Impacts of prolonged sitting with mild hypercapnia on vascular and autonomic function in healthy recreationally active adults

Abstract

<jats:p> Prolonged sitting, which is known to impair peripheral vascular function often occurs in spaces (e.g. offices) with mild hypercapnic atmospheres. However, the effects of prolonged sitting in hypercapnic conditions on vascular function are unknown. Therefore, the purpose of this study was to investigate the effects of prolonged sitting in mild hypercapnic conditions on vascular and autonomic function in humans. Methods: 12 healthy young adults participated in two experimental visits which consisted of sitting for 2.5 hours in a control condition (PSIT) or a mild hypercapnic condition (HCAP, CO2=1,500 ppm). During each visit, heart rate variability (HRV), blood pressure (BP), pulse wave velocity (PWV), augmentation index (AIx), brachial and popliteal artery flow mediated dilation (FMD), and near infrared spectroscopy (NIRS) were assessed before and after prolonged sitting. Results: Sitting significantly decreased AIx in both groups (P&lt;0.05). Brachial and popliteal FMD were reduced with sitting (P&lt;0.05), and the reduction in popliteal FMD was amplified by HCAP (P&lt;0.05). Baseline microvascular oxygenation was decreased following sitting in both groups (P&lt;0.05). However, microvascular reoxygenation upon cuff release was slower only in HCAP (P&lt;0.05). HRV, HR, BP, and PWV did not significantly change with sitting in either group (P&gt;0.05). Conclusion: Prolonged sitting attenuated both brachial and popliteal endothelial function and was associated with perturbed microcirculation. Additionally, mild hypercapnic conditions further impaired peripheral endothelial and microvascular function. Together, these findings suggest that prolonged sitting is accompanied by a host of deleterious effects on the vasculature, which are exacerbated by mild hypercapnia. </jats:p>

Effects of Acute Prolonged Sitting and Interrupting Prolonged Sitting on Heart Rate Variability and Heart Rate in Adults: A Meta-Analysis

“…Of these, 29 randomized cross-over trials underwent full text screening and 8 were excluded (Chaput and Tremblay, 2007 ; Bourdin et al, 2010 ; Jean-François et al, 2010 ; Larsen et al, 2014 ; Restaino et al, 2015 ; Botter et al, 2016 ; Garten et al, 2018 ; Snarr et al, 2019 ). The final analysis included 22 studies (27 trials) with 21 studies reporting HR data (Shvartz et al, 1983 ; Chowienczyk et al, 1994 ; Higgins et al, 2011 , 2019 ; Thosar et al, 2012 ; De Brito et al, 2015 ; Restaino et al, 2015 ; Wennberg et al, 2016 ; Barone Gibbs et al, 2017b ; Cabak et al, 2017 ; Vranish et al, 2017 ; Carter et al, 2018 ; Garten et al, 2018 ; Horiuchi et al, 2018 ; Sperlich et al, 2018 ; Credeur et al, 2019 ; Dogra et al, 2019 ; Evans et al, 2019 ; Kowalsky et al, 2019 ; Cheng-Hsuan et al, 2020 ; Headid et al, 2020 ) and seven studies reporting HRV data (Shvartz et al, 1983 ; Chowienczyk et al, 1994 ; Thosar et al, 2012 ; Restaino et al, 2015 ; Cabak et al, 2017 ; Kruse et al, 2018 ; Credeur et al, 2019 ). Additionally, 13 of the HR studies reported interruption conditions to the bout of prolonged sitting (De Brito et al, 2015 ; Wennberg et al, 2016 ; Barone Gibbs et al, 2017b ; Cabak et al, 2017 ; Vranish et al, 2017 ; Carter et al, 2018 ; Garten et al, 2018 ; Kruse et al, 2018 ; Sperlich et al, 2018 ; Dogra et al, 2019 ; Evans et al, 2019 ; Kowalsky et al, 2019 ; Headid et al, 2020 ), however there were not enough HRV studies reporting interruption conditions (Cabak et al, 2017 ; Kruse et al, ...…”

