Evaluation of pharmacological aids on physical performance after a transmeridian flight

Purpose: The purpose of this study was to evaluate physical performance (st atic and dynamic) of U.S. Air Force reservists after an eastbound air trave l across seven time zones and to estimate the pharmacological aids slow-rel ease caffeine and melatonin versus placebo in attempt to overcome the decli ne in performance. Methods: 27 American volunteers were randomly divided in to three groups: caffeine 300 mg, melatonin 5 mg, and placebo (lactose, cap sules). Two days before the flight and 10 d after, three tests were perform ed: hand grip strength test (static performance), squat jump test (maximal height), and multiple jump test (power and endurance). All measures were re peated twice a day: morning and afternoon. Results: Zn placebo conditions, the static performance of the dominant hand decreased significantly during the first three mornings and tended to decrease the fourth morning. Simulta neously, the caffeine group's static performance increased significantly, w hereas the melatonin group maintained its levers. No significant difference s were observed the afternoons. No statistical differences appeared for the nondominant hand in the mornings or afternoons. Dynamic capacities present ed no significant degradation after the travel. In the placebo group, for t he squat jump test, performance increased from the fourth day. No real expl anation can be given about this result. Conclusions: We demonstrated that s low-release caffeine and melatonin might be used to compensate for jet-lag troubles and particularly for the static physical performance decrease. The slow-release caffeine seems to be the best treatment, but its effects are only demonstrated on previously damaged performance. These preliminary resu lts need further investigation, but we are the first to report a beneficial effect of slow-release caffeine and melatonin on physical performances aft er jet-lag.