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Chapter 3 Effects of Progressive Resistance Training (PRT) on Glycosylated Haemoglobin (HbA1c) and Lipid Profiles in Participants with Type 2 Diabetes Mellitus.
Abstract
Background: The influence on different types of exercise on risk factors for cardiovascular diseases have rarely been investigated in south African setting, however numerous trials worldwide have demonstrated that supervised resistance training may be a viable effective exercise modality for the improvement of glycaemic control and lipid profiles in persons type 2 diabetes mellitus.
Aims: The purpose of the study was to determine the efficacy of a 20 week progressive resistance training (PRT) and a dietary education programme on baseline blood glucose and lipid profiles in a cohort of 80 male and female type 2 diabetics from ages 40-65 years. Participants were of African heritage and were recruited in a resource-poor setting from the outpatients’ clinic at the Mamelodi Hospital in Gauteng, South Africa.
Methods: A randomised controlled trial design was adopted for the study. Subjects were assigned to a PRT group (n=40) and control group (n=40). Participants in the PRT group were exposed to progressive resistance training and dietary education whilst the control group (CT) where only exposed to dietary education. The outcome measures entailed an assessment of glycosylated haemoglobin (HbA1c), high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglycerides (TG) and total cholesterol (TC) count.
Conclusion: The PRT and dietary education program combined failed to show a better improvement in metabolic parameters, than a dietary education program alone. Although this study failed to demonstrate a statistically significant change of at least 1% in the HbA1c it is important to note that even the 0.5% difference achieved, can be considered as clinically significant. PRT needs to be of sufficient frequency and intensity to be effective as a treatment modality in persons with type 2 diabetes.
Keywords: Resistance training, glycosylated haemoglobin (HbA1c), Lipid Profile, Type 2 diabetes mellitus, community setting.
Introduction
Diabetes Mellitus (DM) is a chronic disorder of carbohydrate, fat and protein metabolism. DM represents a heterogeneous group of disorders that have hyperglycemia as a common feature which is often associated with poor lifestyle and obesity [1, 2]. The incidence of type 2 DM is increasing markedly in adult populations around the world [3]. As populations age and become urbanised, and as obesity becomes more prevalent [4, 5], the incidence of type 2 DM rises. The striking epidemiological features of type 2 DM is the wide variation in population and individual prevalence and the strong positive correlation with relative body fat [6, 7] as well as socio-economic deprivation which, in turn, is associated with poor diet and other adverse lifestyle factors [8]. The main underlying factors associated with type 2 DM include genetic and environmental factors. These factors are urbanisation and industrialisation, increased longevity and changes in lifestyle from a traditional healthy and active way of life to a modern, sedentary and stressful life characterised by the overconsumption of energy-dense food [3].
The key factor in managing body weight is energy balance. When energy expenditure equates to energy intake, body weight is maintained, thus preventing initial weight gain or weight regain after weight loss. To promote weight loss it is necessary to create an energy imbalance that elicits an energy deficit. Structural physical activity contributes to energy deficit by increasing total energy expenditure, which thus promotes weight loss [9].
All patients with type 2 DM require active dietary management because this is an essential component of successful diabetic care [10, 11]. Dietary control involves balancing complex issues and needs, that are tailored to lifestyle, cultural and religious customs and to the overall diabetic management strategy of each individual patient [11]. There are three important goals related to dietary habits, i.e. essential nutrition, prevention of vascular complications and adaptation to metabolic problems. An optimal diet should provide all the essential nutrients bearing in mind that the person with type 2 DM needs the same essential nutrients as the general population. A balanced diet aims to reduce central obesity improve serum lipid profile and lower blood pressure, all of which contribute to increased morbidity and mortality in a person with diabetes [12]. Food intake in type 2 DM patients must be balanced with exercise and hypoglycemic treatment [13], to avoid the twin perils of hypoglycemia and hyperglycemia. Most patients with type 2 DM are overweight; therefore they need to limit their energy intake.
Glycated haemoglobin provides an accurate and objective measure of glycaemic control over a period of weeks to months. Components of adult haemoglobin (HbA1) can be separated from unmodified haemoglobin (HbA0) by ion-exchange chromatography, and these haemoglobin moieties are increased in diabetes by the slow non-enzymatic covalent attachment of glucose and other sugars (glycation) The rate of formation of glycated haemoglobin is directly proportional to the ambient blood glucose concentration; a rise of 1% in glycated haemoglobin corresponds to an approximately 2 mmol/l increase in average blood glucose. Glycated haemoglobin concentration reflects integrated blood glucose control over the lifespan of the erythrocytes (120 days). Estimation is weighted by changes in glycaemic control occurring in the month before measurement (representing 50% of the glycated haemoglobin concentration). When initially diagnosed, type 2 DM can be controlled with diet and exercise because both contribute to weight loss. As weight is reduced insulin receptor numbers increase and insulin resistance is diminished. Exercise also contributes to weight loss by creating an increased demand for glucose in skeletal muscle and exercise promoting an increase in insulin receptors [15].
