Protein Supplementation Does Not Augment Adaptations to Endurance Exercise Training
Jonvik KL, Paulussen KJM, Danen SL, Ceelen IJM, Horstman AM, Wardenaar FC, VAN Loon LJC, VAN Dijk JW. Med Sci Sports Exerc. 2019 Oct;51(10):2041-2049. doi: 10.1249/MSS.0000000000002028.
Take-Home Message
People performing a 12-week endurance training program with protein supplementation had similar improvements in maximal oxygen uptake and performance as people training and consuming a placebo drink.
Summary
An athlete can use protein supplementation after resistance training to augment strength and muscle mass gains. Endurance athletes are also increasingly using protein supplementation after exercise to improve their performance. However, it remains unclear if protein supplements help improve a person’s endurance during training. These authors conducted a double-blind, randomized, placebo-controlled trial to see if frequent protein supplementation during 12 weeks of endurance training would improve maximal oxygen uptake and endurance performance. The authors randomly assigned 60 nonobese males into 2 groups: protein group and placebo group. Before the beginning of a 12-week training protocol, each participant performed a maximum oxygen uptake test (VO2max), muscle function test, 10-kilometer time trial, and dual-energy x-ray absorptiometry to determine lean mass. During the 12-week program, each participant exercised on a cycle ergometer 3 times/week during supervised training sessions (Mondays, Wednesdays, and Fridays). Each Monday, the participants performed a 6 x 4-minute interval at 85%-90% heart rate max with 4-minute active recoveries. Each Wednesday, the participants completed one 60 minute cycle at 75%-80% heart rate max. Each Friday, the participants performed three sets of 6 x 1-minute work intervals at 90%-95% heart rate max with an active recovery period between each repetition and set. After each training session and 15 minutes before bedtime each participant consumed 250 mL of either protein or carbohydrate placebo drink. The protein drink contained 28.7 g protein, while the carbohydrate placebo drink contained 25.8 g carbohydrate.
Four participants in the placebo group withdrew from testing due to injuries or personal reasons. At the end of the 12-week regime, the groups had similar maximum oxygen uptake, performance on a time trial, and muscular endurance. However, the researchers noticed that the protein group may have experienced slightly greater improvement in leg lean mass than the placebo group.
Viewpoints
Overall, this study is interesting because it demonstrates that an athlete who is trying to increase their maximal oxygen uptake and performance in cycling does not need to supplement with protein. More and more athletes are trying protein supplementation to augment their training; but, this study offers compelling evidence that there may be no added benefit for endurance athletes. However, it is unclear if these findings apply to endurance athletes in different sports (e.g., runners or swimmers). Furthermore, it is unclear if protein supplementation would help an athlete who does endurance and resistance training. We need more studies like this well-controlled trial to help us teach our athletes about the benefits/harms of various supplements they are trying. Clinicians should work with coaches and athletes to decide if protein supplementation has a role in their training plan.
Questions for Discussion
What are your thoughts on protein supplementation in an athlete who trains strictly aerobically? Do you think the result would have been different if the researchers paired their endurance training with resistance training?
Written by: Daniel Webb
Reviewed by: Jeffrey Driban
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I think protein supplementation is beneficial for all athletes no matter what they train, even for aerobic ones. I say this because it will help increase muscle mass, therefor creating larger/leaner muscles to perform the same work. This will in effect make the work easier and allow the athlete to perform at a higher level. Even in this experiment the group that was given the protein was shown to have increased their lean leg muscle mass. I think this increase in leg muscle mass would help those athletes in the long term (for cycling) because it will allow them to create more force in every turn of the pedals. The results would have been different if the researchers included resistance training because the protein group would have outperformed the placebo group at the conclusion of the study. I agree with the viewpoint that protein doesn’t help in an athlete’s oxygen uptake, but I am curious if protein could help with building stronger muscles that are involved with breathing, such as the scalenes for example. I wonder if protein increasing the efficiency/size/strength of those muscles would increase an athlete’s aerobic performance. Overall I thought this summary was informative and raised interesting questions. Questions I am constantly asked in an athletic training room are, “What protein is best?” and “How much protein should I take?” Occasionally, I am asked if they should take protein at all by cross country athletes. These types of studies will definitely be beneficial for athletic trainers with athletes eager to raise their level of performance.
As someone that trains anaerobically, I definitely see a benefit with supplementing with protein post-workout. I think it would be interesting to compare anaerobic vs. aerobic athletes and see how protein affects them differently. Also, I wonder if there is other research out there that suggests a supplement that helps increase an aerobic athlete’s endurance. Overall, I think that protein supplementation is still important and can just help improve an athlete’s overall health if they are not getting enough grams of protein in their everyday diet. I think that this topic is going in the right direction and more research can be done to see how beneficial supplements (not just protein) are to athletes and if they are really necessary to their everyday lives.
As an athletic training student, and an avid weight lifter I have firsthand experience with protein supplementation. I also participated in track and field (granted I was a sprinter) which is an aerobic activity for the most part. I agree with Michael in saying that protein supplements may help aerobic athletes to build their muscle mass thus making them stronger overall. However, with the goal of increasing endurance and VO2 max, I don’t think protein supplements are the answer. Many young athletes believe they should take a protein supplement because they see their peers taking one or hear good things about its effects. But every athlete is different, especially comparing anaerobically trained athletes to aerobically trained. Because of this, I think that research like this is important to show that taking a protein supplement may not be the answer for every athlete. As athletic trainers we must consider the sport the athlete participates in, their goals, and body composition before recommending supplements. To answer the question about differing results when adding resistance training- I definitely think that the protein group would have had a much larger difference in muscle mass and strength gains from the placebo group.