Lipid Metabolism at Two Different Walking Speeds in Obese Individuals: Pilot Study

Abstract

Exercise is an important factor of obesity and overweight management. American College of Sports Medicine recommends that 150–250 minutes per week and up to 60 minutes per day of moderate‐intensity aerobic exercise should be performed for weight gain prevention or modest weight reduction. Walking is a common and relatively safe form of aerobic exercise that can easily be incorporated into weight management programs. The energy expenditure associated with walking has been reported to be either linearly or slightly exponentially related to speed. Thus, interval walking training has been developed as a novel free‐living training modality that improves physical fitness and cardiovascular risk factors in humans.PURPOSEto determine if an interval walking exercise increases fat breakdown, fat utilization, and energy expenditure to a greater extent, compared with constant walking exercise in obese adults.METHODSThis study was set as randomized crossover design. Six sedentary obese individuals (BMI ≥ 30 kg/m2 and 18–50 yrs) were recruited. Initially six subjects were randomly assigned into a constant speed walking group (CON) or an interval walking group (INT). Then, CON became INT and INT became CON. The constant speed walking consists of a single bout of 40 min walking exercise at 45% of VO2max on a treadmill. The interval walking consists of a single bout of 40 min walking exercise with cycles of alternating 3‐min slow (30% of VO2max), 3‐min moderate (45% of VO2max), and 3‐min fast (60% of VO2max) walking. Energy expenditure and fat usage were measured at rest and every 10min during walking exercises via indirect calorimetry. Blood samples were drawn at rest and every 10min during walking exercises to measure glycerol levels. Two‐way ANOVA was used to determine differences in energy expenditure and fat utilization between the groups.RESULTSThe net rates of fat utilization (g/min) and calorie expenditure (kcal/min) were not different between the groups during walking exercises. Also, blood glycerol concentrations were not different between the groups at any time points of exercise. However, the net rates of fat utilization, calorie expenditure, and blood glycerol concentrations were significantly higher at 30min and 40min of exercise, compared to those at 10min of exercise in both groups.CONCLUSIONOur data show that walking speeds might not be a primary factor to regulate fat utilization and energy expenditure during low and moderate exercise intensities. However, an increase in fat metabolism and energy expenditure during walking exercises may be attributed to the longer duration of exercise. Thus, these findings may provide a better exercise strategy to increase lipid breakdown and prevent weight gain in overweight/obese people.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.