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Caffeine improves endurance in 75-yr-old citizens: a randomized, double-blind, placebo-controlled, crossover study

¹Surgical Research Unit, Department of Surgery, Herning Hospital, Herning; and ²Surgical Research Unit, Department of Surgery L, University Hospital of Aarhus, Aarhus, Denmark

Submitted 16 March 2005 ; accepted in final form 29 July 2005

This study investigated the effect of caffeine on physical performance in healthy citizens aged 70 yr. The randomized, double-blind, placebo-controlled, crossover study was conducted in 15 men and 15 women recruited by their general practitioner. Participants abstained from caffeine for 48 h and were randomized to receive one capsule of placebo and then caffeine (6 mg/kg) or caffeine and then placebo with 1 wk in between. One hour after intervention, we measured reaction and movement times, postural stability, walking speed, cycling at 65% of expected maximal heart rate, perceived effort during cycling, maximal isometric arm flexion strength, and endurance. Analysis was by intention to treat, and P < 0.05 was regarded as significant. Caffeine increased cycling endurance by 25% [95% confidence interval (CI): 13–38; P = 0.0001] and isometric arm flexion endurance by 54% (95% CI: 29–83; P = 0.0001). Caffeine also reduced the rating of perceived exertion after 5 min of cycling by 11% (95% CI: 5–17; P = 0.002) and postural stability with eyes open by 25% (95% CI: 2–53; P = 0.03). Caffeine ingestion did not affect muscle strength, walking speed, reaction, and movement times. At the end of the study, 46% of participants correctly identified when they received caffeine and placebo. Caffeine increased exercise endurance in healthy citizens aged 70 yr, but the participants' reasons for stopping the test may have varied between subjects, as the cycling test was done at 55% of maximal oxygen consumption. Further studies are required to investigate whether caffeine can be utilized to improve the physical performance of elderly citizens.

fatigue; perceived exertion; postural stability; elderly