The Science of Carbohydrate and Protein Supplementation for Minimizing Muscle Damage

As ultrarunning continues to expand in popularity and distance, many runners utilize nutrition supplementation to improve performance and aid post-exercise recovery. A recent study on the effects of carbohydrates and protein on endurance capacity and muscle damage helps solidify previous recommendations.

Published in the Journal of the International Society of Sports Nutrition, ten male runners performed three run-to-exhaustion tests while ingesting randomly assigned supplements 30 minutes before each run. Blood tests were taken, and muscle soreness markers were recorded to analyze the effects of the supplements.

Previous Research

It is well established that carbohydrates and protein post-exercise improve recovery more than carbohydrates alone. 

In addition, previous studies have found supplementing carbohydrates with additional protein may improve exercise performance. However, these findings are likely attributed to extra calories in exercise performance. Moreover, where additional calories were equivalent, studies had yet to show improved endurance performance when protein was supplemented with carbohydrates before or during the endurance performance test. 

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The Study’s Findings

Since markers of muscle damage increased after long-distance running, they explored the effects of the carbohydrate plus protein strategy on endurance capacity and muscle damage. In general, ingesting 20–40 grams of high-quality protein can increase muscle protein synthesis rates and reduce muscle damage. To develop a better understanding of the function of a protein, they explore, in part, whether protein supplementation before exercise could reduce muscle damage and improve performance.

The researchers theorized that protein supplementation before exercise would reduce muscle damage and improve performance compared to carbohydrate supplementation alone. 

Ten recreationally active male runners who trained at least three times a week were recruited from the China Athletics College of Beijing Sports University with a mean age of 21. Participants were not allowed to take other supplements during the experiment and were asked to avoid high-intensity training before testing. 

Participants performed three run-to-exhaustion tests on a treadmill and were assigned different supplements randomly in each running test. Between each test, there was a week-long “washout period.” 

Before the first test, maximum oxygen uptake (VO2max) was recorded. After the first test, markers were recorded (i.e., blood, urine, and muscle soreness). On the second day of testing, markers were re-recorded, and muscle soreness was registered 24 hours after the initial test.

The run-to-exhaustion test was divided into two phases with no time interval between the phases. In phase 1, the subjects ran for 60 minutes at 70% of their VO2max. 

After completing the 60-minute run, the subjects ran to exhaustion at 80% VO2max in phase 2. Researchers stopped the test at the runner’s request or if the runner had trouble breathing, chest discomfort, dizziness, etcetera. 

Researchers randomly assigned participants to supplements during the three tests. The researchers and subjects were blinded to the supplements the subjects received for each test.

The carbohydrate supplement was maltodextrin dosed at 0.4 g/kg BM. The protein supplement was whey protein isolate dosed at 0.4 g/kg BM. In addition, subjects were supplemented with carbohydrates at 1.2 g/kg BM during phase 1, which was ingested every 10 minutes as a liquid.

The three different supplement strategies were 1) carbohydrates 30 minutes before phase 1 and before phase 2, 2) protein 30 minutes before phase 1 and ingesting carbohydrates before phase 2, and 3) carbohydrates 30 minutes before phase 1 and consuming protein before phase 2.

The study found no significant difference in time-to-exhaustion between the three supplement strategies. However, the study found that protein supplementation is preferable to carbohydrate supplementation alone to reduce muscle damage caused by running and accelerate recovery after exercise. Moreover, protein supplementation before activity has a better protective effect on the damage caused by long-term running.

“The reason protein supplement during exercise was effective might be that the protein intake in advance increases the concentration of amino acids in the blood, thereby reducing muscle damage and speeding up recovery after exercise,” said the researchers. “Moreover, previous studies have shown that prolonged exercise can increase intaking protein oxidation.”

A possible explanation for this is that the protein supplement provided more amino acids during exercise than in the carbohydrate-only group, thereby speeding up recovery after exercise. 

“In the case of sufficient carbohydrate intake, protein intake before or during exercise cannot extend the time that runners run to exhaustion in endurance exercise,” said lead researcher Yiheng Liang. “For endurance exercise, compared with carbohydrate supplementation alone, the supplement of carbohydrates and protein strategy can effectively reduce muscle damage caused by endurance exercise and promote fatigue recovery after exercise.”

Practical Applicability

While these findings may not be revelatory, they may assure previous nutritional recommendations.

The study may invoke the grandeur of powers from a jar, but in practice, real food is preferable rather than ingesting mere powder.

For professional trail runner and nutritionist Stephanie Howe, Ph.D., this study wouldn’t change how she recommends an athlete eat for performance. 

“My takeaway from this study is that we keep recommending what we are currently telling athletes. Ingest carbohydrates with a little fat and protein prior to exercise,” said Howe. “Take in carbohydrates during exercise. Refuel immediately after with carbohydrates and protein.”

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The reach of the study’s practical implications is not likely pertinent to the bulk of an athlete’s training.

“Very rarely do athletes do maximal time to exhaustion during a training run. So the levels of muscle damage are probably a bit exaggerated here. It would be more interesting to see if any differences exist after 60-90 min of running at 65-70% VO2max (typical distance and even a bit into tempo effort),” said Howe. “That could be a more realistic scenario, but my guess is we wouldn’t see much difference between the groups.”

Overall, the results were somewhat lackluster since there was no significant difference in the performance marker. However, the study still holds merit as it reinforces the previous guidelines for runners to consume foods with carbohydrates, fats, and protein before exercise. 

“It confirms the recommendations to consume carbohydrates with some protein and fat prior to exercise (i.e., peanut butter on toast, yogurt with berries, etc.),” said Howe. “It’s very rare to find an occasion where an athlete consumes just carbohydrates. Most eating occasions contain mixed meals of nutrients.”