Four-week experimental plus 1-week taper period using live high train low does not alter muscle glycogen content.

This study aimed to investigate the effects of a 4-week live high train low (LHTL; FiO2 ~ 13.5%), intervention, followed by a tapering phase, on muscle glycogen concentration. Fourteen physically active males (28 ± 6 years, 81.6 ± 15.4 kg, 179 ± 5.2 cm) were divided into a control group (CON; n = 5), and the group that performed the LHTL, which was exposed to hypoxia (LHTL; n = 9). The subjects trained using a one-legged knee extension exercise, which enabled four experimental conditions: leg training in hypoxia (TLHYP); leg control in hypoxia (CLHYP, n = 9); leg trained in normoxia (TLNOR, n = 5), and leg control in normoxia (CLNOR, n = 5). All participants performed 18 training sessions lasting between 20 and 45 min [80-200% of intensity corresponding to the time to exhaustion (TTE) reached in the graded exercise test]. Additionally, participants spent approximately 10 h day-1 in either a normobaric hypoxic environment (14.5% FiO2; ~ 3000 m) or a control condition (i.e., staying in similar tents on ~ 530 m). Thereafter, participants underwent a taper protocol consisting of six additional training sessions with a reduced training load. SpO2 was lower, and the hypoxic dose was higher in LHTL compared to CON (p < 0.001). After 4 weeks, glycogen had increased significantly only in the TLNOR and TLHYP groups and remained elevated after the taper (p < 0.016). Time to exhaustion in the LHTL increased after both the 4-week training period and the taper compared to the baseline (p < 0.001). Although the 4-week training promoted substantial increases in muscle glycogen content, TTE increased in LHTL condition.

Effects of chronic cholinergic stimulation associated with aerobic physical training on cardiac morphofunctional and autonomic parameters in spontaneously hypertensive rats.

We investigated hemodynamic, cardiac morphofunctional, and cardiovascular autonomic adaptations in spontaneously hypertensive rats (SHRs) after aerobic physical training associated with chronic cholinergic stimulation. Fifty-four SHRs were divided into two groups: trained and untrained. Each group was further subdivided into three smaller groups: vehicle, treated with pyridostigmine bromide at 5 mg/kg/day, and treated with pyridostigmine bromide at 15 mg/kg/day. The following protocols were assessed: echocardiography, autonomic double pharmacological blockade, heart rate variability (HRV), blood pressure variability (BPV), and baroreflex sensitivity (BRS). Physical training and pyridostigmine bromide reduced BP and HR and increased vagal participation in cardiac autonomic tonic balance. The associated responses were then potentialized. Treatment with pyridostigmine bromide increased HRV oscillation of both low frequency (LF: 0.2-0.75 Hz) and high frequency (HF: 0.75-3 Hz). However, the association with physical training attenuated HF oscillations. Additionally, treatment with pyridostigmine bromide also increased LF oscillations of BPV. Both treatment groups promoted morphofunctional adaptations, and associated increased ejection volume, ejection fraction, cardiac output, and cardiac index. In conclusion, the association of pyridostigmine bromide and physical training promoted greater benefits in hemodynamic parameters and increased vagal influence on cardiac autonomic tonic balance. Nonetheless, treatment with pyridostigmine bromide alone seems to negatively affect BPV and the association of treatment negatively influences HRV.

Chronic cholinergic stimulation promotes changes in cardiovascular autonomic control in spontaneously hypertensive rats.

Hypertension is often accompanied by autonomic dysfunction, which is detrimental to cardiac regulation. On the other hand, cholinergic stimulation through inhibition of acetylcholinesterase appears to have beneficial effects on cardiac autonomic control. Thus, our objective was to investigate the effects of chronic cholinergic stimulation on hemodynamic and cardiovascular autonomic control parameters in spontaneously hypertensive rats (SHR). For this, 26-week-old SHR (N = 32) and Wistar Kyoto rats (WK; N = 32) were divided into two groups: one treated with vehicle (H2O; N = 16) and the other treated with pyridostigmine bromide (PYR; N = 16) in drinking water (25 mg/kg/day) for 2 weeks. All groups were subjected to recording of arterial pressure (AP) and heart rate (HR), quantification of ejection fraction (EF), evaluation of cardiac tonic autonomic balance by means of double autonomic blockade with methylatropine and propranolol, analysis of systolic AP (SAP) and HR variability (HRV), and evaluation of baroreflex sensitivity (BRS). AP, HR, and EF were reduced in the SHR-PYR group compared with the SHR-H2O group. Evaluation of autonomic parameters revealed an increase in vagal tone participation in cardiac tonic autonomic balance and reduced SAP variability; however, no changes were observed in HRV or BRS. These results suggest that chronic cholinergic stimulation with pyridostigmine bromide promotes reduction in the hemodynamic parameters AP, HR, and EF. Additionally, tonic autonomic balance was improved and a reduction in LF oscillations of SAP variability was observed that could not be attributed to BRS, as the latter did not change. Further studies should be conducted to identify the mechanisms involved in the observed responses.

Las comparaciones entre las ecuaciones de predicción de la tasa metabólica en reposo y la calorimetría indirecta en los adolescentes obesos / Comparisons between predictive equations of resting metabolic rate and indirect calorimetry in obese teenagers

Objective: To measure the accuracy of predictive equations of resting metabolic rate (RMR) in obese teenagers in relation to indirect calorimetry (IC). Methods: This study was conducted with 116 obese teenagers (60 males; 13.7±1.1 years). The RMR was calculated from Harris and Benedict, Schofield, WHO, Henry and Rees equations. The RMR was measured by the QUARK-RMR system. The comparison between predictive equations and IC was by the Student's t test. The reliability of data between predictive equations and IC was verified by the typical error of measurement (TEM) and the coefficient of variation (CV%). Results: Henry's equation was significantly different from IC (p<0.02). The CV% found for each equations compared to IC turned was low. However, when the TEM was measured it was considered high in absolute values which can cause errors when estimating the RMR. Therefore, it is important that specific predictive equations are developed for Brazilian obese teenagers.

Objetivo: Medir la precisión de las ecuaciones predictivas de la tasa metabólica de reposo (TMR) en los adolescentes obesos en relación con la calorimetría indirecta (CI). Métodos: El estudio se realizó en 116 adolescentes obesos (60 niños, 13,7 ± 1,1 años). La TMR se calculó a partir de las ecuaciones predictivas de Harris y Benedict, Schofield, OMS, Henry y Rees. La TMR se midió por el sistema de QUARK-TMR. La comparación entre las ecuaciones de predicción y IC se realizó mediante el test t de Student. La fiabilidad de los datos entre IC y ecuaciones de predicción fue verificada por el error típico de la medición (TEM) y el coeficiente de variación (CV%). Resultados: La ecuación de Henry fue significativamente diferente de IC (p <0,02). El CV% encontrado para cada ecuación en comparación con IC fue bajo; no obstante, cuando se midió el TEM, este fue considerado alto en valores absolutos que puede provocar errores al estimar la TMR. Por lo tanto, es importante que ecuaciones de predicción específicas sean desarrolladas para adolescentes obesos brasileños.