Effects of inspiratory muscle-training intensity on cardiovascular control in amateur cyclists

Chronic effects of inspiratory muscle training (IMT) on autonomic function and baroreflex regulation are poorly studied. This study aims at evaluating chronic effects of different IMT intensities on cardiovascular control in amateur cyclists. A longitudinal, randomized, controlled blind study was performed on 30 recreational male cyclists undergoing IMT for 11 wk. Participants were randomly allocated into sham-trained group (SHAM, n = 9), trained group at 60% of the maximal inspiratory pressure (MIP60, n = 10), and trained group at critical inspiratory pressure (CIP, n = 11). Electrocardiogram, finger arterial pressure, and respiratory movements were recorded before (PRE) and after (POST) training at rest in supine position (REST) and during active standing (STAND). From the beat-to-beat series of heart period (HP) and systolic arterial pressure (SAP), we computed time domain markers, frequency domain indexes in the low frequency (0.04–0.15 Hz) and high frequency (HF, 0.15–0.4 Hz) bands, an entropy-based complexity index (CI), and baroreflex markers estimated from spontaneous HP-SAP sequences. Compared with SHAM, the positive effect of MIP60 over the HP series led to the HF power increase during REST (PRE: 521.2 ± 447.5 ms2; POST: 1,161 ± 878.9 ms2) and the CI rise during STAND (PRE: 0.82 ± 0.18; POST: 0.97 ± 0.13). Conversely, the negative effect of CIP took the form of the decreased HP mean during STAND (PRE: 791 ± 71 ms; POST: 737 ± 95 ms). No effect of IMT was visible over SAP and baroreflex markers. These findings suggest that moderate-intensity IMT might be beneficial when the goal is to limit cardiac sympathetic hyperactivity at REST and/or in response to STAND

Arterial stiffness in type 2 diabetes: determinants and indication of a discriminative value

OBJECTIVES: To identify the clinical discriminative value and determinants of arterial stiffness in individuals with type 2 diabetes mellitus (T2DM). METHODS: This prospective cohort study included 51 individuals (53.57±9.35 years) diagnosed with T2DM (stage glucoseX126 mg/dL; diagnostic time: 87.4±69.8 months). All participants underwent an initial evaluation of personal habits, medications, and history; arterial stiffness assessment by carotid-femoral pulse wave velocity (cfPWV) using SphygmoCor; and blood laboratory analysis. A statistical analysis was performed using SPSS software, and values of pp0.05 were considered significant. RESULTS: A cut-off cfPWV value of 7.9 m/s was identified for T2DM [Sensitivity (SE): 90% and Specificity (SP): 80%]. A subgroup analysis revealed higher glycated hemoglobin (Hb1Ac) (p=0.006), obesity (p=0.036), and dyslipidemia (p=0.013) than those with cfPWV X7.9 m/s. Multivariate analysis identified higher stage glucose (p=0.04), Hb1Ac (p=0.04), hypertension (p=0.001), and dyslipidemia (p=0.01) as determinant factors of cfPWV; positive and significant correlation between cfPWV and glucose (r=0.62; p=0.0003) and Hb1Ac (r=0.55; p=0.0031). CONCLUSIONS: In T2DM, an indicator of the discriminative value of arterial stiffness was cfPWV of 7.9 m/s. Clinical findings and comorbidities, such as hypertension, glucose, poor glycemic control, and dyslipidemia, were associated with and were determinants of arterial stiffness in T2DM. Reinforcement of monitoring risk factors, such as hypertension, dyslipidemia, and glycemic control, seems to be essential to the process of arterial stiffening. Confirmation of this discriminative value in larger populations is recommended

Circulatory and ventilatory power markers in patients with diabetes mellitus – influence of glycemic control

Introduction and aim. Cardiorespiratory function has been shown to be impaired in individuals with type 2 diabetes mellitus (T2DM). Some deficiencies in cardiopulmonary exercise test (CPET)-derived variables are known, however, the influence of glycemic control on cardiovascular integrity indices as circulatory power (CP) and ventilatory power (VP), deserve to be instigated. The aim was to investigate the influence of glycemic control on CP and VP indices in T2DM. Material and methods. T2DM individuals of both sexes aged between 40 and 64 years were allocated into two groups: Good glycemic control (GGC, n=11; HbA1c≤7%) and insufficient glycemic control (IGC, n=26; HbA1c>7%). All participants underwent a CPET on a treadmill using a gas analyzer and a laboratory blood test. CP values were obtained by the product of peak of oxygen uptake and systolic blood pressure (SBP) and VP by dividing SBP by the ventilatory efficiency (VE/VCO2 slope). The level of significance was set at p<0.05. Results. No baseline differences were found between the groups, except for the expected fasting glucose and glycated hemoglobin. No differences were found between GGC and IGC groups for CP (4756.05±1061.67 and 4434.15±1247.83 mmHg.ml.kg-1min-1, p=0.460) and VP (5.85±1.08 and 5.86±1.31 mmHg, p=0.978), respectively. Conclusion. CP and VP were similar in individuals with T2DM regardless of glycemic control. Predictive ability of these variables in health outcomes deserves to be further investigated in T2DM

Arterial stiffness can predict cardiorespiratory fitness in type 2 diabetic patients?

Introduction and aim. Arterial stiffness (AS) has been associated with reduced cardiorespiratory fitness (CRF). The aim of this study was to verify if there is a relationship between augmentations index (AIx), as an index for AS assessment, and CRF in individuals with type 2 Diabetes Mellitus (T2DM). Material and methods. Observational cross-sectional study including 32 individuals diagnosed with T2DM who performed two evaluations: 1. Arterial stiffness assessment using SphygmoCor and 2. CRF throughout a cardiopulmonary exercise test on a treadmill ergometer. Oxycon Mobile® device was used to obtain oxygen uptake consumption at peak (V˙O2peak); oxygen uptake efficiency slope (OUES) determined by linear regression in reason of the logarithmic transformation of the ventilation and V˙O2 obtained every minute of exercise test. Statistical analysis comprised Pearson’s Correlation and linear regression analysis performed in SigmaPlot. Results. There was a significant correlation between AS and CRF: AIx and OUES; AIx@75 and; OUES. In linear regression, AIx was determinant for V˙O2peak and OUES – AIx and; AIx@75 and V˙O2peak. Conclusion. AS was associated with CRF in individuals with T2DM. These results contribute to the body of evidence linking arterial functional properties to CRF and suggests greater attention for this important index