Effects of alternating standing and sitting compared to prolonged sitting on cerebrovascular hemodynamics
Previous research suggests that prolonged sitting may acutely reduce cerebral blood flow velocity (CBFv). The purpose of this study was to evaluate the effects of alternating standing and sitting vs prolonged sitting on CBFv.
This randomized crossover study enrolled working adults (N = 25) with pre-to-stage 1 hypertension not using antihypertensive medications, and a body mass index (BMI) from 25 to < 40 kg/m2. Subjects participated in two simulated workday conditions: (1) sitting continuously (SIT), and (2) alternating standing and sitting every 30 min (SS). Beat-to-beat systolic, mean and diastolic CBFv were recorded bilaterally for 1 min via insonation of the middle cerebral artery using transcranial Doppler ultrasonography before (morning), between (midday) and following (afternoon) two 3-h 40 min work periods.
Mean ± SD age was 42 ± 12 years, blood pressure (BP) was 132 ± 9/83 ± 8 mmHg, and BMI was 32 ± 5 kg/m2. Cerebrovascular hemodynamics did not differ across condition (P > 0.05). There were, however, significant nonlinear effects of time (decrease from morning to midday; increase from midday to afternoon) on systolic CBFv (P = 0.014), mean CBFv (P = 0.001), diastolic CBFv (P = 0.002), and pulsatility index (P = 0.038). When overall time effects were evaluated during each time interval, mean and diastolic CBFv significantly decreased morning to midday and all CBFv increased from midday to afternoon. When separated by condition, significant time effects were observed for all CBFv during SIT (P < 0.02) but not SS (P > 0.05).
In individuals with elevated BP and BMI, CBFv significantly decreased by midday and increased by afternoon, especially during a workday of prolonged sitting. Future studies should evaluate the combination of frequent walks and a sit-stand desk to break up prolonged sitting.
KeywordsSedentary behaviour Sit-stand desk Cerebrovascular hemodynamics Transcranial Doppler
Cerebral blood flow velocity
Carotid-femoral pulse wave velocity
Carotid-radial pulse wave velocity
Diastolic blood pressure
Mean arterial pressure
Pulse wave velocity
Transcranial Doppler ultrasonography
The authors would like to thank Humanscale and the National Institutes of Health through Grant Number UL1TR000005 (University of Pittsburgh CTSI, providing research registry support) for their support. The authors would also like to thank University of Pittsburgh's K. Leroy Irvis Fellowship and the University of Kansas Alzheimer's Disease Center (P30 AG035982) for supporting Dr. Perdomo's time.
Compliance with ethical standards
Conflict of interest
Dr. Gibbs discloses funding from Humanscale. Drs. Perdomo, Kowalsky, Balzer and Mr. Taormina disclose no conflicts of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Written informed consent was obtained from all participants.
- 2.Chomistek AK, Manson JE, Stefanick ML, Lu B, Sands-Lincoln M, Going SB, Garcia L, Allison MA, Sims ST, LaMonte MJ (2013) Relationship of sedentary behavior and physical activity to incident cardiovascular disease: results from the Women’s Health Initiative. J Am Coll Cardiol 61(23):2346–2354CrossRefGoogle Scholar
- 3.Biswas A, Oh PI, Faulkner GE, Bajaj RR, Silver MA, Mitchell MS, Alter DA (2015) Sedentary time and its association with risk for disease incidence, mortality, and hospitalization in adults a systematic review and meta-analysis sedentary time and disease incidence, mortality, and hospitalization. Ann Intern Med 162(2):123–132CrossRefGoogle Scholar
- 11.Gorelick PB, Scuteri A, Black SE, DeCarli C, Greenberg SM, Iadecola C, Launer LJ, Laurent S, Lopez OL, Nyenhuis D (2011) Vascular contributions to cognitive impairment and dementia a statement for healthcare professionals from the American Heart Association/American Stroke Association. Stroke 42(9):2672–2713CrossRefGoogle Scholar
- 23.Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LA, Izzo JL Jr, Jones DW, Materson BJ, Oparil S, Wright JT Jr (2003) The seventh report of the joint national committee on prevention, detection, evaluation, and treatment of high blood pressure: the JNC 7 report. JAMA 289(19):2560–2571CrossRefGoogle Scholar
- 24.Buckley JP, Hedge A, Yates T, Copeland RJ, Loosemore M, Hamer M, Bradley G, Dunstan DW (2015) The sedentary office: a growing case for change towards better health and productivity. Expert statement commissioned by Public Health England and the Active Working Community Interest Company. Br J Sports Med 49 (21): 1353–1353Google Scholar
- 28.Naqvi J, Yap KH, Ahmad G (2013) Ghosh J (2013) Transcranial Doppler ultrasound: a review of the physical principles and major applications in critical care. Int J Vasc Med 2013:629378Google Scholar
- 29.Weber T, Ammer M, Rammer M, Adji A, O’Rourke MF, Wassertheurer S, Rosenkranz S, Eber B (2009) Noninvasive determination of carotid–femoral pulse wave velocity depends critically on assessment of travel distance: a comparison with invasive measurement. J Hypertens 27(8):1624–1630CrossRefGoogle Scholar
- 30.Mattace-Raso F, Hofman A, Verwoert G, Wittemana J, Wilkinson I, Cockcroft J, McEniery C, Yasmin Laurent S, Boutouyrie P, Bozec E, Hansen T, Torp-Pedersen C, Ibsen H, Jeppesen J, Vermeersch S, Rietzschel E, De Buyzere M, Gillebert T, Van Bortel L, Segers P, Vlachopoulos C, Aznaouridis C, Stefanadis C, Benetos A, Labat C, Lacolley P, Stehouwer C, Nijpels G, Dekker J, Ferreira I, Twisk J, Czernichow S, Galan P, Hercberg S, Pannier B, Guérin A, London G, Cruickshank J, Anderson S, Paini A, Agabiti RE, Muiesan M, Salvetti M, Filipovsky J, Seidlerova J, Dolejsova M (2010) Determinants of pulse wave velocity in healthy people and in the presence of cardiovascular risk factors:‘establishing normal and reference values’. Eur Heart J 31(19):2338–2350CrossRefGoogle Scholar
- 31.Townsend RR, Wilkinson IB, Schiffrin EL, Avolio AP, Chirinos JA, Cockcroft JR, Heffernan KS, Lakatta EG, McEniery CM, Mitchell GF (2015) Recommendations for improving and standardizing vascular research on arterial stiffness a scientific statement from the American Heart Association. Hypertension 66(3):698–722CrossRefGoogle Scholar
- 34.Kar G, Hedge A (2016) Effects of sitting and standing work postures on short-term typing performance and discomfort. In: Proceedings of the Human Factors and Ergonomics Society annual meeting, vol 1. SAGE Publications, pp 460–464Google Scholar