Here is the design of a clinical trial:

Official Title: BEAT DB-study; Breathing Exercises in Asthma Targeting Dysfunctional Breathing-a Randomised Controlled Trial

Included conditions:
- Dysfunctional Breathing in Asthma

Study Armgroups:
- {'label': 'Breathing Exercises', 'type': 'EXPERIMENTAL', 'description': 'Individual instruction from a nurse at baseline aimed at knowledge on pharmacological treatment and optimized inhalation techniques. The participants will be encouraged to use online video instruction.\n\nThree physiotherapist-sessions of Breathing Exercises (BrEX) with duration of 60 minutes (the initial) and 30 minutes (other sessions) at week 1, 4, and 9. The participant is expected to do 10 minutes of home exercise twice daily. The entire intervention combines elements of the Papworth method, and the Buteyko technique.', 'interventionNames': ['Other: Breathing Exercises']}
- {'label': 'Usual care', 'type': 'OTHER', 'description': 'Individual instruction from a nurse at baseline aimed at knowledge on pharmacological treatment and optimized inhalation techniques. The participants will be encouraged to use online video instruction.\n\nBesides the individual instruction described above, patients will receive only short information given initially at recruitment. They are allowed to receive instruction in positive expiratory pressure-treatment and physiotherapy targeting other problems than dysfunctional breathing (DB).', 'interventionNames': ['Other: Usual care']}

Interventions:
- {'type': 'OTHER', 'name': 'Breathing Exercises', 'description': 'Key points in the intervention are\n\n* Reduction (or normalising) of the respiration rate; use of rhythmic, nasal inspiration, diaphragmatic breathing; reduction of depth of breath, longer expiration; breath-holding at functional residual capacity.\n* Relaxation, especially the neck, jaw, tongue, and shoulders. Emphasizing the impact of gravity to the body.\n* Inclusion of the breathing modification into walking and other physical activities.\n* Daily home exercise of BrEX.', 'armGroupLabels': ['Breathing Exercises'], 'otherNames': ['BrEX']}
- {'type': 'OTHER', 'name': 'Usual care', 'description': 'Participants will receive only short information given initially at recruitment. No instruction or booklet will be distributed in the Usual care-Group.', 'armGroupLabels': ['Usual care'], 'otherNames': ['UC']}

Primary Outcomes:
- {'measure': 'Mini Asthma Quality of Life Questionnaire (MiniAQLQ)', 'description': 'MiniAQLQ is a disease-specific patient-reported outcome on experiences during the previous two weeks. The original version of AQLQ (32 items) is recommended for clinical use, whereas this shortened version is suggested for research. In moderate to severe asthma cohorts, MiniAQLQ has good reliability (ICC 0.83-0.86) and strong validity (criteria validity to AQLQ, r≥0.80; construct validity against ACQ, r=0.69). MiniAQLQ has 15 items in four domains (symptoms, activity limitation, emotions, environment), which are answered using a 7-point Likert scale (1=maximum impairment; 7=no impairment).', 'timeFrame': 'Primary endpoint: Change from baseline to 6 months follow up. Secondary endpoints will be 3 and 12 months follow up.'}

Please estimate the sample size based on the assumption: 
The sample size calculation assumes a power of 90%, a significance level (p value) of 0.05 (two-sided), and accounts for potential drop-outs.
Sample size
        As argued by Norman et al,73 no universal minimal important difference (MID) exists, as MID depends on the clinical setting, population and the intervention. However, it can often be estimated as half a standard deviation (SD).73 Thomas et al. (breathing exercises vs education by a nurse in mild to moderate asthma) found a 0.38 change in MiniAQLQ score.27

        We will use the effect size found in Thomas et al27 as MID in our sample calculation (with a calculated SD of 0.76) and expect to find a similar or higher effect size, as (a) BrEX will be an add-on intervention to standard specialist care instead of a head-to-head comparison as in Thomas et al, and (b) as this secondary care asthma population is expected to have a higher disease burden due to asthma, that is, greater room for improvement.
        There is an inherent risk of the trial being underpowered because the SD of MiniAQLQ after BrEX in secondary care is unknown. However, based on previous studies,27 28 we expect that our SD will be sufficient to reflect the population.
        For the present trial, the sample size needed is 172 to detect a 0.38 unit difference between groups in MiniAQLQ score (SD of 0.76, power of 90%, and p value of 0.05 (two-sided)). To allow for drop-outs, we will aim to randomise 190 participants.