We are aware of only a few other studies that have examined the effects of a similar blend of supplements on exercise performance and/or energy expenditure [11, 13, 20, 61]. For example, Yoshioka and colleagues [11] reported higher energy expenditure after a meal containing red pepper and Cediranib in vivo caffeine when compared to a HM781-36B control meal. Similarly in obese individuals, capsaicin and caffeine (among other ingredients) enhanced resting

metabolic rate by 90 kJ, which suggested that these supplements exhibited a thermogenic effect at rest [20]. In addition, Ryan et al. [13] indicated that a caffeine- and capsaicin-containing supplement increased energy expenditure in healthy sedentary subjects before, during, and after 1 hour of light aerobic exercise. Therefore, these results collectively suggested that the potential thermogenic benefits of supplements containing caffeine and capsaicin may be more realized at rest (5,19,22) and during light aerobic exercise (19) than during anaerobic (1-RMs) and high-intensity aerobic (TTE at 80% VO2 PEAK) exercises as indicated by the results of the present study. Several studies have examined the ergogenic benefits of caffeine supplementation as indicated

by several thorough literature reviews [3, 5, 16, 18, 41, 62–64]. selleck kinase inhibitor Most of this literature focuses on the effects of caffeine supplementation on relatively low- to moderate-intensity endurance performance [2, 5, 14, Ribociclib 16, 17, 62]. Fewer studies have reported changes in muscle strength after caffeine supplementation [15, 39, 43]. Beck et al. [39] and Kalmar and Cafarelli [15] reported caffeine-induced increases in 1-RM bench press strength and voluntary muscle

activation, respectively. However, Astorino et al. [43] and Beck et al. [39] also reported no caffeine-related changes in 1-RM leg press and leg extension exercises, respectively. In addition, Bond et al. [42] and Jacobson et al. [45] reported no changes in isokinetic strength of the leg extensors and flexors after various doses of caffeine. It has been suggested that calcium is more readily available for release from the sarcoplasmic reticulum after caffeine administration in rodents and frogs [33–37]. In addition, caffeine may alter the activation thresholds of motor neurons, resulting in increased motor unit firing and activation of more muscle [32]. In the present study, however, there was only 200 mg of caffeine in the TPB supplement, which is less than most caffeine doses administered in previous studies [15, 32, 42, 43, 45, 65, 66]. Therefore, the lack of observed differences in the present study may have been due to the relatively small dose of caffeine in the TPB supplement, since the ergogenic effects of both caffeine [2, 17, 67] and capsaicin [22, 52] may be dose-dependent. Although the effects of caffeine on strength measures are relatively inconclusive, studies have reported improvements in endurance performance after caffeine supplementation [2, 5, 14, 16, 17, 62].