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ORIGINAL ARTICLE
Year : 2020  |  Volume : 11  |  Issue : 1  |  Page : 16-19

Cardiorespiratory fitness of medical students in a health institute in Eastern India


Department of Physiology, Veer Surendra Sai Institute of Medical Sciences and Researches, Burla, Odisha, India

Date of Submission24-Aug-2020
Date of Acceptance21-Oct-2020
Date of Web Publication23-Dec-2020

Correspondence Address:
Dr. Sunil Kumar Jena
Department of Physiology, Veer Surendra Sai Institute of Medical Sciences and Researches, Burla - 768 017, Odisha
India
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/mjmsr.mjmsr_38_20

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  Abstract 


Background: VO2 max is the single most reliable indicator of cardiorespiratory fitness (CRF). More is the VO2 max more is the CRF and aerobic capacity of an individual. The status of CRF ultimately indicates the physical fitness. This study was conceptualized to estimate the CRF of medical students. Materials and Methods: This study included 161 apparently healthy participants, which included 101 male and 60 female MBBS students. The study was started after approval of the ethics committee. Each participant was clearly understood the study protocol and its output. Each participant signed the written consent form. Body weight was estimated without shoes and light clothing. The resting heart rate (RHR) was calculated by palpating radial pulse. VO2 max was determined by a predefined predicted equation using three factors, i.e., age, body weight, and RHR. VO2 max = 3.542+ (−0.014 × age in year) + (0.015 × body weight [kg]) + (−0.011 × RHR). Statistical analysis was done by unpaired test. Results: Mean VO2 max of male and female was 56.4 ± 4 and 51.9 ± 6 ml/kg/min, respectively. This difference was significant at P = 0.000. 26.7%, 28.7%, and 26.7% of males were good, excellent, and superior, respectively, in VO2 max. 13.3%, 8.3%, and 70% of females were good, excellent, and superior, respectively, in VO2 max. 21.7%, 21.1%, and 42.8% of total participants were good, excellent, and superior, respectively, in VO2 max. Conclusion: CRF of male was better than female. The majority of students' CRF was up to mark and minimal students need care to improve their CRF.

Keywords: Aerobic capacity, cardiorespiratory fitness, physical inactivity, sedentary lifestyle, VO2 max


How to cite this article:
Jena SK. Cardiorespiratory fitness of medical students in a health institute in Eastern India. Muller J Med Sci Res 2020;11:16-9

How to cite this URL:
Jena SK. Cardiorespiratory fitness of medical students in a health institute in Eastern India. Muller J Med Sci Res [serial online] 2020 [cited 2021 Mar 5];11:16-9. Available from: https://www.mjmsr.net/text.asp?2020/11/1/16/304594




  Introduction Top


Cardiorespiratory fitness (CRF) also known as aerobic capacity is one of the most important indicators of physical fitness. It is the ability of the body to perform dynamic large-muscle exercise for prolonged period at moderate-to-high intensity.[1] Maximum oxygen consumption (VO2 max) is considered the most widely accepted measure of CRF. VO2 max gives a baseline estimate of one's heart and lung functioning and can be used to follow-up the progress of daily physical exercise.[2] The World Health Organization also has suggested that VO2 max is the single best indicator of CRF in graded maximal exercise.[3] Studies have shown that high levels of CRF in young adults are associated with a lower risk of having calcification in the coronary arteries and prevents the development of early atherosclerotic vascular disease.[4] Physical inactivity and sedentary lifestyle lead to the accumulation of excess adipose tissues and a state of chronic inflammation, which is a major factor in the development of noncommunicable diseases (NCDs). Regular physical exercise increases CRF level and suppresses the chronic inflammatory state of obesity that ultimately decreases the risk for NCD.[5] Measurement of VO2 max is, therefore, considered an important part in the evaluation of the cardiorespiratory health and aerobic fitness. VO2 max is expressed in L/min as the absolute value or in ml/kg/min as the relative VO2 max. VO2 max can be estimated using different tests, by direct or indirect methods. There are some predicted equations used for VO2 max estimation. These equations are used for VO2 max estimation rather than direct measurement, as it is cost-effective and relatively easier.[6]

Hence, this study emphasized on cardiovascular fitness in terms of maximum aerobic capacity (VO2 max) among the young adult male and female medical students in a health institute in eastern India. There is a need for the students to measure and analyze their fitness for their own benefit and improvement. For better productivity, the students should be healthy and have good physical fitness. Medical students of today are the physicians of tomorrow, and a good physician must be physically fit and mentally alert. The aim of this study was to estimate CRF of healthy medical students.


  Materials and Methods Top


This cross-sectional study was conducted in human physiology laboratory in a health institution in the eastern part of India. The study was approved by the institutional ethical committee of the same institute where the study was conducted. This study was completed between October 2019 and March 2020. MBBS students of this medical institution were taken as the participants for this study. A total of 161 participants were selected for this study which included 101 male and 60 female students. Participants were between the age group of 20 and 25 years. Students were properly explained about the protocol and output of the study. All participants gave their consent to participate in the study and signed the consent form in the presence of principal investigator.

