Here is the design of a clinical trial:

Official Title: Effectiveness of the Pilates Method Versus Aerobic Exercises in the Treatment of Chronic Non-specific Low Back Pain in the Elderly: Randomized Controlled Trial

Included conditions:
- Low Back Pain

Study Armgroups:
- {'label': 'Pilates Group', 'type': 'EXPERIMENTAL', 'description': 'Elderly will be submitted to a specific exercise program of modified Pilates method performed in the mat and apparatus. In the first session, participants will receive basic guidance on the Pilates training and activation of the power house. The session will be divided in: global warming and stretching (5 minutes), Pilates exercises for upper and lower limbs, abdomen and spine (45 minutes), global stretching (5 minutes) and local relaxing massage (5 minutes).The session will consist of a minimum of 5 exercises and a maximum of 15 Pilates exercises. The elderly will receive 16 individual sessions with duration of 60 minutes, twice a week, with a total of eight weeks of treatment.', 'interventionNames': ['Other: Pilates Group']}
- {'label': 'Aerobic Group', 'type': 'ACTIVE_COMPARATOR', 'description': 'The Aerobic Group will be submitted to an exercise program with global stretching (for lower and upper limbs and column with two repetitions and 30 seconds of maintenance in each segment) for 10 minutes, walking on a treadmill for 20 to 40 minutes and relaxing massage for 5 minutes. The intensity of the effort during walking on a treadmill will be based on a combination of heart rate (based on the percentage of maximum heart rate: 208 - (0.7 x age)) and rate of perceived effort assessed by the Borg scale. Exercise will be performed respecting the fraction of 50-75% of maximum heart rate and levels between 12 to 13 (moderate intensity) of the Borg scale. The elderly will receive 16 individual sessions with duration of 60 minutes, twice a week, with a total of eight weeks of treatment.', 'interventionNames': ['Other: Aerobic Group']}

Interventions:
- {'type': 'OTHER', 'name': 'Pilates Group', 'description': 'Elderly will be submitted to a specific exercise program of modified Pilates method performed in the mat and apparatus. In the first session, participants will receive basic guidance on the Pilates training and activation of the power house. The session will be divided in: global warming and stretching (5 minutes), Pilates exercises for upper and lower limbs, abdomen and spine (45 minutes), global stretching (5 minutes) and local relaxing massage (5 minutes).The session will consist of a minimum of 5 exercises and a maximum of 15 Pilates exercises. The elderly will receive 16 individual sessions with duration of 60 minutes, twice a week, with a total of eight weeks of treatment.', 'armGroupLabels': ['Pilates Group']}
- {'type': 'OTHER', 'name': 'Aerobic Group', 'description': 'Elderly will be submitted to an exercise program with global stretching (for lower and upper limbs and column with two repetitions and 30 seconds of maintenance in each segment) for 10 minutes, walking on a treadmill for 20 to 40 minutes, and relaxing massage for 5 minutes. The intensity of the effort during walking on a treadmill will be based on a combination of heart rate (based on the percentage of maximum heart rate: 208 - (0.7 x age)) and rate of perceived effort assessed by the Borg scale. Exercise will be performed respecting the fraction of 50-75% of maximum heart rate and levels between 12 to 13 (moderate intensity) of the Borg scale. The elderly will receive 16 individual sessions with duration of 60 minutes, twice a week, with a total of eight weeks of treatment.', 'armGroupLabels': ['Aerobic Group']}

Primary Outcomes:
- {'measure': 'Pain intensity', 'description': 'Pain intensity will be measured by an 11-point Pain Numerical Rating Scale', 'timeFrame': 'Eight weeks after randomization'}
- {'measure': 'Disabitity', 'description': 'Disability associated with low back pain will be measured using the 24-item Roland Morris Disability Questionnaire', 'timeFrame': 'Eight weeks after randomization'}

Please estimate the sample size based on the assumption: 
two-tailed t-test, α=0.05, power=80%, 15% loss to follow-up
Sample size
        The study was designed to detect a clinically significant 2-point difference in pain intensity assessed by the Pain Numerical Rating Scale (estimate for standard deviationâ=â2.5) and a 5-point difference in disability assessed by the Roland Morris Disability Questionnaire (estimate for standard deviationâ=â6.5) [49, 50] eight weeks after randomization, using a two-tailed t-test of difference between means and assuming Î±â=â0.05, statistical power of 80% [51], and loss to follow-up of 15%. Estimations indicated that 34 patients per group will be required using pain intensity to calculate sample size, and 37 patients per group using disability. Therefore, the biggest number resulting from sample size calculation will be considered, which corresponds to 74 patients. To reach this number, the study will be promoted in community newspapers and on the internet.