الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 120 |  |  |
| | | from | 120 | | |
Abstract
Overweight and obesity levels have escalated worldwide, and these trends are occurring in both developed and developing countries. It has been estimated that nearly 30% of the world’s population are either overweight or obese nowadays.
Most exercise protocols designed to induce fat loss have focused on regular steady state exercise such as walking and jogging at a moderate intensity. Disappointingly, these kinds of protocols have led to negligible weight loss. Thus, exercise protocols that can be carried out by overweight/obese inactive individuals that more effectively reduce body fat are required. Accumulating evidence suggests that HIIT has the potential to be an economical, effective and time efficient exercise protocol for reducing fat of obese individuals.
The present study compared MIT to HIIT as part of a twelve week diet and exercise program for 90 overweight/obese women divided into two groups of 45 each,this cohort composed exclusively of females could be considered as a strength of the study in comparison to the majority of HIIT data evaluating mixed samples, or men only. Nutrition Intervention was conducted in the form of nutrition education sessions and modest calorie restriction (~500 kcal/day) for both experimental groups.
The present study was carried out in HIPH Integrated Health clinicand two private gyms. The study was conducted from November 2018 to April 2019.The study was conducted on two phases:
1. Pre-assessment baseline phase: wasto answer a pre-designed questionnaire including socio- economic data, disease history, dietary habits, lifestyle habits and Physical activity level.Laboratory investigations were carried out for every subject in the two groups regarding fasting plasma glucose, fasting Insulin and HOMA-IR and Serum Cholesterol,triglycerides, LDL-C andHDL-C. Body composition parameters body weight, total body fat and lean body mass were analyzed. Anthropometric measurements were taken in the form of waist, hip, mid-arm circumferences and triceps skin fold thickness.
2- Interventional phase:was for 12 weeks in the form of diet and exercise program where the candidates of each experimental group were subjected to nutritional intervention in the form of individualized nutritional counseling session and nutrition education sessions. Each subject was given a simple meal plan for a calorie restricted diet according to her energy requirements based on the guidelines recommendations. Body composition analysis andanthropometric measurements were measured at the beginning, at the 6th week and at the end of the study.
The exercise program:
1- The MIT group candidates followed the standard routine exercise prescription in the obesity / overweight treatment which is brisk walking 5 times per week 30 minutes each. (Moderate intensity exercise at 65%VO2max).
2- Each subject recruited in the HIIT group had a fitness test (4-7 minutes) before and after the 12 week program. The HIIT protocol consisted of 6 short (30 s), 10 medium (60 s), and 15 long (90 s) intervals during the first, second, and third month respectively progressed from 75%to 100% VO2max including exercises involving different body parts.
3- The final assessment was done after the end of the 3rd month to measure the change body composition analysis, anthropometric measurements and laboratory investigations.
The collected data were statistically analyzed and results can be summarized as follow: The mean age of the studied sample was 29.8 6.5 and 31 6.7 years in HIIT and MIT groups respectively. Of the study population, 42.3% were single, 36.9% were married and 1.8% were divorced. While 45.9% were professional, 13.5% were student and 21.6% were housewives.
The median duration since the previous weight loss trial was 6 months in the HIIT group while it was 12 months in the MIT group indicating the higher personal motivation level and weight consciousness in the HIIT group. Moreover, the MIT subjects were 77.8% using screens more than 3 hours per day while the HIIT group were only 46.7%. Additionally, in the MIT group 66.7% of the candidates reported daily intake of high caloric snacks while 53.3 % had occasional intake of 1 to <3 times per weekin the HIIT group, also 57.8% of the MIT group subjects reported to have their previous weight loss trials with a specialist in contrary to the 42.2% of the HIIT candidates who reported to have it by themselves.
Furthermore, the PAI was 51 % inactive in the MIT group in comparison to 40% in the HIIT group indicating again the level of health and exercise awareness and motivation. Finally, psychological causes as boredom, loneliness and lack of motivation were the most frequent reported causes of weight loss trials failure representing 80% in the MIT group and 60 % in the HIIT group.
The study also revealed after12 weeks (interventionphase), a significant decrease in both groups, in body composition, anthropometry and laboratory parameters, with higher results in the HIIT group. Regarding the weight in the HIIT group decreased by 11.74 ± 3.19 Kg while decreased by 6.44 ± 2.87in the MIT group. The body fat mass in the HIIT group fat mass showed a decrease by 13.92 ± 4.84% and only by 6.54 ± 7.57% in the MIT group.As for lean body mass, a significant decrease in by 3.27% in the MIT group while HIIT group almost kept the same lean body mass. Regarding the VO2max, there was a significant increase (3.12%) is achieved in the HIIT group by the end of the study. The waist circumference also showed a decrease in the HIIT group by 8.24 ± 2.94% and a lesser one (4.53 ± 8.76 %) in the MIT group denoting the higher effect of HIIT on visceral adiposity.
Concerning metabolic parameters, fasting plasma glucose,fasting plasma insulin and HOMA-IR decreased by 4.26 ± 4.89 %, 19.43 ± 18.95 % and 39.0 ± 19.20 % respectively in the HIIT group and by 2.69 ± 4.77 %, 6.04 ± 12.61% and 12.80 ± 38.54 % respectively in the MIT group.
