Here is the design of a clinical trial:

Official Title: Effects of Heavy-load Resistance Training During (Neo-)Adjuvant Chemotherapy on Muscle Cellular Outcomes in Women With Breast Cancer

Included conditions:
- Breast Cancer Female

Study Armgroups:
- {'label': 'Intervention group', 'type': 'EXPERIMENTAL', 'description': 'Participants will receive supervised heavy-load resistance training twice a week during treatment with chemotherapy (approximately 16-weeks). After end of chemotherapy, participants will be encouraged to continue the training program and are provided with 12-month membership at a local gym.', 'interventionNames': ['Other: Heavy-load resistance training']}
- {'label': 'Control group', 'type': 'ACTIVE_COMPARATOR', 'description': 'Participants will be encouraged to continue with their usual activities during chemotherapy and not start resistance training (approximately 16-weeks). After end of chemotherapy participants will be offered to attend a 2-week introduction to the strength-training program and provided with a 12-month membership at a local gym.', 'interventionNames': ['Other: Control']}

Interventions:
- {'type': 'OTHER', 'name': 'Heavy-load resistance training', 'description': 'Supervised heavy-load resistance training during chemotherapy treatment', 'armGroupLabels': ['Intervention group'], 'otherNames': ['Physical exercise', 'Physical training']}
- {'type': 'OTHER', 'name': 'Control', 'description': 'Activity as usual during chemotherapy', 'armGroupLabels': ['Control group'], 'otherNames': ['usual care']}

Primary Outcomes:
- {'measure': 'Assessment of changes in muscle fiber cross-sectional area', 'description': 'Change from baseline in muscle fiber cross-sectional area at 16 weeks. Through immunohistochemical staining of muscle fiber cross-sections will muscle fiber area be assessed for type 1 and type 2 muscle fibers', 'timeFrame': 'From baseline to the 16 week time-point'}

Please estimate the sample size based on the assumption: 
Statistical power of 80% requires 10 participants per group; to achieve 95% power, 16 participants per group are needed. The sample size accounts for potential drop-outs.
2.3
        Sample size
        The power calculation is based on results from strength training effects in prostate cancer patients on androgen deprivation therapy, the Physical Exercise and Prostate Cancer trial (PEPC trial).[10] With a similar effect on muscle fiber size (+898âÂ±â840âÎ¼m2), we need 10 participants in each group to get a statistical power of 80% in the present study, to further enhance the power up to 95%, we need 16 participants in each group. Consequently, 50 participants (25 in each arm) will be recruited to account for drop-outs during the intervention. The power calculation is based on the PEPC trial[10] but findings from the study by Mijwel and colleagues[13] strongly support similar expectations in breast cancer patients on chemotherapy.