Journal Title (Medline/Pubmed accepted abbreviation): J. Appl. Physiol.
Page numbers: 1096-1101
doi (if applicable): 10.1152/japplphysiol.00141.2010
Background:Carnosine is a dipeptide that is synthesized from ß-alanine and histidine and is present in high concentrations in skeletal muscle. Increased dietary ß-alanine leads to increased muscle carnosine concentrations. Carnosine functions as an acid buffer and a calcium regulator and performs other cellular functions. Is has been shown in some, but not all, studies that increased muscle carnosine levels can improve performance. It is still unknown exactly which type of athlete (trained, untrained) involved in which types of physical activity (aerobic vs. anaerobic, power vs. coordination, etc.) can benefit most from increased carnosine concentrations and, therefore, ß-alanine supplementation.
Hypothesis/purpose of study:
Part 1 (cross-sectional): Is performance related to muscle carnosine concentration?
Part 2: (intervention): Does ß-alanine supplementation improve performance in trained rowers?
Subjects:19 elite Belgian rowers, 18 male and 1 female (one male did not participate in the intervention study and there was one drop out from the intervention study). Of the 17 subjects completing the intervention study, there were 8 in the ß-alanine group and 9 in the placebo group. The mean ages of the subjects were 24.2 y for the ß-alanine group and 21.7 y for the placebo group. Mean body weights were 83.7 kg in the ß-alanine group and 81.2 kg in the placebo group.
Part 1: Cross-sectional observational
Part 2: Double-blind, placebo-controlled intervention study
Treatments and protocol:
Part 1: Magnetic resonance imaging (MRI) was used to determine carnosine content in the soleus (part of the calf muscle) and the gastrocnemius medialis (inner, larger calf muscle). Rowing performance was measured for four different distances- 100 m, 500 m, 2,000 m, and 6,000 m. Male participants were ranked and partitioned into "high carnosine" and "low carnosine" groups.
Part 2: For 7 wks, the participants consumed 5 g ß-alanine per day, or a placebo (maltodextrin). One week before intervention, and during the last weekk, carnosine levels were acquired using MRI. The last week, the participants rowed a warm-up for 20 min and then "all out" for 2,000 m. Lactate levels were acquired by capillary blood samples after the warm-up, after the 2,000 m distance, and 3 min of recovery.
Interpretation of findings/Key practice applications: ß-alanine has been shown to improve performance in several previous studies. In this study, the 4.3 sec faster time was not statistically significant, most likely due to small sample size. However, in a race environment, a 4.3 sec advantage could represent the difference between winning and losing an event. Further, the study showed that those with the greatest increase in muscle carnosine had the largest improvement in race times at 2000 m.