Background: The present study compared the effects of training and detraining periods of high-intensity interval training (HIIT), moderate-intensity interval training (MIIT) and moderate-intensity continuous training (MICT) on functional performance, body composition, resting blood pressure and heart rate in elderly women nursing home residents. Methods: Forty-six volunteers (age, 80.8 ± 5.2 y; body mass, 69.8 ± 5.2 kg, height, 164.2 ± 4.12 cm) were divided into groups that performed treadmill exercise twice-weekly HIIT (4 bouts of 4-min intervals at 85-95% of the maximal heart rate [HRmax], interspersed by 4 min at 65% HRmax), MIIT (4 bouts of 4 min intervals at 55-75% HRmax, interspersed by 4 min at 45-50% HRmax) and MICT (30-min at 55-75% HRmax). Tests were performed before and after 8 weeks of training and 2 and 4 weeks of detraining. ANCOVA was used to analyze dependent variable changes. Results: After 8 weeks HIIT promoted greater reductions in body mass (HIIT = – 1.6 ± 0.1 kg; MICT = – 0.9 ± 0.1 kg; MIIT = – 0.9 ± 0.1 kg; p = 0.001), fat mass (HIIT = – 2.2 ± 0.1%; MICT = – 0.7 ± 0.1%; MIIT = – 1.2 ± 0.1%; p < 0.001) and resting heart rate (HIIT = – 7.3 ± 0.3%; MICT = – 3.6 ± 0.3%; MIIT = – 5.1 ± 0.3%; p < 0.001) and greater improvement in the chair stand test (HIIT = 3.4 ± 0.1 reps; MICT = 2.5 ± 0.1 reps; MIIT = 3.1 ± 0.1 reps; p < 0.001) when compared to MIIT and MICT. These improvements were sustained after 2 and 4 weeks of detraining only in the HIIT group. Conclusion: HIIT promoted greater benefits for body composition and functional performance than MICT and MIIT and also showed less pronounced effects of detraining. This suggests that the intensity of physical exercise is an important factor to consider when prescribing exercise to the elderly.