High-intensity training in patients with spinal and bulbar muscular atrophy Abstract Objective Long duration, moderate-intensity exercise is not well tolerated in patients with spinal and bulbar muscular atrophy (SBMA). This study investigated whether patients with SBMA can benefit from high-intensity training (HIT). Methods Ten patients with SBMA were randomized to 8 weeks of supervised HIT [n = 5; age = 50 (25–63) years] followed by 8 weeks of self-training or 8 weeks of no training followed by 8 weeks of non-supervised HIT [n = 5; age = 50 (26–54) years]. Training consisted of 2 × 5-min exercise periods with 1-min cyclic blocks of intermittent maximal intensity exercise on an ergometer bike. Maximal oxygen capacity (VO2max) and workload (Wmax) were measured before and after training by incremental exercise tests. Plasma creatine kinase levels, self-rated muscle pain, muscle fatigue, and activity level were monitored throughout the training period. Results Eight patients completed training. One patient dropped out after 5 weeks of training for private reasons. Another patient was excluded after 4 weeks due to lack of compliance. Eight weeks of training increased both VO2max(1.9 ± 2.3 ml min−1 kg−1; p = 0.04) and Wmax (15.6 ± 17.9 W; p = 0.03) in the 8 patients who completed training. There were no changes in plasma creatine kinase levels, self-reported muscle pain or muscle fatigue activity level after training. Conclusion This pilot study suggests that high-intensity training is safe and improves fitness in patients with SBMA. Unlike low- and moderate-intensity training, HIT is efficacious and favored over other training forms by the patients.