- 1 ABSTRACT
- 2 CHAPTER ONE
The study compared the effect of different intensity levels of continuous training on physiological and body composition variables of adolescent students of Imperial School Kudend Kaduna Metropolis, Nigeria. The training programme comprised warm-up, continuous jogging and cool down activities ineach training session. A total of eighty(80) overweight adolescent male students aged 15 to 17volunteered to participate in this study. A 1 x 2 x 3 factorial experimental research design was used. Three experimental study groups and one control group in which participants were given different treatments. In this design, participants underwent low, moderate, and high-intensity training for 9 weeks.The training consisted of continuous jogging for 30 minutes on three alternate days a week at < 40-45% , < 45-50% and < 50-55% HR max of the participants from 1st to 3rd, 4th-6th and 7-9th weeks of training, respectively, for low-intensity group; < 50-55%, < 55-60%, 60-65% HR max of the participants from 1st-3rd,4th-6th and 7-9th weeks of training, respectively, for moderate-intensity group and < 60-65%, < 65-70%, < 70-75% HR max of the participants from 1st- 3rd,4th- 6th and 7-9th weeks of training, respectively, for high-intensity group. Rate of Perceived Exertion scale was used to monitor the exertion of training throughout the research period. All participants were tested for MAP, RHR with Electronic sphygmomanometre (automatic arm cuff Blood Pressure and heart rate monitor) Omron CEO 197 and %BF and VF with Omron HBF 516B full body sensor body composition monitor and VO2 max with cooper‟s 12-minute run test, before starting the training (base-line), this was repeated after 3rd, 6th and 9th weeks of training. The baseline average values for MAP were 85.717, 85.365, 84.951 and 84.134 mm Hg, RHR 75.00, 74.600, 73.00, 72.950 bpm, VO2 max 35.336, 35.478, 345.464 and 35.324 ml.kg /min-1, %BF 21.25, 21.40, 20.85 and 20.95 and VF 11.450, 11.650, 10.750 and 10.700, for low, moderate, high and control groups, respectively.
The data collected were analysed using descriptive and repeated-measures analysis of variance and Scheffe post-hoc test at 0. 05 level of significance. The participants MAP mean value of 82.600 mm Hg -3.6%, 76.615 mm Hg – 10.3%, 78.184 mm Hg -6.9%, 86.170 mm Hg -2.4%for low, moderate, high-intensity and control group respectively. RHR mean value 69.00 bpm -8.0%, 66.450 bpm -10.9%, 64.100 bpm -12.2% and 75.300 bpm 3.0%, for low, moderate, high-intensity and control groups, respectively.VO2max mean value 42.335ml.kg./min-1 16.5%, 49.521 ml.kg./min-1 28.4%,53.740 ml.kg./min-1 34%, 33.44 ml.kg /min-1 -5.3%, for low, moderate, high-intensity and control group respectively. %BF mean value 17.10 -19.5%, 15.65 -26.9%, 12.05 -42.2% and 21.92 4.6%.for low, moderate, high-intensity and control groups respectively and VF mean value 8.250 -27.5%9, 7.150 -38.6%, 4.200 60.9% and 11.530 2.9% for low, moderate and high- intensity and control group respectively after 9 weeks of continuous training.
The results revealed significant decrease in MAP (P < 0.01), RHR (P < 0.001), %BF(P < 0.001) andVF (P <0.001) at low, moderate and high-intensity training. The result also indicated a significant increase in VO2max (P <0.001) across the 3 training intensities due to 9 weeks of continuous training. It was concluded that low, moderate and high-intensity continuous training conducted at 40-55% HR max low-intensity, 55 to 65% HR max for moderate-intensity and 60 to 75% HR max for high-intensity for 30 minutes on three alternate days a week for 9 weeks significantly decrease MAP, RHR, %BF, and VF and significantlyincreasedVO2max of overweight male adolescent students. Since continuous training was found to significantly improve the physiological and body composition variables, it was recommended that health professionals and fitness centres should use this method of training on overweight adolescents to reduce cardiovascular risk factor and improve body oxygen transport and utilisation.
