COVID-19 infection was identified in Wuhan, China at the end of 2019 and turned into apandemic in a short time. In our country, the pandemic continues at full speed andpatients are being treated in various clinical pictures. In its clinical classification,the World Health Organization (WHO) divides COVID-19 disease into four stages: mildsymptomatic disease, pneumonia, severe pneumonia, acute respiratory distress syndrome(ARDS), sepsis and advanced stage with septic shock. Case reports and cross-sectionalstudies report a list of more than 200 different symptoms in the development of postCOVID-19 syndrome. Shortness of breath, persistent smell and taste disturbances, fatigueand neuropsychological symptoms (headache, memory loss, slowed thinking, anxiety,depression and sleep disturbances) are the most commonly reported symptoms.Musculoskeletal symptoms such as pain (myalgia), muscle weakness, arthralgia and fatigueare also common. Exercise endurance tests are used to predict the prognosis of thedisease in chronic lung diseases, to determine functional exercise capacity, to evaluatethe response of the disease to treatment and to interpret the results of clinical trials.Covid-19-induced lung infections and long periods of isolation may have negative effectson respiratory muscle strength, pulmonary function values and physical activity level. Ithas been reported that only one week of bed rest can cause serious muscle loss of up to20%. Covid-19 infection increases the likelihood of asthma-like symptoms. In some cases,pneumonia and increased dyspnea are also seen. When volleyball players with Covid-19infection were examined, respiratory muscle strength and fev1/fvc values were lower thanexpected.When looking at the interaction between infections and sleep, it was observed thatdifferent infections had different effects on sleep, with some infections increasing theamount of sleep while others decreased it. The increase in inflammatory mediatorsassociated with systemic infection is thought to increase the amount of REM sleep andtotal sleep duration, perhaps in an effort to conserve energy and counteract infection.Some infections have a negative effect on the immune system, reducing the amount ofsleep. Covid infection is also thought to have negative effects on sleep. The symptoms ofCOVID-19 in the chronic phase can further negatively affect physiological, psychologicaland social outcomes, physical activity and ultimately muscle performance and quality.Post-infection physical function and fitness can worsen even two years after the disease.In COVID-19 patients recovering 3 months after hospital discharge, limitations weremainly related to reduced muscle mass, low oxidative capacity or both, rather thancardiac or respiratory exercise limitation.Symptoms experienced during Covid-19 infection are thought to have negative effects onexercise endurance. In order to meet the metabolic needs of the musculoskeletal systemmuscles during exercise, cardiac output, ventilation, pulmonary and systemic blood flow,oxygen and carbon dioxide exchange in a way to maintain acid-base balance andoxygenation, and their compatible response to each other are required. Exercise enduranceassessments are an important parameter to determine the functional level of the patient.Eighty-eight percent of individuals with Covid-19 infection showed a decrease inrespiratory muscle strength in the evaluation performed 5 months later. The direct effectof respiratory muscles may cause permanent dyspnea problems. Muscle strength, exercisecapacity, dyspnea perception, fatigue severity perception, pain, balance, kinesiophobia,psychosocial and cognitive status, quality of life should be routinely evaluated in thepost-COVID-19 period in patients admitted to the clinic, and a targeted functionalrehabilitation program should be prepared in the light of these evaluations, taking theseparameters into consideration during the rehabilitation process.