1. Chapter Overview
Physical activity is not just “good advice”—it is a therapeutic intervention with specific dosages and safety protocols. For the CDE exam, move beyond general encouragement. You need to know the specific frequency, intensity, and type of exercise recommended, as well as the evidence-based strategies to prevent hypoglycemia in Type 1 diabetes (which often appear as clinical scenarios on the exam).
2. Key Messages (The "Gold Nuggets")
The “Dose”: The target is 150 minutes of moderate-to-vigorous aerobic exercise per week.
Consistency Matters: There should be no more than 2 consecutive days without exercise to maintain insulin sensitivity benefits.
Combination is Key: Performing both aerobic and resistance exercise is optimal for glycemic control.
Sedentary Behaviour: Habitual sitting is an independent health risk. Even if a patient exercises daily, prolonged sitting the rest of the day increases mortality risk.
T1D Hypoglycemia: Specific strategies, such as performing resistance training before aerobic training, can stabilize blood glucose.
3. Types of Exercise & Benefits
A. Aerobic Exercise
Definition: Continuous, rhythmic movement of large muscle groups (e.g., walking, cycling).
Benefit (T2D): Improves A1C, triglycerides, and blood pressure.
Evidence: >150 min/week reduces A1C by ~0.89%; ≤150 min/week reduces A1C by ~0.36%.
Benefit (T1D): Lowers mortality and complications; improves fitness.
B. Resistance Exercise
Definition: Brief repetitive exercises with weights, bands, or body weight.
Benefit (T2D): Improves A1C, insulin resistance, and muscular strength.
Optimal Prescription: 3 sets of 8 repetitions, 3 times per week.
C. Interval Training (HIIT)
Definition: Alternating short periods of vigorous effort with recovery.
Benefit: Greater gains in fitness; in Type 1 diabetes, it is associated with less risk of hypoglycemia compared to continuous aerobic exercise.
4. Safety and Screening
Who needs an ECG/Stress Test?
Asymptomatic: Most people do not require medical clearance for low-to-moderate intensity activity.
High Risk: Assessment (resting ECG and possibly stress test) is recommended for people ≥40 years old (or with diabetes duration >15 years T1D / >10 years T2D) who want to undertake very vigorous or prolonged exercise (e.g., competitive racing).
Complications & Exercise
Retinopathy: Proliferative retinopathy should be treated/stabilized before vigorous exercise (risk of hemorrhage).
Neuropathy: Moderate weight-bearing exercise is safe and does not increase ulcer risk (provided there are no active ulcers). Daily inspection of feet is mandatory.
5. Managing Glucose in Type 1 Diabetes (High Yield)
Managing blood glucose around exercise for T1D is a frequent exam topic.
A. Preventing Hypoglycemia
Carbohydrates: Ingest carbs before/during/after exercise.
Insulin Adjustment:
Reduce prandial (bolus) insulin by 25% to 75% for meals preceding exercise.
Reduce basal rates (CSII) or suspend basal (only if the activity is ≤45 minutes).
Reduce overnight basal by ~20% to prevent nocturnal lows.
Exercise Order: Perform Resistance exercise BEFORE Aerobic exercise. This sequence keeps blood glucose more stable than the reverse.
Sprinting: A brief (10-second) maximal sprint can raise blood glucose (via counter-regulatory hormones) to counter a drop.
B. Hyperglycemia & Ketones
The Rule: If BG >16.7 mmol/L + Unwell? -> Test Ketones.
Positive Ketones: Postpone vigorous exercise; administer insulin.
Negative Ketones: Exercise is generally safe (ensure hydration).
6. Diabetes Canada Clinical Practice Guidelines Recommendations
These are the “Must Memorize” graded recommendations for the exam.
Aerobic Target: Accumulate a minimum of 150 minutes of moderate-to-vigorous aerobic exercise per week, spread over at least 3 days, with no more than 2 consecutive days without exercise.
Grade B, Level 2.
Resistance Target: Perform resistance exercise at least 2 times per week (preferably 3).
Grade B, Level 2.
Sedentary Time: Minimize sedentary time and periodically break up long periods of sitting (e.g., every 20-30 mins).
Grade C, Level 3.
T1D Strategies: To reduce hypoglycemia in Type 1 diabetes:
Reduce bolus/basal insulin.
Perform brief (10s) maximal sprints.
Perform resistance exercise before aerobic exercise.
Grade D, Level 4.
Screening: People ≥40 years wishing to undertake very vigorous exercise should be assessed for adverse event risk.
Grade D, Consensus.