This was a quasi-experimental study. The study participants were recruited through a convenient sampling method. The study was conducted in the Research Laboratory of the Physiology Department at Eastpoint College of Medical Sciences and Research Centre (EPCMSRC), Bengaluru, Karnataka, India, between December 2023 and April 2024, after obtaining ethical clearance from the Institutional Ethical Committee of EPCMSRC (No. EPCMSRC/ADM/IEC/2022-23/20, dated 12.08.2022). First-year medical {Bacheolar of Medicine and Bacheolar of Surgery (MBBS)} students were approached with the study protocol seeking volunteers. Written informed consent was obtained from each participant.

Inclusion criteria: Students who were apparently healthy and had normal or decreased Hb concentration were considered. Both male and female students aged 18-23 years who were willing to participate in the study were included.

Exclusion criteria: Students who smoked, were on medication for any condition, had respiratory allergies or infections, or any other diseases were excluded from the study. Students involved in any physical conditioning programmes, such as regular dance practice, aerobics, or any sport, were also not considered.

Sample size calculation: Sample size was estimated [4] using the formula:

where, Z is the conventional multiplier for alpha=0.05=1.96

P=Proportion/Prevalence=0.41

d=is the allowable error=8.3%

n=Z² pq/d²

A total of 150 students volunteered to participate in the study. After exclusions, a total of 136 students were recruited.

When the participants arrived at the laboratory, a blood sample was collected by pinprick, and Hb estimation was conducted using Sahli’s acid hematin method. Based on the level of Hb concentration, participants were classified into a normal group (Hb% above 12 g/dL for females and above 14 g/dL for males) [12]. The anaemic group was further classified as mild anaemia (Hb% between 10 and 11.9 g/dL), moderate anaemia (Hb% between 8 and 9.9 g/dL), and severe anaemia (Hb% below 8 g/dL) [12].

After a relaxation period of 10 minutes, a resting PFT was recorded for each participant. The PFT parameters recorded included FVC, timed vital capacity, FEV1, the ratio of FEV1/FVC, and PEFR, all measured using a Windows-based digital spirometer (Spirowin).

Following this, exercise testing was performed using a bicycle ergometer (INCO) with an electronic gear shift and intensity ranging from 25 to 800 watts. Participants were instructed regarding the exercise protocol, which comprised a warm-up period of pedalling without resistance for five minutes, followed by pedalling with a progressive increase in resistance every two minutes up to 800 watts for the next 15 minutes. Participants were advised to stop and discontinue the exercise if they felt breathless or uncomfortable. Immediately after the exercise, the PFT was recorded again for comparison.

The data were entered into an Excel spreadsheet, and statistical analysis was performed using the Statistical Package for the Social Sciences (SPSS) version 20.0 for Windows. Descriptive analysis was conducted using the mean and standard deviation for quantitative variables, and frequency and proportion for categorical variables. The Chi-square test was performed to determine whether there was any association within the categorical data. An independent sample t-test was used to find any significant differences in the means between the groups when the data followed a normal distribution. A paired t-test was employed to compare pre- and post-exercise values within the groups. A p-value of <0.05 was considered statistically significant.

The present study is a quasi-experimental study that was conducted on 136 participants aged between 18 and 23 years. Of these participants, 57 (41.9%) were male and 79 (58.1%) were female. The characteristics of the participants has been depicted in [Table/Fig-1].

In a total of 136 participants, the prevalence of anaemia was 22.1%, meaning that 30 participants had anaemia, while 106 (77.8%) participants had a normal level of Hb. Out of these 30 participants with anaemia, 24 (17.64%) had mild anaemia (Hb ranging from 10 to 12 g/dL), whereas six participants had moderate to severe anaemia (Hb level <10 g/dL). Anaemia was also found to be more common in 24 females than in six males, which was statistically significant, p<0.006 [Table/Fig-2].

The height (p=0.114), weight (p=0.399), and Body Mass Index (BMI) (p=0.987) of all participants, including both the normal and anaemia groups, were measured and calculated. There was no statistically significant difference in these parameters among the participants (p-value >0.05) [Table/Fig-1].

All participants completed the exercise testing without incident. The dynamic ventilatory tests were performed, and FVC, FEV1, FEV1/FVC, and PEFR were recorded in both groups. The exercise responses of all participants, along with various percentage predictions of FVC, FEV1, FEV1/FVC, and PEFR, are depicted in [Table/Fig-3].

The PFTs were recorded before and after exercise and compared between the normal and anaemic groups. Intergroup comparisons of PFT parameters, including FVC, FEV1, FEV1/FVC, and PEFR, showed that the values were significantly lower (p<0.05) in the anaemia group before exercise compared to the normal group [Table/Fig-3].

