Key takeaways:

• Exercise capacity, oxygen uptake and ventilation at peak exercise were significantly reduced in e-cigarette and conventional cigarette users vs. never smokers.
• Vascular function also followed this pattern.

In healthy young adults with normal spirometry, e-cigarette users and conventional cigarette smokers had similar poorer exercise capacity and vascular function vs. never vapers/smokers, according to findings published in ERJ Open Research.

“This work is the first of its kind to identify reduced vascular function, ventilation efficiency and exercise capacity in people who vape and never smoked,” Azmy Faisal, PhD, senior lecturer of cardiorespiratory physiology at Manchester Metropolitan University and principal investigator of the study, told Healio.

“The consequences of this finding are significant and potentially question how care is currently delivered, particularly for vascular patients where exercise therapy is standard of care and smokers are encouraged to switch to vaping if they cannot stop,” Faisal said.

In a cross-sectional study, Faisal and colleagues assessed 25 e-cigarette users (mean age, 22.8 years; 16 men; mean e-cigarette use length, 3.1 years), 25 conventional cigarette smokers (mean age, 23 years; 16 men; mean smoking length, 5.1 years) and 25 never e-cigarette users or smokers (mean age, 23 years; 16 men) — all healthy, active young adults with normal spirometry — to determine how systemic vascular function, cardiorespiratory responses to exercise and exertional symptoms differ between the groups.

Healio previously reported on some findings from this study when it was presented at the 2024 European Respiratory Society Congress.

Faisal told Healio the motivation for this study came from an earlier study he conducted with colleagues at Imperial College London that found a lower exercise capacity in smokers with normal lung function.

“This raised our concerns regarding the increasing popularity and growing trend of vaping and its possible effects on the fitness levels of young adults, even before any noticeable effects on lung function,” he said.

All individuals attended two visits. During the first visit, researchers collected lung function measurements via spirometry, as well as blood lactate, lung volumes and symptom measurements via an incremental cycle exercise test.

During the second visit, individuals provided blood samples for the evaluation of vascular inflammatory markers, and researchers measured brachial artery flow-mediated dilation (FMD).

Results

The level of cotinine (nicotine metabolite) in e-cigarette users was 80.7 ng/mL^–1, which did not significantly differ from the level of 65.5 ng/mL^–1 in conventional cigarette users, according to the study.

Resting lung function measures and resting cardiovascular parameters also did not differ between the three groups.

“Numerous studies have indicated that both vaping and smoking result in detrimental alterations to the blood vessels,” Faisal told Healio. “Ultrasound examinations and blood testing in our study revealed that vapers and smokers exhibited diminished blood vessel functionality (increased inflammation and reduced dilation) when compared to those who did not smoke or vape.”

When assessing vascular function, as represented by FMD, researchers observed significantly decreased values in the e-cigarette and conventional cigarette groups vs. the never smoker group (4.7% and 4.5% vs. 8.1%; both P < .05).

In terms of vascular inflammatory markers, e-cigarette users had significantly elevated thrombospondin-2 vs. never smokers (4.2 ng/mL^–1 vs. 2.2 ng/mL^–1; P < .05), as well as elevated vascular cell adhesion molecule-1 (363 ng/mL^–1 vs. 279 ng/mL^–1; P < .05).

Similarly, conventional cigarette smokers had significantly heightened thrombospondin-2 vs. never smokers (3.7 ng/mL^–1 vs. 2.2 ng/mL^–1; P < .05), as well as heightened IL-1 receptor antagonist (190.6 pg/mL^–1 vs. 133.5 pg/mL^–1; P < .05).

When assessing exercise capacity (work rate) at peak exercise, researchers found significantly lower measures among e-cigarette and conventional cigarette users vs. never smokers (182 watts and 178 watts vs. 219 watts; both P < .05).

This pattern of reduced measures in e-cigarette and conventional cigarette users vs. never smokers continued to be observed in oxygen uptake at peak exercise (both 35.1 mL/kg^–1/min^–1 vs. 41.2 mL/kg^–1/min^–1; both P < .05), as well as minute ventilation at peak exercise (97.8 L/min^–1 and 98.9 L/min^–1 vs. 116.1 L/min^–1; both P < .05).

Switching to submaximal exercise, researchers found that the e-cigarette and conventional cigarette groups differed from the never smoker group in several measures. Measures that were increased in the e-cigarette and cigarette groups included blood lactate, minute ventilation, minute ventilation/carbon dioxide production ratio (meaning lower exercise ventilatory efficiency), breathing frequency, dyspnea Borg scores and leg discomfort Borg scores.

“The surprising findings in our study were that both vaping and tobacco smoking reduced breathing efficiency (increased the effort of the lungs to blow out carbon dioxide) and increased blood lactate levels early in exercise testing (suggesting impaired skeletal muscle function) to similar levels,” Faisal told Healio.

“These, together with diminished resting systemic vascular function, led to reduced exercise capacity, shortness of breath and intense leg fatigue in vapers and smokers compared with individuals who neither smoked nor vaped,” he said.

Implications, future research

Reflecting on the results, Faisal said they demonstrate how vaping and smoking may not be so different from each other in their studied population.

“Vaping is an important tool the NHS actively encourages as part of standard smoking cessation advice, but the long-term effects are poorly defined,” he said. “This is because vaping avoids only some of the harmful substances in traditional smoking.

“This research provides early evidence that vaping is at least as harmful as smoking in young adults who never smoked before,” Faisal continued. “People who vape had worsened exercise capacity due to shortness of breath, blood vessel changes and leg fatigue, similar to counterparts who smoked.”

Faisal also highlighted that these findings “clearly support the UK Tobacco and Vape Act 2026 and the NHS 10-year plan to prevent young people developing heart, lung and vascular disease in the future."

Further, the results may mean early peripheral arterial disease treatment recommendations could one day be updated, according to Faisal.

“Importantly, switching to vaping and exercise therapy are prescribed by vascular specialists to treat early peripheral arterial disease,” he told Healio. “While more research is needed, this may mean current treatment recommendations need further consideration.”

Moving forward, Faisal said the next step is MRI studies.

“We have seen interesting and novel findings of early signs for impaired resting vascular functions, and lung and skeletal muscle functions during exercise that may contribute to worsening exercise capacity, breathlessness and leg discomfort in vapers and smokers; however, it’s a challenge to know from this observational study if the associations we find are causal,” Faisal told Healio.

“There is growing interest in understanding the physiological and radiological changes associated with vaping,” he continued. “We are planning to conduct a series of MRI studies to better understand the mechanisms associated with worsened fitness levels in vapers.”

For more information:

Azmy Faisal, PhD, can be reached at azmy.faisal@mmu.ac.uk.