Abstract
【Background】 It is well known that hyperinsulinemia is improved by physical activity, but the effective amount of walking remains unclear.
【Methods】 In the present study, we examined the walking time during fast walking（6km/h） required for insulin-sparing action using urinary C-peptide excretion as an index. Six healthy adult females participated in Study 1, and another 6 healthy adult females participated in Study 2. Four experiments consisted of control, walking at 6 km/h for 1 or 2 or 3 hours. Walking was divided equally between morning and afternoon. After urine samples were collected before walking（6:00 to 8:00），daytime（8:00 to 20:00）and nighttime（20:00 to 8:00 the next day） urine samples were collected in Study 1. On the other hand, daytime urine samples were collected separately（8:00 - 12:00, 12:00 - 16:00, 16:00 - 20:00）in Study 2.
【Results】 In both the Study 1 and Study 2, the urinary C-peptide excretion levels during the daytime were significantly lower in all the 1-hour, 2-hour and 3-hour walking experiments than in the control. In the Study 2 and when the results of the both studies were aggregated, the urinary C-peptide excretion levels during the daytime were tended to be lower in walking for 2 hours and significantly lower in walking for 3 hours than in walking for 1 hour. No significant differences were observed between walking for 2 hours and 3 hours.
【Conclusions】 Walking at 6 km/h for 1 hour/day or more is expected to reduce urinary C-peptide excretion and induce insulin-sparing effects.