OPERATIONAL DEFINITION OF TERMS
The technical terms used in the study are defined below in their operational sense
- Continuous Training: This is the work out protocol in which the activities are performed without break for specific period of time.
- Adolescent: A person aged from 15-17 years who are in Senior Secondary School
- Low-Intensity training: Continuous exercise protocol performed at 40-55% HRmax or RPE of 7-12 that does not cause any noticeable change in breathing rate.
- Moderate-Intensity training: Continuous exercise protocol performed at 50-65% HRmax or RPE of 11-14 that is conducted whilst maintaining a conversation uninterrupted.
- High-Intensitytraining: Continuous exercise protocol performed at 60-75% HRmax or RPE of 13-16 which makes breathing harder or puff.
1.1 Background of the Study
The strong relationship between physical activity (PA), health and wellness is not in doubt because PA has many health and fitness benefits which are well documented. These benefits are enjoyed due to regular participation in an exercise programme. At the time when exercise scientists demonstrated the association between longevity and exercise, researchers (Nieman, 1998; Venkateswarlu, 2010; Kenny, Wilmore & Costill, 2012; & Heyward, 2014)in the field of cardiology began to understand that regular physical exercise reduces cardiovascular risk factors by reducing blood pressure, type-2 diabetes, hypertension, stroke, gallbladder disease, post-menopausal breast cancer, colon and other cancers.
The primary goal of exercise may dictate the mode (type), frequency, duration and intensity of the exercise prescription. The concern about the proper dose of exercise prescription that will bring about a desired effect (response) is similar to the physician‟s need to know the type and quantity of a drug as well as the time frame over which it must be taken to cause the desired health effects (Powers & Howley, 2012). It is a common fact that the dose of physical activity improves health-related outcomes, such as lower mean arterial pressure (MAP), resting heart rate (RHR), percent body fat (%BF), visceral fat (VF) and increased maximum oxygen uptake (VO2max). Evidences from experts (Plowman & Smith, 2008; Venkateswarlu, 2011; Powers & Howley, 2012; Heyward, 2014) have shown that continuous aerobic exercise positively influences physiological variables such as MAP, RHR, VO2max, % BF and VF. If the primary goal of the exercise
programme is to develop and maintain cardiorespiratory fitness and other physiological variables, such prescribed exercise should be of continuous nature. This mode of exercise allows the individual to maintain constant exercise intensity. The most popular modes of continuous training are walking, jogging, and cycling (Kenney, Wilmore & Costill, 2012; Heyward, 2014). All have been found to show significant improvements when the frequency,duration and intensity of exercise are held and are prescribed in accordance with sound scientific principles.
Recent research studies clearly demonstrated strong evidences that participation in regular physical activity (PA) of continuous training enhances fitness benefits as well as cardiovascular function among adolescents, such as improved heart and muscular functions, build and maintain healthy bones, enhanced blood circulation and metabolic rate, and favourably influence body composition (Lee & Paffenbarger, 2000; Mackenzie, 2000; Gibala, Little, MacDonald, & Hawley, 2012; Wade, 2013; Heyward, 2014; Gladmohesh & Sundaramurthy, 2015).
