Sophy J. Perdomo

Energy expenditure of deskwork when sitting, standing or alternating positions

Background Recent guidelines recommend accruing 2-4h of standing or light activity during the working day. Use of sit-stand desks could achieve this goal, but whether standing can meaningfully increase energy expenditure (EE) is unclear. Aims To study EE, heart rate, feelings and productivity during deskwork while sitting, standing or alternating positions. Methods We measured EE by indirect calorimetry in working adults over three randomly ordered 60-min conditions while performing deskwork: continuous sitting (SIT), 30min of each standing and sitting (STAND-SIT) and continuous standing (STAND). We also assessed heart rate, productivity and self-reported energy, fatigue and pain. Linear mixed models compared minute-by-minute EE and heart rate across conditions. Non-parametric tests compared remaining outcomes across conditions. Results The study group comprised 18 working adults. Compared with SIT, STAND-SIT engendered an additional 5.5±12.4 kcal/h (7.8% increase) and STAND engendered an additional 8.2±15.9 kcal/h (11.5% increase) (both P < 0.001). Alternating positions to achieve the recommended 4h/day of standing could result in an additional 56.9 kcal/day for an 88.9kg man and 48.3 kcal/day for a 75.5kg woman. STAND-SIT and STAND also increased heart rate over SIT by 7.5±6.8 and 13.7±8.8 bpm, respectively (both P < 0.001). We observed no meaningful differences in feelings or productivity. Conclusions Desk-based workers could increase EE without added discomfort by using a sit-stand desk. These findings inform future research on sit-stand desks as a part of workplace interventions to increase EE and potentially improve health.

Effect of alternating standing and sitting on blood pressure and pulse wave velocity during a simulated workday in adults with overweight/obesity

Objective: Reducing prolonged sitting at work has been recommended by an expert panel, but whether intermittent standing improves vascular health is unclear. We aimed to test whether using a sit–stand desk could reduce blood pressure (BP) and pulse wave velocity (PWV) during a simulated workday. Methods: Overweight/obese adults with pre-to-Stage 1 hypertension completed a randomized crossover study with two simulated workday conditions: STAND–SIT (alternating standing and sitting condition every 30 min) and SIT (continuous sitting condition). Oscillometric BP was measured hourly. Carotid–femoral, carotid–radial, and carotid–ankle PWV were measured in the morning, mid-day, and late afternoon using tonometry. Results: Participants [n = 25, 64% male, 84% white, mean (SD) age: 42 (12) years] had average resting SBP of 132 (9) mmHg and DBP of 83 (8) mmHg. In linear mixed models, STAND–SIT resulted in a significantly lower DBP (mean ± SE: −1.0 ± 0.4 mmHg, P = 0.020) and mean arterial pressure (MAP) (−1.0 ± 0.4 mmHg, P = 0.029) compared with SIT. SBP (−0.9 ± 0.7 mmHg, P = 0.176) was not different across conditions. Carotid–ankle PWV was significantly lower during the STAND–SIT vs. SIT condition (−0.27 ± 0.13 m/s, P = 0.047), whereas carotid–femoral PWV (−0.03 ± 0.13 m/s, P = 0.831) and carotid–radial PWV (−0.30 ± 0.18 m/s, P = 0.098) were not. Changes in MAP partially explained changes in PWV. Conclusion: Interrupting prolonged sitting during deskwork with intermittent standing was a sufficient stimulus to slightly, but statistically significantly, decrease DBP, MAP, and carotid–ankle PWV. Though the clinical significance of the observed effects is modest, regular use of a sit–stand desk may be a practical way to lower BP and PWV while performing deskwork.

Effects on carotid-femoral pulse wave velocity 24 h post exercise in young healthy adults.

Arterial stiffness, often measured by carotid–femoral pulse wave velocity (cfPWV), is a subclinical marker of cardiovascular disease that is known to be reduced by exercise training. Exercise is also known to have acute vascular effects, yet it is unclear whether exercise 24 h before cfPWV testing influences this outcome. Thirty healthy, young adults completed a supervised, 30-min bout of moderate-to-vigorous intensity treadmill running. cfPWV, systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) were measured both before (after 48 h of abstaining from exercise) and 24 h after (with no additional exercise) the exercise session. From pre-exercise to 24 h post exercise, cfPWV decreased from 6.05±0.82 to 5.84±0.87 m s−1 (P=0.02), SBP from 119.7±13.8 to 116.8±11.4 mm Hg (P=0.03) and DBP from 65.1±5.7 to 63.2±5.4 mm Hg (P=0.02), with no significant changes in HR. cfPWV was positively correlated with SBP pre-exercise (r=0.54, P<0.01) and post exercise (r=0.53, P<0.01). Changes in blood pressure explained 4–5% of the variability in cfPWV change; adjustments slightly attenuated the 24-h effects of exercise on cfPWV. Some evidence of gender differences was observed with higher cfPWV in males across assessments (P<0.05) and statistically significant reductions in cfPWV in males (−0.36±0.54 m s−1 (P=0.02)) but not in females (−0.07±0.31 m s−1 (P=0.41)). In conclusion, cfPWV decreased 24 h after an exercise bout, suggesting that exercise completed in the past 24 h should be considered before cfPWV testing.

Reducing sedentary behaviour to decrease chronic low back pain: the stand back randomised trial

Objective The Stand Back study evaluated the feasibility and effects of a multicomponent intervention targeting reduced prolonged sitting and pain self-management in desk workers with chronic low back pain (LBP). Methods This randomised controlled trial recruited 27 individuals with chronic LBP, Oswestry Disability Index (ODI) >10% and desk jobs (sitting ≥20 hours/week). Participants were randomised within strata of ODI (>10%–<20%, ≥20%) to receive bimonthly behavioural counselling (in-person and telephone), a sit-stand desk attachment, a wrist-worn activity-prompting device and cognitive behavioural therapy for LBP self-management or control. Self-reported work sitting time, visual analogue scales (VAS) for LBP and the ODI were assessed by monthly, online questionnaires and compared across intervention groups using linear mixed models. Results Baseline mean (SD) age was 52 (11) years, 78% were women, and ODI was 24.1 (10.5)%. Across the 6-month follow-up in models adjusted for baseline value, work sitting time was 1.5 hour/day (P<0.001) lower comparing intervention to controls. Also across follow-up, ODI was on average 8 points lower in intervention versus control (P=0.001). At 6 months, the relative decrease in ODI from baseline was 50% in intervention and 14% in control (P=0.042). LBP from VAS was not significantly reduced in intervention versus control, though small-to-moderate effect sizes favouring the intervention were observed (Cohen’s d ranged from 0.22 to 0.42). Conclusion An intervention coupling behavioural counselling targeting reduced sedentary behaviour and pain self-management is a translatable treatment strategy that shows promise for treating chronic LBP in desk-bound employees. Trial registration number NCT0224687; Pre-results.