The effects of physical fatigue and altitude on physiological, biochemical, and performance responses.

OAM report.PDFTech ReportFAA-AM-82-10DOT/FAA/AM-82/10Performance testsHypoxiaFatigue (Physiological condition)PhysiologyBiochemistrySimulationAltitudeHeart ratePhysical fitnessExperimentsHuman subject testingUrinalysisAminesUnited StatesCivil Aerospace Medical InstituteHiggins, E. ArnoldMertens, Henry W.McKenzie, Jess M.Funkhouser, Gordon E.White, Mary AnnMilburn, Nelda J.Civil Aeromedical InstituteUnited States. Office of Aviation MedicineNTL-AVIATION-Aviation Energy and EnvironmentNTL-AVIATION-Aviation Human FactorsUS Transportation CollectionTwelve healthy young men were evaluated in each of four experimental conditions involving the possible combinations of two exercise conditions given prior to performance testing (1 h of heavy exercise vs. no exercise) and two altitude conditions (ground level vs. 12,500 ft) which were administered during performance testing. Performance was measured during a 2 1/4-h test session with the Multiple Task Performance Battery (MTBP) which involved time-shared performance in monitoring of warning lights and meters, mental arithmetic, problem solving, and tracking.Heart rate was statistically higher after exercise than after no exercise and statistically higher at 12,500 ft than at ground level. Norepinephrine excretion was higher during exercise experiments than during no-exercise experiments. There was no altitude effect for this measurement. The overall composite score of MTPB performance was significantly lower at 12,500 ft than at ground level. The adverse effect of higher altitude was greatest in the tracking task. The 1-h period of vigorous physical exercise had no statistically significant main effect on overall MTPB scores.Residual effects of exercise resulting in increased arousal may account for the tendency for performance to be slightly higher in the case of problem solving. The interaction of altitude with exercise was also significant in the case of tracking performance. The most important aspect of the interaction was that tracking performance was significantly better at 12,500 ft following exercise. This finding is possibly due to the increase in cardiovascular circulation induced by prior exercise and exercise "breaks" should be examined in future research