Preventive Physical Activity Intervention in Head and Neck Cancer

This study is testing whether a structured exercise program during radiation therapy (with or without chemotherapy) helps patients with head and neck cancer maintain their physical fitness, reduce fatigue, and improve quality of life during and after treatment. **You may be eligible if:** - You have been diagnosed with head and neck cancer (affecting the throat, pharynx, or voice box) - You are receiving radiation therapy aimed at curing your cancer **You may NOT be eligible if:** - You have already had surgery for your head and neck cancer - You have had prior treatment for head and neck cancer - You have a tracheostomy (breathing tube in the neck) - You are unable to participate in physical exercise - You cannot complete a 6-minute walking test - You cannot fill out questionnaires in Swedish - You have a prior neurological or neuromuscular condition Talk to your doctor to see if this trial is right for you.