Whether a nocturnal exercise with concomitant increase of body temperature (Tb) would intensify circadian phase delay compare to exercise with a suppressed Tb increase was examined. Seven healthy men (20.57 ± 2.88 yrs, 174.43 ± 4.05 cm, 70.13 ± 6.07 kg, 10.74 ± 1.92% fat) participated in two tests. Each lasted 5-days. On the day of 1 of each test, subjects maintained habitual sleep time (23:00-07:00, 0.2 lux) in laboratory. From day 2 thru 5, they biked for 60 min at 55% of maximal capacity beginning at 01:30 (15 lux). Then they went to bed at 04:00 and woke at 12:00. During test, they exercised either at 26℃ with elevating Tb (ET) or at 17℃ with cooling devices for suppressing Tb (ST). Two tests were counter balanced and separated by 2 weeks. During exercise, rectal (Tre) and skin (Tsk) temperatures, and heart rate were continuously recorded. Body weight changes during exercise were measured. Urine volume and saliva sample were collected. Blood samples were taken at 23:00, 03:30, 07:00, and 12:00 on day 1 and 5 of tests and analyzed for melatonin. The average weight loss for 4 days of exercise in ET and ST was 0.62 ± 0.09 and 0.22 ± 0.07 kg, respectively (p<.001). Tre increased during exercise but not different between conditions. Tsk maintained at 32℃ in ET and 24℃ in ST (p<.001). Tb were higher in ET than ST during exercise (p<.05). The average total urine volume passed was 0.07 ± 0.07 in ET and 0.11 ± 0.07 liter in ST (p<.05). The melatonin concentration at day 1 was 23 ± 26, 107 ± 45, 98 ± 46, and 14 ± 5 in ET and 18 ± 10, 108 ± 65, 103 ± 75, and 14 ± 12 pg/ml in ST for each time period. At day 5, it was 9 ± 3, 64 ± 41, 122 ± 73, and 54.1 ± 17.8 in ET and 8 ± 1, 68 ± 21, 111 ± 52, and 32 ± 14 pg/ml in ST. Differences of melatonin between ET and ST at day 5 of 12:00 as well as between day 1 and 5 at 12:00 of both conditions were noticed (p<.05). Salivary cortisol and immunoglobulin-A were not different. A nocturnal exercise induced a circadian phase delay in both conditions. However, body temperature increase during exercise intensified the shift indicating the importance of thermal load during exercise for circadian shift.
This study was designed to investigate the effects of increment of physical activity for 12 weeks through aerobic exercise training or change from own vehicle to public transportation for commuting on physical fitness, insulin resistance, inflammatory markers, and liver function in middle-aged men. Forty-four subjects, aged 30-50 yrs, were randomly assigned to either one of three groups, i.e., aerobic exercise training group (TR: n=14), change to public transportation group (PT: n=15), or control group (CON: n=15). Subjects in TR performed aerobic exercise for 30 min per sessions, three sessions per week, subjects in PT changed from their own vehicle to public transportation for commuting, and subjects in CON maintained their life patterns during the same intervention period. Physical fitness, insulin resistance, inflammatory markers, and liver function were measured at pre- and post-test, and the data were analyzed by repeated two-way ANOVA. Main results of the present study were as follows: 1) All variables related to physical fitness improved significantly in TR. Right grip strength, standing long jump, side step test, and sit-and-reach improved significantly in PT. 2) Although there were no significant changes in all variables related to insulin resistance, the variables tended to be improved in TR and PT. 3) TNF-α decreased significantly in TR and PT. IL-6 and CRP tended to be improved in TR and PT; however, the changes did not reach statistical significant level. 4) ALT decreased significantly in PT. AST and γ-GT tended to be improved in TR and PT; however, the changes did not reach statistical significant level. It was concluded that the 12 weeks of change to public transportation as well as aerobic exercise training would be beneficial for physical fitness and inflammatory markers. These interventions also would be possible to improve insulin resistance and liver function. The increment of physical activity through change from own vehicle to public transportation was found to be equally beneficial for health promotion compared to aerobic exercise.
