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54 Cuenca-Martínez et al. | Journal of Clinical and Translational Research 2024; 10(1): 52-61
2.3. Randomization

Randomization was performed using a computer-generated
random sequence table with a balanced three-block design
(GraphPad Software, Inc., CA, USA). An independent researcher
generated the randomization list, and a member of the research
team who was not involved in the assessment of the participants
or the intervention was in charge of the randomization and
maintained the list. The patients included were randomly assigned
to one of the three groups using the random sequence list, ensuring
concealed allocation.
2.4. Blinding Figure 1. An illustration of the intervention.
Abbreviations: AO: Action observation; MI: Motor imagery; SO: Sham
The assessments and interventions were performed by different observation.
physical therapists. The evaluator was blinded to the participants’
group assignment. All the intervention procedures were performed years smoking)/20 [36]. The levels of the smoking index were
by the same physical therapist who had experience in the field mild (<5 packs), moderate (5 – 15 packs), or strong (>16 packs).
and was blinded to the purpose of the study. All participants were
blinded to their group allocation. 2.7. Outcome measures

2.5. Interventions 2.7.1. Baseline variables
2.5.1. MI (A) Physical activity levels
The level of physical activity was objectified through
The participants who carried out the MI training performed 10 the International Physical Activity Questionnaire (IPAQ),
sets of 1 min per set. In each minute of imagining, participants which allows the participants to be divided into three groups
had to imagine themselves, as the first person, kinesthetically according to their level of activity: high, moderate, and low or
(i.e., trying to feel at all times what they were imagining), forcibly inactive [37]. This questionnaire has shown acceptable validity
taking in air and pulling it out by inflating a balloon as hard as and psychometric properties to measure total physical activity.
they could. The imagination process lasted for an uninterrupted Therefore, the psychometric properties of the questionnaire
duration of 50 s. For the remaining 10 s, participants had to were accepted for use in studies that required the measurement
imagine taking in as much air as possible by expanding their of physical activity; reliability was approximately 0.65 (r = 0.76;
chest box as much as they could to perform a forced expiration 95% CI 0.73 – 0.77) [38].
technique (high expiratory flow technique known as FET).
During the intervention, the physical therapist gave small neutral (B) Imagery ability
guidelines such as “keep imagining,” or “try to feel what you are The movement imagery questionnaire-revised (MIQ-R) is an
imagining” (Figure 1). 8-item self-report inventory used to assess visual and kinesthetic

2.5.2. AO MI ability. Four different movements are included in the MIQ-R,
which comprises four visual and four kinesthetic items. Each
The participants in the AO group performed the same exercise participant rated the ease or difficulty of generating the mental
intervention as the MI group, but instead of imagining the motor image on a 7-point scale in which 7 indicated “very easy to see/
gestures, they had to observe a person performing the respiratory feel” and 1 “very difficult to see/feel.” The internal consistencies
exercises. The duration and distribution of the intervention were of the MIQ-R have been adequate, with Cronbach’s α coefficients
the same as in the MI group (10 sets of 1 min per set) (Figure 1). ranging above 0.84 for the total scale, 0.80 for the visual subscale,
and 0.84 for the kinesthetic subscale [39].
2.5.3. Sham observation (SO)
2.7.2. Primary outcomes
Participants in this group underwent a SO protocol. A video
only composed of nature images was visualized for 10 min, (A) Pulmonary function
without visualizing any motor gesture. This kind of SO protocol Pulmonary function was assessed by performing forced
has been used in previous research [34,35] (Figure 1). spirometry (Spirodoc, Medical International Research, Roma,
Italy) following the American Thoracic Society’s (ATS)
2.6. Smoking index
criteria [40] to obtain the following parameters: forced expiratory
st
The pack per year index is a smoking load tool for lifetime volume during the 1 s (FEV ), forced vital capacity (FVC), forced
1
tobacco exposure. A pack per year index is defined as 20 expiratory ratio (FEV /FVC), maximum voluntary ventilation
1
cigarettes smoked every day for 1 year. It was calculated using (MVV), and peak expiratory flow (PEF). The patient was seated
the formula (number of smoked cigarettes per day × number of in a chair with the backrest supporting his back, and during the
DOI: http://doi.org/10.36922/jctr.00117