Bronchial asthma is a heterogeneous chronic inflammatory disease of the airways, characterized by variable expiratory airflow limitation, bronchial hyperresponsiveness, and recurring symptoms of wheezing, breathlessness, chest tightness, and cough. According to the Global Burden of Disease Study, asthma affects approximately 262 million people worldwide and accounted for 461,000 deaths in 2019. In India, the prevalence of asthma ranges from 2.05% to 4.5% in adults, translating to an estimated 30–35 million affected individuals. The cornerstone of asthma management remains pharmacological therapy — inhaled corticosteroids (ICS), long-acting beta-agonists (LABA), short-acting bronchodilators, and biologics for severe refractory asthma. Despite optimal medical therapy, a significant proportion of patients continue to experience suboptimal asthma control, exercise limitation, and impaired quality of life. This has prompted growing interest in non-pharmacological complementary approaches, particularly breathing exercises and pulmonary rehabilitation. Dysfunctional breathing patterns are highly prevalent in asthma patients, with studies reporting prevalence as high as 29–75%. These include upper chest breathing, mouth breathing, hyperventilation, and respiratory muscle inefficiency — each contributing to worsening symptoms beyond the airway inflammation itself. Breathing exercises targeting these patterns have a plausible biological rationale: improving respiratory muscle strength and endurance, reducing minute ventilation, enhancing diaphragmatic excursion, and promoting nasal breathing and physiological CO2 levels. Several breathing techniques have been studied in asthma: the Buteyko method (nasal breathing and reduced tidal volume), diaphragmatic breathing, pursed-lip breathing, yoga pranayama, and inspiratory muscle training. Systematic reviews by Bruton et al. (2018) and a Cochrane review by Freitas et al. (2020) suggest modest but clinically meaningful improvements in symptoms and quality of life, though evidence on objective spirometric outcomes remains inconsistent. In the Indian context, yoga-based pranayama and traditional breathing practices have cultural acceptance and accessibility advantages. However, rigorous RCT evidence from this population, particularly measuring spirometric lung function as a primary outcome, is lacking. This study was therefore designed to evaluate, through a randomized controlled trial, the effect of a structured multimodal breathing exercise program on lung function parameters, asthma control scores, and quality of life in adult patients with mild-to-moderate persistent bronchial asthma.

2.1 Study Design This was a single-center, prospective, open-label randomized controlled trial conducted at the Outpatient Department of Respiratory Medicine at Tertiary Care Hospital over a period of 6 months. 2.2 Participants Inclusion criteria: Adults aged 18–60 years with physician-diagnosed bronchial asthma as per GINA 2022 criteria; classified as mild-to-moderate persistent asthma; FEV1 40–80% predicted; receiving stable pharmacotherapy for at least 4 weeks prior to enrollment; willing to attend supervised sessions and provide written informed consent. Exclusion criteria: Severe or uncontrolled asthma (FEV1 <40%); history of smoking (>5 pack-years); coexisting COPD, bronchiectasis, or interstitial lung disease; significant cardiac, neuromuscular, or musculoskeletal conditions precluding exercise; current participation in any other pulmonary rehabilitation program; pregnancy. 2.3 Sample Size Sample size was calculated based on a minimum clinically important difference of 200 mL in FEV1 (SD 380 mL), with 80% power and 5% significance level (two-tailed). This yielded n=57 per group; rounding up with 5% allowance for dropout gave 60 per group (n=120 total). 2.4 Randomization and Allocation Concealment Participants were randomized in a 1:1 ratio using computer-generated random numbers (block randomization, block size 4). Allocation was concealed using sequentially numbered, sealed opaque envelopes opened by an independent research coordinator at the time of enrollment. 2.5 Interventions Intervention Group — Breathing Exercise Program + Standard Pharmacotherapy The structured breathing exercise program consisted of three components performed for a total of 45 minutes per day, 6 days per week, for 8 weeks: 1. Diaphragmatic (Abdominal) Breathing — 15 minutes: Participants were trained by a physiotherapist to breathe using the diaphragm, with one hand on the chest and one on the abdomen. Emphasis was placed on slow, deep inhalation through the nose with abdominal rise, and controlled exhalation. 2. Pursed-Lip Breathing — 10 minutes: Inhalation through the nose for 2 counts followed by exhalation through pursed lips for 4 counts. This technique was practiced to prolong exhalation, reduce air trapping, and decrease respiratory rate. 3. Buteyko Technique — 20 minutes: Controlled nasal breathing with deliberate reduction of tidal volume; breath-holding exercises (Control Pause); emphasis on nasal breathing throughout all activities of daily living. The first two weeks consisted of supervised sessions at the physiotherapy department (3 sessions/week), followed by home-based practice for the remaining 6 weeks with a structured exercise diary. Compliance was assessed via diary review and phone follow-up at weeks 2, 4, and 6. Control Group — Standard Pharmacotherapy Only The control group continued their existing prescribed pharmacotherapy (ICS +/- LABA, rescue SABA as needed) without any structured breathing exercise program. Both groups received standard asthma education at enrollment. 2.6 Outcome Measures Primary outcomes: Spirometric parameters — Forced Expiratory Volume in 1 second (FEV1), Forced Vital Capacity (FVC), FEV1/FVC ratio — measured at baseline, week 4, and week 8 using a calibrated spirometer (Spirolab III, MIR, Italy) per ATS/ERS 2019 guidelines. Secondary outcomes: Peak Expiratory Flow Rate (PEFR); Asthma Control Test (ACT) score (range 5–25; score ≥20 = well-controlled); Asthma Quality of Life Questionnaire (AQLQ) score (range 1–7; higher = better QoL); Frequency of rescue bronchodilator use per week. 2.7 Statistical Analysis Data were analyzed using SPSS version 26 (IBM, USA). Continuous variables were expressed as mean ± SD; categorical variables as frequencies and percentages. Within-group changes from baseline were analyzed using paired t-test. Between-group differences at each time point were compared using independent samples t-test. Repeated measures ANOVA was used to assess changes across three time points. A p-value <0.05 was considered statistically significant. 2.8 Ethical Approval The study was approved by the Institutional Ethics Committee (IEC/2022/XXXX). Written informed consent was obtained from all participants prior to enrollment. The trial was conducted in accordance with the Declaration of Helsinki and ICH-GCP guidelines.