With regard to lipid profile, a significant decrease in plasma total cholesterol (-8.13%), LDL cholesterol (-13.95%) and triglycerides (-4.92) while(-4.93%), (-7.62%) and(-2.38%) respectively in the MIT group. Both types of exercise increased the HDL-cholesterol significantly but a higher level (almost 25%) was achieved in HIIT group in comparison to 8% in the MIT group.
The present study results demonstrated that both training types at moderate and high intensity were beneficial to body mass loss and decrease the total fat mass of young obese women. Recommending HIIT consists of influencing some of at least 9 variables (e.g. work interval intensity and duration, relief interval intensity and duration, exercise modality, number of repetitions, number of series, between-series recovery duration, and intensity) in addition to minimal time commitment with more pleasure during training. This could be one of the causes why HIIT has a dramatic effect on insulin sensitivity and blood lipids in addition to cardiorespiratory endurance. So, the present data allow concluding that HIIT could bemore appealing to individuals interested in fat reduction and could be used as an efficient and safe strategy to prevent obese females from being affected by several diseases but the use of it must beindividualized.
6.2. Conclusions
According to the results provided from the baseline assessment, participants in the HIIT group exhibited a reproducible results across the 12 week program from a sedentary behavior in the majority of metabolic and physiological factors indicating that any subsequent changes observed, in comparison to that of MIT, were in all likelihood a result of effects stemming from the HIIT intervention.
After the supervised highly motivating HIIT exercise for 3 times per week for 12 weeks, the HIIT group reported a significant decrease in weight, body fat mass, visceral adiposity with maintained lean body mass. In addition to, a significant increase in the cardiorespiratory endurance. Regarding the metabolic parameters, there were statistically significant reductions in total cholesterol, LDL-C, triglycerides, fasting plasma glucose, Insulin and HOMA-IR while there was a significant increase in the HDL-C.
When all these results were compared with these of the MIT group, although they were significant too, except for the significant loss of the lean body mass, the HIIT group results were higher, which could be attributed primarily to the effect of the type of exercise as HIIT or MIT.
Since both exercise protocols have been proved as useful to reduce body weight, the decision on the intensity of exercise prescription should be individualized and based on outcomes different from fat or weight loss. In this regard, HIIT appears to induce improvements in cardiorespiratory endurance and similar improvements in some cardio-metabolic risk factors in comparison to MIT. Certainly, this improvement in cardio-respiratory endurance is a valuable outcome because it has a significant inverse relationship with all causes of risk of death in obese or type 2 diabetes subjects.
Moreover, for some persons introducing submaximal short repeats in the exercise schedule and the game-like nature of interval training makes it an attractive alternative to MIT and represents a stimulus that diminish the boring aspects of a constant exercise session and augments the long term adherence to regular exercise. On top of that, the importance of the substantially less time commitmentHIIT requires compared to MIT.
In the contrary, before prescribing HIIT the potential risk of injuries or acute cardiovascular events should also be carefully considered especially in obese population.
Finally, the importance of person’s diet and nutritional aspects (with exercise intervention) for body composition, insulin sensitivity and lipid profile improvements in obese women should be underlined.
In conclusion, judging from the array of positive and beneficial findings that were observed in this interventional study, there is sufficient evidence to suggest that the HIIT concept can positively impact upon the weight loss profile and the metabolic profile of overweight and obese adult women better than the standard exercise prescription used in the obesity treatment although both were significantly effective except for the loss of the lean body mass in the MIT group in comparison to its preservation in the HIIT group. Additionally, HIIT’s benefit in improving cardiorespiratory endurance, and its feasibility and tolerance by obese persons should be highlighted.
6.3. Recommendations
To promote proper weight loss in the form of fat mass loss and preservation of the lean body mass in adult overweight/ obese women based on the results of the present study, the recommendations are as follows:
1. Individually tailored life-style recommendations contribute to better long term outcomes of the treatment of metabolic diseases so should be promoted as the single and effective treatment strategy. NO lifestyle recommendation fits all.
2. The present study findings can have ramifications for public health messages and future obesity management strategies because of the reduction in obesity related health risks that stem from the significant loss of abdominal visceral adipose tissue in the HIIT group.
3. The importance of the integration between the fitness /exercise coach role in raising the fitness awareness, motivation level, and supervision of the validity of the training in addition to that of the nutrition specialist in the education, monitoring and tailoring the diet suitable to the energy needs of the person in implementing the obesity treatment strategies.
4. Measuring the VO2max during training and adjust the workload accordingly to represent the subjects’ improving fitness.
5. Studying the effect of HIIT on normal weight adults’ males or females.
6. With increasing numbers of overweight/obese children and adolescents, it is important to identify which activities are most beneficial for this group to take part in. The value of HIIT could be tested in this population.
7. It would be beneficial to study the effect of HIIT on the metabolic profiles of lifestyle induced chronic diseases like Diabetes mellitus, hypertension and cardiovascular diseases.
8. Promotion of the change to the healthy lifestyle and the need for a framework for policy makers, advocacy groups, researchers, clinicians, communities, and other stakeholders to understand and implement the most effective approaches. New strategic initiatives and partnerships are needed to translate this evidence into action.