PHYSICAL FITNESS INDEX AS A MEASURE OF CARDIOVASCULAR ENDURANCE IN SWIMMERS AND NONSWIMMERS

Background and Objective: Recreational swimming is a good way to relax, while enjoying a full-body workout and is recommended for the prevention and treatment of hypertension and cardiovascular disease. The present study compares the physical fitness in young freestyle swimmers practicing regularly and non-swimmers to measure the cardiovascular endurance. Materials and Methods: This Study was carried out at tertiary health centre of Municipal Corporation of Greater Mumbai on medical students after the informed and written consent. Sixty male medical students of age group 18 – 25 years fulfilling the inclusion criteria were included. Their Physical Fitness Index was calculated. The data was analysed using student’s‘t’ test. P less than 0.05 were considered the level of significance. Result: In this study we found that, the Physical Fitness Index (PFI) in swimmers is significantly higher than in non-swimmers and is statistically significant. (p = 0.000). Discussion and Conclusion: Swimming as a recreational aerobic exercise performed can be recommended for use in everyday activities in fitness clubs. In addition, it can serve as a basis for the development of new aerobic programs aimed at the future.


Introduction
Swimming is an effective exercise activity to develop cardiovascular endurance, because it causes body to use the aerobic energy system to fuel the movements. Cardiovascular endurance is the ability of the heart, blood vessels, and lungs to supply oxygen to working muscles.When exercise activities are sub maximal and done over a period of time, the aerobic energy system is effective at providing body with the oxygen it needs. However, swimming at high speeds can require using the anaerobic energy system. According to Health Guidance, cardiovascular endurance is the body's ability to exert itself over a period of time while efficiently providing the tissues with fuel and getting rid of aerobic waste 1 . It requires heart, lungs and blood circulatory system -known collectively as cardio respiratory system -work together effectively to develop cardiovascular endurance with consistent aerobic exercises. Activities that require and develop cardiovascular endurance include aerobic exercise, such as running, biking, rollerblading and swimming 2 . Swimming is an excellent all-around activity that exercises most of the major muscle groups and the cardio respiratory system. Swimming is a sport which is suitable for people of many different ages and fitness levels. Swimming places very little stress on the joints compared to many activities. Swimming is a form of exercise that is good for cardiovascular endurance. It stimulates blood circulation and easily increases the heart rate. As the muscles begin working out they require more and more oxygen which requires a faster heart rate for the additional oxygen to be delivered to the muscles. Swimming is another great choice because, like cross-country skiing, it's a full body exercise. The more body parts involve in IJBAR (2012) 03(01) www.ssjournals.com workout, the more calories will burn 3 . When swimming, as with any cardiovascular activity, including high-intensity intervals increases endurance. Swimming has long been considered one of the most "perfect" sports because of its low injury rate and the amazing benefits of swimming, regardless of one's age or ability. While injuries do occur in the sport, they tend to be associated with the very highest levels of competition or are due to a swimmer not performing the strokes correctly. Swimming is better because of buoyancy, Water Temperature, Water Resistance, Cardiovascular Endurance, Muscular Strength and Endurance, Flexibility and Weight Management 4 . Hence the present study was undertaken to understand and compare the Cardiovascular Endurance in Swimmers and Nonswimmers by measuring the Physical Fitness Index.

Materials and Methods:
The present Study was carried out at tertiary health centre of Municipal Corporation of Greater Mumbai on medical students after the informed and written consent. In the present study, sixty male medical students of age group 18 -25 years fulfilling the inclusion criteria were included and were divided into two groups. One group was the study group, comprising of 30 students who are swimmers, practicing for at least 3 months regularly with one session of 30-60 minutes duration per day and minimum three days in a week were include in the study group. The control group comprised of 30 students who are nonswimmers. Students with history of any valvular heart diseases, who have undergone any major surgery like abdominal, cardiac and pulmonary, students with acute illness such as respiratory tract infection, gastroenteritis and students with history of any neuromuscular disorders and skeletal abnormalities, were excluded from the study. Prior to testing, pre-test instructions were given and test was properly explained and demonstrated. The student steps up and down on the platform at a rate of 20 steps per minute for 5 minutes. After completion of the test, numbers of heart beats are counted between 1 to 1.5 minutes, 2 to 2.5 minutes, and 3 to 3.5 minutes. The Physical Fitness Index score was determined as PFI Score = (100 x test duration in seconds) / (2 x sum of heart beats in the recovery periods).

