Background There is increasing evidence of the link between adult obesity levels and travel behaviour: countries with highest levels of active travel generally have the lowest obesity rates. Walking is a popular, familiar, convenient, and free form of exercise that can be incorporated into everyday life and sustained into old age. Walking at a moderate pace (5 km/hour) expends sufficient energy to meet the definition of moderate intensity physical activity. The study aims to objectively examine the contribution of walking to work on adult physical activity levels.

Methods Employees (n = 145) at 17 workplaces in Bristol, who lived within 2 miles of the workplace, were asked to wear accelerometers for 7 days from waking in the morning to going to bed at night, and to carry a GPS receiver during the daily commute to and from work. GPS data were matched with accelerometer data to provide a measure of duration of the journey and associated physical activity. Outcome measures included: overall volume of physical activity; moderate to vigorous physical activity (MVPA) levels; temporal pattern of physical activity (to identify when activity has increased and whether there is a compensatory decrease in activity at other times), and; objective measures of routes taken and physical activity associated with journey.

Results Daily physical activity volume for employees using the car compared to those who walk (Mean (SD)) of 310.5 (149.7) vs 570 (177) (p < 0.001) counts per minute. MVPA in minutes for employees using the car compared to those who walk shows 41.4 (31.7) vs 84.4 (25.4) (p < 0.001). Sedentary time in minutes for employees using the car compared to those who walked was 627.7 (73.8) vs 576.7 (94.8) (p = 0.017). Employees who walked to work showed higher accelerometer counts per minute between 6–9am and 4–7pm which was maintained throughout the day compared to those who used the car. Combined GPS and accelerometer trace showed the journey to work provides employees with more MVPA.

Conclusion We are not aware of any other study in adults using objective methods to measure the contribution of walking to work on physical activity levels. Our study clearly shows that the daily commute provides an opportunity for adults who live within walking distance of their workplace to meet their daily physical activity requirements and reduces sedentary time.