Improved aerobic capacity in a randomized controlled trial of noncombustible nicotine and tobacco products

Abstract

Smoking negatively impacts aerobic capacity, primarily by reducing V̇O2max, the gold standard measure of cardiorespiratory fitness. While smoking cessation is known to improve vascular function, exercise performance, and oxygen uptake, its specific impact on V̇O2max remains underexplored. Specifically, no research has yet evaluated V̇O2max changes following a switch to electronic cigarettes (ECs) or heated tobacco products (HTPs). This is a secondary analysis of the CEASEFIRE trial, a 12-weeks randomized controlled switching trial comparing the impact of ECs or HTPs on changes in smoking behaviour. The trial offers a unique opportunity to prospectively examine the relationship between smoking behavior and aerobic capacity, and to examine-for the first time-the specific impact of exclusive EC or HTP use on V̇O2max. Changes in VO₂max were analized across three smoking phenotypes: continuous smokers, those who reduced smoking, and those who abstained from smoking Additionally, VO2max was also evaluated specifically in participants who completely abstained from smoking tobacco cigarettes, evaluating outcomes in exclusive EC and HTP users. Quitters showed the greatest improvement in VO2max at both week 4 (2.4 ± 1.7 mL kg^-1 min^-1) and week 12 (2.7 ± 1.9 mL kg^-1 min^-1). Reducers also exhibited significant VO2max increases (1.3 ± 1.9 mL kg^-1 min^-1 at week 4: 1.9 ± 1.8 mL kg^-1 min^-1 at week 12), while Failures (i.e. those who continued smoking) showed no change. Exclusive use of EC and HTP resulted in statistically significant and clinically relevant improvements in V̇O2max. Compared to baseline, V̇O₂max significantly increased at week 4 (EC: 38.4 ± 5.9 to 41.0 ± 6.1 mL kg^-1 min^-1; HTP: 39.2 ± 6.7 to 41.4 ± 6.4 mL kg^-1 min^-1, both p < 0.0001) and week 12 (EC: 38.4 ± 5.9 to 41.4 ± 6.3; HTP: 39.2 ± 6.7 to 41.6 ± 6.5 mL kg^-1 min^-1, both p < 0.0001). No significant differences between EC and HTP were observed at either time point. Rapid improvements in V̇O2max can happen when healthy smokers switch to exclusive use of ECs or HTPs. These findings reinforce the potential cardiorespiratory benefits of smoking cessation and harm reduction strategies.

Keywords: Aerobic capacity; Heated tobacco products; Smoking cessation; V̇O2max; e-cigarettes.

Fig. 1

Means ± SDs relevant to the values of V̇O₂ max at baseline, week 4 and week 12 separately for smoking phenotype classification. Time (p < 0.0001), smoking phenotype classification (p = 0.01) and sex p < 0.0001 had a significant effect on V̇O₂ max (Repeated Measures ANOVA model, adopting time as within factor and classification and sex as between factors).

Fig. 2

Means ± SDs relevant to the changes in V̇O₂ (ΔV̇O₂) max at week 4 and week 12 separately for phenotype smoking classification. P values were computed by means of one-way ANOVA and Fisher’s protected Least Significant Difference. MCID; the minimum clinically important difference is defined as an improvement in anaerobic threshold of at least 2 ml O2/kg/min.

Fig. 3

Means ± SDs relevant to the changes in V̇O₂ (ΔV̇O₂) max at week 4 and week 12 separately for EC and HTP users, in Quitters only. P values were computed by means of one-way ANOVA. MCID; the minimum clinically important difference is defined as an improvement in anaerobic threshold of at least 2 ml O2/kg/min.