Effect of exercise intensity on body composition in overweight and obese individuals: A prospective study

 

Kiran Kumar Patnaik¹, S Bethiun^2*, Y V A Ramalakshmi³

 

 

Abstract               Background: Obesity is a major health problem due, in part, to physical inactivity. The amount of activity needed to prevent weight gain is unknown. Exercise is an important component of weight loss program. Recently, high intensity exercise done for less duration is emerging and gaining importance. Our aim was to investigate the intensity of exercise required to produce a significant change in anthropometric and body composition measurements. Materials and Methods: Volunteers, sedentary overweight and obese in the age group of 19-35 years, were randomized into group I (n=30) those performing moderate intensity exercise at 50-74% of heart rate maximum reserve for 40 min and group II (n=30) high intensity exercise at 75%-84% of heart rate maximum reserve for 20 min on a bicycle ergometer for a duration of 15 weeks. Skin fold calliper was used for anthropometry. Results: There was a significant change in the weight, waist hip ratio, skin fold thickness, circumference measures, fat mass, fat percentage, and lean body mass among moderate (p<0.05) and high intensity group (p<0.05). A significant change in fat mass (p<0.05) lean body mass (p<0.05) and fat % (p<0.05) in the high intensity group compared to moderate intensity group was observed. Conclusion: It is concluded that 15 weeks of exercise at high intensity is more effective in changing the body composition in overweight and obese individuals.

Key Words: Waist hip ratio, lean body mass, moderate, high intensity exercise

 

 

 

INTRODUCTION

Obesity is one of the greatest public health challenges of the 21st century. Overweight and obesity drastically increase a person’s risk of developing chronic non-communicable diseases (NCDs), including cardiovascular disease, cancer and diabetes.¹ World Health Organisation (WHO) projected that by the year 2025, 75% of the global obese population would be in low income countries including india.² Furthermore, obesity is already responsible for 2% - 8% of health costs and 10% - 13% of deaths in several industrialized countries.¹ According to the World Health Organization, at least 2.8 million adults die each year as a result of being over- weight or obese. In addition, 44% of the diabetes burden, 23% of the ischemic heart disease burden and between 7% and 41% of certain cancers are attributable to overweight and obesity. The prevalence of overweight and obesity has increased to epidemic proportions in the industrialized world and is now dramatically on the rise in low and middle-income countries, particularly in urban settings.³The reason for the increasing trend of obesity in adults is a sedentary life style. It is important to prevent obesity, and exercise is established as an important component of behavioral weight loss program.⁴ The National program for prevention and control of diabetes and cardiovascular disease suggests moderate to vigorous activity for 5-7 days/week.⁵ The availability of a valid index of body composition is important for health professionals so that persons at risk for developing obesity-related diseases can be successfully screened.⁶ Percentage body fat is strongly associated with risk of chronic diseases such as hypertension, dyslipidemia, diabetes mellitus and coronary heart disease.⁷ BMI, WC, waist-hip ratio and skin fold thickness have been used extensively to measure body fatness in epidemiological and clinical studies. BMI has been used to determine overweight and obesity because it is simple, inexpensive and non-invasive. It is a surrogate measure of body fatness since it measures excess weight rather than excess body fat.⁸ Recognizing exercise protocols that are effective in reducing body fat and individuals are important. Also an effective exercise training depends on exercise intensity and the duration. Different types of exercise are studied for the purpose of weight loss. Traditional steady state low and moderate intensity exercises done over a period of 45-60 min almost every day in a week have resulted in noteworthy change in body weight thereby reducing cardiovascular and metabolic disease risk. Recently, high intensity intermittent exercise (HIT) that involve repeated brief sprinting at an all- out intensity followed immediately by low intensity exercise or rest done for 3-4 days in a week of less duration is gaining importance for the purpose of weight loss and change in body composition. It is also considered as an economical exercise protocol for reducing fat in overweight individuals.^9,10 Studies have examined moderate and high intensity exercise for a change in body composition and have reported conflicting results. Limited work have investigated the low volume HIT on people with risk for cardio metabolic disorders and their impending benefits are still uncertain.^11,12 The optimal amount of exercise necessary to produce a change in body composition is yet to be ascertained and moreover, an exercise program to be operational, must be economical and easy to implement without the necessity of complicated exercise equipment. Therefore, we investigated, a protocol of moderate and high intensity exercise on a simple stationary bicycle ergometer that was required to produce significant change in body composition in overweight and obese individuals.¹³

