The Effects Of Interval And Continuous Training Physical Education Essay
In todays society where appearance and health is a major part of modern life, there is a growing awareness of overweight and obesity in the World. For many reasons such as appearance, health many overweight and obese people undertake some form of diet or exercise program to overcome this. In many grocery stores fitness magazine can be found describing new fat diets “shed 2 stone in 4 weeks”. Weight-loss drinks have become more and more popular as they may aid in weight loss, although most people favour eating actual food than a shake every couple of hours every day.
More health clubs have become available all around the country, being easy to access and offering guarantee weight loss. These clubs help people in losing weight, however usually does little to encourage them to stay as they have already received there signing up fee. Success in weight loss programs comes by adherence to exercise, however for a majority of people this is the major issue. These health and fitness clubs strive on selling membership to the general public and most don’t encourage people to stay.
More exercise and changes in diet are the key factors to weight loss. A change in diet helps weight loss by restricting total caloric as well as fat intake (C. Curioni & P.Lourenco, 2005). A change in exercise patterns also aids weight loss by increasing caloric and fat expenditure (L N. Keim et al., 1990 & V. Mougios, et al., 2006)
Many individuals attempt to lose weight, though never meeting their goals.
This is usually due to someone attempting a diet and exercise program for a brief time, lack of changes in their appearance or weight make the participant want to quit (A. Grediagin, et al., 1995) as well as lack of time and interest (Willis & Campbell, 1992) have shown to prevent devotion to their weight loss program (Kempen et al. 1995). Body composition is one of the most frequently studied subjects (R. Bryner, et.al 1997). To date, a number of studies have reported the efficacy of high intensity exercise on various physiological parameters related to weight loss (R. Bryner, et al. 1997; J. Jakicic. et al. 2004; V. Mougios et al. 2006).
Both men and women begin dieting and exercise programs in an attempt to lose weight however many fail to continue to either exercise or diet usually due to a decrease in results. However, women tend to struggle compared with men when losing weight (Gleim, 1993). Factors include smaller body sizes (Gleim, 1993), less fat free mass (Pollock et al., 1998; Westerterp, 1998), and lower resting metabolic rates (RMR) (Westerterp, 1998) than men. Men’s testosterone levels are higher than women, which causes males to have a greater muscle mass and absolute RMR than women (D.W McArdle, et.al 1996). These factors cause female’s energy expenditures to be less than that of male, so it critical to find an exercise program or diet program for females that will create the necessary results needed for the participants to make sure they continue with that program.
The Conventional way of low intensity exercise was considered to be more beneficial way to reduce weight than high intensity exercise because of the greater percentage of fat calories are burned during low intensity exercise (McArdle et al., 1996). Previous research has shown that higher intensity exercise is associated with greater improvements in cardiovascular fitness and greater caloric expenditure, which in turn can assist in improving health as well as weight loss (Perna, et al. 1999, O’Donovan, et al. 2005).
However it has been shown that high intensity exercise requires a greater percentage of calories (kcal) during and after exercise and is often greater than that of lower intensity exercise (O’Donovan, et al. 2005). Substantially following exercise, fat metabolism and RMR has been shown to be elevated for up to 24 hours (Bielinski, Schultz, & Jéquier, 1985; Treuth, Hunter, & Williams, 1996).
It is has been highly debated whether if high intensity interval training can be used as a possible treatment intervention in promoting weight loss.
In continuous steady state training the speed which the participant exercises at stays the same intensity throughout the duration of the protocol. Whereas the participant completes 10 intermittently exercises at a high intensity alternating with a lower intensity every few moments in the high intensity interval training.
Comparing the two training protocols over the same amount of calories expended during a high intensity high intensity interval training program as in a more moderate intensity steady state training program the substrate utilization during these exercises will differ (K. Wallman, et al. 2009).
Higher intensity exercise would use primarily use glycogen during exercise whereas a more moderate intensity program would use primarily fat (K. Wallman, et al. 2009). A typical individual would interpret this information as an argument that low steady state intensity exercise is better for burning fat.
