Research Watch

Reference
Lunden ND, Saunders MJ and Todd MK. Postexercise Carbohydrate-Protein- Antioxidant Ingestion Decreases Plasma Creatine Kinase and Muscle Soreness. Int J Sports Nutr Exerc Metab 2007;1:109-123

Abstract
The authors investigated the effects of postexercise carbohydrate-protein-antioxidant (CHO+P+A) ingestion on plasma creatine kinase (CK), muscle soreness, and subsequent cross-country race performance. Twenty-three runners consumed 10 mL/kg body weight of CHO or CHO+P+A beverage immediately after each training session for 6 d before a cross-country race. After a 21-d washout period, subjects repeated the protocol with the alternate beverage. Postintervention CK (223.21 ± 160.71 U/L; 307.3 ± 312.9 U/L) and soreness (medians = 1.0, 2.0) were significantly lower after CHO+P+A intervention than after CHO, despite no differences in baseline measures. There were no overall differences in running performance after CHO and CHO+P+A interventions. There were, however, significant correlations between treatment differences and running mileage, with higher mileage runners having trends toward improved attenuations in CK and race performance after CHO+P+A intervention than lower mileage runners. We conclude that muscle damage incurred during training was attenuated with postexercise CHO+P+A ingestion, which could lead to performance improvements in high-mileage runners.

My thoughts
This is another in a line of Pacfic Health Laboratories research from the Saunders group. Pacific Health Laboratories produce the Endurox and Accelerade product ranges, as well as Satiatrim (a weight management product).
This was a randomised cross over trial, which looked at the effect of a carbohydrate supplement, compared to a carbohydrate-protein-antioxidant supplement, on muscle soreness and creatine kinase (a marker of muscle damage) levels in 24 cross country runners.
It is worthy to note that while there were 24 subjects included in the final analysis, this was only 67% of the initial study group, with 5 failing to complete data recording and 8 did not comply with the external exercise requirements.
The results show similar trends to earlier reports in different study groups and different exercise situations. Cross country running tends to provide an interesting model, as the downhill segments increase eccentric loading on the athletes, creating larger levels of delayed onset muscle soreness.
The final conclusion seems somewhat extrapolated from the results, which showed no differences in running performance, but perhaps points the way to a larger longer term training trial that allows a large group of athletes to be selected into a randomised controlled trial, that follows their total mileage, tracks feelings of muscle pain and ultimately attempts to measure a performance gain at the end of the trial. These longer term trials are important because if there is a performance benefit of using these products, it is likely to be small in the acute setting, but if the benefits are somewhat additive over time, it may produce an attractive performance benefit to the athlete.
But even though the use of protein in endurance sports is still a novel approach, this provides further evidence for the use of a carbohydrate-protein (and antioxidant) beverage following training sessions.