Vmax encore

Participants performed a preliminary session during which anthropometry and maximal aerobic capacity were assessed. Height and weight were also measured using a wall‐mounted stadiometer (HR‐200, Tanita, Arlington Heights, IL) and digital scale (BWB‐800, Tanita, Arlington Heights, IL), respectively. Body composition was measured by dual‐energy x‐ray absorptiometry (GE‐LUNAR Prodigy module, GE Medical Systems, Madison, WI). Aerobic fitness (VO_2max) was assessed using an incremental exercise test to exhaustion on an upright cycle ergometer (Kettler ErgoRace, Virginia Beach, VA) in accordance with guidelines from the Canadian Society of Exercise Physiology (CSEP, 1996). Following a self‐paced warmup and at least 10‐minute rest period, the protocol commenced with an external workload of 80 W that increased at a rate of 20 W·min⁻¹ until physical or volitional exhaustion. Expired gases were measured via breath‐by‐breath indirect calorimetry using a metabolic cart (Vmax Encore, Care Fusion, Yorba Linda, CA).

All subjects underwent a 4‐week weight stabilization period before initiating metabolic testing (±2 kg). Body composition was assessed by dual‐energy X‐ray absorptiometry (iDXA; GE Healthcare) and basal metabolic rate was measured by indirect calorimetry (Vmax Encore, CareFusion). Three‐day food records were completed by the subjects (two weekdays, one weekend) and verified by a dietitian for completion. Their nutritional analysis was conducted using The Food Processor software (version 11.3.285, ESHA Research). Plasma parameters were measured as follows: lipids and apoB by COBAS Integra 400 analyzer (Roche Diagnostic), apoB48 by ELISA (Fuji Films/WAKO), glucose by an automated analyzer (YSI Inc., InterScience), insulin and C‐peptide by radioimmunoassay kit (Millipore Corporation), PCSK9 by ELISA kit (Circulex), and IL‐1Ra by high‐sensitivity ELISA kit (R&D system, Minneapolis, MN, USA)(Bissonnette, Saint‐Pierre, et al., 2018; Bissonnette et al., 2013, 2015; Lamantia et al., 2017; Wassef et al., 2015).

During all sessions, expired air was continuously recorded using a breath-by-breath gas analyzer (Vmax Encore metabolic cart, CareFusion Corp, California, USA). PPO was the average power output on the last 2-min stage of the maximal incremental test. Heart rate (HR) and cardiac output (Q) were evaluated during all tests using thoracic electrical bioimpedance (Physioflow, Manatec Biomedical, France). All devices were calibrated according to manufacturer guidelines before every test. Arteriovenous O₂ difference [(a-v)O₂-diff (ml/dl)] was calculated using the following equation: (a-v)O₂-diff = VO₂ (L/min)/Q (L/min)^*100 and stroke volume (SV) was calculated from Q and HR. VO₂max, maximal Q (Qmax), maximal SV (SVmax), and maximal (a-v)O₂-diff were defined as the highest values achieved over a 30-s period during the incremental test. Time over 90 and 95% of VO₂max, Qmax, and HRmax were calculated for all sessions. Peak VO₂, peak Q and peak HR were also calculated for each session, and defined as the highest 30-s average for VO₂ and Q and highest 5-s average for HR value reached during the session.

The study design was previously described for these subjects (21 (link)). Briefly, 1 week before isotope studies, all subjects underwent dual-energy x-ray absorptiometry (DEXA) to assess body fat distribution and lean mass, ¹H magnetic resonance spectroscopy (¹H-MRS) to determine hepatic TG content, and hyperinsulinemic-euglycemic (H-E) clamp to measure insulin sensitivity (Figure 1A). Subjects then maintained an ad libitum diet for 4 days, keeping a record of food intake to allow the individual daily caloric intake to be determined. Subjects were then placed on a 3-day standard meal plan prepared by the Clinical and Translational Research Center kitchen, consisting of 50% carbohydrate, 35% fat, and 15% protein with a daily caloric intake reflective of their usual diet. The final standard meal occurred at 12:00 pm the day before isotopic studies, marking the beginning of a 24-hour fast. Subjects presented to the Advanced Imaging Research Center (AIRC) at 8:00 am the following day to undergo the isotope studies to assess in vivo hepatic metabolism. Indirect calorimetry was performed before the H-E clamp and the isotope study (Vmax Encore, CareFusion). All subjects underwent the same protocol, and the cross-sectional design obviated the need for randomization or blinding.

Spirometry was performed using automated equipment (Vmax Encore™, CareFusion, Yorba Linda, CA, USA) according to recommended techniques (Miller et al., 2005 (link)).

At baseline and 3 months, a submaximal exercise test is performed on a cycle ergometer (Corival, Lode B.V. Groningen, The Netherlands), and submaximal cardiorespiratory fitness is measured by breath-by-breath indirect calorimetry using a Vmax Encore metabolic cart (Carefusion, San Diego, CA, USA). Procedures are adjusted from standard fitness testing protocols [45 ] to suit participant clinical presentation. Total and relative (kg BM) oxygen consumption ( $\stackrel{.}{V}$ O₂ per min) are determined and will be reported. The height of the seat is individually adjusted for participant leg length and participants are asked to keep a cadence of 60–70 pedal rounds per minute. Heart rate is measured by a pulse belt (Polar Electro, Kempele, Finland) and RPE by Borg Scale [28 (link)] during the ~ 16-min assessment. Participants begin the test with an 8–10 min light warm up and start at 1 W/kg FFM and increase 0.5 W/kg FFM every 3 min until they cannot maintain the watt output at ≥60 rpm, or they reach a rating of perceived exertion (RPE) of 15–17. Data are used to establish aerobic economy as previously reported [46 (link), 47 (link)].