Caffeine Supplementation Had No Effect on Endurance Capacity in Elderly Subjects Who Had Abstained from Caffeine-Containing Nutrition for 8 Hours

Abstract

Background: In this study, we investigated the effect of acute caffeine ingestion on physical performance after only 8 hours of caffeine abstinence. Methods: The study was a randomized, double-blind, cross-over study and included 30 healthy subject aged ≥70 years who had been recruited by their general practitioner. The participants abstained from caffeine for 8 hours (overnight) and the next morning they received placebo and then caffeine (6 mg/kg), or caffeine and then placebo at an interval of 1 week. One hour after the intervention we measured cycling endurance (ergometer), perceived effort during cycling (Borg scale), postural stability (force platform), and maximal isometric arm flexion strength and endurance (dynamometer chair). Blood samples were taken before the intervention, before cycling, after 5 minutes of cycling, and at exhaustion. Results: The participants had a usual coffee intake of six cups/day and after 8 hours of caffeine abstinence the plasma concentration of caffeine was 4.1 μM. Caffeine supplementation almost 10-fold increased the caffeine concentration and increased the lactate, epinephrine, and free fatty acid concentrations. However, caffeine supplementation did not significantly change the primary end point of cycling endurance, which was −10.6% (95% confidence interval: −22.7% to 3.3%, p=0.123) during caffeine supplementation as compared with placebo. Further, caffeine supplementation did not change significantly the perceived effort during cycling (p=0.084), maximal muscular strength (p=0.516), or isometric submaximal endurance (p=0.340). Caffeine increased postural sway. Conclusions: In habitual coffee drinkers abstaining from caffeine for 8 hours, caffeine supplementation did not improve physical performance, but impaired postural stability.