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Effects of protein during exercise

One year ago, a very good friend and respected colleague passed away, way too young. Kevin Tipton was loved by many and had a great impact on the field of sports nutrition, especially in the field of protein metabolism. To commemorate the life and the scientific achievements of Kevin, I will make sure a blog goes out every year that highlights some of his research.


This time I have picked a popular question that gets asked very often: Do I need to take protein with my carbohydrate during exercise? We are all aware of the carbohydrate electrolyte drinks, the high carb drinks, and the gels that are commercially available as carbohydrate sources. But should we be thinking of protein as well? And could adding protein to these drinks be beneficial?



Protein + carbohydrate during exercise = improved performance?

In 2010, a study was published with Leigh Breen, who was a PhD student at the time working with Kevin and myself, to address this question (1). At the time there were a few studies that suggested that adding protein could help, but there were also studies that were much more controlled that had not found any benefit. The studies that found effects had added protein to a carbohydrate drink and thus it was impossible to know whether the observed beneficial effects were due to the protein, or due to the increased amount of energy consumed. Also, in these studies the amount of carbohydrate ingested was small and far below the recommended amounts.


So, in this study, Leigh Breen made sure the recommended amount of carbohydrate was ingested (65 g/h) and in one condition an additional 19g/h of a protein hydrolysate was ingested (for an explanation what a protein hydrolysate is, read this blog). The study was cross-over, counterbalanced and double blind. Subjects performed a 2h exercise test followed by a time trial that lasted about 60 min. In addition, measurements were performed of recovery the day after (soreness, muscle function, plasma CK (creatine kinase), a marker of muscle damage).


So what did we find?

There was no difference in performance between the two trials with identical power outputs in the carbohydrate and carbohydrate+ protein condition (both averaged 247W). There was also no difference in heart rate or ratings of perceived exertion. So protein really had no effect in this study. Not a positive but also not a negative effect.


The added protein also had no effect on markers of recovery. Muscle function was identical, muscle soreness was identical and plasma CK was also not different. So there was no measurable difference in muscle function, the subjects were equally sore the next day and an objective measure in blood also showed no difference. Overall, the conclusion of this study was quite definitive: there is no effect of adding protein if you follow the carbohydrate intake guidelines.


Overall, the conclusion of this study was quite definitive: there is no effect of adding protein if you follow the carbohydrate intake guidelines.

Kevin took pride in designing very thorough studies with attention to detail and this study was an example of one of such studies. In the months leading up to this study a research project was published that wasn’t quite as thorough and we wrote a letter to the editor explaining all the things that weren’t done and weren’t picked up in the peer review process. After that, this study was performed, and the conclusion was quite different.


Reference

  1. No effect of carbohydrate-protein on cycling performance and indices of recovery. Leigh Breen, Kevin D Tipton, Asker E Jeukendrup. Med Sci Sports Exerc 42(6):1140-8, 2010.

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