Post-COVID-19 syndrome is associated with persistent symptoms such as fatigue, reduced physical activity, and impaired respiratory function. Circadian rhythm differences (chronotype) may influence lifestyle behaviors including physical activity, nutrition, and sleep patterns.
This observational cross-sectional study aims to compare respiratory muscle strength, physical activity levels, and nutritional habits among individuals with post-COVID-19 syndrome according to their chronotype (morning, intermediate, and evening types).
Additionally, genetic analysis of the CLOCK gene polymorphism will be performed to support objective evaluation of circadian rhythm differences. The findings of this study may help to better understand the role of circadian rhythm in post-COVID-19 syndrome and contribute to the development of individualized rehabilitation and lifestyle interventions.
Diagnosed with Post-COVID-19 Syndrome
Aged between 18-65 years
Able to read and understand Turkish
Voluntary participation
Recent myocardial infarction or pulmonary embolism
Severe uncontrolled chronic diseases
Neurological or orthopedic conditions limiting mobility
Psychiatric or neurological disorders affecting cooperation or test compliance
The study population consists of post-COVID-19 syndrome patients aged 18-65 years who are referred to the Hacettepe University Cardiopulmonary Rehabilitation Unit. Participants will be classified into morning-type and evening-type chronotypes.
Other
Cross-sectional
Not listed
Respiratory Muscle Strength
Maximal inspiratory pressure (MIP), maximal expiratory pressure (MEP) values will be recorded with mouth pressure device.
Dynamic respiratory muscle strength
Respiratory muscle strength index (S index) will be assessed using a portable POWERbreathe K5 device.
Respiratory muscle endurance
Respiratory muscle endurance test at constant threshold load will be used.
Physical Activity Level
Physical activity levels will be assessed using the International Physical Activity Questionnaire Short Form (IPAQ-SF), expressed as MET-min/week. The total weekly IPAQ score (MET-min/week) were then used to classify participants into three categories: Low PA (individuals who did not meet criteria for moderate or high categories); Moderate PA (≥3 days of vigorous-intensity activity of at least 20 min per day; ≥5 days of moderate-intensity activity and/or walking of at least 30 min per day; or 3-5 or more days of any combination of walking, moderate-intensity or vigorous intensity activities achieving a minimum total PA of at least 600 MET-min/week); high PA (vigorous activity on at least 3 days with a minimum total PA of at least 1500 MET-min/week or 7 days of any combination of walking and moderate or vigorous activities with a minimum total PA of 3000 MET-min/week).
Dietary Intake
Dietary intake will be assessed using 24-hour dietary recall records analyzed for macro and micronutrient intake.
Chronotype Classification
Chronotype will be determined using the Munich Chronotype Questionnaire (MCTQ), categorizing participants into morning-type and evening-type groups.Total MCTQ scores can range from 16 to 86, with the lowest values representing extreme-late chronotypes.
Fatigue Severity
Fatigue will be assessed using the Fatigue Severity Scale (FSS). Total FSS score ranges between 0-7. Total FSS score 4 and more indicates severe fatigue.
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