The aims of this study were to describe rheumatoid arthritis patients' compliance with continued exercise after participation in a 2-year supervised high-intensity exercise program and to investigate if the initially achieved effectiveness and safety were sustained. Data were gathered by follow-up of the participants who completed the 2-year high-intensity intervention in a randomized controlled trial (Rheumatoid Arthritis Patient In Training study). Eighteen months thereafter, measurements of compliance, aerobic capacity, muscle strength, functional ability, disease activity, and radiological damage of the large joints were performed. Seventy-one patients were available for follow-up at 18 months, of whom 60 (84%) were still exercising (exercise group: EG), with average similar intensity but at a lower frequency as the initial intervention. Eleven patients (16%) reported low intensity or no exercises (no-exercise group: no-EG). Patients in the EG had better aerobic fitness and functional ability, lower disease activity, and higher attendance rate after the initial 2-year intervention. At follow-up, both groups showed a deterioration of aerobic fitness and only patients in the EG were able to behold their muscle strength gains. Functional ability, gained during the previous participation in high-intensity exercises, remained stable in both groups. Importantly, no detrimental effects on disease activity or radiological damage of the large joints were found in either group. In conclusion, the majority of the patients who participated in the 24-month high-intensity exercise program continued exercising in the ensuing 18 months. In contrast to those who did not continue exercising, they were able to preserve their gains in muscle strength without increased disease activity or progression of radiological damage.