3.1 Participant Flow and Baseline Characteristics A total of 148 patients were screened; 120 met eligibility criteria and were randomized (60 per group). At 8-week follow-up, 114 participants completed the study (57 in each group; 5% dropout rate). There were no significant differences between groups at baseline in age, sex, disease duration, smoking history, or baseline spirometry (Table 1). 3.2 Primary Outcomes — Spirometric Lung Function At 8 weeks, the intervention group demonstrated significantly greater improvements in all spirometric parameters compared to the control group (Table 2). FEV1 improved by 18.4% from baseline in the intervention group versus 4.2% in controls (p<0.001). FVC improved by 14.7% versus 3.6% (p=0.002). FEV1/FVC ratio improved by 6.1% versus 1.4% (p=0.008). Improvements were progressive and statistically significant at both week 4 and week 8 time points on repeated measures ANOVA (p<0.001 for time x group interaction). 3.3 Secondary Outcomes — Asthma Control and Quality of Life The ACT score improved significantly in the intervention group from 14.2 ± 2.8 at baseline to 20.6 ± 2.4 at week 8, compared to 14.1 ± 3.0 to 16.3 ± 2.9 in the control group (p<0.001). The proportion achieving well-controlled asthma (ACT score ≥20) was 63.2% in the intervention group versus 28.1% in controls at week 8 (p<0.001). AQLQ total score improved from 3.92 ± 0.71 to 5.84 ± 0.63 in the intervention group versus 3.89 ± 0.68 to 4.62 ± 0.71 in controls (p<0.001). Improvements were observed across all four AQLQ domains — symptoms, activity limitations, emotional function, and environmental stimuli — with the greatest gain seen in the activity limitation domain (Table 3). Table 1: Baseline Characteristics of Study Participants (N=120) Characteristic Intervention Group (n=60) Control Group (n=60) Age (years), Mean ± SD 34.8 ± 9.6 35.3 ± 10.1 Sex (Male), n (%) 32 (53.3%) 30 (50.0%) Disease duration (years) 7.4 ± 4.2 7.1 ± 4.6 BMI (kg/m²) 23.6 ± 3.8 24.1 ± 3.5 Baseline FEV1 (% predicted) 62.4 ± 10.3 63.1 ± 9.8 Baseline FVC (% predicted) 74.2 ± 11.1 73.8 ± 10.7 Baseline FEV1/FVC (%) 66.8 ± 6.4 67.2 ± 6.1 Baseline PEFR (L/min) 284.6 ± 52.3 281.9 ± 49.8 Baseline ACT Score 14.2 ± 2.8 14.1 ± 3.0 Baseline AQLQ Score 3.92 ± 0.71 3.89 ± 0.68 No statistically significant between-group difference at baseline (p>0.05 for all variables). BMI = Body Mass Index; ACT = Asthma Control Test; AQLQ = Asthma Quality of Life Questionnaire Table 2: Changes in Spirometric Parameters at Week 4 and Week 8 Parameter Intervention Baseline Intervention Week 8 Control Week 8 p-value* FEV1 (% predicted) 62.4 ± 10.3 73.9 ± 9.6 65.8 ± 9.9 <0.001 FVC (% predicted) 74.2 ± 11.1 85.1 ± 10.4 76.5 ± 10.8 0.002 FEV1/FVC (%) 66.8 ± 6.4 70.9 ± 5.8 67.7 ± 6.0 0.008 PEFR (L/min) 284.6 ± 52.3 347.9 ± 48.6 298.1 ± 51.4 <0.001 *p-value for between-group difference at Week 8 (independent samples t-test); FEV1 = Forced Expiratory Volume in 1 second; FVC = Forced Vital Capacity; PEFR = Peak Expiratory Flow Rate Table 3: Asthma Control Test and Quality of Life Scores at Baseline and Week 8 Outcome Measure Intervention Baseline Intervention Week 8 Control Week 8 p-value ACT Total Score (5-25) 14.2 ± 2.8 20.6 ± 2.4 16.3 ± 2.9 <0.001 ACT Well-controlled (score ≥20) 3 (5.3%) 36 (63.2%) 16 (28.1%) <0.001 AQLQ — Symptoms domain 3.78 ± 0.84 5.71 ± 0.72 4.48 ± 0.78 <0.001 AQLQ — Activity limitation 3.62 ± 0.91 5.89 ± 0.68 4.31 ± 0.84 <0.001 AQLQ — Emotional function 4.11 ± 0.79 5.94 ± 0.61 4.82 ± 0.74 <0.001 AQLQ — Total Score (1-7) 3.92 ± 0.71 5.84 ± 0.63 4.62 ± 0.71 <0.001 Rescue bronchodilator use (puffs/week) 8.4 ± 3.1 3.2 ± 1.8 6.1 ± 2.4 <0.001 ACT = Asthma Control Test; AQLQ = Asthma Quality of Life Questionnaire (Juniper) 3.4 Adverse Events No serious adverse events related to the breathing exercise program were reported. Two participants in the intervention group reported mild dizziness during initial Buteyko breath-holding exercises, which resolved with technique modification. There were no exercise-induced bronchospasm episodes recorded during supervised sessions.