Participant selection was done by face-to-face interview and routine health checkup. A total of 173 students were screened for participant selection, and finally, 161 participants were recruited. Apparently healthy MBBS students between 20 and 25 years without daily routine exercise were included in the study. Students suffering from any chronic disease, psychologically not sound, practicing routine exercise were excluded from the study. Weight measurement was recorded by standard analog weighing machine (VIRGO Model no 9811 B). Body weight was measured without shoes in light clothing to the nearest 0.5 kg. Participants were instructed to stand motionless on analog weighing machine in such a way that body weight should be distributed equally on each leg. Weighing machine was standardized every day before measurement with known weight of 10 kg. Then, the exact weight of the participant was noted down. Recording RHR was done between 8 and 9 am after 5–10 min rest. After arrival in the laboratory, participants were instructed to sit in a chair for 5–10 min in relaxed body and mind. Then, the radial pulse was palpated for 1 min. Three similar readings were taken at an interval of 1 min, and the average of three was considered the RHR of the participant. VO2 max was determined by a predefined predicted equation using three factors, i.e., age, body weight, and RHR. The equation was: VO2 max = 3.542 + (−0.014 × age in year) + (0.015 × body weight [kg]) + (−0.011 × RHR).[7] The unit of VO2 max was ml/kg/min. This equation was used because it was easy to implement, cost-effective, and timesaving. The normative value of VO2 max was taken as reference value correspondence to age 20–29 years both in male and female as shown in [Table 1].[8] This reference value was used for the frequency distribution of participants in different categories CRF.
Table 1: Normative value of VO2 max

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Statistical analysis was done by statistical software SPSS 16 software version (IBM Corporation, Armonk, New York, USA). The statistical test used was unpaired t-test. P < 0.05 was considered to be statistically significant.


  Results Top


This study was completed with 161 participants that included 101 male and 60 female participants.

[Table 2] depicts the comparison of different variables among male and female participants. The mean age of male and female was 20.8 ± 0.79 and 21 ± 1 years, respectively. This difference was not at a significant level. The mean body weight of male and female was 66.7 ± 12 and 58.4 ± 6 kg, respectively. This difference was significant at P = 0.000. The mean resting heart rate (RHR) of male and female was 78 ± 10 and 77 ± 5 per min, respectively. This difference was not at a significant level. Mean VO2 max of male and female was 56.4 ± 4 and 51.9 ± 6 ml/kg/min, respectively, shown in [Figure 1]. This difference was significant at P = 0.000.
Table 2: Comparison of variables between male and female

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Figure 1: The mean VO2 max of male and female

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[Table 3] and [Figure 2] depict the distribution of participants into their fitness level according to groups classified on the basis of normative value of VO2 max. Among males, 26.7% was superior, 28.7% was excellent, 26.7% was good, 13.8% was fair, and 4.9% was poor. Similarly, among female participants, 70% was superior, 8.3% was excellent, 13.3% was good, 5% was fair, and 3.3% was poor. Among all participants, 42.8% was superior, 21.1% was excellent, 21.7% was good, 10.5% was fair, and 4.3% was poor.
Table 3: Frequency distribution of participants

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Figure 2: Frequency distribution of participants according to cardiorespiratory fitness

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  Discussion Top


CRF can be assessed by the volume of oxygen consumption while doing exercise at maximum capacity. Fit people have higher VO2 max values and can do exercise more intensely than the unfit people. VO2 max is an internationally accepted parameter for the assessment of CRF indicates oxygen utilization by skeletal muscle during maximal exercise. It provides an idea about the cardiovascular, respiratory, and skeletal system to deliver and utilization of oxygen. When exercise is done, up to certain time increase in oxygen consumption is proportional to energy expenditure, and all the energy need is met by aerobic process. Hence, more is the VO2 max, more will be the aerobic capacity of a person.[9]

The present study suggested that the mean VO2 max in male (56.4 ± 4 ml/kg/min) was more than female (51.9 ± 6 ml/kg/min), and this variation was significant at P = 0.000. This suggested that female is at the lower side of fitness level in comparison to male. The result of this study was similar to the study done by Sydney et al., and their study was done among young adults.[10] Another study done by Stevens et al. also suggested similar result to this study, and they suggested that females are less fit than males.[11] The possible causes of low VO2 max in female could be more body fat and less lean body mass as well as sedentary lifestyle. Furthermore, more hemoglobin level in male carrying more oxygen could be the cause of more VO2 max in male.[12] Another study by Nabi et al. worked on VO2 max in medical students and found similar result as suggested in this study. They suggested low VO2 max in female may be due to reduced physical activity and unhealthy behavior of female.[13]

