Musculoskeletal Sequelae of Post-COVID-19 Syndrome: A Systematic Review

<b>Background/Objectives:</b> COVID-19 infection is a respiratory illness that affects multiple body systems, including the musculoskeletal system. In August 2024, Colombia reported 6 million infections and a 2.2% mortality rate related to COVID-19. Post-COVID-19 syndrome (PCS) is a chronic condition occurring after the acute infection, typically characterized by fatigue, weakness, pain, and sarcopenia, impacting the patient's quality of life (QoL). This systematic review aimed to identify musculoskeletal sequelae, including peripheral muscle strength, fatigue, and QoL, in patients with PCS. <b>Methods:</b> We searched the PubMed, Scopus, and Web of Science databases for cross-sectional, case-control, and cohort studies focusing on musculoskeletal sequelae in patients with COVID-19 infection published between 2020 and 2025. Study quality and risk of bias were assessed using the MINORS and the ROBINS-E scales, respectively. <b>Results:</b> Thirteen studies (n = 5657 patients) met the eligibility criteria. Seventy-six percent of studies indicated muscle weakness as the most common sequela, primarily in older adults and individuals with comorbidities (obesity, diabetes, and chronic obstructive pulmonary disease). General fatigue (reported in 76% of the studies) significantly influenced patients' daily lives, whereas 90% of patients reported some level of deterioration in their QoL, primarily regarding mental health, bodily pain, and physical performance. <b>Conclusions:</b> Patients with PCS who required mechanical ventilation showed reduced muscle strength and poor physical performance, especially older adults. Inactive individuals had worse musculoskeletal sequelae, while physical activity was associated with better strength levels. Although QoL improved after 12 months, the combination of aerobic exercise with adequate nutrition is essential to promote muscle recovery, reduce fatigue, and improve overall functional capacity in post-COVID-19 patients.