Abstract
Sedentary work has become increasingly common within Johannesburg’s working population, raising concerns about its impact on cardiovascular health. Estimated maximal oxygen consumption (VO2max), a key indicator of cardiovascular fitness, offers meaningful insight into the physiological consequences of prolonged occupational sitting.
Aim
The aim of the study was to investigate the impact of sedentary work conditions on the estimated VO2max of the working population in Johannesburg.
Methods
A cross-sectional quantitative design was implemented following a pilot study establishing strong test-retest reliability for the adapted treadmill six-minute walk test (Intraclass Correlation Coefficient [ICC] = 0.99; standard error of measurement [SEM] = 10.39 m; minimum detectable change at 95% confidence [MDC95] = 28.81 m). The main sample included 96 adults (48 sedentary; 48 non-sedentary; 47 males and 49 females; mean age = 43.99 ±13.66 years). Participants were further stratified into age categories (18–29; 30–49; 50–65 years) for comparative analysis. Demographic, cardiovascular, and physical activity data were collected, and estimated VO2max was obtained using a submaximal treadmill-based six-minute walk test (objective measure) and thereafter calculated using a validated submaximal prediction equation. Occupational classification (sedentary vs non-sedentary) was determined using a structured occupational questionnaire assessing sitting time and primary job tasks. Group comparisons were conducted using chi-square tests, Mann-Whitney U tests, and age- and gender- stratified analyses.
Results
Non-sedentary participants demonstrated significantly higher estimated VO2max than sedentary participants (U = 595.00, p < 0.001), with all non-sedentary participants classified in the high estimated VO2max category (100%), compared with only 20.83% of sedentary participants. Age-specific analyses indicated significant associations in the 30-49 year (p < 0.001) and 50- ...