Another potential mediating factor receiving less attention in the literature may be the influence of different

protein sources [13, 14], as a majority of studies to date have used only whey protein [14]. Recently, a small body of research has emerged exploring the potential benefit of co-ingesting protein hydrolysates with CHO during endurance exercise [13, 15]. Protein hydrolysates are produced from purified protein sources, with each hydrolysate being a mixture of various length peptides together with free amino acids. Hydrolysates consisting of small chain amino acids have been Foretinib shown to increase digestion and absorption kinetics [16, 17] and induce a PF-6463922 concentration greater insulinemic response when ingested alone [17] or with CHO post exercise [18, 19]. However protein hydrolysates differ from one another nutritionally, and may therefore elicit different physiological responses [20]. For example, chronic consumption of hydrolysates produced from fish protein has been shown to increase BIBW2992 research buy fatty acid oxidation and reduce adipose tissue mass in

rats when compared to an equal energetic amount of soy protein [21]. The increased reliance on lipid metabolism observed by Liaset and colleagues has provided the rationale for others to explore the potential performance enhancing effects of fish protein hydrolysates in the context of endurance exercise in humans. The novel work of Vegge and colleagues aimed to determine if a commercially

available fish protein hydrolysate (Nutripeptin™) would improve endurance capacity better than either CHO or CHO plus whey protein consumption [15]. The results did not substantiate a performance benefit per se (as assessed at the end of the endurance ride with a five minute mean-power test), however the authors did observe similar physiologic responses between the carbohydrate and Nutripeptin™ conditions, but not the carbohydrate Aprepitant plus whey condition. Although these findings were inconclusive, the positive performance response of some participants and the evidence suggesting there may be a metabolic influence (i.e. greater fat oxidation) warrants further investigation. Therefore, the purpose of the current study was to further examine the efficacy of introducing a fish protein hydrolysate concurrently with CHO and whey protein on endurance exercise metabolism and performance. Methods Subjects Twelve apparently healthy men volunteered to participate in the study and had the following characteristics: median (IQR) age of 23 (6) years; height (mean ± SD) 176.5 ± 5.7 cm; body mass 76.0 ± 8.3 kg; maximal oxygen consumption (VO2max) 52.5 ± 5.2 ml.kg.min-1; and maximal power output (Wmax) 294 ± 19 W. All were engaged in aerobic training 3–5 d.wk-1 prior to and throughout the data collection period.