Effects of different exercise training modalities in post-COVID-19 individuals: a systematic review of randomized controlled trials

Purpose Although the COVID-19 pandemic has ended, long-term effects persist. Exercise training (ET) supports recovery, but evidence on optimal modalities is limited. This study evaluated the effects of different ET modalities in post-COVID-19 individuals.Methods A systematic search identified randomized controlled trials (RCTs) up to 23 September 2025, involving adults with COVID-19. Studies compared ≥4-week interventions—aerobic training, high-intensity interval training (HIIT), or combined training (aerobic plus resistance training)—with usual care (UC). Risk of bias and certainty of evidence were assessed using RoB 2.0 and GRADE.Results Eighteen RCTs (N = 1171) were included. Interventions varied in intensity and duration. Most studies had “some concerns” regarding bias, and overall certainty of evidence was low to very low. Overall, ET modalities were associated with improvements in functional capacity (VO2peak or six-minute walk distance) and muscle strength, although not all studies showed significant differences vs. UC. HIIT demonstrated the greatest VO2peak gain (mean difference: 6.17 ml.kg−1.min−1). Effects on quality of life, anxiety, and depression were inconsistent. Most cardiopulmonary parameters (VE/VCO2 slope, OUES) showed no significant changes, with mixed results for O2 pulse and ventilation.Conclusions Despite heterogeneous protocols and low certainty of evidence, structured ET appears beneficial for post-COVID-19 recovery. Multiple ET approaches may be effective rather than a single “optimal” approach.