Intragroup comparisons of pre- and post-exercise PFT, including FVC, FEV1, FEV1/FVC, and PEFR in both the normal and anaemia groups, revealed a slight improvement following exercise. However, these changes were not statistically significant (p>0.05) in either group [Table/Fig-4].

The present study aimed to investigate the effect of exercise on pulmonary function in individuals with anaemia among first-year medical students. A total of 136 students were recruited for the study, and all participants underwent bicycle exercise testing to quantify the pulmonary effects of anaemia. The prevalence of anaemia in this study was 22.1%, which is lower than that reported in previous studies [2-4]. Among the student participants with low Hb levels, 18% had mild anaemia, 2.1% had moderate anaemia, and 2.9% had severe anaemia. A higher proportion of females (80%) were affected by low Hb levels compared to males (20%) within the group. This finding contrasts with a study by Kanchana R and Pushpa K in which anaemia was found to be more prevalent in males than in females [4].

The PFT parameters, including FVC, FEV1, FEV1/FVC, and PEFR, were lower in the anaemic group compared to the normal group before exercise. The PFT parameters, including FVC, FEV1, FEV1/FVC, and PEFR, were lower in the anaemic group compared to the normal group, which was statistically significant (p<0.05). This demonstrates a strong association between anaemia and functional deficits, which is in accordance with a study conducted by Scholz BD et al., [13]. Edgerton VR et al., also reported improved work performance in participants with normal Hb levels compared to those with lower Hb levels [14]. Low Hb impairs tissue oxygenation, which causes dyspnoea on mild exertion and easy fatigability. The reduced strength of the respiratory muscles, including the diaphragm, decreases pulmonary function as well as work capacity in individuals with anaemia. All PFT parameters were found to be decreased in participants with anaemia in a study conducted by Kumari AK et al., which is similar to the findings of present study [15].

Studies have shown a significant correlation between BMI and lung function, with lower FEV1/FVC%, which is attributed to mechanical restrictions in chest movement among overweight individuals. In the current study, the FEV1/FVC% was lower in the anaemic group compared to the normal group; however, no significant difference in BMI was observed among the participants [16].

The present study found no significant changes in respiratory parameters following exercise in both the anaemia and normal groups, as evidenced by intragroup comparisons. Similarly, Jeong Y et al., observed no clear relationship between pulmonary function and anaemia or Hb levels in healthy non smokers [17]. However, a study conducted by Thaker H et al., reported a decrease in these parameters post-exercise in obese individuals compared to those with a normal BMI, which contrasts with the findings of this study [18]. The reason for this may be the increased body fat percentage, which causes mechanical restrictions on the movement of the abdomen and thorax, as well as increased airway resistance in overweight and obese individuals [18].

Although the PEFR showed improvement after exercise in the anaemic group, its mean value remained significantly lower compared to that of the normal participants. This may be due to the fact that PEFR is more sensitive to the muscular elements of respiration, which could explain the lower values observed in anaemia, both before and after exercise [15]. When the oxygen-carrying capacity of the blood declines, it leads to the accumulation of lactate and other metabolites, as well as tissue hypoxia, which can result in muscle fatigue, including in the diaphragm [14].

The study by Singh HD and Peri S reported that PEFR is higher in males than in females. They also observed elevated values of PEFR in athletes, police, and army personnel, highlighting the significance of nutrition and physical fitness in maintaining respiratory strength [19]. Furthermore, regular engagement in integrated exercises that target respiratory muscles has been shown to improve lung function [20]. However, the current study did not assess the difference in PEFR between genders; nonetheless, there was an improvement in the post-exercise values among the anaemic group, which was statistically significant (p=0.001).

The Hb estimation by Sahli’s method is a visual technique that relies on manual interpretation, which makes it prone to errors. A larger sample size might improve the applicability and relevance of the findings. Additionally, factors such as environmental influences and nutritional status should be taken into consideration in future studies.

The prevalence of anaemia among first-year medical students was 22.1%, with a higher proportion of females affected compared to males. In the present study, no significant change in pulmonary function was observed after exercise in either the normal or anaemic group. Maintaining normal levels of Hb is crucial for optimal health; therefore, the correction of anaemia is essential. Regular exercise is beneficial for enhancing pulmonary function and overall fitness.

Declaration: The abstract of present study was presented at 70^th Annual National conference of Physiologists and Pharmacologists (APPICON) held in Chennai from 11^th to 13^th December 2024.