[Effects of short-term intervention of walking on body mass index, waist circumference, and related indicators of working population]

Objective: To quantify the effects of short-term walking intervention on body mass index (BMI), waist circumference, and related indicators of working population. Methods: The China Motivational Healthy Walking Program in 2016 recruited 29 224 individuals from 139 demonstration areas for comprehensive prevention and control of chronic and non-communicable diseases at the national level and 70 areas at the provincial level. All subjects volunteered to participate into this program. The intervention lasted 100 days from June to September 2016. The walking behavior, height, weight and waist circumference of subjects were measured using a uniform pedometer, body composition tester, height tester and waist-to-hip caliper before and after the intervention. Daily average steps, daily average effective steps, and the percent of fulfilling continuous walking per day were used as main indicators in this study. Self-administered questionnaires were used to collect demographic characteristics, behaviors and chronic diseases. With the adjustment of potential confounding factors, multilevel regression was used to quantify the effect of walking on BMI and waist circumference, and multilevel logistic regression was used to quantify the effect on overweight or obesity and central obesity. Results: A total of 12 368 subjects completed walking interventions and all measurements included in this study. The mean±SD age of all subjects was (41.19±8.99) years, and 5 155 (59.17%) of them were women. After 100-day intervention, all outcome variables decreased significantly. For every additional 1 000 steps per day, subjects would have extra decrease in BMI of 0.023 kg/m(2) [β (95%CI): -0.023 (-0.030, -0.017)], in waist circumference of 0.046 cm [β (95%CI): -0.046 (-0.071, -0.020)], and the likelihood for becoming overweight or obesity was 0.97 times [OR (95%CI): 0.97 (0.95, 0.98)] that of before intervention. With additional 1 000 effective steps per day, the difference between baseline and endpoint increased by 0.028 kg/m(2) [β (95%CI): -0.028 (-0.035, -0.020)] in BMI and 0.062 cm [β (95%CI): -0.062 (-0.091, -0.033)] in waist circumference. The likelihood of progressing into overweight or obesity was 0.97 times [OR (95%CI): 0.97(0.95, 0.98)] that of before-intervention, and the likelihood of becoming central obesity was 0.98 times [OR (95%CI): 0.98(0.96, 0.99)] that of before-intervention. Compared to subjects with low level percent of fulfilling continuous walking per day, those with high level would have an extra decrease in BMI by 0.150 kg/m(2) [β (95%CI): -0.150 (-0.22, -0.079)], in waist circumference by 0.340 cm [β (95%CI): -0.340 (-0.620, -0.064)], and the likelihood of becoming overweight or obesity decreased to 0.74 times that of the low level group [OR (95%CI): 0.74(0.62, 0.89)] and the likelihood of becoming central obesity decreased to 0.78 times that of the low level group [OR (95%CI): 0.78 (0.68, 0.91)]. Conclusion: Strengthening walking exercise in the short term has a positive effect on promoting working population to reduce BMI and waist circumference, and prevent overweight, obesity and central obesity.