Resting metabolic rate is increased after a series of whole body … – Nature.com

Study design

The study was a parallel randomized trial. Thirty-two healthy men between the aged 21 to 23years old were recruited and randomly assigned to two 16-member groups: a group participating in the WBV intervention (n=16) and a group without the intervention (placebo: PL, n=16). Participants drew numbers from 1 to 32: even numbers were placed in the WBV group, odd numbers in the PL group. The men were physically active, but did not engage in competitive sports. Only healthy men with normal BMI and similar physical activity were included in the study. Exclusion criteria were metabolic diseases, overweight or obesity, use of stimulants and pharmaceuticals, and anxiety disorders. Medical qualification for participation in the project was made by a physician.

Diet, physical activity, body composition and resting metabolic rate were analyzed in the participants. Body composition analysis and RMR measurement were performed twice, i.e. before and after completion of the WBV series (n=10). The intervention lasted 2weeks and WBV was performed 5 times a week (MondayFriday) in the hours up to noon. All subjects completed the full series of 10 WBV, as well as all scheduled tests were performed in the study. Participation in the study was voluntary, and participants at any stage of the project were allowed to opt out of further participation. All study participants signed a consent form to participate in the project. The project was approved by the Bioethics Committee of Opole Medical School (no. KB/56/NOZ/2019).

Whole body vibration was performed in the vibration therapy laboratory, in which constant environmental conditions were maintained. The average temperature in the laboratory was 21.70.46 C and the humidity was 54.20.70%. Cycloidal-oscillatory vibration was used in the study. WBV was applied by a physiotherapist/exercise physiologist, and during WBV the participant was supervised by the researcher. The intervention was performed in a prone position, as previously described17, with the use of a RAM Vitberg+Base Module (active medical device, class IIa) enhanced with a RAM Vitberg+Metabolism module (active medical device, class I) (Vitberg, Poland). Whole body vibration was applied using the Base Module, applying vibration to the trunk, upper limbs and thighs area, and additionally local vibration (Metabolism module) directed to the abdominal area. The physical stimulus was continuous vibration with variable values of frequency, amplitude and acceleration, which ranged, respectively: 2552Hz, 0.10.5mm and 6.913.5m/s2. The vibration stimulus was generated in three directional perpendicular (3D). A single WBV lasted 29min. During the placebo treatment, the similar device was used, which did not generate vibration, but only a sound identical to the vibration. The procedures and body position were identical to the vibration intervention.

The body composition of the men was examined twice before and after the intervention. Body composition was measured by Dual Energy X-ray Absorptiometry (DEXA) (Lunar Prodigy, GE, USA) according to the manufacturers guidelines. Body mass (BM), fat-free mass (FFM), fat mass (FM) and percent body fat (%FAT) were determined. Body height was measured without shoes, in a standing position to the nearest 1mm, with the head in the Frankfurt plane, using a stadiometer (Seca, Germany). In addition, body mass index (BMI) was calculated for each subject.

Men completed 4-day food diaries, in which they recorded the weight or volume of each food consumed. The serving size was assessed subjectively by the participant on the basis of the Album of Product and Food Photography19. The caloric content of the diet and the proportion of carbohydrates, proteins and fats in the diet was then calculated by a qualified nutritionist, using the Diet 6.0 software (Food and Nutrition Institute, Warsaw, Poland).

Physical activity was assessed using the International Physical Activity Questionnaire (IPAQ, short Polish version20), which the participants completed on the first day of the intervention. Before completing the questionnaire, they were instructed on its purpose and how to fill it out. The questionnaire was completed in the presence of the researcher, who instructed or answered any questions the respondents might have.

RMR was measured in fasting, always at the same time of day (morning), between 6:00 a.m. and 10:00 a.m. Prior to the first RMR measurement, participants were instructed on how to prepare for the measurement, i.e. avoid exercise for 3 days before the scheduled measurement, be properly hydrated, and not use any stimulants before the study (nicotine, caffeine). Participants were also recommended not to change their diet or physical activity during the intervention. RMR was measured in the supine position in an air-conditioned laboratory, at a constant temperature of 21C, after a prior rest of about 15min in the supine position. Resting metabolic rate, was measured by indirect calorimetry using a Cortex MetaLyzer 3R ergospirometer (Germany), using the breath by breath method. The ergospirometer was calibrated each time according to the manufacturers requirements (gas and volume calibration). Oxygen uptake (VO2), carbon dioxide production (VCO2), respiratory quotient (RQ), RMR, and substrate utilization (carbohydrate [CHO], fat [FAT], protein [PRO]) and energy expenditure (EE) from each substrate were measured during the measurement. Resting metabolism was expressed absolutely (kcal/day) and relatively to body mass (kcal/kg/day) and to body surface area (RMR/BSA) (kg/m2/day). RMR and other indices measured by calorimetry were determined from a 5-min measurement period during which steady state was observed in oxygen uptake. The steady state was considered to be fluctuations in oxygen uptake within10%. The averages from steady state were used to calculate REE using the Weir21 formula without using urinary urea nitrogen. All calculations were performed using dedicated metabolic rate measurement software provided by ergospirometer manufacturer (Cortex, Germany).

Sample size was estimated a priori using G*Power 3.1.9.7 (Dusseldorf, Germany). The following options were selected in the software: test family=f tests; statistical test=ANOVA repeated measures, within-between interaction; type of power analysis=compute required sample sizegiven , power, and effect size. Input parameters into the software were as follows: effect size f=0.4; error probability=0.01; power=0.95; number of groups and measurements=2; correlation among measures=0.5; nonsphericity correction=1.0. The required sample size was 16 subjects per group (total sample size=32). Data distribution was checked using the ShapiroWilk test. Homogeneity of variance within the groups was tested via Levenes test Analysis of variance (ANOVA) with repeated measures or one-way ANOVA was used to analyze the data obtained. In case of significant changes (p<0.05) in the analysis of variance, post-hoc analysis was performed using the Tukey test. Additionaly, in post hoc analysis (if significant), the effect size (Cohens d) between baseline and WBV (placebo) treatment was calculated and interpreted as small (0.20), medium (0.50), or large (0.80)22. Data are presented as mean and standard deviation. The STATISTICA 13 package (StatSoft, Inc., Tulsa, OK, USA) was used for calculations.

The study was conducted in accordance with the Declaration of Helsinki and approved by the Bioethics Committee of Opole Medical School in Poland (no. KB/56/NOZ/2019). All participants were informed about the study protocol, voluntarily took part in the experiment and signed informed consent.

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