Altered cardiac contractility and aerobic muscular capacity markers during exercise in patients with obesity and DMT II

Abstract

Background: Impaired exercise capacity influences obesity and diabetes disease progression and vice versa. The primary objective of this prospective, observational, real-world study was to characterize exercise capacity in patients with obesity or type II diabetes mellitus and healthy controls by cardiac capacity (cardiac output (CO), cardiac power output (CPO)) and peripheral muscle capacity (peak power output (Pmax) and arterio-venous oxygen difference (avDO2)). The effects of an exercise and lifestyle intervention on these cardiac and peripheral muscular markers in obese and diabetic patient groups were additionally evaluated.

Methods: At a university sports medicine outpatient clinic, 24 obese (OB) and 38 diabetes mellitus type II (DM) patients and 20 healthy controls (HE) were investigated in a cross-sectional analysis. OB and DM were reexamined after a standard of care exercise intervention. Parameters were assessed at rest and during a cardiopulmonary exercise test (CPET). Blood pressure, impedance cardiography, and respiratory gas analysis were continuously recorded during CPET.

Results: At Pmax, CO and CPO were lower in DM compared to obese (CO 16.26 l/min vs. 18.13 l/min, p < 0.04; CPO 5.67 W vs. 4.81 W, p < 0.01). HE did not differ in CO (18.19 l/min)) or CPO (5.27 W) from OB and DM. Maximum CPO in OB and DM was based on higher stroke volume and blood pressure, while HE had higher heart rates. Pmax was higher (p < 0.01) in HE (268 W) compared to OB (108 W) and DM (89 W), mainly caused by a higher (p < 0.01) avDO₂ (HE 18.22 ml/dl, OB 10.45 ml/dl, DM 9.65 ml/dl). Exercise intervention improved Pmax in both groups of patients (+ 16 W in OB, + 12 W in DM), which was attributed to increased avDO₂, but not to cardiac parameters.

Conclusions: Obese patients had higher cardiac power outputs and were primarily limited by muscular performance, while diabetic patients showed both muscular and cardiac limitations. Healthy subjects had comparable cardiac power outputs with significantly lower pressure-volume loads. Resistance training improved the alteration of our patient groups in exercise capacity. Future research is needed to interpret our findings regarding clinical endpoints, such as mortality and hospitalization.

Trial registration: The study was retrograde registered in the German Clinical Trial Register (DRKS00032545, 24.08.2023).

Keywords: Cardiac power output; Diabetes; Exercise performance; Muscle; Obesity; Oxygen consumption; Stroke work.

Fig. 1

Study Flow Chart. Examination on days 1 and 3, 2 and 4 were identical. 3 Examination days 3 and 4 were only carried out for patients of the longitudinal data analyses in the study cohort. ECG: Electrocardiogram, CPET: Cardiopulmonary exercise test,

Fig. 2

Correlation between maximum oxygen consumption and CO (black dot) and avDO₂ (gray square) in (A) healthy subjects, (B) obese patients and (C) DMTII patients; correlation between maximum oxygen consumption and stroke work (black empty triangle) and cardiac power output (gray triangle) in (D) healthy subjects, (E) obese patients and (F) DMTII patients, r = correlation coefficient, *= significant correlation