PurposeExercise proved to reduce cancer-related symptoms and prolong survival in some cancer types. However, brain tumor patients are often advised against strenuous exercise. Here, we summarize our experience with a submaximal exercise program for glioma patients: ActiNO (ActiveinNeuro-Oncology).MethodsGlioma patients were invited to participate in the program. Since 2011, a sports scientist individualized two one-hour sessions per week adapted to the patients’ symptoms. One session consisted of bicycle ergometry (average workload: 75% of maximum heart rate), the other of whole-body resistance training. Both sessions were further complimented by coordinative elements. Cardiorespiratory fitness was assessed using the ”Physical Work Capacity” procedure. Patients were followed up regularly to assess adherence to the program and disease activity.ResultsUntil December 2019, 45 glioma patients, median-aged 49 years (IQR 42–59), were included in the analysis. Most patients suffered from glioblastoma (58%), followed by diffuse lower-grade astrocytoma (29%). In overall 1828 training sessions, two minor epileptic events occurred (1 speech arrest; 1 focal seizure). During fitness assessment, all patients achieved at least 75% of their age-adjusted maximum heart rate. Peak workload averaged 172 W (95% CI 156–187). Median survival of participating glioblastoma patients was 24.1 months (95% CI 8.6–39.5).ConclusionThis supervised training program with submaximal exertion was feasible and safe in glioma regardless of WHO grading. Based on these experiences, we initiated a prospective multicenter study to objectify improvements in physical performance and quality of life in patients with glioblastoma.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11060-023-04354-y.