Module 3: Cardiovascular Exercise & Diabetes

Module 3: Cardiovascular Exercise Principles - Week 3

• Module focuses on exercise prescription for common chronic conditions, specifically diabetes.
• Learning objectives include defining diabetes, identifying physiological processes involved in blood glucose regulation and contributing factors to high blood glucose levels in type 2 diabetes, identifying treatment goals and justifying exercise's role, describing complications of exercise in diabetics, and designing effective exercise strategies for type 2 diabetes management.

Diabetes

• Chronic metabolic disease characterized by hyperglycemia.
• Results from defects in insulin secretion and/or inability to utilize insulin.
• Types:
  • Type 1: Autoimmune disease causing beta cell destruction in pancreas, stopping insulin production.
  • Type 2: Metabolic disease from insulin resistance in peripheral tissues and defective insulin secretion.
  • Gestational Diabetes: Glucose intolerance during pregnancy due to contra-insulin effects.

Blood Glucose Control

• Blood glucose control is impaired in type 2 diabetes.
• 24-hour blood glucose control was studied by Van Dijk et al. (2015).

Glucose Transport in Skeletal Muscle

• Overview of glucose transport within skeletal muscle.
• Key factors like glucose, blood, insulin, exercise, cytosol, GLUT-4, and vesicles are involved.
• Glucose transport can be stimulated by insulin or exercise.

Prevalence and Diagnosis

• Prevalence of diagnosed diabetes among individuals aged one year and older, by age group and sex in Canada (2014/15) is presented.
• Worldwide prevalence data for diabetes in adults (20–79 years) across Europe, North America and Oceania (2010) is presented.

Diagnostic Criteria

• Diagnostic criteria for diabetes are not provided in the given text.

Type 2 Diabetes: Progressive Development

• Discusses type 2 diabetes care, highlighting insulin-sensitizing agents and implications for cardiovascular disease prevention (1998).

Insulin-Stimulated Glucose Transport

• Elevated glucose circulates, stimulating pancreas to release insulin.
• Insulin binds to receptors on target tissues (e.g., skeletal muscle).
• 50-80% of insulin-stimulated glucose uptake occurs in skeletal muscle.
• 40% of body mass is affected by the process.
• Key proteins involved include IRS, AKT, AS160 and GLUT-4.

Pathophysiology of Insulin Resistance

• Adipose tissue (AT) becomes insulin resistant before skeletal muscle.
• Healthy AT vs. Adipocyte hypertrophy.
• Lipolysis and related factors.
• Effects of excess lipids on insulin signaling, including reactive lipids like diacylglycerols (DAGs) and ceramides.

Diabetic Complications

• Acute complications: Hyperglycemia (manifestations), Hypoglycemia (potential causes), Diabetic ketoacidosis, Hyperglycemic hyperosmolar nonketotic syndrome.
• Chronic complications: Peripheral neuropathies (somatic, autonomic), Nephropathies, Retinopathies, Macro/microvascular complications, Diabetic foot ulcers, and Infections.

Prevalence of hyperglycemia

• Hyperglycemia was present in 13 out of 24 hours in "well-controlled" diabetics.

Exercise Regulation of Glucose

• Acute exercise reduces plasma glucose for an extended timeframe.
• Exercise enhances glucose transport independently of insulin.
• Mechanisms like adenosine diphosphate (ADP), accumulation of calcium (Ca2+), and reactive oxygen species (ROS) are involved in exercise-stimulated glucose transport.

Exercise Prescription in Diabetes

• Goals of exercise training in diabetes include glucose control, prevention of diabetes-related complications, and CVD risk factor reduction.

Exercise Testing in Diabetes

• Recommendations include ECG stress testing for individuals with diabetes who have been sedentary and/or desire vigorous intensity activities.
• Annual CVD risk factor assessments are crucial for detecting silent ischemia, which is commonly undetected in diabetic patients.

Exercise Prescription Recommendations

• Combined endurance and resistance exercise is recommended to develop and maintain cardiorespiratory fitness, body composition, and muscular strength/endurance.
• Food intake adjustments are necessary for individuals on hypoglycemic medications.

Glucose Regulation During Exercise

• Glucose utilization and production are balanced under normal conditions, maintaining glucose homeostasis for individuals without diabetes. However, for individuals with diabetes, there can be imbalances leading to hypo/hyperglycemia.
• During exercise there should be close monitoring of blood glucose levels and carbohydrate intake to prevent hypoglycemia. This applies particularly for individuals who are on insulin or blood sugar lowering drugs

Summary and Key Points

• Key points regarding exercise-stimulated glucose transport and exercise prescription in diabetic patients are discussed.
• Individuals should consider their medication schedule, diabetic complications, exercise goals/benefits, individual training needs, and contraindications during exercise.