Physical Activity Assessment—Self-Reported Versus Pedometer-Measured, and Associations with Health Markers Among University Students in South Africa

Accurate measurement of physical activity is crucial for promoting health and preventing non-communicable diseases, particularly in Sub-Saharan Africa, where the dual burden of infectious and chronic diseases presents significant public health challenges. While self-reported tools are commonly used, they are often limited by recall and social desirability biases. This study aimed to compare self-reported physical activity with objectively measured pedometer data and explore their associations with fitness and anthropometric indicators among university students. A cross-sectional study was conducted among 60 full-time students at a South African university. The study was conducted in two phases: For phase 1, participants completed the International Physical Activity Questionnaire (IPAQ). For phase two, participants wore pedometers for seven consecutive days to measure total and aerobic step counts. Fitness was assessed using the Harvard Step Test to calculate the Physical Efficiency Index (PEI), and anthropometric data (BMI, waist-to-hip ratio, body fat percentage) were recorded. Statistical analyses included Spearman's correlations, Mann-Whitney U test, Kruskal-Wallis H test, and multivariable linear regression. While 83.3% of participants self-reported high physical activity levels, pedometer data indicated that 61.7% accumulated fewer than 1500 aerobic steps per day and 53.3% recorded fewer than 5000 total steps. No significant association was found between self-reported activity and pedometer-measured steps (<i>p</i>-value = 0.748 and <i>p</i>-value = 0.835, respectively). Objective measures showed significant positive correlations between aerobic steps and PEI (<i>r</i> = 0.274, <i>p</i>-value = 0.034) and significant negative correlations with BMI (<i>r</i> = -0.489, <i>p</i>-value < 0.001) and body fat percentage (<i>r</i> = -0.255, <i>p</i>-value = 0.046). Older age and female gender were associated with lower step counts. This study reveals a significant overestimation of physical activity in self-reports compared to objective measures and stronger links between objectively measured steps and key health outcomes. The findings highlight the need to integrate objective monitoring tools into public health practice and youth-focused interventions in Sub-Saharan Africa. They underscore the importance of exploring context-specific factors influencing activity levels. Enhancing measurement accuracy is vital for advancing evidence-based strategies and achieving Sustainable Development Goal 3.