Caffeine Improved Time to Exhaustion But Did Not Change Alternative Maximal Accumulated Oxygen Deficit Estimated During a Single Supramaximal Running Bout

Abstract

The aim of the current study was to investigate the effects of acute caffeine supplementation on anaerobic capacity determined by the alternative maximal accumulated oxygen deficit (MAOD) in running effort. Eighteen recreational male runners [29 ± 7years; total body mass 72.1 ± 5.8 kg; height 176.0 ± 5.4cm; maximal oxygen uptake (VO) 55.8 ± 4.2 ml·kg ·min] underwent a graded exercise test. Caffeine (6 mg·kg) or a placebo were administered 1 hr before the supramaximal effort at 115% of the intensity associated with VO in a double-blind, randomized cross-over study, for MAOD assessment. The time to exhaustion under caffeine condition (130.2 ± 24.5s) was 11.3% higher (p = .01) than placebo condition (118.8 ± 24.9 s) and the qualitative inference for substantial changes showed a very likely positive effect (93%). The net participation of the oxidative phosphorylation pathway was significantly higher in the caffeine condition (p = .02) and showed a likely positive effect (90%) of 15.3% with caffeine supplementation. The time constant of abrupt decay of excess postexercise oxygen consumption (τ) was significantly different between caffeine and placebo conditions (p = .03) and showed a likely negative effect (90%), decreasing -8.0% with caffeine supplementation. The oxygen equivalents estimated from the glycolytic and phosphagen metabolic pathways showed a possibly positive effect (68%) and possibly negative effect (78%) in the qualitative inference with caffeine ingestion, respectively. However, the MAOD did not differ under the caffeine or placebo conditions (p = .68). Therefore, we can conclude that acute caffeine ingestion does not modify the MAOD, reinforcing the robustness of this method. However, caffeine ingestion can alter the glycolytic and phosphagen metabolic pathway contributions to MAOD.

Potential pitfalls when investigating the ergogenic effects of caffeine in mice

“…In addition, higher levels of blood lactate were observed at the end of the exercise protocol, in agreement with increased exercise workloads (Figures 1C for three-month-old mice and Figure 1E for seven-month-old mice). Even when significant, the observed ergogenic effect in both groups of animals was modest compared to the overt effect seen in humans [8,9]. Therefore, we wonder whether the mice were effectively in the blood peak of caffeine and whether it differs when the sympathetic nervous system is stimulated by physical activity [28].…”

“…The ergogenic effects of caffeine have been demonstrated in different sport modalities, namely running [8,9], cycling [10,11], rowing [12], track and field [3], team sports [4], and martial arts [13], among others.…”

Effect of caffeine ingestion on anaerobic capacity quantified by different methods

“…Posterior investigation provided additional evidence of test and retest reliability of MAOD ALT [43]. A recent study found that caffeine increased time to exhaustion at 115% of VO 2 peak, but the MAOD ALT had not increased [26]. The authors suggested that caffeine promotes improvement in exercise tolerance by its action on the central nervous system rather than by an increase in AC.…”

“…This approach assumes that the EPOC fast may correspond to the total energy used to resynthesize high-energy phosphate stores (i.e., alactic component) [24], while the O 2 equivalent from blood lactate accumulation ([La - ]) may represent the glycolytic energy cost (i.e., lactic component) [25]. A recent study has pointed out that caffeine improves supramaximal exercise endurance but not MAOD ALT , suggesting that either MAOD ALT is not sensitive enough to detect changes in AC with caffeine or that the potential effect of caffeine during supramaximal exercise is a different fatigue-related process [26]. Therefore, studies testing caffeine effects using different approaches to estimate AC are required to provide insights as to whether caffeine-induced improvement on AC can be equally detected by these different methods.…”

Carbohydrate mouth rinse reduces rating of perceived exertion but does not affect performance and energy systems contribution during a high-intensity exercise

“…Furthermore, no significant differences for aerobic, anaerobic lactic, anaerobic alactic and total energy expenditure were found in the present study. Regarding the anaerobic contribution in high intensity exercise, studies verifying the effect of caffeine 24 and metformin 25 showed that even with a higher time to exhaustion, there was no significant difference in the anaerobic contribution in these exercises, probably because the anaerobic energy reserve may be a finite source 26 . On the other hand, as well as CHO mouth rinse, CHO intake did not increase time to exhaustion and anaerobic contribution in physically active cycling at 110% PPO 27 .…”