Effects of motor imagery and action observation on respiratory function in mild smokers: a randomized single-blind controlled pilot trial

Abstract

Background: Motor imagery (MI) and action observation (AO) training can activate brain areas involved in planning, adjusting, and automating voluntary movement in a manner similar to that when these activities are being performed. Aim: The main objective of this study was to assess the effects of MI and AO training on respiratory function in mild smokers. Methods: A single-blind placebo-controlled pilot trial was designed. A total of 27 mild smokers were randomized into three groups: MI (n = 9), AO (n = 9), and sham observation (SO; n = 9) groups. The MI and AO groups performed mental training of breathing exercises while the SO group observed a landscape without a human agent. The primary outcomes were pulmonary function parameters (forced expiratory volume during the 1st s [FEV1], forced vital capacity [FVC], FEV1/FVC ratio, maximum voluntary ventilation [MVV], and peak expiratory flow [PEF]), and the secondary outcomes were maximal inspiratory/expiratory pressures (MIP/MEP) and perceived fatigue. All outcome measures were assessed at baseline and post-intervention. Results: Regarding the pulmonary function parameters, only the AO group showed significant within-group differences in FEV1 (mean differences [MD] = 0.37 L (0.17 – 0.56), P = 0.001), FVC (MD = 0.1 L (0.02 – 0.16), P = 0.008), and PEF (MD = 0.74 L/s (0.29 – 1.18), P = 0.002) with a small-to-moderate effect size. No differences were found in FEV1/FVC ratio and MVV. With regard to the maximal static pressures, only the AO group showed significant within-group differences in MEP with a small effect size (MD = 11.22 cm H2O (0.19 – 22.2), P = 0.046). Finally, both AO and MI groups showed significantly greater perceived fatigue with regard to SO group with a large effect size (P < 0.05). Conclusion: AO training has a slight impact on some pulmonary function parameters, such as FEV1, FVC, or PEF, as well as on MEP when applied in isolation and in a single session. Relevance for Patients: Although it is still early to draw some solid conclusions, AO training could be used in combination with respiratory exercises to see if the effect is greater than exercises in isolation. The study of movement representation strategies on pulmonary function is a field that has been sparingly explored so far. This paper offers some interesting data to be considered for further research.