Athletes with a compressed recovery time (i.e., soccer/tennis tournaments, track/swim meets, or simply an intense mid season schedule), are constantly seeking ways to prepare their body for the next event.  The process of recovery from such heavy exercise is highly complex, including aspects of fuel replenishment (glycogen replacement), muscle repair (muscle protein synthesis), and rehydration.  For more information on maximizing muscle protein synthesis see my previous blog.  Carbohydrates (CHO) taken immediately after the event has long been known to improve glycogen resynthesis.  Recently attention to CHO and protein (PRO) has been reported by some to enhance post-exercise recovery compared to CHO alone.  In particular Chocolate Milk has generated a significant amount of research funding (from interest groups such as the National Dairy Council) and media attention as the new “trendy” recovery drink.

Chocolate milk (CM) contains lactose, sucrose, high-fructose corn syrup (and other sweetners) as its carbohydrate component and casein (80%) and whey (20%) as its high quality proteins.  CM has a relatively high electrolyte content (including sodium, potassium, and calcium), which in addition to its CHO/PRO co-ingestion may play an important role in post-exercise rehydration.  CM also contains fats  (most of CM advocates recommend low fat products), flavanoids and a
small amount of caffeine.

The big question:  does consuming CM for recovery improve future sport performance?

The majority of chocolate milk studies stating its effectiveness for post exercise recovery are compared against CHO only drinks.  There is good evidence that protein in addition to CHO intake improves rehydration, muscle protein synthesis and glycogen replacement (when CHO ingestion is less than 1.2g/kg/hr).  Thus comparing CM against CHO only drinks is an unfair comparison at this point.

CM should be compared against an isocaloric CHO + PRO source.  To date  there have been only 3 small studies (with relatively weak methodological design) that have measured trained cyclists time to exhaustion after approximately an hour of high intensity intervals and a recovery period.  2 of these studies found chocolate milk enhanced time to exhaustion compared with the CHO + Pro comparison beverage (Endurox R4).  The other study reported chocolate  milk and a CHO + Pro beverage of similar macronutrient composition produced similar effects on subsequent time to exhaustion trials.  The volume of CM consumed in these studies was approximately 500ml immediately after the exercise protocol and another 500ml 2hrs after (the exact amount was calculated based on the weight of the subject).

Aside:

The validity of time to exhaustion testing as a measure of sport performance has be widely criticized.  Timed trials provide a more valid measure of true sport performance.  Only one study used a timed trial (again in cyclists) to compare CM consumption versus an isocaloric CHO drink and a noncaloric placebo drink (and not an isocaloric CHO+PRO drink).  This basically says CM is a better recovery drink versus drinks like the original Gatorade or Powerade, but still doesn’t compare against isocaloric CHO + PRO recovery drinks (such as Gatorade G Series Recover, Accelerade, Endurox R4 or the many other powder based recovery products).

So yes…chocolate milk does have some value as a recovery aid…however further comparisons  between isocaloric CHO + PRO recovery drinks and powders need to be investigated to state with confidence chocolate milk’s superiority.

Another consideration: CM is convenient and cost-effective (compared to many of the CHO + PRO drink/powder options).  Thus many of its advocates will argue that all performance and recovery measures being equal that CM is a great immediate post event (within 30 mins is optimal) source of sodium, potassium, CHO and PRO.  Many teams are already handing out CM on the sidelines after games etc…watch for this to become much more common in the near future as more and more trainers, team doctors and coaches jump on the band wagon.  The optimal volume of consumption has not been established at this point.

Is Chocolate Milk for everyone?
Milk proteins are generally thought to be a highly bioavailable, natural source of protein.   However, in some people the whey component of milk proteins may not fully digest in the intestines (and thus the crucial amino acid components are not utilized!).  Naturopathic doctors believe that in as much as half the population the immune system mounts a reaction against these milk proteins, either localized in the intestines or affecting the whole body – this is what Naturopath’s refer to as a “sensitivity”.  If you are one of those people (I am included in this group!) you may experience bloating or gastrointestinal distress after consuming dairy products.  This sensitivity and digestibility issue may be reason enough to find an alternative to CM as a recovery aid (shh…don’t  tell any of the powerful dairy farmers groups).

For a great (non-biased, well referenced) read on a variety of popular recovery drinks on the market check out http://www.athleteinme.com/ArticleView.aspx?id=358

Saunders MJ.  Carbohydrate-Protein Intake and Recovery from Endurance Exercise: Is Chcolate Milk the Answer?  Current Sports Medicine Reports.  2011;10(4):203-210.

Ferguson-Stegall et al.  Postexercise carbohydrate-protein supplementation improves subsequent exercise performance and intracellular signalling for protein synthesis.  Journal of Strength & 
Conditioning Research. 2011;25:1210-24

Howarth KR, Moreau NA, Phillips SM and Gibala MJ.  Coingestion of  protein with carbohydrate during recovery from endurance exercise stimulates skeletal muscle protein synthesis in humans.  Journal of Applied Physiology.  2009;106(4):1394-1402.

Thomas K, Morris P, Stevenson E. Improved endurance capacity following chocolate milk consumption compared with 2 commercially available sport drinks. Appl. Physiol. Nutr. Metab. 2009;34:78Y82.