurance athletes.

Practical Application
Clearly the research to date suggests that milk may be a superior post-workout drink following resistance training (at least compared to a fast protein like soy) and may have benefits for endurance athletes as well in terms of promoting glycogen synthesis, recovery and re-hydration following training.
Anyone who has read The Protein Book (or my other books for that matter) knows that I’m big on milk and milk proteins, they have massive advantages in terms of their protein content, dairy calcium, and other effects. Milk is readily available, tasty and relatively inexpensive.
However, there are a couple of caveats. For large athletes who need a large amount of carbohydrates or protein following training, milk may not be an ideal way of getting it. A typical 8-oz serving of milk contains roughly 12 grams of carbohydrates and 8 grams of protein. A large resistance training athlete might need 4-5X that many nutrients following training and drinking that much milk may not be feasible.
A compromise solution might be to use milk as a base and add extra nutrients (such as maltodextrin or dextrose powder for carbs and protein powder for protein) to achieve a higher nutrient density than milk itself can provide. So 16 oz. (2 cups) of milk with extra carbs/protein would get the benefits of milk along with sufficient nutrients for larger athletes to recovery. Similar comments would apply to endurance athletes who often need very large amounts of carbs following exhaustive training; drinking 4+ cups of milk following training may not be feasible.
As a final comment, if there is one major problem with milk for many people, it’s the presence of lactose (milk-sugar). Lactose, like all digestible carbohydrates requires a specific enzyme to be broken down called lactase. However, some people lose the ability to produce lactase/digest lactose; this can occur either completely or relatively (in the latter case, folks can handle small amounts of dairy).
Lactose intolerance, which should not be confused with a true milk allergy, can cause stomach upset, gas, and diarrhea in predisposed people; it’s racially based and some ethnicities are more or less likely to have problems. For those with lactose intolerance, but who wish to use milk following training there are several options.
The first is to find a source of lactose free milk. Brands such as Lactaid add lactase to milk to digest the lactose into glucose and galactose; this typically results in sweeter milk but without the offending lactase. Lactase pills are also available which can be taken with milk to help with digestion. Finally, there are products which claim to increase lactase levels in the gut and some people find that milk consumed with other food is tolerable; additionally, regular yogurt consumption can improve the ability to digest lactose.