The effect of sedentary behaviour on cardiovascular biomarkers in active, healthy adults

Abstract

Sedentary behaviour (SB) is an independent predictor of cardiovascular disease (CVD) morbidity and mortality, yet little is known about the effect of SB on markers of cardiovascular health in active adults. Therefore the aim of the study was to determine whether increased SB is associated with greater cardiovascular risk in an active population. Twenty-six healthy participants (aged 27.9±8 years, 16 males) were recruited and visited the laboratory on two occasions. During visit one, body composition (waist and hip circumference and body fat percentage (BF%)) were measured, and following 15 minutes of supine rest, ultrasound assessment of brachial and femoral artery flow-mediated dilation (FMD) and carotid artery intima-media thickness was conducted. Carotid-femoral pulse wave velocity and middle cerebral artery blood flow velocity were assessed via applanation tonometry and transcranial Doppler ultrasonography respectively. Continuous blood pressure and carotid artery reactivity (via ultrasound) were recorded during the cold pressor test (CPT). During visit two, cardiorespiratory fitness (CRF; VO2peak) was assessed using the modified Bruce protocol. Physical activity (PA) and SB was objectively measured for seven days via accelerometry and inclinometry respectively. Participants were grouped into tertiles according to sedentary time: LoSIT (n=9), MidSIT (n=9) and HiSIT (n=8) and univariate ANCOVAs determined the effect of SB on cardiovascular biomarkers across the groups. Data is presented as mean±standard deviation. There was a significant difference between groups in hip circumference (LoSIT 96.9±3.2cm, MidSIT 99.3±4.8cm, HiSIT 106.3±7.9cm; P=0.026), BF% (LoSIT 17.81±5.80%, MiSIT 22.40±9.61%, HiSIT 27.60±7.11%; P=0.035) and VO2peak (LoSIT 50.58±3.65ml/min/kg, MidSIT 47.52±9.1465ml/min/kg, HiSIT 39.75±7.5965ml/min/kg; P=0.043). There was no effect of SB on vascular markers and CPT responsiveness (P>0.05). In conclusion, in an active population, SB appears to be detrimentally associated with CRF and body composition, whilst exceeding the guidelines of 150 minutes of moderate-vigorous or 75 minutes of vigorous intensity PA per week appears to be protective of the vasculature.