Background <p>This protocol was developed to describe the design of a randomised controlled trial that will examine the clinical efficacy of a 4-week comparison of high-intensity vs. low-intensity physical training for people suffering from anxiety. The hypothesis is that the high-intensity group will have greater benefit in terms of reduced anxiety symptoms, improved physical health (blood pressure) and better adherence.</p> Methods <p>Thirty adults aged 18 to 70 years diagnosed with an anxiety disorder will be recruited for this study. Participants will be randomised into an intervention group (high-intensity training) and a control group (low-intensity training). Randomisation will be performed using counterbalanced block randomisation in a 1:1 ratio, stratified by sex. Both groups will perform 4 weeks of twice-weekly training supervised by an exercise physiologist. The primary outcome will be the total score on the Hospital Anxiety and Depression Scale (HADS) and the total score on the Beck Anxiety Inventory (BAI). The secondary outcomes include blood-pressure changes and adherence. Evaluations will be performed at baseline and following 4 weeks of the interventions, and 6 months after the termination of the intervention period (secondary endpoint).</p> Discussion <p>By investigating the clinical efficacy of a 4-week training intervention, we hope to provide applicable and generalisable knowledge about the efficacy of physical training for people suffering from anxiety disorders.</p> Trial registration <p>Clinical Trials <a href="https://clinicaltrials.gov/study/NCT06881758">NCT06881758</a>. Registered on 17 March 2025.</p>