 

MATERIAL AND METHODS

This study was conducted in the department of Physiology, Maharajah institute of medical sciences (MIMS), Nellimarla, Vizianagaram. Ethical committee approval was obtained from the institute. Written material explaining the purpose of the study was circulated among the subjects, volunteers who wished to participate in the study reported to the Physiology department. Informed written consent was taken from volunteers. They were assigned to moderate or high intensity exercise group randomly based on lot method. Sedentary overweight and obese individual (BMI ≥ 25) in the age group of 19-35 were included. Exclusion criteria comprised individuals with history of previous surgery, cardiopulmonary and musculoskeletal disorders, diabetics, hypertensives, and asthmatics. Complete clinical examination, necessary investigations were done.75 volunteers enrolled for the study. 60 of them completed the 1 weeks exercise protocol. 15 opted out due to various reasons not related to exercise injury.

Anthropometric measurements: A digital weighing scale that could measure to the nearest 0.1 kg was used to record weight, and height was measured to the nearest centimeter using a stadiometer, in the Frankfurt plane position. Waist circumference was measured in centimeters (cms) midway between the uppermost point on the iliac crest and the lowermost margin of the ribs with the measuring tape parallel to the ground and patient in inspiration. Hip circumference was measured in cms at the maximum circumference of the buttocks at the level of the greater trochanter.¹⁴ Waist hip ratio was calculated to be waist circumference in cms divided by hip circumference in cms. Mean of three readings of each measurement was taken for the calculation of WHR. Mid arm, mid-thigh and mid-calf circumference were also measured.¹⁵

Measurement of body Composition: Skin fold measurements were taken from various sites including biceps, triceps, scapular, abdominal, supra-iliac, thigh and medial calf sites according to standard procedures using skin fold caliper. All skinfolds were measured to the nearest 1 mm. Mean of 3 readings was recorded at all the sites. All measurements were taken by the same investigator before and after completion of exercise protocol. Durnin’s age specific equations (1974) was adopted to calculate body density that was further used in Siri’s equation (1961) to determine the total body fat. Fat percentage, fat mass, lean body mass¹⁶were derived using standardized equations.

Exercise Protocol:¹³ Subjects were instructed to abstain from caffeine and alcohol at least two days prior to the exercise session and have food two hours prior to the exercise session. During the visit to the laboratory, subjects were well acquainted with the exercise protocol for two weeks and encouraged to get their doubts clarified. Exercise was performed on the bicycle ergometer at the fixed weight to reach the calculated target heart rate using karvonen formula.¹⁷ Exercise protocol for moderate intensity exercise group included performance of steady state cycling at the heart rate of 50%-74% of heart rate maximum reserve for a duration of 40 min, 5 days/week (n=30) and High intensity exercise group (n=30) performed 8 sec sprint cycling on bicycle ergometer at the heart rate of 75%-84% of heart rate maximum reserve followed by 12 sec of low intensity cycling for a duration of 20 min, 3 times/week with 5 min of warm

up and 5 min of cool down in both the groups.

 RESULTS

Of the 75 volunteers 60 completed the exercise protocol. They were grouped into Group I (n=30) who performed moderate intensity exercise and Group II (n=30) who performed high intensity exercise respectively. The baseline characteristics of the study population, mean age 25.3±6.2, 24.2±5.6 and BMI28.24±2.5, 28.69±3.2 of the participants in both the groups respectively were similar.

 

Table 1: Comparison of body composition before and after moderate intensity exercise

 

Comparison of the anthropometric measurements and body composition before and after exercise in group I is shown in Table I. All the measurements showed a significant change after performance of moderate intensity exercise fora period of 15 weeks.

Table 2: Comparison of body composition before and after high intensity exercise

 

The comparison of the measures before and after completion of exercise protocol in group II showed a significant change as presented in Table II.

 

 

Figure 1: Comparison of change in body composition between high and moderate intensity exercise groups

Figure 2: Comparison of change in circumference between high and moderate intensity exercise groups.

Fig. 1 shows the change in the body composition measures between group I and II, there was a significant improvement in the lean body mass and a decrease in fat mass, fat percentage in both the groups. Change was statistically significant in group II when compared with group I. Comparing the change in circumference measurements between both the groups significant change in the mid arm circumference (Fig. 2) in the high intensity group was observed. Comparison of Waist hip ratio between two groups did not show a statistical significance. But there was a significant decrease in sum of skin fold measurements group I and II. But comparing the change in skin fold measurements between the groups did not show statistical significance.

