The respiratory system plays a vital role in sustaining life by facilitating gas exchange and maintaining acid-base balance. Lung volumes and respiratory muscle strength are key components in evaluating pulmonary health, and both are influenced by levels of physical activity (1). A sedentary lifestyle, characterized by prolonged physical inactivity and low energy expenditure, has become increasingly prevalent worldwide due to modern occupational patterns, urbanization, and technological advancements (2). This lifestyle is associated with adverse physiological consequences, including compromised respiratory function, reduced ventilatory efficiency, and weakened respiratory musculature (3).

In contrast, regular physical training, particularly in endurance athletes, enhances pulmonary performance through increased lung capacity, improved airway conductance, and strengthened respiratory muscles (4). Several studies have reported that athletes, especially those involved in aerobic sports, tend to have significantly higher Forced Vital Capacity (FVC), Forced Expiratory Volume in one second (FEV₁), and Peak Expiratory Flow Rate (PEFR) compared to their sedentary counterparts (5). Furthermore, respiratory muscle strength, measured through Maximum Inspiratory Pressure (MIP) and Maximum Expiratory Pressure (MEP), is typically more developed in physically active individuals due to adaptive mechanisms induced by regular exertion (6).

Despite the established benefits of exercise on pulmonary function, limited studies have directly compared respiratory parameters between sedentary individuals and trained athletes in the same demographic group. This gap in literature necessitates further investigation to emphasize the respiratory consequences of physical inactivity and to reinforce the value of exercise as a preventive strategy.

Hence, the present study aims to compare lung volumes and respiratory muscle strength between individuals leading a sedentary lifestyle and those actively engaged in athletic training.

A total of 60 healthy male participants aged between 20 and 30 years were recruited. They were divided into two groups: 30 sedentary individuals and 30 trained athletes. The sedentary group included individuals with no history of regular physical activity or structured exercise for at least six months. The athlete group consisted of individuals involved in endurance sports (e.g., running, swimming, cycling) with a minimum training duration of five sessions per week for the past year.

Inclusion and Exclusion Criteria

Participants were included if they were non-smokers, had no history of respiratory or cardiovascular disease, and provided informed consent. Individuals with acute illness, chronic pulmonary disorders, recent respiratory infections (within 2 weeks), or those on medications affecting lung function were excluded.

Pulmonary Function Testing

Lung volumes were measured using a calibrated digital spirometer (SpiroTech ST-95), adhering to the American Thoracic Society (ATS) guidelines. Parameters recorded included Forced Vital Capacity (FVC), Forced Expiratory Volume in 1 second (FEV₁), and Peak Expiratory Flow Rate (PEFR). Each participant performed three acceptable maneuvers, and the best of the three readings was used for analysis.

Respiratory Muscle Strength Assessment

Maximum Inspiratory Pressure (MIP) and Maximum Expiratory Pressure (MEP) were recorded using a portable respiratory pressure meter (MicroRPM). Participants were instructed to inhale and exhale against a closed shutter following a full expiration or inspiration, respectively. The highest value from three consistent trials was recorded for both MIP and MEP.

Statistical Analysis

Data were analyzed using SPSS version 25.0 (IBM Corp., Armonk, NY). Results were expressed as mean ± standard deviation (SD). An independent t-test was used to compare the pulmonary function and respiratory muscle strength between the two groups. A p-value < 0.05 was considered statistically significant.

A total of 60 male participants were included in the study, equally divided into two groups: sedentary individuals (n = 30) and trained athletes (n = 30). The mean age in the sedentary group was 24.1 ± 2.8 years, while in the athlete group it was 23.7 ± 2.5 years. Both groups were comparable in age and BMI (p > 0.05).

Pulmonary Function Test Results

The comparison of lung volumes between the two groups showed significantly higher values in athletes across all spirometric parameters. The mean Forced Vital Capacity (FVC) in athletes was 5.12 ± 0.61 L, whereas in sedentary individuals it was 3.87 ± 0.48 L (p < 0.001). Similarly, athletes demonstrated a higher Forced Expiratory Volume in 1 second (FEV₁) (4.34 ± 0.42 L) compared to the sedentary group (3.21 ± 0.37 L, p < 0.001). Peak Expiratory Flow Rate (PEFR) was also significantly greater in athletes (615.2 ± 43.5 L/min) than in the sedentary group (471.6 ± 39.2 L/min, p < 0.001). These findings are summarized in Table 1.

Table 1: Comparison of Pulmonary Function Parameters Between Groups

Respiratory Muscle Strength

Athletes also showed superior respiratory muscle performance. The Maximum Inspiratory Pressure (MIP) in the athlete group was 132.4 ± 14.8 cmH₂O, significantly higher than in the sedentary group (94.5 ± 12.1 cmH₂O, p < 0.001). Maximum Expiratory Pressure (MEP) followed a similar trend, with athletes recording 181.7 ± 21.3 cmH₂O compared to 137.2 ± 17.9 cmH₂O in the sedentary group. These data are presented in Table 2.

Table 2: Respiratory Muscle Strength in Sedentary vs Athlete Groups

The findings of this study revealed that trained athletes exhibit significantly higher lung volumes and greater respiratory muscle strength compared to individuals with a sedentary lifestyle. These differences were evident in all measured parameters including FVC, FEV₁, PEFR, MIP, and MEP. These observations are in line with earlier studies indicating that regular physical training leads to notable improvements in pulmonary function and ventilatory muscle performance (1,2).

The elevated FVC and FEV₁ in athletes could be attributed to the increased elastic recoil of the lungs and enhanced thoracic mobility induced by long-term aerobic exercise (3). These physiological adaptations result from repeated exposure to high ventilation demands during endurance training, leading to improved lung compliance and respiratory muscle coordination (4). A study by Mehrotra et al. demonstrated that competitive swimmers had significantly larger FVC values than non-athletes, supporting the current findings (5). Likewise, rowing and running, which demand sustained respiratory effort, have been associated with superior lung function indices (6,7).

Respiratory muscle strength, as measured by MIP and MEP, was also found to be significantly higher among athletes. These muscles respond to physical conditioning in much the same way as skeletal muscles in other regions, undergoing hypertrophy and increased endurance with repeated loading (8). Harms et al. reported that trained individuals could generate greater inspiratory and expiratory pressures, which was correlated with their training status and ventilatory workload (9).

Conversely, sedentary individuals demonstrated reduced pulmonary capacity and muscle strength, which may be due to physical deconditioning and reduced stimulation of the respiratory musculature (10). The low mechanical stress on the lungs and chest wall in sedentary individuals can lead to atrophy of respiratory muscles and decreased compliance of the thoracic cavity (11). Such individuals are also more likely to experience shallow breathing and reduced lung expansion, which over time contributes to restrictive lung patterns (12).

It is also important to consider the role of systemic benefits from exercise, such as improved cardiovascular fitness, enhanced oxygen transport, and better mitochondrial efficiency, which collectively influence pulmonary efficiency (13). Furthermore, regular physical activity is associated with reduced inflammation and oxidative stress, factors that are known to affect lung tissue integrity and function (14).

While our findings strongly support the benefits of physical training on respiratory health, this study is limited by its cross-sectional nature and male-only sample. Longitudinal studies across varied populations and age groups would provide a more comprehensive understanding of the long-term impact of lifestyle choices on pulmonary function (15).

This study demonstrates that trained athletes have significantly higher lung volumes and respiratory muscle strength compared to sedentary individuals. Regular physical activity leads to favorable adaptations in pulmonary function, emphasizing the importance of an active lifestyle in maintaining optimal respiratory health and preventing functional decline associated with physical inactivity.

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