The new research was published in the Journal of the International Society of Sports Nutrition. It was the work of a group of researchers associated with Beijing Sport University.
The goal of the research was to determine which of the various formulation strategies pursued by energy drink manufacturers (carbohydrates alone or carbohydrates plus protein) helped a small cohort of runners the best.
The researchers recruited 11 health young men studying at the sport school. The subjects were training at least six hours a week. One subject dropped out during the course of the trial because of injury.
Is timing of protein intake important?
The researchers noted that previous studies have shown that post exercise protein intake combined with carbohydrate has helped boost athletes performance in subsequent training sessions. Teh purpose of he present trial was to examine what the effects of adding protein to a carbohydrate intervention would be if taken immediately before or even during an event.
The subjects underwent three phases in the trial, each of which had two supplementation interventions. One phase used a carbohydrate-only intervention in both parts of the test, while the others supplemented with a protein/carbohydrate drink first, followed by a carbohydrate-only drink, while the third arm reversed that order. The protein used was a whey protein isolate and maltodextrin was chosen as the carbohydrate source. The protein was supplied at a dose of 1.2 grams per kilogram of body weight, with teh carbohydrate dose came in at 0.4 g/kg.
Muscle damage markers suppressed
In each phase, they ingested one of the supplement interventions 30 minutes before the start of the test and then warmed up with an hour long treadmill run at 70% of their VO2 max. Then they downed the second supplement intervention and performed a running test to exhaustion at 80% VO2 max. They also had their blood drawn at baseline and at the conclusion of the test and supplied urine samples There was a 7 day washout period between the tests.
The researchers analyzed the blood for levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatine kinase (CK), and myoglobin (MB), which are associated with exercise-inuduced muscle damage.
The researchers found that both approaches of adding protein — either well before the start of exercise or as an acute intervention during exercise, helped quell the inflammation markers better than the carbohydrate alone. However, none of the interventions showed an appreciable effect when it came to how long the subjects could persist in the time to exhaustion test.
“Carbohydrate and protein supplement strategies can reduce muscle damage caused by endurance exercise, but they do not improve endurance exercise capacity,” they concluded.
Source: Journal of the International Society of Sports Nutrition
Effects of carbohydrate and protein supplement strategies on endurance capacity and muscle damage of endurance runners: A double blind, controlled crossover trial
Authors: Liang Y, et al.