Functional Capacity, Subjective Dyspnea and Fatigue in Smokers

April 14, 2026 updated by: Kubra Kardes, Istinye University

Relationship Between Functional Capacity and Subjective Dyspnea and Fatigue in Young Adult Smokers

Smoking remains a significant public health problem among the young adult population. Epidemiological studies in Turkey show a steadily decreasing age of smoking initiation and a remarkably high rate of smoking among university-aged individuals. Exposure to secondhand smoke is known to have negative effects on the respiratory system, cardiovascular system, and peripheral muscle function.

Impaired lung ventilation, reduced gas exchange, and insufficient oxygen transport due to smoking can lead to decreased exercise tolerance, premature fatigue, and increased perception of exertional dyspnea. These effects can manifest as a decrease in functional capacity even before the development of a clinically significant respiratory disease.

Functional capacity is an important indicator reflecting an individual's ability to perform daily living activities and is frequently assessed in clinical research using submaximal exercise tests. The 6-Minute Walk Test is a widely used, valid, and reliable test for assessing cardiorespiratory endurance and overall functional status. Similarly, the 1-Minute Sit-Stand Test is recommended as a practical and applicable method for evaluating lower extremity muscle endurance and functional performance.

Dyspnea is a multidimensional symptom reflecting an individual's subjective perception of respiratory discomfort and is assessed using scales such as the Modified Medical Research Council and the Borg Dyspnea Scale. The Turkish Thoracic Society's dyspnea assessment reports indicate that exertional dyspnea may increase in smokers even if respiratory function tests are within normal limits.

Fatigue, on the other hand, is a significant symptom that negatively affects an individual's daily living activities and physical functionality, arising from inflammatory processes, impaired oxygenation, and decreased physical activity levels associated with smoking. The Fatigue Severity Scale is a validated and reliable scale for assessing the impact of fatigue on an individual's physical and social life.

While studies in the literature examine the effects of smoking on respiratory function and exercise capacity, studies that address the relationship between functional capacity and subjective dyspnea and fatigue in young adult smokers are limited. In particular, evaluating functional test results such as the 6-Minute Walk Test and the 1-Minute Sit-Stand Test together with dyspnea and fatigue perception will contribute to the early identification of subclinical functional effects.

The aim of this study is to examine the relationships between functional capacity (6-Minute Walk Test, 1-Minute Sit-Stand Test, and Timed Up and Go Test) and subjective dyspnea (Modified Medical Research Council Scale - mMRC) and fatigue level (Fatigue Severity Scale) in young adult smokers aged 18-30 years. The findings of this study are expected to draw attention to the functional effects of smoking in young adults, contribute to the development of preventive health approaches, and facilitate the planning of physiotherapy-based assessment and intervention programs.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Study Type

Observational

Enrollment (Estimated)

107

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Turkey (Türkiye)
      • Istanbul, Turkey (Türkiye), 34010
        • Kubra Kardeş
        • Contact:
        • Sub-Investigator:
          • Yunus Emre Tutuneken, Asst. Prof.
        • Sub-Investigator:
          • Cicek Gunday, Asst. Prof.

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

The study was planned to include volunteer individuals aged 18-30 who are university students and currently smoke.

Description

Inclusion Criteria:

  • Being between 18 and 30 years of age.
  • Being actively enrolled in university.
  • Being a current smoker,
  • Having been a regular smoker for at least the last 6 months,
  • Having a daily cigarette consumption of ≥1 cigarette/day.
  • Volunteering to participate in the study and providing written informed consent.
  • Having the cognitive and physical capacity to understand and complete the tests to be administered.

Exclusion Criteria:

  • Having a diagnosed chronic respiratory disease (asthma, COPD, bronchiectasis, interstitial lung disease, etc.),
  • Having had an upper or lower respiratory tract infection within the last 4 weeks. Having a diagnosed heart disease (coronary artery disease, heart failure, arrhythmia, etc.),
  • Having a history of uncontrolled hypertension.
  • Having orthopedic problems affecting walking, sitting/standing, or balance,
  • Having a history of lower extremity surgery or serious injury within the last 6 months.
  • Having a history of neurological disease affecting balance, coordination, or motor control (stroke, multiple sclerosis, epilepsy, etc.).
  • Having a systemic disease that may prevent participation in exercise (uncontrolled diabetes, severe anemia, etc.),
  • Being pregnant or within the first 6 months postpartum.
  • Having conditions that may endanger the participant's safety during functional tests, o Refusal to complete the tests or inability to cooperate during the evaluation.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Group 1
Assessment group
Other: Assessment
In accordance with standard testing protocols, all participants will undergo the following assessments in order: Physical Activity Assessment (International Physical Activity Questionnaire), Functional Capacity Assessment (6-Minute Walk Test, 1-Minute Sit-to-Stand Test, and Timed Up and Go Test), Subjective Dyspnea Assessment (Modified Medical Research Council Dyspnea Scale), and Fatigue Severity Assessment (Fatigue Severity Scale).

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
6-Minute Walk Test
Time Frame: 4 weeks
Participants will be asked to walk the longest possible distance in a straight corridor for 6 minutes. At the end of the test, the total walking distance will be recorded in meters. The test will be administered according to the standard protocol recommended by the American Thoracic Society.
4 weeks
1-Minute Sit-Stand Test
Time Frame: 4 weeks
Participants will be recorded on the number of times they stand up completely from a chair and sit down again within 60 seconds without using their arms. This test is a valid and reliable method for evaluating lower extremity muscle endurance and functional performance.
4 weeks
Timed Up and Go Test
Time Frame: 4 weeks
Participants will be asked to stand up from a chair, walk 3 meters, turn around, return to the starting point, and sit back down in the chair; the test duration will be recorded in seconds. The Timed Up and Go test is a widely used, valid, and reliable test for evaluating functional mobility, balance, and gait performance.
4 weeks
Subjective Dyspnea Assessment
Time Frame: 4 weeks
Participants' perception of dyspnea will be assessed using the Modified Medical Research Council Dyspnea Scale. The Modified Medical Research Council scale ranges from 0 to 4, with higher scores indicating greater perceived dyspnea severity. This scale is widely used to evaluate the level of dyspnea experienced during activities of daily living.
4 weeks
Fatigue Assessment
Time Frame: 4 weeks
Fatigue level will be assessed using the Fatigue Severity Scale. The Fatigue Severity Scale consists of 9 items, each scored on a scale from 1 to 7, and the final score is calculated as the mean of all items (range: 1-7). Higher scores indicate greater fatigue severity, and a mean score of ≥4 is considered clinically significant fatigue. The Turkish version of the FSS has been shown to be valid and reliable.
4 weeks

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Physical Activity Level
Time Frame: 4 weeks
Participants' physical activity level will be assessed using the International Physical Activity Questionnaire - Short Form. Data will be expressed as MET-minutes/week, where higher values indicate higher levels of physical activity. Based on International Physical Activity Questionnaire - Short Form scoring guidelines, participants will be classified into low, moderate, and high physical activity levels.
4 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Istinye University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

April 15, 2026

Primary Completion (Estimated)

July 15, 2026

Study Completion (Estimated)

July 30, 2026

Study Registration Dates

First Submitted

April 3, 2026

First Submitted That Met QC Criteria

April 3, 2026

First Posted (Actual)

April 9, 2026

Study Record Updates

Last Update Posted (Actual)

April 17, 2026

Last Update Submitted That Met QC Criteria

April 14, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2026/4

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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