Diurnal Variations of Body Temperature and Reaction Time Accompanying Early Morning and Evening Aerobic Routines

Approved: Redacted for Privacy Don-rd y Campbell The primary purpose of this study was to determine the effects of early morning and evening bouts of aerobic exercise upon the diurnal pattern of reaction time and body temperature. An effort was made to classify subjects according to the rhythmic trends identified with 'morning' and 'evening' type persons. Eight physically active male students of Oregon State University between the ages of 18 and 27 volunteered to serve as subjects. Four 'morning' and four 'evening' efficient types comprised the two test groups. Diurnal orientation was determined using questions designed to detect physiological and psychological orientation to the two extremes of day. Treatments consisted of three different jogging routines of six days each. Exercise bouts were submaximal, lasting 15-30 minutes. The first six day period all subjects ran at their customary time, establishing a baseline for subsequent comparisons. The two following weeks subjects were scheduled for periods of 0630 and 1830 running, in random order. During all three treatment periods, visual and auditory reaction time and temperature were measured. Testing was accomplished on a rotating schedule of two and three-a-day visits at 0800, 1400 and 2000, or 1100 and 1700 hours. In this manner, the testing procedure was replicated three times, at 48 hour intervals for all individuals, over all treatment periods. Two way analysis of variance was employed to determine effects of subject type and jogging schedule upon reaction time and temperature. The diurnal patterns that manifested themselves between 0800 and 2000 were analyzed by means of a triple classification ANOVA of trend components. The .05 level of confidence was the basis for rejection or acceptance of each hypothesis tested. The results of the study indicated that: a) no significant difference of reaction time or temperature existed between evening and morning types, or between jogging regimes or interaction of those two variables; b) no significant differences existed between trends for subject types; however, c) reaction time and temperature variation over the day exhibited a rhythmic trend and; d) significant difference of trend between treatments was found. Quantitatively neither exercise scheduling nor subject type affect the body's mean response as measured by reaction time and temperature. The curves of morning and evening persons were not significantly different. However, when compared with the control week, trends associated with evening and morning runs reflected phase purturbation indicative that the time of day one exercises can affect the synchrony of psychomotor performance and body