FeelFit: High-intensity Interval Training to Improve Self-reported Physical Fitness in Brain Tumor Patients

The FeelFit trial is testing whether high-intensity interval training (HIIT) — short bursts of intense exercise followed by rest — can improve how brain tumor patients feel about their physical fitness and energy levels. HIIT is an efficient form of exercise that may be manageable even for people going through cancer treatment. **You may be eligible if...** - You are 18 years or older - You have been diagnosed with a primary brain tumor - Your disease is stable (no sign of tumor growth on imaging or clinically) - You are not currently receiving any cancer treatment and haven't been for at least 2 months - You feel your physical fitness is reduced - You can speak, read, and write in Dutch **You may NOT be eligible if...** - Your general functioning is significantly impaired (Karnofsky Performance Score below 70) - You participated in a HIIT program within the last month - You have a medical reason that prevents you from exercising Talk to your doctor to see if this trial is right for you.