Physical exercise is largely recommended for adolescents with asthma given its benefits in reducing systemic inflammation, enhancing exercise capacity, and improving asthma control.1 Conversely, a sedentary lifestyle in this population is linked to poorer disease management and a decline in overall health.2 Evidence also suggests that children with asthma engage in less physical activity than their non-asthmatic peers,3-5 raising concerns about potential differences in motivation and exercise behavior.

Exercise behavior refers to the patterns and actions related to physical activity that individuals intentionally engage in for improving or maintaining physical fitness, health, or well-being. Beyond individual factors like frequency, intensity, duration, and type, exercise behavior is also influenced by psychological, social, and environmental determinants. Intrinsic motivation, social support from family and peers, and the accessibility of facilities and outdoor spaces play crucial roles in promoting an active lifestyle. Motivation influences performance in both healthy adolescents6 and those with chronic respiratory diseases.7 The Self-Determination Theory (SDT)8,9 posits that human beings are driven by Amotivation, Extrinsic and Intrinsic Motivation. SDT analyzes the degree to which motivation is more or less self-determined, how different types of motivation lead to varying outcomes, and how social conditions support or hinder human well-being through basic psychological needs (BPN). Supporting the BPN of autonomy, competence, and relatedness fosters more intrinsic, autonomous motivation, which is fundamental for psychological well-being, enhancing behavioral engagement, and improving adherence to physical activity programs.8,9

Assessing motivation for exercise in adolescents with asthma is especially important, as this population faces the dual challenge of coping with psychological and physical changes during adolescence, alongside managing a chronic disease that can affect their social life.10,11 Asthma symptoms often lead to physical and psychological difficulties, directly impacting daily activities and diminishing the quality of life.12 While regular physical exercise plays a crucial role in asthma rehabilitation, low adherence and motivational challenges are frequently observed, despite its well-documented benefits.13

Given the importance of adopting and maintaining regular physical exercise in this population, it is essential to explore the role of behavioral factors, such as motivation. However, the current literature lacks studies investigating the behavioral profile of adolescents with asthma regarding their motivation for physical exercise. To date, to our knowledge, only one qualitative study, based on the SDT framework, has explored motivation for physical activity (PA) and exercise among adolescents with asthma.14 This study revealed an amotivated profile for PA,8,9 citing barriers like lack of asthma knowledge among teachers, embarrassment regarding asthma symptoms, inability to keep pace with peers, and seasonal challenges.14 Similar barriers for PA have been reported in other studies.15

Thus, the objective of this study was to identify the behavioral profile for physical exercise in adolescents with asthma, to characterize clusters based on Motivational Regulations (MR) and Basic Psychological Needs (BPN) for exercise, and to compare quality of life, asthma control, and disease severity across these clusters.

This exploratory, observational, cross-sectional study was conducted at two centers in Brazil: São Paulo and Londrina. Participants were prospectively recruited between May 2021 and December 2022 during routine medical consultations at the Allergy, Clinical Immunology, and Rheumatology Outpatient Clinic, Pediatrics Department, Universidade Federal de São Paulo, and the Pulmonology Outpatient Clinic of the Clinical Hospital Universidade Estadual de Londrina. The recruitment was initially intended for a cross-cultural adaptation and validation study of a self-efficacy questionnaire (unpublished data).

All adolescents with asthma were evaluated during a single face-to-face visit, after obtaining written informed consent from their legal guardians and the adolescents' own signatures on the Term of Assent. The study received approval from the Research Ethics Committees of Universidade Pitágoras Unopar Anhanguera de Londrina (protocol number: 33873520.9.2002.0108) and Universidade de Nove de Julho (protocol number: 33873520.9.0000.5511).

The inclusion criteria for the study were adolescents aged 12 to 18 years, native Brazilians, accompanied by a parent or guardian at the consultation, with a clinical diagnosis of asthma made by a pulmonologist based on the Global Initiative for Asthma (GINA) guidelines. The exclusion criteria included participants or families wishing to withdraw from the study, adolescents with chronic conditions (neurological or mental) that impaired their ability to understand the questionnaires, and those with other chronic respiratory diseases (bronchiolitis obliterans, cystic fibrosis, and allergic rhinitis).

The general data collected included age, weight, height, personal history, and self- or parent-reported comorbidities to characterize the sample. Lung function was evaluated using spirometry following international guidelines.16 Participants performed both pre- and post-bronchodilator maneuvers. The recorded variables were forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), and the FEV1/FVC ratio, which are key measures in assessing pulmonary function.

For the classification of asthma control levels and severity, the GINA criteria were adopted. Based on responses to four questions regarding the last four weeks: (a) presence of daytime symptoms more than twice a week, (b) nighttime symptoms, (c) use of reliever medication more than twice a week, and (d) activity limitations; disease control was categorized as follows: (1) Controlled: None of the questions received a positive answer; (2) Partially controlled: One or two questions received a positive answer; (3) Uncontrolled: Three or four questions received a positive answer.