Among male participants, 82.1% were in the category of superior, excellent, and good. In the same way, among female participants 91.6% were in the category of superior, excellent, and good. Out of total participants, about 85% of participants were in superior, excellent, and good category. Our study suggested that majority of participants' CRF was up to mark, but about 15% of participants' CRF level was not up to mark. Although it seems less, around 15% of participants were in fair and poor category of CRF. Hence, these proportions of participants' CRF were not up to mark and to be improved. The possible reason for the low CRF of participants could be the low physical activity and unhealthy lifestyle behavior.[13] Physical inactivity and unhealthy lifestyle are one of the important factors of increasing body weight and adiposity. Researchers in their study have suggested that adiposity is negatively related to CRF.[14] In this study, adiposity could not be excluded to be the possible cause of low CRF in some participants. After careful review of several studies, we found that the researchers have suggested that low CRF is linked to increase the chance of cardiovascular disease or other causes of death independent of cardiovascular risk factors by 2–5 times.[14],[15],[16],[17],[18] Studies also have suggested that a minimal improvement of CRF just like improvement of one metabolic equivalents can reduce the mortality about 10%–15%.[19],[20],[21]


  Conclusion Top


This study suggested that CRF of male medical students was better than female. The majority of students VO2 max was up to mark; hence, their fitness level was satisfactory. Minimal students' CRF was not satisfactory, and they have to improve their CRF level by regular exercise practice.

Limitations of study

Cardiopulmonary exercise testing is the better predictor of VO2 max which was not done in this study, and it could be lacunae. This study could have been stronger by considering adiposity as one of the variables. Further, RHR could have been calculated by a more acceptable technique electrocardiogram.

Acknowledgment

This study could not be completed without the unconditional cooperation of participants. Thanks to laboratory staffs of the department of physiology for their support.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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American College of Sports Medicine. ACSM's Guidelines for Exercise Testing and Prescription. 6th ed. Philadelphia, PA: Lippincott Williams and Wilkins; 2006.  Back to cited text no. 1
    
2.
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Shephard RJ, Allen C, Benade AJ, Davies CT, Di Prampero PE, Hedman R, et al. The maximum oxygen intake. An international reference standard of cardio respiratory fitness. Bull World Health Organ 1968;38:757-64.  Back to cited text no. 3
    
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8.
Heywood V. The physical fitness specialist manual, the cooper institute for aerobics research, Dallas TX, revised 2005. In: Heywood V, editor. Advanced Fitness Assessment and Exercise Prescription. 5th ed. Champaign, IL: Human Kinetics; 2006.  Back to cited text no. 8
    
9.
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Sidney S, Haskell WL, Crow R, Sternfeld B, Oberman A, Armstrong MA, et al. Symptom-limited graded treadmill exercise testing in young adults in the CARDIA study. Med Sci Sports Exerc 1992;24:177-83.  Back to cited text no. 10
    
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Stevens J, Cai J, Evenson KR, Thomas R. Fitness and fatness as predictors of mortality from all causes and from cardiovascular disease in men and women in the lipid research clinics study. Am J Epidemiol 2002;156:832-41.  Back to cited text no. 11
    
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Hingorjo MR, Zehra S, Hasan Z, Qureshi MA. Cardiorespiratory fitness and its association with adiposity indices in young adults. Pak J Med Sci 2017;33:659-64.  Back to cited text no. 12
    
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Nabi T, Rafiq N, Qayoom O. Assessment of cardiovascular fitness [VO2 max] among medical students by Queens College step test. Int J Biomed Adv Res 2015;6:418-21.  Back to cited text no. 13
    
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Swift DL, Lavie CJ, Johannsen NM, Arena R, Earnest EP, O'Keefe JH, et al. Physical activity, cardiorespiratory fitness, and exercise training in primary and secondary coronary prevention. Circ J 2013;77:281-92.  Back to cited text no. 15
    
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Kodama S, Saito K, Tanaka S, Maki M, Yachi Y, Mihoko A, et al. Cardiorespiratory fitness as a quantitative predictor of all-cause mortality and cardiovascular events in healthy men and women: A meta-analysis. JAMA 2009;301:2024-35.  Back to cited text no. 17
    
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Balady GJ, Larson MG, Vasan RS, Leip EP, O'Donnell CJ, Levy D. Usefulness of exercise testing in the prediction of coronary disease risk among asymptomatic persons as a function of the Framingham risk score. Circulation 2004;110:1920-25.  Back to cited text no. 18
    
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Myers J, McAuley P, Lavie C, Despres JP, Arena R, Kokkinos P. Physical activity and cardiorespiratory fitness as major markers of cardiovascular risk: Their independent and interwoven importance to health status. Prog Cardiovasc Dis 2015;57:306-15.  Back to cited text no. 19
    
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21.
Mora S, Redberg RF, Cui Y, Whiteman MK, Flaws JA, Sharrett AR, et al. Ability of exercise testing to predict cardiovascular and all-cause death in asymptomatic women: A 20-year follow-up of the lipid research clinics prevalence study. JAMA 2003;290:1600-7.  Back to cited text no. 21
    


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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