Effects of Exercise Duration and Intensity on Maximal Exercise Capacity Over 6 Months in Coronary Heart Disease and Type 2 Diabetes—A Secondary Analysis of the <scp>LeIKD</scp> Trial

Exercise training is recommended in coronary heart disease (CHD) and type 2 diabetes (T2DM) patients alike; however, uncertainty remains on the influence of exercise intensity and duration in older patients with both entities. To address this, we performed a secondary analysis including 201 patients (67.9 ± 8.2 years; 84.1% men) from the LeIKD trial (NCT038359), which introduced 6 months of home-based telemedicine-supported exercise intervention in patients with CHD and T2DM. We assessed the relationships between exercise duration and intensity with change in peak oxygen uptake (V̇O₂peak) (simple and multiple regression analyses, α = 0.05). V̇O₂peak increased by 0.42 mL/kg/min per hour of endurance exercise/week (95% CI: 0.17-0.66, p = 0.001). Exercise intensity was not significantly associated with the change in V̇O₂peak (p = 0.10). In a subgroup of patients with high adherence (≥ 66.7% of prescribed total duration and meeting prescribed exercise duration in ≥ 50% of weeks of intervention), a 10% increase in exercise intensity (mean % heart rate reserve (HRR)) was associated with an increase in V̇O₂peak of 0.26 mL/kg/min (95% CI: 0.00-0.52; p = 0.05). Longer training duration within the initial 2 weeks of intervention was significantly associated with high adherence over 6 months (increased likelihood per 10 min/week: OR of 1.09 [95% CI: 1.05-1.14], p < 0.001). Therefore, exercise duration but not intensity influences changes in V̇O₂peak during exercise intervention in a high-risk population of older patients with CHD and T2DM. In patients with high adherence to exercise duration, higher exercise intensity led to an additional increase in V̇O₂peak. Training duration within the first 2 weeks was an important predictor of long-term adherence. Trial Registration: https://www.clinicaltrials.gov: Identifier: NCT038359.