Physical Activity, Sleep Quality, and Respiratory Function in Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is a common sleep disorder characterized by recurrent upper airway collapse during sleep, leading to apneas and hypopneas. OSA negatively affects sleep quality, daytime functioning, and overall health and is associated with cardiovascular and metabolic disorders. Although continuous positive airway pressure (CPAP) is the primary treatment, adherence may be challenging. Physical activity and exercise have shown beneficial effects on OSA symptoms, sleep quality, and respiratory function. However, evidence regarding the relationship between habitual daily physical activity and these outcomes remains limited. Therefore, this study aims to investigate the effects of physical activity habits on sleep quality and respiratory parameters in individuals with OSA.

• Physical Activity Education (Behavioral): Participants will receive physical activity education supported by illustrated materials and brochures. Recommendations will include: (1) aerobic exercise, with at least 150 minutes of moderate-intensity activity weekly (e.g., walking or cycling) over at least 3 days; (2) muscle-strengthening exercises targeting major muscle groups 2-3 days per week, with 3 sets of 8-15 repetitions; (3) balance and flexibility exercises 3 days per week; and (4) diaphragmatic breathing exercises for 15-30 minutes per session, 3 days per week. Exercise sessions will include 5-10 minutes of warm-up and cool-down. Periodic follow-up contacts will encourage adherence throughout the 24-week intervention. All participants will continue prescribed CPAP therapy.

Primary outcomes

• Pittsburgh Sleep Quality Index (PSQI) [0.,12., and 24. weeks]: A 19-item self-report questionnaire assessing sleep quality and disturbances over the previous month, including sleep duration, latency, efficiency, and daytime dysfunction. Total scores range from 0 to 21, with higher scores indicating poorer sleep quality. Scores above 5 indicate poor sleep quality.
• CPAP Adherence Data [0., and 24. weeks]: CPAP device data will be downloaded to assess average nightly usage, mask leak, and treatment pressure. Good adherence will be defined as CPAP use for at least 4 hours per night on at least 5 nights per week.
• MIP-MEP measurement [0.,12., and 24. weeks]: In centimeters of water (cmH2O), it will be obtained using a Respiratory Muscle Strength Measurement Device-MIP-MEP (MD Diagnostics Ltd., RP Check, United Kingdom) in accordance with the recommendations of the American Thoracic Society.
• Forced Vital Capacity (FVC) measurement [0.,12., and 24. weeks]: It is the amount of air expelled after maximum inspiration following a normal breath, expressed in liters. While healthy individuals can forcefully exhale air for 2-3 seconds, this time can be as short as 10-15 seconds for individuals with airway problems. At the end of the test, the expected reference value should be between 80-120%. This will be performed using a spirometer (Cosmed, Pony FX, Italy). The best forced vital capacity (FVC) maneuver from at least 3 attempts will be selected according to the criteria of the American Thoracic Society. To perform the spirometric maneuvers, participants will sit upright with their feet on the floor and the nose clip correctly positioned.
• FEV₁ (Forced Expiratory Volume in 1 Second) [0.,12., and 24. weeks]: It is the volume of air exhaled in the first second after forced expiration. Although measured in liters, it actually indicates the airflow rate. In healthy individuals, at least 72% of the air should be exhaled, reflecting the function of the large airways. This will be performed using a spirometer (Cosmed, Pony FX, Italy). To perform the spirometric maneuvers, participants will sit upright with their feet on the floor and the nose clip correctly positioned.
• FEV1/FVC ratio [0.,12., and 24. weeks]: This ratio is obtained by dividing FEV1 by FVC and evaluates airway patency and lung function. In a normal individual, this ratio is around 70-80%. This will be performed using a spirometer (Cosmed, Pony FX, Italy). To perform the spirometric maneuvers, participants will sit upright with their feet on the floor and the nose clip correctly positioned.
• FEF 25%-75% (Maximal Mid-Expiratory Flow Rate [0.,12., and 24. weeks]: It refers to the average airflow rate during forced expiration, when 25% to 75% of the volume is expelled. It is measured in liters per second. It reflects the function of the medium and small airways. A value above 80% of the reference value is normal. This will be performed using a spirometer (Cosmed, Pony FX, Italy). To perform the spirometric maneuvers, participants will sit upright with their feet on the floor and the nose clip correctly positioned.
• Baecke Habitual Physical Activity Questionnaire (BHPAQ) [0.,12., and 24. weeks]: 16-item self-report questionnaire assessing habitual physical activity over the previous year across three domains: occupational activity (8 items), sports activity (4 items), and leisure-time activity (4 items). The total score is calculated by summing the three domain scores.

