Here is the design of a clinical trial:

Official Title: Personalized Trimodal Prehabilitation for Gastrectomy

Included conditions:
- Gastric Cancer

Study Armgroups:
- {'label': 'Prehabilitation group', 'type': 'EXPERIMENTAL', 'description': 'Patients in the experimental group will undergo prehabilitation before the elective surgery for gastric cancer.', 'interventionNames': ['Other: Prehabilitation']}
- {'label': 'Control group', 'type': 'NO_INTERVENTION', 'description': 'Patients in the control group will not undergo prehabilitation.'}

Interventions:
- {'type': 'OTHER', 'name': 'Prehabilitation', 'description': 'Patients will undergo 6 Minutes Walking Test (6-MWT), spiroergometry (VO2 max; AT), a grip strength test, a timed Up \\& Go (TUG) test, 10 m sprint test and sit to stand test before and after prehabilitation. The trimodal intervention will involve:\n\n1. Nutritional intervention\n2. Psychological intervention\n3. Exercise intervention', 'armGroupLabels': ['Prehabilitation group']}

Primary Outcomes:
- {'measure': 'Postoperative morbidity rate by Clavien-Dindo', 'timeFrame': 'At 90 days postoperatively'}

Please estimate the sample size based on the assumption: 
80% power, two-sided level of significance of 5%, and a drop-out rate of up to 10%.
2.10
        Sample size
        The sample size calculation was done using GâPower 3.1.9.4 software using the reduction of 90 days postoperative complication rates as the primary outcome. Based on the assumption that the percentage of patients developing postoperative complications after gastrectomy is approximately 50% for the control group (based on our centers historical experience and results from RCTs)[2,3] and can be reduced to 25% in the prehabilitation group (based on results of recent RCT showing 50% reduction of postoperative complications by prehabilitation),[15] a group sample size of 58 patients is needed to achieve 80% power in detecting this difference in 90-days postoperative morbidity at a two-sided level of significance of 5%. Under the assumption of a drop-out rate of up to 10%, a total of 128 patients (64 per group) needs to be enrolled in the study.