Asthma severity was classified into three levels: (1) Mild: well-controlled with reliever medication or low-dose inhaled corticosteroids, anti-leukotrienes, or chromones; (2) Moderate: well-controlled with low-dose inhaled corticosteroids combined with long-acting bronchodilators; (3) Severe: requiring high-dose inhaled corticosteroids and long-acting bronchodilators to remain controlled, or remaining uncontrolled despite such treatment.

Motivational regulation for physical exercise was evaluated using the Behavioral Regulation in Exercise Questionnaire-2 (BREQ-2), which measures amotivation as well as intrinsic and extrinsic motivation. The instrument consists of 19 Likert-type items with five response options (0 = "Not true for me" to 4 = "Very true for me"). These items comprise five different motivational loci: amotivation, external regulation, introjected regulation, identified regulation, and intrinsic regulation. In the controlled forms of regulations (amotivation, external regulation, and introjected regulation), lower scores reflect less behavioral control. In autonomous forms of regulations (identified and intrinsic regulation), higher scores indicate greater autonomy in exercise behavior. Each motivational regulation is scored from 0 to 4, with higher values indicating greater endorsement of that regulation as a reason to exercise. The Self-Determination Index (SDI) was also calculated, ranging from -24 (lowest self-determination) to 20 (highest self-determination). This version of the questionnaire has been validated for use with Brazilian adolescents.17,18

The Basic Psychological Needs in Exercise Scale (BPNES) was used to assess participants’ perceptions of support for basic psychological needs in exercise. The scale contains 12 items, divided into three subscales representing the psychological needs: Autonomy, Competence, and Relatedness. Responses ranged from 1 (“Disagree”) to 5 (“Strongly agree”).17 Higher scores indicate greater perceived support for each psychological need. This instrument has also been validated for use with Brazilian adolescents.19

To evaluate quality of life, the Pediatric Quality of Life Inventory (Peds-QL) was used. This instrument combines both generic and disease-specific scales. The validated Brazilian Portuguese version20 consists of 23 items, distributed across four domains: Physical function, Emotional function, Social function, and School function. A psychosocial domain score is derived by summing the emotional, social, and school function scores. Each item uses a five-point Likert scale (0 = "Never" to 4 = "Almost always"), which is subsequently transformed into a linear scale from 0 to 100, with higher scores reflecting better health status. The assessment period covers experiences from the from month.20

Statistical analysis was conducted using SPSS® (version 22.0). Categorical variables were expressed as absolute and relative frequencies (%), and numerical data were reported as mean (µ) and standard deviation (SD) or median and interquartile range (IQR), depending on normality distribution as assessed by the Shapiro-Wilk test. A two-step cluster analysis was performed using two models: (1) a Motivational Regulations Model, which included amotivation, external regulation, introjected regulation, identified regulation, and intrinsic regulation scores; and (2) a Basic Psychological Needs Model - which included autonomy, competence, and relatedness scores. The optimal number of clusters was determined based on the best combination of low Bayesian Information Criterion (BIC), high ratio of distance measures, and high ratio of BIC changes, as well as meaningful conceptual considerations. The silhouette coefficient (ranging from -1 to +1) was used to assess the quality of the cluster solution, with higher values indicating better cohesion within clusters and separation between them. Clusters were compared using the independent Student T-test, Mann-Whitney test, or Chi-Square test, as appropriate. Statistical significance was set at p < 0.05.

A total of 160 participants were assessed for eligibility. Of these, 10 were excluded due to incomplete questionnaire responses, 4 had chronic disease with cognitive impairment, and 2 presented with other associated lung diseases (Figure 1). The final sample comprised 144 participants, with 80 recruited from São Paulo and 64 from Londrina. Most participants were male, exhibited mild airway obstruction, and had controlled asthma. Table 1 provides an overview of the participants' general characteristics, along with their Motivational Regulation and Basic Psychological Needs profiles. Overall, adolescents demonstrated more autonomous reasons for exercising and moderately recognized the support of basic psychological needs in their practice. Comparative analyses between adolescents from the two research centers are presented in Supplementary Table S1.

Figure 1.

Flowchart of the study.

All participants were eligible for cluster analysis, as described in Supplementary Table S2. The clusters were labeled based on the theoretical framework of SDT. Cluster 1 displayed high levels of autonomous regulation, lower levels of controlled regulation, and perceived stronger support for basic psychological needs. This cluster was labeled as the ‘More autonomous behavior and high perceived support’ cluster. Cluster 2 exhibited low levels of autonomous regulation, high levels of controlled regulation, and reported less support for their basic psychological needs. This cluster was named the ‘Less autonomous behavior and low perceived support’ cluster. Table 2 presents the characteristics and differences between the two clusters. The silhouette coefficient for the model was 0.40, suggesting a fair-quality solution. Among the predictor components, relatedness showed the highest relative importance (1.00) in estimating both the BPN and MR models.

Cluster 1, ‘More autonomous behavior and high perceived support’