Sports drinks containing protein are better at improving athletes' performance. Research published in BioMed Central's open access Journal of the International Society of Sports Nutrition has shown that drinks containing a mix of carbohydrate and protein are superior to carbohydrate-only drinks in improving cyclists' recovery from exercise.
John Berardi of Precision Nutrition worked with researchers from Gettysburg College and The University of Western Ontario to study which energy drink best helped cyclists recover after a strenuous ride. Scientist Live discussed his findings with him.
What led you investigate whether the addition of protein to carbohydrate recovery beverages improved short term recovery over carbohydrate only drinks?
My interest in this topic stemmed back to a conference I attended in 2000. At this conference, Dr Donald Layman from the University of Illinois presented some interesting data in which rodents were fed various beverages containing different macronutrient mixtures during and after treadmill exercise. Interestingly, the rodents given a combination of protein and carbohydrate saw the most positive changes in markers of protein and glycogen synthesis.
At that time, I was curious as to whether this same phenomenon would be seen in both strength and endurance athletes. So I began a progression of studies looking at what happens when we give different macronutrient mixtures to athletes performing strength training and endurance training. Specifically, I wanted to see how these types of macronutrients would impact performance recovery, glycogen recovery, markers of muscle damage, muscle soreness, and motivation to exercise.
I wasn't the only one interested in this area. Indeed, since 2000, over a dozen papers have been published looking at various pieces of the recovery puzzle. And our work has narrowed in on the acute recovery of muscle glycogen and exercise performance using protein and carbohydrate drinks after exercise.
Can you describe your experiment briefly and why you designed it that way? How did it differ from previous experiments designed to test similar things?
This study was a follow-up to a previous study we did in conjunction with Dr Tom Price at Yale Univeristy. In both studies we had experienced cyclists and triathletes report to the lab and perform an all-out, 60 min cycling trial. The idea was to have them cover as much distance as they could in these 60 minutes.
Then, during a 6 hour recovery period, we gave the subjects placebo supplements, carbohydrate only supplements, or carbohydrate plus protein supplements immediately after the exercise session, 1 hour after the session, and 2 hours after the session.
Then, at 4 hours post exercise we fed them all the same standardized meal. And finally, 6 hours after the previous session they tried to duplicate their morning ride. Again, the rode as far as they could in 60 minutes.
Now, we did expect their performance to be worse during the second ride when compared to the first. There just didn't seem to be enough time to fully recovery from a ride of that duration and intensity. However, we were curious as to whether the differences in nutrient provision would lead to
differences in subsequent performance.
Indeed, we found that not only did the carbohydrate plus protein groups see an increase in muscle glycogen recovery (+22-34%), they also saw lower muscle fatigue/soreness, increased vigor, and, perhaps most importantly, improved performance.
In the carbohydrate and placebo groups, subjects cycled between 1.05-1.25km less during the second vs. their first ride. However, in the carbohydrate plus protein group, subjects cycled only 0.3km less. This is a pretty huge difference in performance drop off. So, essentially, under these study conditions, using carbohydrate and protein vs. carbohydrate alone leads to better performance recovery
between exercise sessions.
Here's the link to our first study: http://www.ncbi.nlm.nih.gov/pubmed/16775553
And here's the link to our present study: http://www.ncbi.nlm.nih.gov/pubmed/19108717
What are the mechanics behind the improved results (as compared with solely carbohydrate based drinks)?
We think the improvement was a function of enhanced muscle glycogen recovery seen with the carbohydrate and protein group. Indeed, in high intensity cycling, performance is well correlated with initial muscle glycogen levels. So the performance benefit could be a function of the higher
glycogen.
In addition, we did see an increase in fat oxidation in the carbohydrate plus protein group during the second performance ride. This increase in fat oxidation could illustrate a carbohydrate sparing effect and that could be linked to the improved performance recovery.
Finally, there may be some sort of central effect going on in which specific amino acids provoked the measured improvements in vigor and and decreases in fatigue seen in the carbohydrate plus protien group. This is highly speculative, though but quite possible based on the known CNS effects of specific amino acids.
What did the supplements in your experiment consist of? Are certain combinations better than others?
Each of the 3 ingested carbohydrate plus protein beverages consisted of a 0.8g/kg mixture of 50% dextrose and 50% maltodextrin and 0.4g/kg of hydrolyzed whey protein. And each of the 3 cabohydrate beverages consisted of a 1.2g/kg mixture of the 50-50 dextrose, maltodextrin beverage.
According to the current literature, the benefits associated with carbohydrate plus protein beverages given either during exercise or within the first few hours after exercise have been seen with drinks containing anywhere from a 4:1 ratio of carbohydrate to protein (see in some other studies) to a
2:1 ratio of carbohydrate to protein (seen in our study). I speculate that the ideal amount and ratio of carbohydrates and protein is dependent on the intensity, duration, and nature of the exercise activity.
As far as the benefits seen in the research with these types of beverages, it's becoming clear that they can help improve immune function in response to exercise, help to increase lean body mass, help to increase muscle glycogen recovery, and can help to improve subsequent exercise performance.
When would be the ideal time for an athlete to ingest the protein-supplemented drink?
Aerobic and anaerobic athletes may be able to benefit from such a beverage as long as their exercise is of high intensity. A walk around the block, a light yoga session, or a beginner pilates session would probably not require such a drink to boost performance, promote recovery, or increase lean mass. And in terms of timing, the majority of the research suggests that the greatest effects are seen when providing these nutrients within 2 hours of exercise.
However, a few recent studies have suggested that these nutrient mixtures may actually be of benefit given before and/or during exercise. However the feasibility of this recommendation would be based on the type of activity.
Finally, what is next for your laboratory?
Well, I'm best described, for lack of a better term, as a freelance researcher. In other words, I have affiliations with several universities including the University of Texas at Austin, Eastern Michigan University, Gettysburgh University, the University of Toronto, and the University of Western Ontario. So, I tend to get involved in all sorts of studies related to nutrition, health, and exercise performance.
For example, in addition to this performance study, I just published a study in the JISSN with Dr Venket Rao and Dr Alan Logan. In this study we found that certain foods and food supplements can positively impact the body's acid- base status.
Another interesting study that I'm involved in with Dr Stephen McGregor is looking at mitochondrial efficiency. We're using an interesting anaerobic performance model and measuring free radical production and oxidative damage markers. New data are showing that given similar metabolic
demands, some individuals have tighter oxidative phosphorylative coupling than others. And this is
indicative of how efficient their mitochondria are.
(Reporting by Marc Landas)