This randomized controlled trial demonstrates that an 8-week structured multimodal breathing exercise program, as an adjunct to standard pharmacotherapy, produces significant and clinically meaningful improvements in spirometric lung function, asthma control, and quality of life in patients with mild-to-moderate persistent bronchial asthma. The magnitude of improvement in FEV1 (+18.4% in the intervention group) substantially exceeds both the minimum clinically important difference of 100–200 mL established in asthma trials and the modest improvement observed with standard pharmacotherapy alone (+4.2% in controls over the same period. The improvement in FEV1/FVC ratio observed in the intervention group is particularly noteworthy, as this parameter directly reflects airflow obstruction — the hallmark physiological abnormality of asthma. Breathing exercises may improve this ratio through multiple mechanisms: strengthened diaphragmatic contraction and improved neuromuscular coordination; reduced functional residual capacity through more efficient exhalation; correction of hyperventilation reducing CO2-mediated bronchoconstriction; and enhanced mucociliary clearance facilitating mucus drainage from small airways. The Buteyko technique specifically targets reduced breathing volume and increased nasal breathing. The physiological basis centers on the Bohr effect — improved CO2 levels from controlled breathing lead to enhanced oxygen delivery to tissues and reduced airway smooth muscle spasm. Our results showing PEFR improvement of 22.3% in the intervention group align with findings from a Cochrane review by Freitas et al. (2020), which reported a pooled improvement in PEFR of 57.4 L/min with Buteyko versus control. The substantial improvement in ACT scores (14.2 to 20.6 in intervention vs. 14.1 to 16.3 in controls) has direct clinical significance: over 63% of intervention participants achieved well-controlled asthma status (ACT ≥20) at week 8, compared to 28% in controls. This translated to a 61.9% reduction in rescue bronchodilator use (8.4 to 3.2 puffs/week), which has implications for both medication costs and long-term safety. These findings are consistent with the study by Bruton et al. (BREATHE trial, Lancet Respiratory Medicine, 2018), which demonstrated that physiotherapist-led breathing retraining improved asthma-related quality of life and reduced rescue bronchodilator use, though that trial used a different composite technique. The improvement across all AQLQ domains — particularly the activity limitation domain — reflects the functional benefits of breathing exercises beyond spirometry. Patients with asthma commonly develop activity avoidance due to fear of exercise-induced symptoms. Breathing retraining may reduce this fear-avoidance behavior by improving respiratory efficiency and patient confidence, contributing to better overall functional status. Strengths of this study include: RCT design with allocation concealment; validated outcome measures; objective spirometric confirmation of lung function changes; and assessment of multiple patient-centered outcomes. Limitations include: open-label design (blinding impossible for exercise interventions); single-center study with moderate sample size; 8-week duration (long-term durability of effects unknown); reliance on self-reported exercise diaries for home-session compliance; and the specific combination of techniques studied may not be generalizable to single-modality programs.

A structured 8-week multimodal breathing exercise program comprising diaphragmatic breathing, pursed-lip breathing, and the Buteyko technique significantly improves spirometric lung function (FEV1, FVC, FEV1/FVC, PEFR), asthma control scores, and health-related quality of life in patients with mild-to-moderate persistent bronchial asthma, when used as an adjunct to standard pharmacotherapy. The program is safe, feasible, and associated with meaningful reduction in rescue bronchodilator use. These findings support the integration of supervised breathing exercise training into multidisciplinary asthma management protocols. Future multicenter trials with longer follow-up periods, larger sample sizes, and dismantling designs to assess the relative contribution of individual techniques are warranted.

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