Reduced vascular function, ventilatory efficiency and exercise capacity in young adult electronic cigarette users

Acute electronic cigarette (E-cigarette) use has shown adverse cardiorespiratory impacts similar to conventional cigarette (C-cigarette) smoking; however, its early effects remain unclear. We aimed to examine the early effects of E-cigarette use on systemic vascular function, cardiorespiratory responses to exercise and exertional symptoms in young adults.

75 healthy active young adults (18-30 years), divided into three age- and sex-matched groups (E-cigarette users, C-cigarette smokers and never-smoker controls; n=25 each, E-cigarette use or smoking duration ≥18 months), underwent an incremental cycle exercise test with standard metabolic, cardiorespiratory, blood lactate and sensory measurements. Brachial artery flow-mediated dilatation (FMD) was assessed using Doppler ultrasound. Blood samples were collected to assess vascular inflammatory markers.

Cotinine (nicotine metabolite) levels were not different between E-cigarette users and C-cigarette smokers (80.7±33.0 versus 65.5±27.6 pg·mL^-1, p=0.2). At peak exercise, both E-cigarette users and C-cigarette smokers had lower exercise capacity, oxygen uptake, and ventilation compared with controls (182±31, 178±27 versus 219±43 watts; 35.1±6.4, 35.1±5.3 versus 41.2±5.9 mL·kg^-1·min^-1; 97.8±24.7, 98.9±21.6 versus 116.1±29.8 L·min^-1, respectively; all p<0.05). Furthermore, E-cigarette users and C-cigarette smokers demonstrated decreased exercise ventilatory efficiency, with higher ventilation, blood lactate, dyspnoea ratings and leg discomfort during submaximal exercise compared with controls. E-cigarette users and C-cigarette smokers showed lower FMD compared with never-smokers (4.7±3.0, 4.5±2.9 versus 8.1±3.5%, p<0.05), which was inversely associated with vascular cell adhesion molecule-1 and thrombospondin-2.

E-cigarette use and C-cigarette smoking were both associated with early detrimental effects on exercise capacity, ventilatory efficiency, systemic vascular function and amplified exertional symptoms.