Strict blood glucose control in type 2 DM is essential because this is a critical factor in reducing the risk of chronic diabetic complications [13]. Research has suggested that in addition to good dietary habits, exercise is one of the cornerstones of DM management [16]. Exercise is often seen as a desirable means to manage excessive weight gain associated with type 2 DM and for its beneficial effect in increasing insulin sensitivity. Because muscle is a major site for insulin-induced glucose disposal and because muscle responds to exercise training, it is reasonable to assume that such changes in muscle tissue might contribute to reduced insulin resistance in people with type 2 diabetes [17-19]. Exercise can have both long-term and short-term effects on insulin action. A strenuous session of exercise improves muscle glucose transport, which reverses rapidly when exercise is stopped [20]. This is then replaced by a marked increase in the sensitivity of the receptors to insulin [21]. The exercising muscle may increase the uptake of glucose by 7 to 20 fold during the first 30-40 minutes, depending on the intensity of the exercise session. Insulin receptors thus become more sensitive to the lower amount of insulin available during exercise. This improvement in insulin receptor sensitivity can last for many hours after the exercise bout is over, even for as long as 2 days if the exercise session was of sufficient intensity and duration [22].
Exercise and Insulin Sensitivity
Bjorntorp and colleagues [23], suggested the use of physical exercise to treat the insulin resistance associated with obesity and type 2 diabetes. They [23] have noted that active middle-aged men had significantly lower fasting insulin concentrations and lower insulin responses to oral glucose than untrained men of the same age and body weight. These findings suggested that regular physical activity is associated with increased insulin sensitivity which led them to study the effects of physical training in obese patients with normal glucose tolerance but insulin resistance. After 12 weeks of moderate intensity aerobic exercise (30-60 minutes, 5 days/week), there was no change in the subjects blood glucose responses but insulin levels were significantly lower, both fasting and following glucose administration [24]. The increase in insulin sensitivity and responsiveness associated with physical conditioning rapidly disappears when exercise is discontinued. Burstein et al. [25], found that much of the effect is gone within 60 hours; other researchers demonstrated that the effect is no longer present after 5 to 7 days without exercise.
Mikines and associates [26], observed that a single bout of aerobic exercise increased the sensitivity and responsiveness of insulin-stimulated glucose uptake in untrained individuals. The effect lasted 2 days but was not observed after 5 days. In addition, physically trained individuals (as compared to untrained individuals) had increased individual action 15 hours after their last training session. Five days after their last training session, insulin responsiveness remained elevated compared with that of untrained subjects, suggesting that training results in a long-term adaptative increase in whole-body responsiveness to insulin [27]. Although the mechanism of this increase is not known, it may be related to increased capillary density in skeletal muscle, enhanced oxidative capacity or other adaptive capacity of skeletal muscle and to other adaptations to training such as elevated skeletal muscle GLUT 4 content [28]. An increase in insulin-stimulated glucose uptake can last 5 to 7 days following cessation of exercise in previously trained subjects, patients with type 2 DM do not have improved fasting blood glucose concentrations during this same period. Some researchers have observed that physical training is associated with lower glycosylated hemoglobin levels [29]. The cumulative result of decreased blood glucose concentrations during and after aerobic exercise rather than a specific effect of physical training is of importance. Since moderate-intensity aerobic exercise usually lowers blood glucose concentrations towards normal in hyperglycemic patients with type 2 diabetes, and since increased insulin-stimulated glucose disposal persists for many hours following a single bout of exercise, it is likely that regular exercise 4 to 7 days a week may decrease blood glucose and glycohemoglobin concentrations without a significant effect on fasting blood glucose or glucose response to meals. The net effect of exercise repeated on a regular basis would improve long-term glucose control in patients with type 2 diabetes [30].