However, this does not take in to account the fact that fat metabolism is increased after high intensity interval exercise, serving as the body’s fuel source for any post-exercise activity, also to replenish the glycogen stores depleted by the high intensity exercise (K. Wallman, et al. 2009)
It’s very difficult for many individuals to maintain an extremely high intensity for an extended period of time, thus requiring that near maximal exercise is completed in a high intensity interval training program rather than a continuous steady state program (W. Schmidt et al., 2001)
Compare the effects of high intensity interval training versus low intensity continuous steady state training on VO2 max in overweight women.
Compare the effects of high intensity interval training versus low intensity continuous steady state training on body composition in overweight women.
Lack of studies dealing with high intensity interval training programs as a potential means of weight loss over a short intervention, this specifies that such research is necessary to determine if high intensity interval training is a worthwhile means to reduce total body weight and fat mass over a shorter period.
1.3 Hypotheses / Research Questions
The two research hypotheses of this study were “null” 1) there would be no significant differences between high intensity interval training and low steady state continuous steady state training in V02 max and in body fat percentage; “alternative” 2) there would be a significant difference between high intensity interval training and low steady state continuous steady state training in VO2 max and body fat percentage.
Subjects were limited to 18 to 34 year-old female non-smokers, not pregnant, not lactating, and not taking any medications that could inhibit metabolism with a body fat percentage 25% – 30%.
Subjects, 4 subjects were assigned to either interval training group or continuous steady state training group.
Body composition was measured using bioelectrical impedance (BIA)
Maximal aerobic capacity was measured using multi stage fitness test (MSFT). The equation was then used to then calculate the VO2max (AD Flouris et.al. 2004 & L L´eger, C Gadoury.1989).
V02 max was used to determine the level at which a subject needed to exercise for a given exercise intensity.
A small group, thus limiting the generalizability of the findings.
Work environment could not be controlled for.
Bioelectrical impedance could only be used for body fat percentage.
Multi stage fitness test (MSFT) to assess VO2 max not graded exercise test (GXT).
Definition of Terms
Aerobic: – exercising which requires the use of oxygen
Anaerobic: exercising without the presence of oxygen as the work intensity is greater than the rate the body can transport oxygen to be used.
Body mass index (BMI): describes relative weight for height. Calculated as weight (kg)/height squared (m2) x 704.5. A BMI of > 25 is considered overweight and a BMI > 30 is considered obese in women.
Calorie: energy unit also known as the kilocalorie (kcal). It takes 3500 kcal to be to burn one pound of fat.
Continuous training: steady-paced, prolonged exercise (McArdle et al. 1996)
Interval training: a form of training that involves high-intensity exercise for a brief period of time with brief periods of rest or low intensity exercise (McArdle et al., 1996)
Maximal oxygen uptake (VO2max): is used to measure cardiovascular fitness
Obesity: unhealthy high body fat percentages, generally considered >30% for women (McArdle et al., 1996)
Overweight: – unhealthy high body fat percentages, generally considered 25% to 30% body fat percentage.
Steady-state: the point that is reached in continuous exercise where workload and heart rate become constant.
2.0 CHAPTER TWO – LITERATURE REVIEW
2.1 Literature Review
Obesity is a worldwide issue associated with serious health, social, and economic problems (Brisbon N, et al. 2005). (World Health Organisation 2005) defines overweight and obesity as ”abnormal or excessive fat accumulation that presents a risk to health”. Obesity has been associated with one or more diseases such as diabetes, hypertension, and cardiovascular disease, which have shown to result in serious health issues and even causes of death (C. Stein and C. Colditz 2004). Obesity can be classified into two different sections these being android obesity, where the main proportion of fat mass is situated around the abdomen and waist area, and gynoid obesity, where a large proportion of fat mass is located in the gluteal and femoral areas (A. Kissebah and G. Krakower 1994). Obesity is usually occurs as the result of an imbalance between calories consumed and calories which are expended. An increased consumption of highly calorific foods, without an equal increase in physical activity, will lead to an unhealthy increase in weight. Also decreased levels of physical activity will result in an energy imbalance and lead to weight gain.
