Effects of an Indoor Cycling Program on Cardio-Metabolic Factors in Women With Obesity and Normal Body Weight
Condition: Obesity; Dyslipidemias; Hypertension; Type 2 Diabetes; Endothelial Dysfunction
MeSH terms: Obesity; Dyslipidemias; Body Weight
Study type: Interventional

Summary: 
      The aim of the research is to (1) evaluate the potential clinical effectiveness and
      biological mechanisms of indoor cycling in the treatment of obesity and (2)
      provide-up-to-date evidence on the impact of indoor cycling in reducing cardiovascular
      disease (CVD) risk factors, namely, hypertension, dyslipidemia, type 2 diabetes, endothelial
      dysfunction. We hypothesize that IC training, can be a good stimulus to mitigate
      cardiovascular risk factors in women with obesity and to improve values of the examined
      indicators towards that occurring in women with normal body weight.

      The study was designed as a prospective exercise intervention trial. The study involved women
      with obesity (OW) and women with normal body weight (NW). Both study groups underwent the
      same 3-month physical training program. Outside the implemented program, all participants
      were instructed to maintain their normal physical activity, diet and not to use any dietary
      supplements. Dietary intake was assessed using interviews conducted at baseline and after
      completion of the trial. The amount of nutrients in participant's daily diet was processed
      and evaluated using a dietetics computer program. The intake of nutrients, total caloric
      intake during the study were constant in both groups. Anthropometric parameters, blood
      pressure and physical capacity were measured and blood samples were taken at baseline and
      after completion of the physical training program.

      The study involved 31 obese or normal weight women aged 34-62. A total of 23 women with
      obesity (body mass index (BMI) ≥ 30 kg/m2; waist circumference > 80 cm) registered and
      screened from among 163 women at the outpatient clinic of the Department of Internal
      Medicine, Metabolic Disorders, and Hypertension, University of Medical Sciences, Poznań,
      Poland were enrolled to OW group. The NW group consisted of 8 healthy women from the
      announcement (BMI ≤ 24.9 and ≥ 18.5 kg/m2).

      Informed consent was obtained from all participants, and the study was approved by the Ethics
      Committee of Poznan University of Medical Sciences (case no. 1077/12; supplement no. 753/13).
      The study conformed to all ethical issues included in the Helsinki Declaration.

      The 3-month intervention consisted of a physical exercise program involving three indoor
      cycling sessions per week, with a total of 36 training sessions. Subjects exercised on cycle
      ergometers Schwinn® Evolution® (Schwinn Bicycle Company, Boulder, Colorado, USA). Each
      session lasted approximately 55 minutes. Training sessions consisted of a 5-min low-intensity
      warm-up (cycling at 50-65% of maximum heart rate (HRmax)), 40 min of main training at an
      intensity of 65-95% of HRmax, 5 min of non-weight-bearing cycling, finishing with 5 min of
      low-intensity cool-down stretching and breathing exercises.

      Main part of the training was interval. Each exercise session consisted of 3 to 4 high
      intensity intervals with intensity exceeding 80% of HRmax, often reaching anaerobic
      threshold. High intensity intervals lasted approximately 4-minutes and were interspersed by
      recovery periods at 65-80% of HRmax.

      HR during sessions was monitored with a Suunto Fitness Solution® device (Suunto, Vantaa,
      Finland). To ensure that assigned exercise intensities were obtained, the average per cent of
      the maximum heart rate during the entire training session was obtained from the device Blood
      samples for biochemical analyses were taken from a basilic vein, after overnight 12-hour
      fasting. In the serum samples, parameters were measured using commercially available
      enzyme-linked immunoassays.

      Both before and after the whole training programme, the following measurements were made:
      body weight and height, BMI, waist and hip circumference, WHR, body composition (DXA),
      total-body skeletal muscle mass index, graded exercise test, isokinetic muscle strength of
      knee flexors and extensors, exercise and resting blood pressure, and the heart rate. Vascular
      endothelial function indices (eNOS, VEGF, TBARS and TAS) as well as TCH, LDL-C, HDL-C, TG,
      oxLDL and CRP of venous blood were determined.

      A sample size was determined according to changes in VO2 peak. A total of 6 subjects in OW
      group and 7 subjects in NW group was calculated to yield at least 80% power of detecting an
      intervention effect as statistically significant at the 0.05 α level.
    

Detailed description: 
      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.
    

Intervention name(s): Indoor Cycling Interval Exercise Training
Intervention type(s): Behavioral
Intervention description(s): The 3-month intervention consisted of a physical exercise program involving three indoor cycling sessions per week, with a total of 36 training sessions. Subjects exercised on cycle ergometers Schwinn® Evolution® (Schwinn Bicycle Company, Boulder, Colorado, USA). Each session lasted approximately 55 minutes. Training sessions consisted of a 5-min low-intensity warm-up (cycling at 50-65% of maximum heart rate (HRmax)), 40 min of main training at an intensity of 65-95% of HRmax, 5 min of non-weight-bearing cycling, finishing with 5 min of low-intensity cool-down stretching and breathing exercises.
Main part of the training was interval. Each exercise session consisted of 3 to 4 high intensity intervals with intensity exceeding 80% of HRmax, often reaching anaerobic threshold. High intensity intervals lasted approximately 4-minutes and were interspersed by recovery periods at 65-80% of HRmax.
Other intervention name(s): Spinning Interval Physical Training
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Intervention model description: The study was designed as a prospective trial where two similar groups of women only differing in body mass participate in the same intervention.
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: obesity; indoor cycling; interval physical training; cardio-metabolic factors