Summer to Winter Variability in the Step Counts of Normal Weight and Overweight Adults Living in the UK

Background: This study investigated whether pedometer-determined activity varies between summer and winter in normal-weight and overweight adults. Methods: Forty-five normal-weight (58% female, age = 39.1 +/- 12.4 years, BMI = 22.2 +/- 2.1 kg/m(2)) and 51 overweight (49% female, age -= 42.1 +/- 12.5 years, BMI = 29.3 +/- 4.5 kg/m(2)) participants completed a within-subject biseasonal pedometer study. All participants completed 2 4-week monitoring periods; I period in the summer and 1 period the following winter. Changes in step counts across seasons were calculated and compared for the 2 BMI groups. Results: Both BMI groups reported significant summer to winter reductions in step counts, with the magnitude of change being significantly greater in the normal-weight group (-1737 +/- 2201 versus 781 +/- 1673 steps/day, P = .02). Winter step counts did not differ significantly between the 2 groups (9250 +/- 2845 versus 8974 +/- 2709 steps/day, P -= .63), whereas the normal-weight group reported a significantly higher mean daily step count in the summer (10986 +/- 2858 versus 9755 +/- 2874 steps/day, P = .04). Conclusion: Both normal-weight and overweight individuals experienced a reduction in step counts between summer and winter; however, normal-weight individuals appear more susceptible to winter decreases in ambulatory activity, with the greatest seasonal change occurring on Sundays. Effective physical activity policies should be seasonally tailored to provide opportunities to encourage individuals to be more active during the winter, particularly on weekends.