Background Conventional nonresisted therapeutic exercises for people with hemophilia involve a careful, low-intensity approach to avoid injuries. Externally resisted exercise is highly efficient for increasing muscle strength in healthy adults but its feasibility for people with hemophilia remains unknown. Objective The purpose of this study was to evaluate muscle activity during upper-body rehabilitation exercises with 2 types of external resistance and without external resistance (conventional) and to examine tolerability, kinesiophobia, and possible adverse effects derived from the session. Design This was a cross-sectional study. Methods Twelve people with hemophilia A/B (11 with severe hemophilia undergoing prophylactic treatment, 1 with mild hemophilia) participated. During the experimental session, participants completed the Tampa Scale of Kinesiophobia and performed 2 exercises - elbow flexion and shoulder abduction - with 3 conditions for each exercise: elastic resistance (externally resisted), free weights (externally resisted), and conventional nonresisted. Surface electromyography signals were recorded for the biceps brachii, triceps brachii, upper trapezius, and middle deltoid muscles. After the session, exercise tolerability and kinesiophobia were assessed. Adverse effects were evaluated 24 and 48 hours after the session. Results Externally resisted exercises provided greater muscle activity than conventional nonresisted therapeutic exercises. The exercises were generally well tolerated and there was no change in kinesiophobia following the session. No adverse effects were observed in the following days. Limitations Small sample size was the main limitation. Conclusions In people with severe hemophilia undergoing prophylactic treatment, elbow flexion and shoulder abduction exercises with external resistance at moderate intensities are feasible and provide greater muscle activity than nonresisted conventional exercises.