The www.selleckchem.com/products/epz004777.html endurance training protocol used in this study was a modification of a widely used protocol in the literature [23, 25, 26]. As shown in Figure 1, distance run increased with time. These data suggest that the training workload was well adjusted, since a plateau in the training volume is a sign of overtraining [27]. No difference was found in the average daily distance run between the QT and PT groups. VO2 peak values in rats vary depending on the methodological test used or on their weight [28]. Our results show that six weeks of quercetin supplementation

did not increase VO2 peak or VO2 at exhaustion in sedentary or trained rats. It must be noted that our protocol did no alter inclination in order to examine the maximum speed achieved. Protocols that do not use an incline are known to induce a lower VO2 peak than others with 15°-20° inclination [28, 29]. However, our results were similar to those recently reported [17], but were in contrast with the ones that reported an increase of VO2 peak by quercetin in sedentary humans [19]. Speed at VO2 peak was also analyzed in this experiment, with no change reported in the quercetin groups. We hypothesized that quercetin would increase VO2 peak due to its ability

to increase mitochondrial biogenesis in mice (6). However, as described above, no differences were observed in any groups on IGF-1R inhibitor measures related to oxygen uptake by quercetin supplementation. These results are similar to those obtained by Bigelman et al [30]. There are several potential reasons MI-503 supplier for these results: firstly, VO2 peak is influenced by muscle mitochondrial oxidative capacity, but relative to endurance capacity, it is limited to a greater extent by oxygen delivery via the cardiovascular system [31]. Secondly, larger doses over extended periods using added flavonoids such as eppigallocatechin G protein-coupled receptor kinase gallate (EGCG) may augment quercetin’s effects on mitochondrial biogenesis. This could be a more appropriate supplement to increase oxygen consumption [16]. However, previous work did not find any ergogenic effect of quercetin and EGCG supplementation in a moderately

trained sample [30]. To examine additional ergogenic effects of quercetin in rats, oxygen consumption and carbon dioxide production were measured during the incremental exercise test. This enabled the calculation of RQ. In all groups of rats, the average RQ remained fairly constant and did not differ between groups (data not shown). When VCO2 is greater than VO2 (RQ>1.0), this point of inflection is correlated with blood lactate accumulation [32]. QT group showed a trend to run longer before reaching an RQ of 1.0 (Figure 4B) indicating that these rats were able to use oxidative metabolism for a longer period. Fatigue in the endurance test is thought to arise primarily from limitations in the periphery, like the cardiovascular system and muscles [6].