Statistical analysis:
The data was recorded and analysed for the statistical significance using student's't' test. P less than 0.05 were considered the level of significance.

Result
In the present study, sixty male medical students of age group 18 -25 years fulfilling all the inclusion criteria were divided into two groups comprising study group, with 30 students who are swimmers, practicing for at least 3 months regularly with one session of 30-60 minutes duration per day and minimum three days in a week and a control group comprising of 30 students who are nonswimmers. In this study we found that, the Physical Fitness Index (PFI) in swimmers is significantly higher than in non-swimmers and is statistically significant. (p = 0.000, Table-1, 2 and 3). Physical Fitness Index in two groups is compared in terms of excellent, good, average and poor by using "Chi-square test". There is statistically significant difference between Physical Fitness Index of the two groups (Table-3  and  4, Fig-1).     (Note: There is statistically significant difference between Physical Fitness Index of the two groups).

Fig-1: Category-wise distribution of Swimmers and Non-Swimmers on the Basis
of Physical Fitness Index.

Discussion:
According to the American Medical Association, Physical Fitness is "the general capacity to adapt and respond favourably to physical effort." Individuals are physically fit when they meet the ordinary and unusual demands of daily life safely and effectively without being overly fatigued, and have energy left for leisure and recreational activities 5 . The Components of Physical Fitness 6 related to Health includes Body Composition, Cardiovascular Endurance, Muscular Strength, Muscular Endurance and Flexibility.
In the present study the Physical Fitness Index (PFI) was estimated in both the groups. Students of the swimmers group were found to be of excellent category (PFI > 90). In the non-swimmers group one student was found to have good score (PFI of 80-90), 27 students with average score (PFI of 55-79) and another two students with poor scores (PFI < 55). Out of 60 students the total number of students belonging to excellent score were 30(50%), those belonging to good score were 1(1.67%), those belonging to average score were 27(45%) and those belonging poor score were 2 (3.33%). Excellent Physical fitness index (PFI) of swimmers group indicates their active life style with regular training has helped them to attain excellent condition of physical fitness.
Our study indicates that Physical fitness index of non-swimmers is poor to average (Mean PFI 69.2 ± 7.7) whereas the swimmers have excellent PFI score (Mean PFI 100.8 ± 4.5). The swimmers have a significantly higher PFI score than the non-swimmers. The results of this study have indicated statistically significant (p = 0.000) difference in physical fitness index (PFI) in the case of the swimmers group compared to the non-swimmers. Earlier studies by Keen and Sloan (1958) 7 , Sloan (1969) 8 and Banerjee (1970) 9 have also shown that physically active students have higher PFI scores than sedentary students. The better fitness of the study group of students is due to the regular physical activity in the form of swimming. Astrand (1956) 10 5 . The disadvantages are that the biomechanical characteristics vary between individuals. For example, considering that the step height is standard, taller people are at an advantage as it will take less energy to step up onto the step. Body weight has also been shown to be a factor. Testing large groups with this test will be time consuming.
The limitations of the present study involve the variation in the Biomechanical characteristics between individuals. For example, considering that the step height is standard, taller people are at an advantage as it will take less energy to step up onto the step. Body weight has also been shown to be a factor. Testing large groups with Harvard's step test will be time consuming. Also the present study has sample size of 60. Statistical analysis could be more conclusive with a large sample size.

Conclusion:
Swimming as a recreational aerobic exercise performed can be recommended for use in everyday activities in fitness clubs. In addition, it can serve as a basis for the development of new aerobic programs aimed at the future.