Here is the design of a clinical trial:

Official Title: E-lombactifs: Evaluation of the Impact a Smartphone Application on Adherence an Exercise Program in Chronic Low Back Pain

Included conditions:
- Chronic Low Back Pain

Study Armgroups:
- {'label': 'group application (GA)', 'type': 'EXPERIMENTAL', 'description': 'benefit from conventional care in a rehabilitation center, therapeutic education program and education in the use of the smartphone application "mon coach dos"', 'interventionNames': ['Other: Education in the use of smartphone app (Mon coach dos)', 'Other: conventional care']}
- {'label': 'Groupe conventional care (GCC)', 'type': 'ACTIVE_COMPARATOR', 'description': 'benefit from conventional care in a rehabilitation center and therapeutic education program', 'interventionNames': ['Other: conventional care']}

Interventions:
- {'type': 'OTHER', 'name': 'Education in the use of smartphone app (Mon coach dos)', 'description': 'In addition to conventional care and the therapeutic education program, GA will benefit from three education sessions (one per week) on the use of the smartphone app mon coach dos', 'armGroupLabels': ['group application (GA)']}
- {'type': 'OTHER', 'name': 'conventional care', 'description': 'conventional care and the therapeutic education program', 'armGroupLabels': ['Groupe conventional care (GCC)', 'group application (GA)']}

Primary Outcomes:
- {'measure': 'EARS : exercise adherence rating scale', 'description': 'EARS assess the adherence in physical activity program.', 'timeFrame': 'day1'}
- {'measure': 'EARS : exercise adherence rating scale', 'description': 'EARS assess the adherence in physical activity program.', 'timeFrame': 'day 15'}
- {'measure': 'EARS : exercise adherence rating scale', 'description': 'EARS assess the adherence in physical activity program.', 'timeFrame': 'day 180'}

Please estimate the sample size based on the assumption: 
Type I error of 5%, statistical power of 90%, and an intraclass correlation coefficient (ICC) of 0.05. The design accounts for between-session and within-session variability, and an average of 5 participants per session.
Sample size estimation
          The sample size estimation for this pilot trial was determined according to the 2010 CONSORT Statement extension for randomised pilot and feasibility trials51 and Cohenâs recommendations52 that define effect-size (ES) limits as small (ES: 0.2), medium (ES: 0.5) and large (ES: 0.8, âgrossly perceptible and therefore largeâ). According to data reported in the literature and considering this study as a pilot, it seems suitable to include 60 patients per randomised group.
          To achieve an ES of 0.8 at 6 months post-randomisation with a type I error of 5% and statistical power of 90%, 33 participants are required per group. However, because of the design of the randomisation, with session as a unit cluster of randomisation, the sample size should be increased to take into account between-session and within-session variability. More precisely, the assumption in randomised controlled trials that the outcome for an individual is completely unrelated to that of any other individual is violated in cluster randomised trials because individuals in any one cluster (session in our case) are more likely to respond in a similar manner. This similarity is known as the intraclass correlation coefficient (ICC). For an average of 5 participants per session and an ICC of 0.05, 38 participants are required in each group. Therefore, to account for losses to follow-up, we will include 120 individuals (ie, 60 patients per randomised group).