“…Seven trials included clinical populations with cardiometabolic diseases including one trial with hypertensive participants (Credeur et al, 2019 ), four trials with overweight/obese participants (Vranish et al, 2017 ; Garten et al, 2018 ; Dogra et al, 2019 ; Kowalsky et al, 2019 ), and two trials with both hypertension and overweight/obese participants (Wennberg et al, 2016 ; Carter et al, 2018 ). Bouts of prolonged sitting ranged from 1 (Headid et al, 2020 ) to 9 (Dogra et al, 2019 ) h with an average duration of 5 h. It should also be noted that all HRV studies (Shvartz et al, 1983 ; De Brito et al, 2015 ; Vranish et al, 2017 ; Carter et al, 2018 ; Garten et al, 2018 ; Wheeler et al, 2019 ) l for <3 h, which was characterized as a short bout of sitting. Of the 22 trials, 13 included interruptions to sitting (De Brito et al, 2015 ; Wennberg et al, 2016 ; Barone Gibbs et al, 2017b ; Cabak et al, 2017 ; Vranish et al, 2017 ; Carter et al, 2018 ; Garten et al, 2018 ; Kruse et al, 2018 ; Sperlich et al, 2018 ; Dogra et al, 2019 ; Evans et al, 2019 ; Kowalsky et al, 2019 ; Headid et al, 2020 ).…”

“…Bouts of prolonged sitting ranged from 1 (Headid et al, 2020 ) to 9 (Dogra et al, 2019 ) h with an average duration of 5 h. It should also be noted that all HRV studies (Shvartz et al, 1983 ; De Brito et al, 2015 ; Vranish et al, 2017 ; Carter et al, 2018 ; Garten et al, 2018 ; Wheeler et al, 2019 ) l for <3 h, which was characterized as a short bout of sitting. Of the 22 trials, 13 included interruptions to sitting (De Brito et al, 2015 ; Wennberg et al, 2016 ; Barone Gibbs et al, 2017b ; Cabak et al, 2017 ; Vranish et al, 2017 ; Carter et al, 2018 ; Garten et al, 2018 ; Kruse et al, 2018 ; Sperlich et al, 2018 ; Dogra et al, 2019 ; Evans et al, 2019 ; Kowalsky et al, 2019 ; Headid et al, 2020 ). The duration and frequency of interruption varied in length from 10 calf raises every 10 min (Cabak et al, 2017 ) to 30 min of walking once (De Brito et al, 2015 ).…”

“…At present specific guidelines for interrupting sitting behavior, i.e., what to substitute prolonged sitting behavior with, are lacking. Interruption strategies including standing (Wennberg et al, 2016 ; Barone Gibbs et al, 2017b ; Carter et al, 2018 ; Kruse et al, 2018 ; Dogra et al, 2019 ), walking (De Brito et al, 2015 ; Evans et al, 2019 ; Kowalsky et al, 2019 ), cycling (Sperlich et al, 2018 ; Dogra et al, 2019 ), calf-raises (Cabak et al, 2017 ), or strength training (Garten et al, 2018 ; Headid et al, 2020 ) have been tested. However, the findings have been inconsistent and the optimal strategy for interrupting prolonged sitting remains unknown.…”

“…The purpose of this meta-analysis was to consolidate the literature investigating the effects of acute prolonged sitting on the cardio-autonomic system, specifically the HR and heart rate variability (HRV) responses (Shvartz et al, 1983 ; Moher et al, 2009 ; Higgins et al, 2011 , 2019 ; Thosar et al, 2012 ; De Brito et al, 2015 ; Restaino et al, 2015 ; Wennberg et al, 2016 ; Barone Gibbs et al, 2017b ; Cabak et al, 2017 ; Kerr et al, 2017 ; Vranish et al, 2017 ; Carter et al, 2018 ; Garten et al, 2018 ; Horiuchi et al, 2018 ; Kruse et al, 2018 ; Sperlich et al, 2018 ; Credeur et al, 2019 ; Dogra et al, 2019 ; Evans et al, 2019 ; Kowalsky et al, 2019 ; Headid et al, 2020 ). Additionally, a secondary purpose of this meta-analysis was to increase our understanding with regard to how interrupting sitting may attenuate CVD effects of prolonged sitting such as HR when available.…”