 

DISCUSSION

In this study we evaluated a total of 60 participants who voluntarily gave consent for the study. They were followed for 15 weeks after dividing them into two groups with 30 participants each. Body composition consists of lean mass, fat mass and water.¹⁸ Evaluation of weight only does not reveal a change in fat or fat free mass. Determination of body composition by anthropometric measures is a convenient and economical method. In our study we found there was significant weight loss both in moderate and high intensity exercise groups, this finding was simliar to Majann et al ¹⁹ and John et al.²⁰, they also concluded participants in to high intensity group did not have greater weight loss than participants in moderate intensity group. These findings are consistent with our observations. The reason for smaller loss of weight in high intensity group could be explained by an increase in the fat free massin same group. If the gain in fat free mass is attributed to muscle hypertrophy then resting metabolic rate increases which is good for long term weight control. Our study results showed that the fat mass and fat percentage has a significant decrease in the high compared to the moderate intensity group. These findings are similar to Knoepfli et al ²¹ who concluded a reduction in absolute body mass, relative total fat mass and an improvement in the waist hip ratio, lean body mass during trainingin football and runners of 25-45 years males for a period of 12 weeks in the football group relating it to the high intensity exercise. Ross et al.²²showed that weight loss is positively associated with the volume of performed physical activity. Bryner et al²³compared two types of exercise intensity, in a age group of 18-34 years women, running for 40-45 min with a heart rate of 132 beats/min moderate intensity, 163 beats/min high intensity and concluded that there was significant drop in percent body fat while in the moderate intensity group the reduction of was not significant. Disimilar results were reported by Desprestal²⁴who studied women who exercised for 90 min at 55% of maximal aerobic power (VO2max) four to five times a week for a period of 14 months. The training program induced a significant mean reduction in body fat mass of 4.6 kg (p<0.01), with no change in fat-free mass. The change has been observed in the moderate intensity group but no comparison was made with the high intensity exercise group. Leijssen et al.¹¹after performing exercise at VO2max 40% (low intensity) and 70% VO2max (high intensity) after 12 weeks of exercise in obese men reported no change in body fat percentage in two groups. Trapp et al²⁵who conducted an exercise program that included high intensity exercise (n=15) for a duration of 20 min and moderate intensity exercise (n=15) of 40 min duration same exercise protocol followed in our study. Trapp et al²⁵observed a 2.5 kg loss of subcutaneous fat in the high intensity group and no change in the moderate intensity group, Fat loss of 50% was attained with less exercise time commitment. Similar results are alsoseen inour study in of favor of high intensity exercise for fat loss. The waist hip ratio also significantly reduced in the high intensity group. Van et al²⁶ concluded simliar findings. This reduction in WHR probably due to the fact that individuals with obesity oxidize more fat during intense physical activity favoring a reduction in WHR²⁷.A significant decrease in the mid arm circumference was noted in the high intensity group. There was a decrease in both the mid- thigh and mid- calf circumference in two groups but on comparison between the groups it did not show a statistical significance. These findings can again be explained by an increase in the lean body mass in both types of exercise in two groups.²⁸ The underlying mechanism behind reduction in body adiposity with high intensity exercise is not clear. Possible mechanisms could be factors affecting energy intake and post-exercise energy expenditure²⁹.Phelan et al³⁰postulated that high intensity exercise allows large amounts of glucose to be utilized and after the exercise training greater contribution of fat oxidation meet the energy requirement. Any exercise protocols must be motivating, stress free and realistic to achieve set goals of physical fitness. We can consider leisure-time, exercise, sport, occupational work and transportation as all forms of physical activity (PA). Exercise is a type of PA that is usually performed repeatedly over an extended period of time with the aim to improve fitness, physical performance or health. On the other end, Physical Fitness (PF) is defined by WHO as the ability to perform muscular work satisfactorily¹. The present study aimed at comparing groups of exercises namely moderate and high intensity protocol required to produce a change in the body anthropometric measures and body composition in overweight and obese individuals. We conclude from our results that both high and moderate intensity exercise are significantly associated with change in the body composition and circumference measurements. High intensity exercise is more effective with less duration for an improvement in the level of physical fitness and a decrease in body weight compared to moderate intensity exercise of extended duration. We believe our results will have good implication, contribution and motivation to weight reduction programs.

 

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