It is estimated that one billion adults are overweight and more than 300 million are obese (World Health Organisation 2008). At least 2.6 million people each year die as a result of being overweight or obese (World Health Organisation 2008). Once being associated with the higher income countries, obesity is now also widespread into the lower and middle income countries, as over “65% of the world’s population live in a country where overweight and obesity kills more people than underweight (World Health Organisation 2008). This includes all high-income and middle-income countries. Globally, 44% of diabetes, 23% of ischaemic heart disease and 7-41% of certain cancers are attributable to overweight and obesity” (World Health Organisation 2008).
2.2 Body Mass Index
The most commonly used measure for identifying if an individual is considered overweight or obese is the Body Mass Index (BMI), is a simple index to classify overweight and obesity in adult populations and individuals. The (World Health Organisation) defines the calculations for BMI as the weight in kilograms divided by the square of the height in meters (kg/m2). The classifications of BMI are underweight (=25.0), pre-obese (25.0 – 29.9), obese (>=30.0), obese class 1 (30.0 – 34.9), obese class 2 (35.0 – 39.9) and obese class 3 (>=40.0).
The body mass index (BMI) is the same within both sexes and for all ages of adults. However, the BMI should be considered as a rough guideline as it may not correspond to the same body fat percentage in different individuals. The BMI classification system is not yet usable for children as their bodies undergo a number of physiological changes as they grow.
2.3 Bioelectrical Impedance Analysis (BIA)
However bioelectrical impedance analysis (BIA) is a commonly used method for estimating body composition (Maughan R 1993). BIA first became available in the mid-1980s the method has become very popular due to its ease of use, portability of the equipment and it’s relatively low cost compared to some of the other major methods in assessing body composition analysis (Maughan R 1993). In spite of the perception that BIA measures “body fat,” the device actually determines the electrical impedance of body tissues, which in turn provides an estimate of total body water (TBW) (Maughan R 1993). TBW results from the BIA, can then estimate fat-free mass (FFM) and body fat (adiposity) (Maughan R 1993).
2.4 Exercise Regimes
Changes in diet and/or exercise patterns are the primary ways for one to lose weight but a combination of caloric restriction and exercise has been shown to be a more effective nonsurgical intervention (C. Curioni and P.Lourenco, 2005). Recent research from (V. Mougios, et al. 2006) has shown that a combination of exercise and dieting has been more effective to optimize fat loss. Past research from (N. Keim, et al. 1990) agrees with this by stating that a change in diet eases weight loss by limiting the total caloric intake for the day. Caloric and fat expenditure is increased by a change in exercise patterns (N. Keim, et al. 1990).
Of relevance, the exercise regime typically employed in an overweight or obese population involves stable aerobic exercise performed at a continuous low to moderately low intensity (Jacobsen et al., 2003). It is undefined whether this form of exercise (continuous), in combination with dieting, is the most effective way to lose fat or to improve general health. Alternatively high intensity exercise burns a larger number of calories when compared with low to low-moderate intensity exercise performed over the same period of time, therefore being more effective solution for fat loss (L. Campbell, et al. 2010, ). Additionally past research from (J. MacDougall, et al. 1998) has shown that high intensity exercise places a larger physiological load on the cardiovascular system compared with lower intensity exercise and therefore may lead to greater results in improvements in aerobic fitness. On the other hand (L. Campbell, et al. 2010) states that many overweight and obese individuals have low levels of fitness, the stress which is put upon their bodies by the high bouts of high intensity exercise may be difficult for them, if not impossible. This is supported by Jakicic et al. (2004) who reported the need for obese/overweight participants to divide their exercise sessions into smaller sections due to their incapability of performing a single continuous session of moderate to high intensity exercise.
Up to now, certain studies have reported the efficacy of high intensity exercise on various physiological restrictions related to weight loss (Jakicic, Marcus, Gallagher, et al. 2004; Mougios, Kazaki, Christoulas, et al. 2006). In addition, O’Donovan et al. (2005) has reported superior improvements in cholesterol, low density lipoprotein (LDL-C) and high density lipoprotein (HDL-C) after research of a 24 weeks period of high-intensity exercise, compared to moderate-intensity exercise. As Interval training includes bouts of high-intensity exercise with stages of rest or lower intensity exercise that allow for part recovery (McArdle et al., 2001), it can be used for most individuals as dependent on their fitness levels the intensity and duration of the interval bouts can be adjusted in order to match an individual, thus making this form of training a suitable option for most people. The studies which have compared high intensity interval training and continuous aerobic exercise in the obese and overweight population have stated that high intensity interval training resulted in greater fat loss (J. King et al, 2001; E. Trapp et al, 2008).