Prentice (2006), ACSM (2011) & Kenney, Wilmore and Costill (2012) agreed that though the mode, frequency, duration and intensity are important for producing training effects, the intensity of the exercise is the most significant factor associated with aerobics development and appears to be the most critical determinant of the physiological responses to training. However, the optimal intensity of activity remains unclear. Kenney, Wilmore and Costill, (2012) defined exercise intensity as the amount of energy expended when exercising and howlight/low, moderate or high/hard an exerciser pushes to gain the benefits. Guidelines for adolescents suggest that 60 minutes or more of either moderate or vigorous aerobic Physical Activity per day three times per week provides additional health benefits. The 1998 Surgeon General Report recommended that American adolescents require at least 30 minutes of moderate intensity PA most days of the week, to maintain cardiovascular wellbeing and that greater intensity of exercise confers greater benefits. Recently, the American Heart Association recommended a minimum of 30 minutes of moderate intensity PA (AHA, 2014). The intensity of aerobic PA can be defined as either absolute or relative scale. An absolute measure of PA intensity is the amount of energy used by the body per minute, while doing the activity without taking into account a person‟s cardiorespiratory fitness. It includes heart rate (HR) and metabolic equivalent (METs). A relative measure of PA intensity is the level of effort required by a person to do an activity. It uses a person‟s level of cardio-respiratory fitness to assess the level of effort. It includes percent of heart rate maximum (%HRmax), percent of heart rate reserve (%HRR), maximal oxygen uptake (VO2max) and Borg‟s scale rate of perceived exertion (RPE) (Norton, Norton & Sadgrove, 2009; Kenney, Wilmore and Costill, 2012); often used to set the intensity level of aerobic physical training into low (light), moderate and high (vigorous/ hard).
Low intensity exercise is an aerobic activity that does not cause any noticeable change in breathing rate and can be sustained for at least 60 minutes. For example, gardening, household cares, walking 4 kilometre per hour or less. Operationally, low intensity activities are those where the metabolic equivalent is between 1.6 to 3.0 METs or the relative intensity of 40% to 55% HRmax, 20 to 40 %HRR,20 to 40 % VO2max and RPE of 11-12 (Norton, Norton & Sadgrove, 2009). Studies revealed that low intensity training (LIT) leads to improvements of both physiological and body composition variables. Fagard (2011); Mughal, Alvi, Akhund and Ansori (2001), reported reduction in MAP of 3 mm Hg after 30 minutes of brisk walking 3-5 times a week at 50% VO2max. Lamina (2010), Teller (2012) and Simon (2013) also reported significant reduction in RHR with slow jogging training programme.
Moderate intensityexercise is an aerobic activity that is able to be conducted whilst maintaining a conversation uninterrupted and may last between 30 and 60 minutes consisting of activities like, walking 4.8 kilometre per hour and not more than 5.5 km/h, bicycling 16 km/h, calisthenics and home exercises. Its intensity ranges from 3 to 6 METs or have a relative intensity of 55 to 70%HRmax, 40 to 60 %HRR, and40 to 60 Percentage VO2max and RPE 13-14 (Norton, K., Norton, L. & Sadgrove, D.,2009). Studies revealed that moderate intensity exercise positively influence both physiological and body composition variables. Abdel-Kader (2011) reported a reduction of 6.7% mean value of BMI after 3 months of moderate intensity aerobic exercise training. Gan, Kriketos, Ellic,Thompson, Kraegen and Chisholm (2003) also reported a reduction in visceral fat (r – 0.544, P= 0.02) after 10 weeks of moderate intensity physical activity and concluded that aerobic moderate intensity PA leads to reduction in visceral fat.
High intensity exercise is intensity level of aerobic PA most often made breathing harder or puff and pant, conversation generally cannot be maintained uninterrupted and may last up to 30 minutes. For example, walking 6 km / hror more, or jogging and running. Its intensity ranges from 6 to 9 METs or a relative intensity of 70 to 90% HRmax, 60 to 85% HRR, 60-85% VO2max and RPE 15-18 (Norton, K., Norton, L. & Sadgrove, D, 2009).
Continuous training can be performed at low, moderate and high intensity level. Studies that have compared different intensities of continuous aerobic exercise showed that high-intensity continuous training leads to significant improvement of physiological and body composition variables (Hottenrott, Ludyga & Schulze, 2012). Airin, Linoby, Zaki, Baki, Sariman, Esham and Azam (2014) reported that continuous training three times per week for six weeks training at 60 – 70% of HRmax for 30 minutes, caused significant reduction in % body fat (0.3%), lean body mass (0.8kg) and BMI (0.5kg/m2).
