Endurance training and racing often involve the execution of very long training sessions lasting multiple hours.  Considering glycogen stores can easily be depleted after a few hours of exercise, supplementation with carbohydrates is known to enhance performance and subsequent recovery.  While sufficient protein intake before and after workouts is important, there has been some debate surrounding the question of whether supplementing with protein is productive during long bouts of exercise. 

Considering the high training load many top endurance athletes perform day-to-day and week-to-week, the ability to optimally perform during the sessions and, just as importantly, recover from them is vital to success and avoidance of over-training. 

Is consuming protein during long rides a good thing

About a decade ago, it was more common for cyclists to consume small amounts of protein intra-workout, due in no small part to the popularity of a products like Hammer Perpetuem, which contains five grams of protein per 34 grams of carbohydrates.  However, recently there has been a greater emphasis on maximizing carbohydrate intake during training and racing, with the most common position among the endurance community being that consuming protein during training is not productive.  Because of this, I wanted to dive into some of the literature to assess if the current “wisdom” pervading the sports nutrition industry is grounded in science.

What the science shows about consuming protein during long training session

Although there are a couple of contrarian studies, the vast majority of independent studies do not find a performance or recovery benefit from consuming protein (when energy matched against carbohydrate intake) intra-workout during long endurance training sessions. As a rule, you should not worry about consuming protein during a workout assuming that:

• You are well-fueled before the workout

• You consume carbohydrates during the workout (~50-120g/hour depending on intensity, duration, where you are in your training cycle, etc.)

• You consume carbohydrates and protein after the workout

Studies show there may be a benefit to consuming protein during training if you are consuming protein in addition to consuming the carbohydrates you would have already planned to consume during the workout — meaning you are simply consuming more calories. However, when energy from both protein and carbohydrates match that just from carbohydrates, or if protein replaces carbohydrates, there does not seem to be a benefit (again this assumes you are well-fueled before the workout).

An interesting representative study

In this 2016 study by Hansen, et al. published in the Journal of the International Society of Sports Nutrition titled “Protein intake during training sessions has no effect on performance and recovery during a strenuous training camp for elite cyclists,” the nutritional intake of the U23 Danish national team was analyzed during a six-day training camp in Lanzarote. 

Purpose of the study

The purpose of the study was to assess if there was an advantage to consuming a “protein-supplemented carbohydrate beverage [compared] to an isocaloric carbohydrate beverage during each session of an intense six-day training camp.”   In this way, the study aimed to establish if replacing some carbohydrates “with protein during exercise would have additional performance and recovery effects beyond that of the protein already present in the recovery beverage.”

Methods

The experimental approach involved a double-blinded, randomized, controlled intervention wherein the athletes were pre-tested and matched in pairs based on training history, weight, VO2 max, and 5-min peak power test results.  After, the athletes were randomized to consume either a carbohydrate drink containing CHO but protein (CHO) or a protein-carbohydrate drink (PRO-CHO) while training during a 6-day cycling camp.  Both groups consumed a recovery beverage after training composed of 18g of protein and 69g of carbohydrates, and only consumed water in the two hours before and one hour after training.   Athletes were further divided into short-distance groups that trained ~25 hours over the six days, or long-distance groups that trained ~29 hours.  The CHO and PRO-CHO cyclist pairs were in the same distance group. 

During training, each athlete consumed one 750-ml bottle of either a PRO-CHO beverage containing 0.2g of protein/kg of rider weight in the form of whey protein hydrolysate and 1 g of CHO/kg or an energy-matched CHO drink containing 1.2g of CHO/kg.   Both groups drank a recovery beverage immediately after exercise.  Other daily energy intake was also controlled.

Before the camp, athletes’ VO2 max, 10-sec max power, and 5-min max power were tested.  Additionally, venous blood samples were gathered to analyze markers of muscle damage (CK, LDH, and myoglobin) and cortisol. Saliva samples were analyzed for IgA.

During the camp, performance data and CK, LDH, myoglobin, cortisol, IgA and weight were analyzed and compared after certain workouts and after the entirety of the camp.  10-sec and 5-min power tests occurred in the morning of D1, after training on D1, and in the morning of D6.  In the mornings of D1, D3, D5, D6 and D7, body weight and blood samples were collected.  Salivary samples were collected in the morning of D1, 5, 6, 7, and 0 and 1h after training on D6.

Results and Conclusions

Results showed that “partial substitution of carbohydrates with whey protein hydrolysate during exercise did not significantly reduce the decline in performance after 4-5 h cycling after five days of strenuous training.  Furthermore, the intake of protein during training did not have a marked influence on the changes in markers of muscle damage (CK and LDH), cortisol, or immune function (salivary IgA) during the training camp.”

•  10-sec peak power did not change significantly in either group when measured pre-workout on day one (D1-pre), post-workout on day one, or pre-workout on day six (D6-post). 

• Average power during the 5-min max power test at D1-pre was 426+/- 11 W and 428 +/- 11 W in CHO and PRO-CHO respectively.  The average power output was lower after training at D1 in both groups (409+/- 8 W and 404 +/- 11 W), as well as in the morning of D6 (410 +/- 11W and 404 +/1 11 W).

• At D1, CK was 63% higher in CHO (203+/- 42.3) than in PRO-CHO (124+/- 16).  In PRO-CHO, CK was higher in the morning of D3, D5, D6 and D7 compared to D1.  In CHO, no significant change was observed.

• LDH was not significantly different between groups at baseline.  LDH was higher at D3 compared to D1 for CHO, and was higher at D6 compared to D1 for PRO-CHO.

• Plasma myoglobin was below detection levels in all morning samples except for on PRO-CHO athlete.

• Coritsol increased over time for each group, and was much higher on D6 and D7, but no mojor differences between groups was observed.

• There was no significant difference in salivary IgA or body weight between groups. 

Takeaways from the study

Since the study found no significant acute ergogenic effect on performance or muscle recovery between the CHO and PRO-CHO groups, there does not appear to be compelling evidence that consuming protein during workouts is helpful, assuming you begin the workout well-fueled and consume sufficient carbohydrate during it. However, you should aim to consume protein and carbohydrates after sessions, as the inclusion of the post-workout recovery beverage in this study should not be ignored.

TLDR

Eat carbohydrates and protein before and after workouts. Focus on carbohydrates during workouts.

Conrad Goeringer is an Ironman Certified Coach based out of Nashville, TN. He is the founder of Working Triathlete and author of the book The Working Triathlete. His passion is helping athletes of all levels and with all schedules achieve their endurance goals. Reach out to learn more about coaching packages and for a free consultation.

References

Hansen, M., Bangsbo, J., Jensen, J., Krause-Jensen, M., Bibby, B..M, Sollie, O., Hall, U.A., Madsen, K. Protein intake during training sessions has no effect on performance and recovery during a strenuous training camp for elite cyclists. J Int Soc Sports Nutr. 2016 Mar 5;13:9. doi: 10.1186/s12970-016-0120-4. PMID: 26949378; PMCID: PMC4779585.