Differences in levels of physical activity between White and South Asian populations within a healthcare setting: impact of measurement type in a cross-sectional study

Objective: We investigate differences between White and South Asian (SA) populations in levels of objectively measured and self-reported physical activity. Design: Cross-sectional study. Setting: Leicestershire, United Kingdom, 2010-2011. Participants: Baseline data was pooled from two diabetes prevention trials which recruited a total of 4282 participants from primary care with a high risk score for type 2 diabetes. For this study, 2843 White (age = 64 ± 8, female = 37%) and 243 SA (age = 58 ± 9, female = 34%) participants had complete physical activity data and were included in the analysis. Outcome measures: Moderate- to vigorous-intensity physical activity (MVPA) and walking activity were measured using the International Physical Activity Questionnaire (IPAQ) and a combination of piezoelectric pedometer (NL-800) and accelerometer (Actigraph GT3X) were used to objectively measure physical activity. Results: Compared to White participants, SA participants self-reported less MVPA (30 vs. 51 minutes per day; P < 0.001) and walking activity (11 vs 17 minutes per day; P = 0.001). However, there was no difference in objectively measured ambulatory activity (5992 steps/day vs. 6157 steps/day; p = 0.75) or in time spent in MVPA (21.5 vs. 18.0 minutes/day; p = 0.23). Results were largely unaffected when adjusted for age, sex and social deprivation. 3 Compared to accelerometer data, White participants overestimated their time in MVPA by 51 minutes/day and SA participants by 21 minutes/day. Conclusions: SA and White groups undertook similar levels of physical activity when measured objectively despite self-reported estimates being around 40% lower in the SA group. This emphasises the limitations of comparing self-reported lifestyle measures across different populations and ethnic groups. Reports baseline data from: Walking Away from Type 2 Diabetes (ISRCTN31392913) and Let’s Prevent Diabetes (NCT00677937)