Secondary outcomes

• International Physical Activity Questionnaire-Short Form (IPAQ-SF) [0. week]: The IPAQ-SF assesses vigorous and moderate physical activity, walking, and sitting time. Total physical activity is calculated as MET-minutes/week, and participants are classified as having low, moderate, or high activity levels.
• Insomnia Severity Index (ISI) [0.,12., and 24. weeks]: 7-item self-report questionnaire assessing insomnia severity and its impact on daily functioning. Total scores range from 0 to 28, with higher scores indicating more severe insomnia symptoms.
• Epworth Sleepiness Scale (ESS) [0.,12., and 24. weeks]: An 8-item self-report questionnaire assessing the likelihood of dozing during daily activities. Total scores range from 0 to 24, with higher scores indicating greater daytime sleepiness. Scores above 10 suggest excessive daytime sleepiness.
• Functional Outcomes of Sleep Questionnaire-Short Form (FOSQ-10) [0.,12., and 24. weeks]: A 10-item self-report questionnaire assessing the impact of sleepiness on daily activities, productivity, activity level, social functioning, and intimate relationships. Total scores range from 5 to 20, with higher scores indicating better functional status.
• Subjective Sleepiness and Sleep Quality [0.,12., and 24. weeks]: Subjective sleepiness will be assessed three times daily (09:00, 12:00, and 20:00) using a 0-10 visual analogue scale (VAS), with higher scores indicating greater sleepiness. Subjective sleep quality will be assessed daily upon awakening using a 0-10 VAS, with higher scores indicating better sleep quality.
• Chalder Fatigue Scale (CFS) [0.,12., and 24. weeks]: An 11-item questionnaire assessing physical and mental fatigue in adults. Items are rated on a 4-point Likert scale, with higher scores indicating greater fatigue severity.
• Hospital Anxiety and Depression Scale (HADS) [0.,12., and 24. weeks]: A 14-item self-report questionnaire assessing anxiety and depression symptoms, with separate 7-item subscales. Each subscale is scored from 0 to 21, with higher scores indicating greater symptom severity. Turkish cut-off scores are 10 for anxiety and 7 for depression.
• Short Form Health Survey (SF-12) [0.,12., and 24. weeks]: A 12-item questionnaire assessing health-related quality of life across physical and mental health domains. Physical Component Summary (PCS-12) and Mental Component Summary (MCS-12) scores range from 0 to 100, with higher scores indicating better health status.
• Quadriceps Isometric Muscle Strength [0.,12., and 24. weeks]: Unilateral isometric knee extension strength will be measured using a handheld dynamometer. Participants will sit with their hips and knees flexed at 90°. Three trials will be performed on each side, and the highest value will be recorded in kilogram-force (kgf).
• Handgrip Strength [0.,12., and 24. weeks]: Dominant handgrip strength will be measured using a Jamar hydraulic hand dynamometer. Participants will sit upright with the elbow flexed at 90° and the forearm in a neutral position. Three trials will be performed with 2-minute rest intervals, and the highest value will be recorded.
• Physical Activity Diary [0.,12., and 24. weeks]: Participants will record their daily physical activities, including activity type, duration, and perceived exertion, to monitor adherence to physical activity recommendations throughout the study.

Sex: All, ages: 18 Years to 65 Years, accepts healthy volunteers

Inclusion Criteria:

* Individuals diagnosed with mild to severe obstructive sleep apnea (OSA) based on laboratory polysomnography (AHI: 5-30 events/hour).
* Individuals diagnosed by a pulmonologist within the past year who initiated CPAP therapy no more than 12 months ago and demonstrate regular use.
* Individuals with habitual snoring.
* Individuals who have not participated in OSA-focused physiotherapy interventions within the past 3 months.

Exclusion Criteria:

* Body mass index (BMI) >40 kg/m².
* Severe substance or alcohol dependence.
* Regular use of sedatives, muscle relaxants, or opioids that may affect sleep patterns.
* Pregnancy or postpartum period (<6 months).
* Medical contraindications to physical activity according to American College of Sports Medicine (ACSM) guidelines, such as unstable coronary artery disease or decompensated heart failure.
* History of stroke or significant respiratory, neuromuscular, inflammatory, or other disorders causing hypercapnia.
* Craniofacial abnormalities, severe upper airway obstruction, or secondary respiratory diseases such as chronic obstructive pulmonary disease (COPD).

• Gülay Aras Bayram, PhD, Principal investigator, Istanbul Medipol Universty