Effects of Exercise on Lipid Control
Regular physical activity leads to reduced risks of cardiovascular disease [31, 32], an effect which is likely due to the beneficial effect on lipid metabolism [32]. Physical inactivity has adverse consequences on cardiovascular risk, due to the detrimental effects on serum lipoprotein concentrations. There are a number of studies that have considered the effects of exercise on lipid profile but there seems to be some uncertainty as to how much exercise is sufficient for health benefits and how much inactivity acts to worsen risk profiles [33]. Research done by Slentz et al. [32], referred to as the STRIDDE study (Studies Targeting Risk Reduction Interventions through Defined Exercise) examined one of many factors dealing with the effects of different amounts and intensities of exercise training on lipoproteins
It was noted that many of the beneficial effects of exercise on lipids and lipoprotein was not observed in the typical lipid profile, but rather it was observed in the effects of exercise on the particle size and particle number. This was an important finding in that the concentrations of low density lipoprotein (LDL) particles, large high density lipoprotein (HDL) particles and large very low density lipoprotein (VLDL) particles are better indicators of cardiovascular risk than are the elements of the traditional lipid profile [34, 35]. In diabetes the plasma cholesterol level is usually elevated and this plays an important role in the development of atherosclerotic vascular disease which is a long term complication of diabetes in humans. The rise in plasma cholesterol level is due to an increase in the plasma concentration of VLDL and LDL [36]. The most common pattern of dyslipidaemia is hypertriglyceridemia and reduced HDL cholesterol levels. DM in itself does not increase levels of LDL, but the small dense LDL particles found in type 2 DM are more arterogenic because they are more easily glycated and susceptible to oxidation [37]. Physical training is associated with a decrease in serum triglycerides levels, particularly very low density lipoproteins, and an increase in high density lipoproteins-2 cholesterol [38].
The American College of Sports Medicine [39, 40] advises a combination of both aerobic and resistance training as part of an exercise regime. In general exercises with higher intensities are associated with poorer compliance [41]. Post-intervention compliance with lifestyle activity involving high intensity aerobic programmes is poor. Furthermore, aerobic training is not ideal for many type 2 patients because of advancing age, obesity and other co-morbid conditions [6, 42, 43]. On the other hand, resistance training leads to improved glycosylated haemoglobin (HbA1C) levels [44] and increases in lean body mass [45-47]. Although this mode of exercise is generally safe, it is often erroneously neglected or absent from exercise programmes. Resistance training has additional benefits apart from improving glycaemic control and insulin sensitivity, such as building muscle mass, strength, endurance and mobility. Circuit-type resistance training thus appears to be a feasible and effective therapeutic modality in moderately obese, sedentary patients with type 2 DM [42].
Aims
The primary focus of this research was to establish the effectiveness of a progressive resistance exercise and dietary education intervention programme on baseline HbA1C and lipid profiles in a cohort of African participants with type 2 DM.
Hypothesis
To implement a progressive resistance training intervention programme and to establish its efficacy based on the primary and secondary hypothesis.
Primary Hypothesis:
The implementation of a progressive resistance training programme would decrease the glycosylated haemoglobin (HbA1c) by 1% given a standard deviation of 2.23% with α=0.05 and β=0.10 in a sample of 80 participants comprising of males and females with type 2 DM.
Secondary Hypothesis:
The implementation of a progressive resistance training programme would yield a significant change in lipid profile comprising low-density lipoprotein, high-density lipoprotein, total cholesterol and triglycerides.
Material and Methods
Participants
The study was undertaken in Mamelodi, a suburb in the City of Tshwane Metropolitan Municipality in the province of Gauteng, South Africa. The participants (n=80) included black male (6=control group and 11=exercise group) and female (34=control and 29=exercise group) participants from 40-65 years with type 2 DM without complications and a known duration of the disease for at least one year.
Most participants were recruited from the outpatient clinic at the Mamelodi government hospital whilst they were waiting to be seen by a doctor. Participants were also recruited from local churches in the Mamelodi area. Participants were excluded according to the following criteria: Cardiovascular contraindications: Unstable angina, untreated severe left main coronary artery disease, angina, hypotension or arrhythmias provoked by resistance training, acute myocardial infarction, end-stage congestive heart failure, severe valvular heart disease, malignant or unstable arrhythmias, large or expanding aortic aneurysm, known cerebral aneurysm, acute deep venous thrombosis, acute pulmonary embolism or infarction, and recent intracerebral or subdural hemorrhage; Musculoskeletal contra-indications: Significant exacerbation of musculoskeletal pain with resistance training as well as unstable or acutely injured joints, tendons or ligaments, fracture within the last 6 months (delayed union) and acute inflammatory joint disease; Other contra-indications: Rapidly progressive or unstable neurological disease, failure to thrive, terminal illness, uncontrolled systemic disease, symptomatic or large abdominal or inguinal hernia, hemorrhoids, severe dementia/behavioural disturbance, acute alcohol or drug intoxication, acute retinal bleeding, detachment/severe proliferative diabetic retinopathy, recent ophthalmic surgery, severe cognitive impairment, uncontrolled chronic obstructive pulmonary disease, prosthesis instability, severe (readings: systolic >160 mmHg and diastolic >100 mmHg) and malignant hypertension, as well as signs and symptoms suggestive of immuno-suppression.
