However, other studies that have tested untrained subjects [26, 65, 68] have found no changes in TTE after caffeine ingestion. Arguments have been made that the subjects’ initial training status is the primary limiting factor for TTE performance [65], especially at relatively high workloads, such as those used in the present study. In support of this hypothesis, Hogervorst et al. [8] reported an 84% increase in TTE after a 2.5-h bout of cycling at 60% of the

VO2MAX with well-trained cyclists after only 100 mg of caffeine was taken at several intervals. Therefore, the ergogenic effects of lower doses of caffeine may be more profound in trained individuals at lower-intensity, longer-duration endurance events. Since the participants in the present study were untrained and the exercise intensity was relatively high (80% VO2 PEAK), the caffeine-induced improvements in performance may have been less evident. NVP-BSK805 cost As with many ergogenic aids, the amount of caffeine supplementation may be proportional to the magnitude of performance improvements. Jenkins et al[5] reported increases in cycling performance with as low as 2 mg of caffeine per kilogram of body mass (mg·kg-1) in trained

cyclists. In contrast, Pasman et al. [29] reported no dose-response mTOR inhibitor relationship between caffeine consumption and TTE at 80% of the maximal cycling wattage (W) with 5, 9, and 13 mg·kg-1. However, even the minimal dose administered by Pasman et al. [29] was approximately 360 mg (5 mg·kg-1 × mean body mass of 72 kg). The absolute caffeine dose administered in the present study was only 200 mg (~2.6 mg·kg-1), which may have limited the potential ergogenic effects that are often observed with caffeine consumption. Nevertheless, our findings were similar Pyruvate dehydrogenase to those of Bell et al. [65], which used a workload at 85% of the VO2MAX and reported mean TTE values of 14.4 and 12.6 min for the caffeine (5 mg·kg-1) and placebo trials, respectively. The results of the present study indicated that the TTE for the TPB supplement was 5% greater than

the PL trial (Table 1), although this finding was not statistically significant (p = 0.403). Therefore, because the caffeine dose administered in the present study was lower than what has been used in previous studies [15, 32, 42, 43, 45, 65, 66], the consequent ergogenic effects of caffeine may also have been limited. The combination of caffeine and capsaicin supplements may potentially yield synergistic, ergogenic effects. For example, the elevation of plasma catecholamines after caffeine or capsaicin ingestion have previously resulted in increased lypolysis [14, 17, 44] and decreased carbohydrate utilization [69]. Yoshioka et al. [12] suggested that the primary mechanism of capsaicin is the β-adrenergic stimulation that induces thermogenesis. Recently, Lim et al.