Relationship between non-invasive haemodynamic responses and cardiopulmonary exercise testing in patients with coronary artery disease.

BACKGROUND: Non-invasive assessment of haemodynamic function by impedance cardiography (IC) constitutes an interesting approach to monitor cardiac function in patients with coronary artery disease (CAD). However, such measurements are most often performed at rest, whereas symptoms are also possible during exertion, particularly at higher intensities. In addition, the association between IC during exertion and cardiopulmonary exercise testing (CPX) is not well understood in these patients, which was the aim of this study. METHODS: Nineteen men (age = 62 ± 6 years) with CAD [left ventricular ejection fraction (LVEF) = 61 ± 10%] underwent a CPX using an incremental protocol on a cycle ergometer, with simultaneous measurement of IC. Cardiac output (CO), stroke volume (SV), cardiac index (CI), peak oxygen consumption (VO2 ), the oxygen uptake efficiency slope (OUES), circulatory power and ventilatory power were determined. RESULTS: Pearson product-moment correlation analysis revealed peak VO2 (r = 0·46) was significantly related to CO. Peak oxygen pulse (0·52) was associated with SV. OUES was associated with resting SV (0·47) and with peak SV (r = 0·52). CONCLUSION: These findings suggest that IC indices are associated with certain, but not all, established CPX measures in patients with stable CAD.

Low-level laser therapy associated with high intensity resistance training on cardiac autonomic control of heart rate and skeletal muscle remodeling in wistar rats.

BACKGROUND AND OBJECTIVE: Phototherapy plus dynamic exercise can enhance physical performance and improve health. The aim of our study was to evaluate the effect of low-level laser therapy (LLLT) associated with high intensity resistance training (HIT) on cardiac autonomic and muscle metabolic responses in rats. STUDY DESIGN/MATERIALS AND METHODS: Forty Wistar rats were randomized into 4 groups: sedentary control (CG), HIT, LLLT and HIT + LLLT. HIT was performed 3 times/week for 8 weeks with loads attached to the tail of the animal. The load was gradually increased by 10% of body mass until reaching a maximal overload. For LLLT, irradiation parameters applied to the tibialis anterior (TA) muscle were as follows: infrared laser (780 nm), power of 15 mW for 10 seconds, leading to an irradiance of 37.5 mW/cm(2), energy of 0.15 J per point and fluency of 3.8 J/cm(2). Blood lactate (BL), matrix metalloproteinase gelatinase A (MMP(-2)) gene expression and heart rate variability (HRV) indices were performed. RESULTS: BL significantly increased after 8-weeks for HIT, LLLT and HIT + LLLT groups. However, peak lactate when normalized by maximal load was significantly reduced for both HIT and HIT + LLLT groups (P<0.05). MMP-2 in the active form was significantly increased after HIT, LLLT and HIT + LLLT compared tom the CG (P<0.05). There was a significant reduction in low frequency [LF (ms(2))] and increase in high frequency [HF (un)] and HF (ms(2))] for the HIT, LLLT and HIT + LLLT groups compared with the CG (P < 0.05). However, the LF/HF ratio was further reduced in the LLLT and HIT + LLLT groups compared to the CG and HIT group (P < 0.05). CONCLUSION: These results provide evidence for the positive benefits of LLLT and HIT with respect to enhanced muscle metabolic and cardiac autonomic function in Wistar rats.