1. 2 Statement of Problem
Despite the established benefits of regular PA on health and well-being among adolescents in developed nations including the United States of America, current levels of PA within school aged youth are widely regarded as insufficient to meet the recommendations for intensity (Ekelund, Tomkinson & Armstrong, 2011). The current era is characterized by kinetic limitations, both in children and adolescents. Children and adolescents today, expend less energy than did their counterparts of 40 years ago, and are 40% less active than they were 30 years ago (Mavrovouniotis, 2012). Adolescents today spend their free time mainly in sedentary behaviours, such as television viewing, computer and video games, use of automation devices as means of transportation to and from school, phone chatting, messaging, washing clothes with machines dryers and other labour-saving and muscular work-saving technologies. This lack of adequate movement in children and adolescents‟ lives is one of the primary predisposing factors of increased morbidity, since many of the chronic diseases of adults are initiated in childhood. These conditions also provide fertile environment for increased risk factors for heart diseases, such as obesity, hypertension and high total cholesterol, or diabetes. These diseases are most often irreversible due to the continuous sedentary lifestyle that has been adopted since childhood. The health consequences of excess body fat, especially visceral fat do not immediately manifest in obesity in some adolescents, but, it translates into unprecedented number of cardiovascular risk factors and metabolic disorders like type-2 diabetes, hypertension, stroke, gallbladder disease, post-menopausal breast cancer, colon and other cancers, osteoarthritis, back pain, physical and mental disabilities (Chia, 2008; Bouchard & Katzmarzyk 2010; Baria, Kamimura, Aoike, Ammiratai, Rocha, Mello & Cupparati, 2016). Marrow (2013), reported that American adolescents have failed to meet national aerobics fitness capacity and have higher odds of not achieving health related physical fitness levels such as improved aerobic capacity, percent body fat and flexibility among others.
Scientific evidence supports the concept that participation in regular aerobic exercise has significant and perceivable benefits for the health of every individual. Guidelines for such aerobic programmes have been provided by health professionals, organizations and experts. Continuous aerobic exercise of moderate intensity for 30 to 40 minutes most days of the week have been the pivot point for which physical exercise attenuates physiological changes of people, irrespective of age and gender (Venkateswarlu, 2011).
However, the precise type and dose of exercise needed to accrue health benefits is a contentious issue with no clear consensus and recommendation for the prevention of inactivity related disorders. Though the mode, frequency, duration and intensity are important for producing training effects, the intensity of the exercise is the most significant factor associated with fitness improvement and appears to be the most critical determinant of the physiological responses to training. However, the optimal intensity of activity remains unclear. There is continued debate as to how much (intensity) can continuous training dose cause physiological changes in adolescents.
The beneficial effects of low, moderate and high level continuous training need to be clarified among adolescents in Nigeria. Thus, research is needed to clarify the effects of different intensity levels of continuous training on physiological and body composition indices of urban based adolescents, such as Kaduna metropolis of Nigeria.
Considering the sedentary lifestyles of urban based adolescents, this study investigated and compare the effects of different intensities of continuous training on mean arterial pressure (MAP), resting heart rate (RHR), VO2max, percent of body fat (% body fat) and visceral fat of non-athletic male adolescents in Kaduna metropolis, Nigeria.
1.3 Research Questions
The following research questions were raised for this study.
- Will MAP, RHR, VO2max, % BF and visceral fat of adolescents change following low intensity continuous training?
- Will MAP, RHR, VO2max, % BF and visceral fat of adolescents change following moderate intensity continuous training?
- Will MAP, RHR, VO2max, % BF and visceral fat of adolescents change followinghigh intensity continuous training?
- Which of these intensity levels will produce the greatest change in MAP, RHR.VO2max, %BF and visceral fat of adolescents in Kaduna metropolis?
1.4 Purpose of the Study
The purpose of this study was to:
- Determine the effects of low intensity level of continuous training on MAP, RHR, VO2max, % body fat and visceral fat of adolescent students in Kaduna metropolis
- Determine the effects of moderate intensity level of continuous training on MAP, RHR, VO2max, % body fat and visceral fat of adolescent students in Kaduna metropolis.
- Determine the effects of high intensity level of continuous training on MAP, RHR,VO2max, % body fat and visceral fat of adolescent students in Kaduna metropolis.
