Here is the design of a clinical trial:

Official Title: Progressive Resistance Training Compared to Neuromuscular Exercise in Patients With Hip Osteoarthritis, and the Additive Effect of Booster Sessions: A Multicenter Randomized Controlled Trial

Included conditions:
- Hip Osteoarthritis

Study Armgroups:
- {'label': 'Group 1:', 'type': 'EXPERIMENTAL', 'description': 'PRT', 'interventionNames': ['Other: Progressive Resistance Training and no booster sessions']}
- {'label': 'Group 2:', 'type': 'EXPERIMENTAL', 'description': 'PRT + Booster sessions', 'interventionNames': ['Other: Progressive Resistance Training and booster sessions']}
- {'label': 'Group 3:', 'type': 'ACTIVE_COMPARATOR', 'description': 'NEMEX', 'interventionNames': ['Other: Neuromuscular exercise and no booster sessions']}
- {'label': 'Group 4:', 'type': 'EXPERIMENTAL', 'description': 'NEMEX + Booster sessions', 'interventionNames': ['Other: Neuromuscular exercise and booster sessions']}

Interventions:
- {'type': 'OTHER', 'name': 'Progressive Resistance Training and no booster sessions', 'description': 'An initial 12-week exercise intervention, consisting of 1-hour group sessions of progressive resistance training supervised by a physiotherapist 2 times per week.\n\nThe sessions consist of a 10-minute submaximal warm up on an exercise bike followed by 50 minutes of PRT with exercises targeting the muscles of the hip and knee joints; leg press, hip extension, hip abduction, hip flexion and knee extension. The progression will be in line with guidelines provided by the American College of Sports Medicine. The intensity will follow repetition maximum (RM) targets, from 12 RM for the first week towards 8 RM for the last weeks.\n\nAfter the 12 weeks, this group consists of patients who are randomized to receive no further treatment. For the following 9 months, these patients are given a membership to a fitness center where they are encouraged to continue the same exercise regime.', 'armGroupLabels': ['Group 1:']}
- {'type': 'OTHER', 'name': 'Progressive Resistance Training and booster sessions', 'description': 'An initial 12-week exercise intervention, consisting of 1-hour group sessions of progressive resistance training supervised by a physiotherapist 2 times per week.\n\nThe sessions consist of a 10-minute submaximal warm up on an exercise bike followed by 50 minutes of PRT with exercises targeting the muscles of the hip and knee joints; leg press, hip extension, hip abduction, hip flexion and knee extension. The progression will be in line with guidelines provided by the American College of Sports Medicine. The intensity will follow repetition maximum (RM) targets, from 12 RM for the first week towards 8 RM for the last weeks.\n\nAfter the 12 weeks, this group consists of patients who are randomized to receive 4 booster sessions (at 1, 3, 5 and 7 months after termination of the initial 12 week intervention). Additionally, for the following 9 months, these patients are given a membership to a fitness center where they are encouraged to continue the same exercise regime without supervision.', 'armGroupLabels': ['Group 2:']}
- {'type': 'OTHER', 'name': 'Neuromuscular exercise and no booster sessions', 'description': 'An initial 12-week exercise intervention, consisting of 1-hour group sessions of progressive resistance training supervised by a physiotherapist 2 times per week.\n\nThe sessions consist of a 10-minute submaximal warm up on an exercise bike followed by 50 minutes of NEMEX training with exercises focused on stability, postural function, postural orientation, lower extremity muscle strength, and functional exercises. Progression is made when an exercise is performed with good sensorimotor control and good quality of the performance and with minimal exertion and adequate control of the movement.\n\nAfter the 12 weeks, this group consists of patients who are randomized to receive no further treatment. For the following 9 months, these patients are given equipment and encouraged to continue the same exercise regime at home without supervision.', 'armGroupLabels': ['Group 3:']}
- {'type': 'OTHER', 'name': 'Neuromuscular exercise and booster sessions', 'description': 'An initial 12-week exercise intervention, consisting of 1-hour group sessions of progressive resistance training supervised by a physiotherapist 2 times per week.\n\nThe sessions consist of a 10-minute submaximal warm up on an exercise bike followed by 50 minutes of NEMEX training with exercises focused on stability, postural function, postural orientation, lower extremity muscle strength, and functional exercises. Progression is made when an exercise is performed with good sensorimotor control and good quality of the performance and with minimal exertion and adequate control of the movement.\n\nAfter the 12 weeks, this group consists of patients who are randomized to receive 4 booster sessions (at 1, 3, 5 and 7 months after termination of the initial 12 week intervention). Additionally, for the following 9 months, these patients are given equipment and encouraged to continue the same exercise regime at home.', 'armGroupLabels': ['Group 4:']}

Primary Outcomes:
- {'measure': 'Change in functional performance measured by the 30-seconds chair stand test', 'description': 'The 30-second chair stand test is a valid and responsive measure of lower-extremity muscle strength evaluating sit-to-stand function, which is limited in people with lower extremity OA.', 'timeFrame': 'Measured at baseline, 12 week and 12 month follow-up.'}

Please estimate the sample size based on the assumption: 
The assumptions include a power of 0.90, a two-sided significance level of α=0.05, and an anticipated dropout rate of 30%.
Sample size
        The sample size calculation is based on the expected between-group difference in the 30 s CST from baseline to 3-month follow-up. Due to lack of hip OA specific data, the sample size calculation relies on data from knee OA. A mean change of 2.5 chair stands was found by Skoffer et al59 in knee OA patients after 4 weeks of PRT and a mean change of 1.0 chairs stands was found by Bennell et al60 after 12 weeks of NEMEX also in knee OA patients, resulting in a difference between treatments of 1.5 chair stands. An SD of 2.52 for the 30 s CST is calculated from the 95%âCI of the change in the intervention group of the study by Skoffer et al.59 Given a power of 0.90 and two-sided significance level Î±=0.05, the estimated sample size for a two-sample means test comparing PRT to NEMEX yields 122 participants. With an anticipated dropout rate of 30%, a total of 160 participants is the estimated sample size. For the primary 12-month comparison, the difference between groups receiving booster sessions and groups not receiving booster sessions is expected to be larger than for the comparison of PRT and NEMEX. Hence, we expect this study to be adequately powered for both comparisons.