Cardiovascular strain and metabolic rate are higher following 15 minutes of standing versus seated computer work

Globally, about 31% of adults are physically inactive. To combat physical inactivity in desk-bound jobs, many have begun to use standing desks. Standing desks are effective for reducing sitting time; however, evidence to support the beneficial metabolic effects are inconclusive. Furthermore, the effectiveness of using standing alone to combat inactivity in lieu of moderate to vigorous physical activity has been questioned. Thus it is unclear what effect sitting versus standing has on energy expenditure while performing desk work. Research investigating the impact of standing desks has not found improvements in cardiometabolic risk factors, and occupational standing may contribute to vascular abnormalities. Importantly, none of these studies measured blood pressure during standing work. This is important as a 12-year follow-up study found that standing occupations were associated with a twofold increase in the risk of heart disease compared to sitting occupations. Therefore, research exploring the metabolic and cardiovascular effects of sitting versus standing is needed. The purpose of this study was to evaluate metabolic and cardiovascular responses to acute bouts of computer work while sitting and standing to clarify the effect of standing desks. All participants signed an informed consent and the procedures were approved by the institutional review board. Participants were asked to complete a medical history and confirmed abstinence from exercise for 24 hours, alcohol, caffeine, over-the-counter or illicit drugs for 12 hours, and eating for 4 hours prior to their visit. Prior to starting the trial participants had their height and body mass measured (Detectco, MO, USA). Resting blood pressure and heart rate were measured using an automated brachial artery blood pressure cuff (Omron BP785N; Omron Healthcare Inc., IL, USA). Trials consisted of two randomized conditions, seated and standing. Throughout the trial cardiovascular responses were measured using the human non-invasive blood pressure (NIBP) continuous monitor with PowerLab and LabChart 8 software (ADInstruments, CO, USA). The NIBP monitor was placed on the middle finger of the non-dominant hand, which was placed in an arm sling to ensure consistent positioning. Metabolism was monitored by outfitting participants with an appropriately sized face mask used to monitor whole body metabolism continuously by measuring oxygen consumption (VO2), carbon dioxide production (VCO2), ventilation (VE), respiratory exchange ratio (RER), ventilatory equivalent for oxygen (VE/VO2) and ventilatory equivalent for carbon dioxide (VE/VCO2) using the VMAX Encore metabolic cart (CA, USA). Each participant spent 15 minutes in each condition before moving on to the next condition. The first 5 minutes of each condition were used as a baseline period followed by 10 minutes of in-condition time. Throughout the trial participants completed a simple mouse-driven computer task. Data from the last 5 minutes of each condition were averaged together and used in the statistical analysis. Cardiovascular measurements were calculated as change scores from the last 2 minutes of the seated baseline. Sitting versus standing conditions were compared using a paired Student’s t-test. Effect size was calculated using Cohen’s d. Analysis was performed using SPSS (IBM, version 25; NY, USA). The a-level was set a priori at P< 0.05. Twenty-three healthy participants (age 23.3 3.3 years; height 1.74 0.12m; body mass 78.1 17.3 kg; body mass index 25.8 4.7 kg/m; 12 men, 11 women) completed the study. Resting values prior to beginning the first baseline were: heart rate (HR) 67 2 bpm; systolic blood pressure (SBP) 112 11mmHg; and diastolic blood pressure (DBP) 66 9mmHg. All cardiovascular and metabolic data are presented in Table 1. Briefly, HR, rate pressure product (RPP) and change in DBP were lower in the sitting condition compared to