- Compare the effects of low, moderate and high intensity levels of continuous training on MAP, RHR, VO2max % body fat and visceral fat of adolescent students in Kaduna metropolis.
1.5 Basic Assumptions
On the basis of available research evidence, the following assumptions were made for the purpose of the study:
- Regular participation in physical activities significantly influence physiological and body composition variables of adolescents.
- The effects of physical training on physiological and body composition variables depend largely on the training intensity level.
- The effects of continuous training on physiological and body composition variable of adolescents can be measured.
To achieve the purpose of this study, the following hypotheses were tested:
There are no significant effects of low, moderate and high intensity levels of continuous training on the physiological and body composition of overweight male adolescent students in Kaduna metropolis, Nigeria
Sub – Hypotheses
- There is no significant difference in the effects of low, moderate and high intensity continuous training on MAP of adolescent students in Kaduna metropolis.
- There is no significant difference in the effects of low, moderate and high intensity continuous training on RHR of adolescent students in Kaduna metropolis.
- There is no significant difference in the effects of low, moderate and high intensity continuous training on VO2max of adolescent students in Kaduna metropolis.
- There is no significant difference in the effects of low, moderate and high intensity continuous training on % body fat of adolescent students in Kaduna metropolis.
- There is no significant difference in the effects of low, moderate and high intensity continuous training on visceral fat of adolescent students in Kaduna metropolis.
1.7 Significance of the Study
The consequences of sedentary life-styles lived by so many of our young people are grave. A physically inactive population is at the risk for many chronic diseases, including heart disease, stroke, colon cancer, diabetes, and osteoporosis. In addition to the toll taken by human suffering, surges in the prevalence of these diseases could lead to crippling increases in the national health care expenditures. Research has shown serious health implication of inactive life-style, characterized by kinetic limitations both in adolescence and adulthood. Therefore, prevention must start with a better understanding of exercise intensity impact in the early years of development. Hence, enhancing efforts to promote participation in physical activity and sports to improve energy expenditure among adolescents should be a critical national priority.
A lot of studies with regard to the effect of exercise training on the body has been carried out on various groups, with health challenges emanating from poor fitness level ofvarious physiological and body composition variables. These studies were aimed at developing exercise programme for treating and controlling these health challenges .But not so much information is available about the effects of intensity levels of continuous aerobic exercise training and which intensity level (low, moderate and high) is effective for producing and maintaining training effects on physiological and body composition of adolescent students in Nigeria.
The findings help the participants to reduce cardiovascular risk factor and provide appropriate exercise intensity for treating and controlling the health challenges associated with overweight.
The findings inthis study helps the government to have a robust long-term national policy to improve aerobic fitness of the children,reduce national health care expenditures and promotes strategies in schools to give adolescents opportunities for walking, jogging, cycling, playing, and sports on daily basis to have active youths for national productivity.
This research is significant to field of study as itcontribute to the available existing body of knowledge as literature on the effects of adolescent activity levels are very scanty, the findings, therefore,provides some basic information beneficial to physical education specialists, exercise scientists, coaches and trainers on how intensity levels of continuous training influence the physiological and body composition variables of adolescents,and which level of intensity of continuous aerobics training influences greater changes in physiological and body composition variables of adolescents in influencing and correcting cardiovascular risk factors.
The results also benefit the community to have active and healthy adolescents and ensurebetter productive citizens for economic growth and development.
1.8 Delimitations of the Study
The study was delimited to the following conditions
- Effects of low, moderate and high-intensity levels of continuous training on physiological and body composition variables of male adolescent students in Kaduna metropolis.
- The training protocol was 3 days per week on alternate days of continuous training
- The physiological components tested were MAP, RHR, and Vo2max.
- The body composition components tested were % body fat and visceral fat.
- The subjects used were male overweight adolescent students of Imperial Schools, Kaduna.
- The ages of the subjects were between 15 and 17 years, but time and duration of training was the same.
- For this study, the Cooper‟s 12-minute run/walk test was used to estimate the participants’ VO2max. A 400- metre track was used so that the number of laps completed was easily counted.