Brain and Peripheral Muscle Oxygenation in Patients With Chronic Obstructive Pulmonary Disease

Overview

This interventional study aims to investigate the acute effects of different types of exercise on cerebral and peripheral muscle oxygenation in patients with chronic obstructive pulmonary disease (COPD). Functional near-infrared spectroscopy (fNIRS) and near-infrared spectroscopy (NIRS) will be used simultaneously to measure oxygenation changes in the prefrontal cortex and the vastus lateralis muscle during rest, Stroop task performance, the six-minute walk test, aerobic, strengthening, and breathing exercises. The study will compare COPD patients and age- and sex-matched healthy controls to determine how brain and muscle oxygenation responses differ between groups and among exercise modalities. The findings are expected to guide the design of safe, individualized pulmonary rehabilitation programs that optimize oxygenation without compromising safety.

Detailed description

Functional near-infrared spectroscopy (fNIRS) and near-infrared spectroscopy (NIRS) allow real-time, non-invasive assessment of tissue oxygenation. Although widely used in neurology and exercise physiology, their application in pulmonary diseases such as COPD remains limited.

This study is designed as a non-randomized controlled, multidisciplinary trial conducted at Yedikule Chest Diseases and Thoracic Surgery Training and Research Hospital, Istanbul. The research team includes specialists in physiotherapy and rehabilitation, pulmonology, and neuroscience.

Participants will undergo a single standardized pulmonary rehabilitation (PR) session comprising three exercise modalities:Aerobic training, Peripheral strengthening exercises and Breathing exercises.

Before and after exercise, participants will perform the Stroop cognitive task to evaluate executive function and its relationship with cerebral oxygenation. Continuous fNIRS and NIRS monitoring will occur at rest, during each exercise, and during recovery.

Interventions

• Other Aerobic Exercise (Treadmill Walking)
  Participants perform treadmill walking for 15 minutes at 60% of the heart rate reserve (HRR), following a 2-minute warm-up period. Exercise intensity is calculated individually using the Karvonen formula. Continuous oxygenation monitoring is conducted via fNIRS (prefrontal cortex) and NIRS (vastus lateralis).
• Other Resistance Exercise (Upper and Lower Limb Strength Training)
  Participants perform resistance exercises for upper and lower limb major muscle groups using 60% of one-repetition maximum (1RM). Each exercise consists of 12 repetitions per set, repeated for 15 minutes with 10-second rest intervals between sets. Movements include shoulder flexion/abduction/extension, hip flexion/abduction/adduction/extension, knee extension, and squatting.
• Other Breathing Exercises
  Participants perform controlled breathing exercises including diaphragmatic, chest, and lateral basal breathing techniques. Each pattern is executed in 10-repetition cycles, repeated for 15 minutes with 10-second rest intervals. All sessions begin with pursed-lip breathing instruction and are performed in a seated position.
• Other Cognitive Task (Stroop Task)
  A computerized color-word interference test (PsychoPy software) is administered before and after the exercise session to evaluate executive function and attention. Performance is analyzed in relation to concurrent fNIRS measurements from the prefrontal cortex.

Primary outcome measures

• Change in cerebral oxygenation during exercise [Time frame: Day 1]

Secondary outcome measures (5)

• Change in peripheral muscle oxygenation [Time frame: Day 1]
• Cognitive performance (reaction time, accuracy in Stroop task) [Time frame: Pre-exercise (baseline) and immediately post-exercise (within 5 minutes after final exercise).]
• Six-Minute Walk Distance (6MWD) [Time frame: Baseline]
• Perceived Dyspnea (Modified Borg Scale) [Time frame: Day 1]
• Physical Activity Level (IPAQ-Short Form) [Time frame: Baseline]

Eligibility criteria

Inclusion criteria

• Age 40-70 years
• Diagnosis of moderate-to-severe COPD (GOLD stage II-III)
• Stable disease (no exacerbation in previous 4 weeks)
• BMI 18.5-24.9 kg/m²
• Manual muscle strength ≥ 4 (MRC scale)
• Ability to perform exercise tests safely
• Written informed consent

Exclusion criteria

• Severe comorbid conditions (uncontrolled cardiac, neurological, or orthopedic disease)
• Need for high-flow oxygen therapy (>2 L/min)
• History of cerebrovascular disease or transient ischemic attack
• Musculoskeletal or dermatological conditions impairing NIRS measurement sites
• Restrictive lung disease, interstitial lung disease, or small-airway disease
• Participation in an exercise program within the last 12 months

Healthy Controls

• Age 40-70 years
• No acute or chronic disease
• Non-smoker
• BMI 18.5-24.9 kg/m²
• No musculoskeletal limitations

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Allocation

Non-randomized

Model

Parallel assignment

Masking

Open label

Primary purpose

Diagnostic

Study locations

Turkey (Türkiye) · 1 center

• Esra Pehlivan — Istanbul

Identifiers

NCT: NCT07285642 · fNIRS&Exercise

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