Journal Title (Medline/Pubmed accepted abbreviation): J Strength Cond Res
Page numbers: 2203-2210
doi (if applicable):
Hypothesis: A cocoa-based protein and carbohydrate prototype drink would decrease skeletal muscle cell and inflammatory biomarkers and perceived soreness compared with water. It was also hypothesized that consuming the test drink before exercise would further reduce oxidative stress biomarkers and perceived soreness.
Subjects: A total of 7 physically active men (mean age = 23 y, mean weight = 82 kg, mean % body fat = 19%, and mean VO2 max = 44 ml/kg/min) were studied. Subjects were not sedentary, but were below the 70th percentile for aerobic capacity.
Experimental design: Completely randomized block
Treatments:Either water or a cocoa-based protein carbohydrate drink (330 mL, 220 kcal, 39 g carbohydrate (25 g sugars, 4 g dietary fiber), 11 g protein, 4 g fat, 3.5:1 carbohydrate:protein ratio
Protocol: Following pre-testing to determine VO2 max and body composition, the subjects engaged in 3 bouts of aerobic exercise, with 3 weeks of rest between them. The exercise consisted of downhill running on a treadmill at -10% grade for 30 min to induce muscle damage and soreness. On each day of exercise, the subjects received one of the following treatment conditions in random order: water only, test drink before exercise, and test drink after exercise. Each subject received each treatment condition once. Blood markers (interleukins 6 and 8, creatine kinase, c-reactive protein) were measured before exercise and at 30-, 60-, 120-, and 360-min intervals postexercise. Urinary isoprostane (15-isoprostane F2t) levels were measured at 24 and 48 h postexercise. To assess perceived muscle soreness, the Lower Extremity Functional Scale was administered at 24 and 48 h postexercise. This scale assesses the subject's level of difficulty with various physical activities due to muscle soreness. Subjects were fed standardized breakfast and lunch meals with low levels of antioxidant nutrients on each exercise testing day.
It is unclear why the consumption of the cocoa-based carbohydrate protein drink after exercise was able to reduce perceived muscle soreness in the absence of a change in blood or urine biomarkers. It might have been interesting to measure urinary 3-methylhistidine levels as a more specific marker of muscle protein degradation. In addition, the subjects would have been aware of the identity of the treatments in this study. Thus, the relatively widespread knowledge in the general public regarding the importance of carbohydrate and protein for muscle recovery might have contributed to the improvement in perceived muscle soreness despite the lack of improvement in blood or urine biomarkers. It might have been helpful to have a carbohydrate-containing control beverage as opposed to just water to make it possible to blind the subjects to the identity of the treatments.