Does combining resistance training with aerobic training improve Hemoglobin A1c (HbA1c) levels more than either type of exercise alone in a patient with familial combined hyperlipidemia and borderline high HbA1c?

Combined Aerobic and Resistance Training for A1C Reduction

Combined aerobic and resistance training produces superior A1C reductions compared to either exercise modality alone, with the most recent high-quality randomized controlled trial demonstrating an absolute A1C reduction of -0.51 percentage points for combined training versus -0.38 for aerobic alone and no significant reduction for resistance alone. 1

Primary Evidence for Combined Training Superiority

The definitive evidence comes from a 2007 randomized controlled trial of 251 adults with type 2 diabetes that directly compared all three modalities head-to-head 1:

• Combined aerobic and resistance training reduced A1C by an additional -0.46 percentage points compared to aerobic training alone (95% CI: -0.83 to -0.09) 1
• Combined training reduced A1C by an additional -0.59 percentage points compared to resistance training alone (95% CI: -0.95 to -0.23) 1
• The absolute A1C reduction for combined training versus control was -0.51 percentage points, compared to -0.38 for aerobic alone and -0.16 for resistance alone 1

A subsequent 2010 JAMA trial confirmed these findings, showing that only the combination exercise group achieved statistically significant A1C reductions (-0.34%; P = .03) compared to control, while neither aerobic alone (-0.24%; P = .14) nor resistance alone (-0.16%; P = .32) reached statistical significance 2

Guideline Recommendations Supporting Combined Training

The American Diabetes Association explicitly states that "clinical trials have provided strong evidence for the A1C-lowering value of resistance training in older adults with type 2 diabetes and for an additive benefit of combined aerobic and resistance exercise in adults with type 2 diabetes" 3. The ADA recommends that adults with diabetes should engage in 2-3 sessions per week of resistance exercise on nonconsecutive days, in addition to at least 150 minutes per week of moderate-intensity aerobic exercise 3

The American College of Sports Medicine and American Diabetes Association joint position statement concludes that "combined training thrice weekly in individuals with type 2 diabetes may be of greater benefit to blood glucose control than either aerobic or resistance exercise alone" 3

Meta-Analytic Evidence

Multiple meta-analyses support the superiority of combined training 4, 5, 6:

• A 2024 network meta-analysis found that combining moderate-intensity aerobic exercise with low-to-moderate-load resistance training showed the most significant improvements in A1C (P-score=0.82) among seven different exercise intervention models 4
• A 2011 meta-analysis of 47 RCTs demonstrated that structured exercise training overall reduced A1C by -0.67%, with combined training producing reductions of -0.51% 6
• Structured exercise durations exceeding 150 minutes per week were associated with A1C reductions of 0.89%, while durations of 150 minutes or less produced reductions of only 0.36% 6

Practical Implementation Algorithm

For patients with borderline high A1C (including those with familial combined hyperlipidemia):

1. Prescribe combined aerobic and resistance training as the primary exercise intervention 3, 1

2. Aerobic component: 150 minutes per week of moderate-intensity exercise (40-60% VO2max, equivalent to brisk walking), spread over at least 3 days with no more than 2 consecutive rest days 3, 7

3. Resistance component: 2-3 sessions per week on nonconsecutive days, including at least 5 different exercises involving large muscle groups, performing 10-15 repetitions to near fatigue per set, progressing to 8-10 repetitions with heavier weights 3

4. Total weekly commitment: Approximately 150-180 minutes when combining both modalities 1

5. Break up sedentary time: Interrupt all sitting periods exceeding 30 minutes with brief standing, walking, or light activity for additional glycemic benefits 3, 8

Additional Metabolic Benefits Beyond A1C

Combined training provides superior benefits beyond glycemic control 4, 2:

• The 2024 network meta-analysis showed combined training produced the most significant improvements in BMI (P-score=0.70), body weight (P-score=0.87), total cholesterol (P-score=1.0), and LDL cholesterol (P-score=0.99) 4
• The 2010 JAMA trial demonstrated that only combined training improved maximum oxygen consumption (+1.0 mL/kg/min; P < .05) and reduced fat mass (-1.7 kg; P < .05) compared to control 2
• All exercise groups reduced waist circumference by 1.9-2.8 cm, which is particularly relevant for cardiovascular risk reduction in familial combined hyperlipidemia 2

Critical Pitfalls to Avoid

Do not prescribe aerobic or resistance training alone when combined training is feasible, as the additive benefit is clinically meaningful and statistically significant 1. The absolute difference of approximately 0.5 percentage points in A1C between combined training and single-modality training translates to meaningful reductions in diabetes complications risk 1

Do not allow more than 2 consecutive days without exercise, as insulin sensitivity benefits dissipate within 48-72 hours 3, 8, 7. Daily exercise or alternating aerobic and resistance training on different days maintains continuous metabolic benefits 3

Do not assume that increasing only aerobic exercise duration compensates for lack of resistance training 1. The mechanisms differ: aerobic exercise primarily improves cardiovascular fitness and insulin sensitivity, while resistance training increases muscle mass and glucose disposal capacity 3. Both are required for optimal A1C reduction 1

Do not focus solely on exercise duration while ignoring intensity, as structured exercise exceeding 150 minutes per week at adequate intensity produces nearly 2.5-fold greater A1C reductions (0.89% vs 0.36%) compared to shorter durations 6