Quark pft

Before each experiment, the subjects performed a forced vital capacity (FVC) manoeuvre while in the supine posture (Quark PFT, Cosmed, Rome, Italy). All pulmonary function testing was performed and reported in accordance with the American Thoracic Society guidelines [24] (link). Expired gases were continuously sampled at the mouth using a mass spectrometer (AMIS 2000, Innovision A/S, Odense, Denmark) and, from these data, the end-tidal partial pressures of O₂ and CO₂ (PETO₂ and PETCO₂) were computed.

The gradient cycling exercise protocol was employed to measure the VO_2max, beginning from 60 W with a pedal frequency of 60 revolutions per minute (rpm). The power output was increased every 2 min at 40 and 20 W for males and females until they became exhausted. During the test period, the Heart Rate (HR) and VO₂ were evaluated using an H12 Heart Rate monitor (Polar, Finland) and Quark-PFT gas metabolism analyzer (COSMED, Italy), respectively. Oxygen uptake is collected by breath by breath, and the average value is extracted every 30 seconds. Note that the VO_2max represents the highest mean value in 30 seconds.

Blood was sampled from each subject in the seated position. Briefly, 5 mL of antecubital vein was harvested by means of venipuncture. An enzymatic assay (Jiancheng Biotech) was conducted for the immediate assessment of blood glucose (GLC), total cholesterol (TC), and triglyceride (TG). As for the remaining blood specimens, they were isolated for a 10 min period at 2000 r/min, followed by aliquoting and preservation at −80 °C to analyze serum insulin (INS) by adopting ELISA (RayBiotech). CV values within and between assays were ≤8.7% and ≤8.6% for variables.
The gradient cycling-exercise protocol initiating from 60 W (pedal frequency = 60 rpm) was adopted for determining VO_2max. Power output was elevated by 40 and 20 W every 2 min for men and women until exhaustion. In our test period, HR and VO₂ were determined by using an HR monitor (H12, Polar, Finland) and gas metabolism analyzer (Quark-PFT, COSMED, Rome, Italy), respectively. VO_2max represented the greatest mean values in 30 s.

An incremental symptom-limited CPET was performed on an electronically braked cycloergometer (Ergoline-800, Mortara, Bologna, Italy), according to our previous study [21 (link)]. The subject was connected to the breath-by-breath lung gas exchange system by the use of a mask and breathing through a bidirectional turbine mass flow sensor (Quark PFT, Cosmed, Rome, Italy). The exercise protocol consisted of 3 min of rest and 3 min of unloaded cycling, followed by an incremental work rate to induce voluntary exhaustion in about 10 min, followed by 3 min of recovery. ECG and pulse oximetry were continuously monitored, and blood pressure was measured every two minutes. VO₂, VCO₂ and the respiratory exchange ratio (VCO₂/VO₂, RER) were computed and averaged every 10 s. The anaerobic threshold (AT) was determined by the V-slope method. The relation between VE and VCO₂ (VE/VCO₂ slope) was calculated as the slope of the linear relationship between VE and VCO₂ from one minute after the beginning of the loaded exercise to the end of the isocapnic buffering period. A submaximal test is defined by RER ≤ 1.05.