High intensity interval training can be conducted in many forms of exercises from cycling to walking, research from (L. Campbell, et al. 2010) looked at the effects of interval exercise on physiological more specifically into continuous versus interval walking in an obese population, whereas (K. Wallman, et al. 2009) exercise interventions required the participants to exercise on a cycle ergometer (Monark 828e, Sweden) as the reduced strain on the body , would occur via cycling, as an exercise intervention in an overweight population.
The research done by (L. Campbell, 2010) stated that potential participants were eliminated if they participated in an excess of 30 minutes of exercise on 3 different occasions per week over the last 6 months K. Wallman, et al. (2009) also stated this. L. Campbell, (2010) also excluded participants if they were ever pregnant, taking medications in relation to beta blockers, blood pressure or a thyroid medication, whereas other research by (K. Wallman, et al. 2009, JW. J. King. 2001, K. Hansen, et al. 2005) didn’t look into eliminating participants if they had these advantages. Participants were also excluded if they had diabetes, had a blood pressure (BP) superior than 160/90, had lost more than five kg in the last three months, had musculoskeletal problems that prevented them from walking (L. Campbell, 2010, K. Wallman, et al. 2009). The daily activity data for a week i.e. the number of steps per day was assessed during weeks 1 and 12 of the intervention using a pedometer (Yamax, Digi-walker, SW-700, Tokyo, Japan) in research by (L. Campbell, 2010). The Yamax Digi-walker pedometer has been reported to accurately and reliably measure steps during walking and running in overweight and obese individuals (Swartz et al., 2003). However other studies did not take into consideration daily activity which is what I did.
How different studies measured their results varied as H. Mohebbi, (2011) interventions consisted of the use body mass index and whole body fat mass and free fat mass (FFM) in order to get their results, whereas (K. Wallman, et al. 2009) used the stadiometer for to measure their height and body mass was determined using Sauter scales. Compared with how the intervention that I used to get my results would be the use of body fat percentages from bioelectrical impedance and looking into physiology adaptations by the MSFT.
2.5 Interval Versus Continuous
The research results reported by (L. Campbell, 2010) used individuals who there were no significant differences for age, body-mass, height and BMI Prior to the intervention for both groups and there were no significant differences between the two groups for VO2peak (ml·kg-1·min-1) K. Wallman, et al. (2009) also approach their investigations this way. The results by (L. Campbell, 2010, K. Wallman, et al. 2009, K. Hansen, et al. 2005) shown that there were no significant differences between both groups for body mass, fat mass or lean mass at baseline but there were significant main effects for time for body mass and fat mass .
Further, while (L. Campbell, 2010) found there were no significant differences between groups for gynoid and android fat mass at baseline or upon the conclusion of the intervention, there was a significant main effect for time found for gynoid fat mass, with reductions in this measure being reflected by large ES in interval and continuous groups. Whereas K. Wallman, et al. (2009) found there was no significant differences, however there was a slight difference in both variables, but results revealed that while there were no significant changes in body mass and android and gynoid fat mass between groups, there was a trend for a decline in android fat mass in the interval group, as established by a large effect size in this group only.
“Declines in total fat and gynoid fat mass were reflected by significant main effects for time, as well as moderate and large effect in both groups” (L. Campbell, 2010). L. Campbell, (2010), K. Wallman, et al. (2009) found that in addition, the decrease in overall body mass over time only was reflected by a moderate effect sizes in the interval group only. These results show that body mass in the interval group are most probable at greater total android fat mass and fat loss in the interventions, as results show interval group are (~22.5% and 28.5%) compared to the continuous group (~17% and 19.2%) (L. Campbell, 2010). Furthermore these results are also support by other similar studies that stated body mass loss (W. Schmidt et al., 2001; J. Volek et al., 2005) and fat mass loss (J. King et al., 2001) after exercise interventions (J. King et al., 2001; W. Schmidt et al., 2001) and also a diet and exercise intervention (J. Volek et al., 2005).
