Physical Rehabilitation of COVID-19 Survivors by Heat Therapy

The novel coronavirus (severe acute respiratory syndrome [SARS]-CoV-2), first identified in December 2019 in Wuhan, China, has since spread worldwide. Older adults and people with underlying medical conditions are at higher risk for developing serious complications and death related to SARS-CoV-2. However, another challenge is arising in regards to the long-term prognosis of COVID-19 survivors. Although limited, the available data on the medium-term outcomes of patients who survived COVID-19 all indicate prolonged symptom duration and disability in a large proportion of adults hospitalized with severe symptoms. In addition, these patients, a majority of whom were older adults or patients with pre-existing health conditions, spent \~10-15 days bedridden and under intensive treatment, which can have lasting consequences on metabolism and cardiovascular functions, mobility, and eventually lead to long-term disabilities. Upon discharge from the hospital, the main option for physical rehabilitation involves exercise training. Although, exercise training can be effective to restore physical function, it is oftentimes associated with low adherence. Considering the severe deconditioning accompanying hospitalization related to COVID-19, there is a critical need for the development of a rehabilitation strategy that is home-based and practical to individuals with diminished physical function. Accordingly, the goal of this project is to compare the benefits of home-based lower limb chronic heat therapy to exercise training on skeletal muscle metabolism, vascular function and functional capacity in older adults during their convalescence from hospitalization due to SARS-CoV-2. Late middle-age and older adults that have been discharged from a COVID-19 hospitalization will be randomly allocated to an exercise intervention group (EX, low resistance \~40 min, 3 times a week at home), a heat-treated group (HT, leg heated garments with skin temperature reaching \~40˚C, 40-55 min, 5 times a week at home), or a control group (CT) for 8 weeks. Specific Aim 1 will test the hypothesis that local heat therapy in previously hospitalized COVID-19 patients can (i) enhance functional capacity, resulting in improvements in mobility and quality of life compared to a non-treated control group, and (ii) that these changes will be similar in magnitude to an exercise intervention. Specific Aim 2 will test the hypothesis that local heat therapy in the same patients can (i) enhance insulin sensitivity as a consequence of improvements in mitochondrial and vascular function compared to a non-treated control group, and (ii) that these changes will be similar in magnitude to an exercise intervention.