Declaration
Dedication
Acknowledgements
Table of Contents
List of Tables
List of Figures
List of Appendices
Publications and Presentations arising form this study
CHAPTER 1: GENERAL INTRODUCTION
1.1 Background, prevalence, impact and aetiology of Diabetes Mellitus (DM)
1.2 General Exercise Guidelines in Type 2 DM
1.2.1 Guidelines for General Exercise Training and Prescription: Effects on the Exercise Response
1.2.2 General Recommendations for Exercise Prescription
1.3 General Effects of Acute Exercise in Patients with type 2 DM
1.3.1 Blood Glucose Levels and Insulin Sensitivity
1.3.2 Hormone levels
1.3.3 Glucose Transport
1.4 General Long Term Effects of Exercise in Patients with type 2 DM
1.4.1 Metabolic Control and Insulin Sensitivity
1.4.2 Body Weight
1.4.3 Cardiovascular Risk Factors
1.5 Resistance Training for the Management of Type 2 DM
1.6 Statement of the Problem
1.7 Significance of the Study
1.8 Aims of the Study
1.9 Research Objectives
1.10 Delimitations of Research
1.11 Structure of the Thesis
1.12 References
CHAPTER 2: HABITUAL PHYSICAL ACTIVITY AMONG AN AFRICAN COHORT OF TYPE-2 DIABETICS IN A SOUTH AFRICAN RESOURCE-POOR COMMUNITY SETTING
2.1 Introduction
2.2 Materials and methods
2.2.1 Participants
2.2.2 Ethical Clearance
2.3 Study Design
2.4 Instrumentation
2.5 Statistical Analysis
2.6 Results
2.7 Discussion
2.8 References
CHAPTER 3: EFFECTS OF PROGRESSIVE RESISTANCE EXERCISE ON GLYCOSYLATED HAEMOGLOBIN (HBA1C) AND LIPID PROFILES IN PARTICIPANTS WITH TYPE 2 DIABETES MELLITUS
3.1 Introduction
3.2 Aims
3.3 Hypothesis
3.3.1 Primary Hypothesis
3.3.2 Secondary Hypothesis
3.4 Methods and materials
3.4.1 Participants
3.4.2 Design, Randomisation and Procedures
3.5 Ethical Clearance
3.6 Intervention Programme
3.6.1 Dietary Intervention
3.6.2 Exercise intervention
3.6.3 Clinical Parameters
3.7 Sample Size
3.8 Statistical Analysis
3.9 Results
3.10 Discussion
3.11 References
CHAPTER 4: THE EFFICACY OF A 20-WEEK PROGRESSIVE RESISTANCE TRAINING (PRT) PROGRAMME ON MORPHOLOGICAL, MUSCULOSKELETAL AND AEROBIC FITNESS IN SUBJECTS WITH TYPE-2 DIABETES MELLITUS
4.1 Introduction
4.2 Aims
4.3 Hypothesis
4.4 Material and Methods
4.5 Ethical Clearance
4.6 Intervention Programme
4.7 Sample Size
4.8 Physical Parameters
4.9 Statistical Analysis
4.10 Results
4.11 Discussion
4.12 References
CHAPTER 5: INFLUENCE OF A DIETARY EDUCATION PROGRAMME ON DIABETES CARE KNOWLEDGE AND ACTIVITIES AMONG TYPE-2 DIABETICS
5.1 Introduction
5.2 Materials and methods
5.3 Ethical Clearance
5.4 Study Design and Sampling
5.5 Intervention Programme
5.6 Instrumentation
5.7 Statistical Analysis
5.8 Results
5.9 Discussion
5.10 References
CHAPTER 6: SUMMARY, GENERAL CONCLUSIONS AND RECOMMENDATIONS
6.1 Brief Description of the Study
6.2 Main Findings
6.3 General Conclusions
6.4 Recommendations for Future Research
6.5 Recommendations for Practice
6.6 References
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