K. Wallman, et al. (2009) research looked into the use of a calorie restricted diet when comparing interval versus continuous, while other studies (J. King, et al 2001, K. Hansen, et al. 2005, L. Campbell, 2010) have shown not to directly look into calorie restricted diet.
Consequently research suggests a combination of both high intensity interval training and calorie restricted diet has shown beneficial improvement in VLDL-C (L. Campbell, 2010). The studies which have compared high intensity interval training to continuous aerobic exercise in the obese and overweight population have reported that high intensity interval training resulted in greater fat loss (J W. King, et al, 2001; E. Trapp et al, 2008).
Nonetheless, the results of the study conducted by (C. Perry, 2008) suggest that further investigation is necessary into the use of interval training on cardiovascular fitness and fat loss amongst an overweight or obese population. C. Perry, (2008) “In particular, a longer intervention period, as well as a higher work to relief ratio associated with the interval exercise may result in greater improvements in cardiovascular fitness and fat loss”. As the results have shown that interval training appears to be an effective form of exercise when improving aerobic performance and fat loss, (C. Perry, 2008) states that future studies should examine the adoptability and sustainability of a cycling interval training regimen in the overweight and obese population. Furthermore J W. King, et al (2001) indicated that there is a lack of studies investigating high intensity interval training programs as a potential means of weight loss compared with low continuous training. This shows that such research must be conducted to determine if high intensity interval training is a viable means to reduce total body weight and fat mass when in complaisant with low continuous training.
Even though previous studies exist concerning the effect of high intensity interval training on performance, interval training has yet to be assessed in a shorter duration than other studies which look into the effects of interval training. Most studies look into the effects of high intensity interval training over a period of 8 weeks or longer (Jakicic, Marcus, Gallagher, et al. 2004; Mougios, Kazaki, Christoulas, et al. 2006). These studies have found a significant difference when comparing body fat percentage/Body composition and performance (J. King et al, 2001; E. Trapp et al, 2008). However if an high intensity interval training program is shown to produce changes in body weight and body composition in a shorter time than 8 weeks plus, perhaps that type of program would be more appealing to those who have difficulty adhering to longer continuous steady state exercise programs.
3.0 CHAPTER THREE – METHOD
The purpose of this study was to compare the effects of high intensity interval versus low steady state continuous training on weight loss and body composition in overweight population. This section will discuss the subjects, instrumentation, research protocol, and the design and analyses that were used in comparing the effects of the two training methods.
The primary criterion for subject selection will be that all subjects will be clinically overweight and obese, overweight is classified having an body fat percentage of 25%During the testing the subjects were not be allowed to make any conscious changes in their eating habits. The purpose of the study was to determine the effects of high intensity interval and low intensity steady state training protocols on weight loss and physiological adaptations, any changes in energy consumption would have an effect on this data. For this study there were 8 subjects/volunteers, which were randomized into two different groups using randomized software, these groups being high intensity interval and continuous steady state training groups. The 8 subjects will be randomly drawn into high intensity interval training and low intensity steady state training groups though computer software tools which was also agreed with by participants and the university itself.
Prior to the study, all subjects were asked to sign an informed consent form (Appendix A) and Par-Q (Appendix B). The informed consent notified subjects of all potential risks involved, including the possibility of musculoskeletal injury and myocardial infarction (J. King et al, 2001) while the Par-Q gave detailed information about the participants health. The experimental protocol and associated risks were explained orally and in writing form to all subjects before written consent will be obtained. The subjects were told that they would be free to leave the study at any time and that their personal records would be kept confidential.
3.2 Tests and Equipment
Each subject completed a 4 week training program, the subjects were told that they would be free to leave the study at any time and that their personal records would be kept confidential. Prior to the study the subjects/volunteers were asked if they are involved in a structured training program and will be excluded from the study if they don’t meet the criteria.
