Effects of an Indoor Cycling Program on Cardio-Metabolic Factors in Women With Obesity and Normal Body Weight

Anthropometric measurements were conducted with the subjects wearing light clothing and no shoes. Weight was measured to the nearest 0.1 kg and height to the nearest 0.5 cm. BMI was calculated as weight divided by height squared (kg/m2 ). Obesity was defined as BMI ≥ 30 kg/m2. Waist circumference (cm) was measured at the level of the iliac crest at the end of normal expiration. Hip circumference was measured at the maximum protuberance of the buttocks. Waist and hip circumferences were measured to the nearest 0.5 cm. Waist-to-hip ratio (WHR) was calculated as waist circumference divided by hip circumference. Index of central obesity (ICO) was calculated as waist circumference (cm) divided by height (cm) (Parikh, et al., 2012). Body composition analysis was assessed using DXA (GE Healthcare Lunar Prodigy Advance; GE Medical Systems, Milan, Italy). The subjects were instructed not to make any intense physical effort in the 24h prior to the examination. The subjects were given complete instructions on the examination procedure. They wore cotton T-shirt, shorts, and socks and lay on the DXA table supine and motionlessly during the testing procedure. They were instructed to remove all metal, rubber, and plastic objects that might affect the X-ray beam. The same well-trained laboratory technician positioned the subjects, performed the scans, and executed the analysis according to the operator's manual, using the standard analysis protocol. Total body fat mass and lean body mass were determined using standard scan mode (in case of moderately obese subjects) or thick scan mode (in case of extremely obese subjects); the absorbed dose of radiation was 0.4 μGy and 0.8 μGy, respectively. To determine the subjects' physical capacity, a Graded Exercise Test (GXT) was performed on an electronically braked cycle ergometer (Kettler ® DX1 Pro, Kettler, Ense, Germany). GXT began at a work rate of 25 W (60 rev/min). The work rate was incremented by 25 W every 2 min until the subject could no longer maintain the required pedal cadence. Each test lasted 4-14.5 min, depending on age and aerobic fitness status. The exercise tests were conducted between 8: 00 and 12: 00 a.m. in an air-conditioned laboratory, 2 h after consuming a light breakfast. Expired gases, minute ventilations (Ve), and heart rate (HR) during GXT were monitored continuously with an automated system (Oxycon Mobile ® ; Viasys Healthcare, Hoechberg, Germany). Oxygen intake (VO 2 ) and carbon dioxide output (VCO 2 ) was measured breath-by-breath and averaged over 15-second periods. Before each trial, the system was calibrated according to the manufacturer's instructions. Peak VO2 was defined as the highest 15-second averaged VO 2 obtained during the final exercise load on the test. HR peak (bpm) was measured as the highest 15-second average value in the test. To determine ventilatory threshold (VT), the V-slope method was administered using computerized regression analysis on the slopes of the CO 2 output versus O2 uptake plot, which detects the beginning of the excess CO 2 output generated from the buffering of H +. The method involves analyzing the behavior of VCO 2 as a function of VO 2 during GXT with a consequent increase in VCO 2 . This results in a transition in the relationship between VCO 2 and VO 2 . The software supplied by Viasys Healthcare was used, supported with a visual inspection on the part of an experienced researcher. As a secondary method, the ventilatory equivalent method (VEQ method) was employed and the point at which the equivalent for oxygen (VE/VO 2 ) increased without a concomitant rise in the equivalent for carbon dioxide (VE/VCO 2 ) was detected. The VT was expressed as a heart rate (HR VT ). Exercise blood pressure was measured during a GXT using a digital electronic tensiometer (model 705IT TM, Omron Corporation, Kyoto, Japan). The measurement was taken during maximal work rate. Exercise HR was measured as the highest 15-second average value in the GXT. Resting blood pressure was measured fasting in the morning hours, in a sitting position with the legs uncrossed and the back and arm supported. Resting HR was measured under the same conditions, using auscultation of the heart by stethoscope. Regular or large adult cuffs were used, depending on the patient's arm circumference.