As this study dealt with the effect of high intensity interval and low intensity steady state training protocols on weight loss, body composition and physiological adaptations, there were be several measures taken. A VO2 max test prior to the study was conducted in order to determine appropriate absolute intensity levels for the subjects. The dependent variables, weight and body composition, was measured at both the beginning and end of the study. Body fat percentage was also recorded both at the beginning and end of the study at similar times in the afternoon.
The most precise way to assess aerobic capacity is the direct measurement of maximal oxygen uptake (VO2max) during a graded exercise test (GXT). However, the direct measurement of VO2max is often limited to laboratory, clinical, and research settings. The requirement to assess aerobic capacity in the general public has led to different development of various field based testing. These tests included the multistage fitness test and 1 mile walk test, previous research by (D J. George et al., 1997; P D. Heil et al., 1995; H M. Malek et al., 2005) reported valid estimates of aerobic capacity when using field based VO2 max testing. The multistage fitness was used in this study due to other commitments where all participants couldn’t arrive at the laboratory’s to conduct the GXT.
The 20-m multi-stage shuttle run test (MSFT) is also known as the Leger test, the beep test, the bleep test (Leger, Mercier, Gadoury, & Lambert, 1988). MSFT (20-m MSFT, Leger et al., 1988; Leger et al., 1989) is often the most used field based fitness test used when testing aerobic capacities of a person, recent study by (Wong et al., 2001; Mota et al., 2002; Guerra et al., 2002; Vicente-Rodriguez et al., 2003; Vicente-Rodriguez et al., 2004) have used the 20-m multistage fitness test for the measurement of aerobic capacity.
The MSFT involved the test subjects to do continuous running in-between two lines which were situated 20 metres apart in time to the recorded beeps. As the test subjects reach the marked line they then stop, turn around by 180° and run in the opposite direction towards the other marked line. The subjects were told they must stop when instructed by a beep from a CD. The starting speed of the MSFT is 8.5 km/h and after about a minute a sound indicates an increase in speed (0.5 km/h per minute) (Leger, A L & Lambert, J. 1982). As the level increase the time it take for the beeps decreases. The test was stopped when a subject was unable to keep up with the pace dictated by the beep sound, and their score was taken. Throughout the test, the participants had to make sure to cover the set distance and touch each line with their foot before proceeding towards the next line.
In order to calculate the predicted VO2 max (predË™VO2 max) for the MSFT an appropriate equations was used (AD Flouris et.al. 2004 & L L´eger, C Gadoury.1989):
â€¢ MSFT: predË™VO2max = MAS Ã- 6.592 âˆ’ 32.678
Each subjects was required to attend the exercise physiology laboratory at Wolverhampton university where their height can be assessed using a stadiometer, their mass be assessed and body fat percentage using bioelectrical impedance. However due to time arrangements participants couldn’t make it to physiology laboratories for testing, therefore the testing was brought to the participants through the portability of the bioelectrical impedance and a portable stadiometer was used to assess the participants height, also they weight was assessed using scales (Seca 769 Upright Scales).
Bioelectrical impedance analysis (BIA) has emerged as one of the most popular methods for estimating relative body fat (National Institutes of Health Technology 1996 & V H. Heyward et al., 1996). BIA was first developed in the 1960s; BIA is also relatively simple, quick and portable and is used in diverse settings, including private clinics and hospitals.
National Institutes of Health Technology (1996) has shown that the BIA method to have approximately the same accuracy as of the skinfold method in a diverse group as also found by (V H. Heyward et al., 1996 & D W. Lockner et al., 1999). Before testing subjects could moderately consume drinks or food, as long as the fluid or food remains within the stomach, not absorbed by body tissue, test results will not be influenced (V H. Heyward et al., 1996). To conduct the BIA all subjects were asked to lie in a supine position on a non-conducting surface, with the arms slightly abducted from the trunk and the legs slightly separated the particular model used was the (Bodystat 1500; Bodystat Ltd, Douglas, UK). The electrodes were placed on the hand and foot of the right side of the body and repeat tests were applied to the same side of the body, new electrodes were employed for each subject. A non-susceptible current then entered the body through the first pair of hand-foot electrodes, and then the second electrode pair is used to determine the voltage drop caused by the body water dependent impedance or total resistance which then determines body fat percentage (V H. Heyward et al., 1996) a few seconds later the test was completed.