Repeat trial and breath averaging: Recommendations for research of VO2 kinetics of exercise transitions to steady-state

Multiple-breath and multiple-trial averaging have been used extensively in research of oxygen uptake kinetics to steady-state. However, specific guidelines outlining correct levels of averaging have not been discussed. The aim of this study was to assess error differences using multiple-trial and multiple-breath averaging systems, and make recommendations for future VO2 kinetics research. Eight male subjects were recruited for this study. Following a maximal cycle test to ascertain each subject’s ventilation threshold, eight identical repetition cycling exercise bouts were administered. The bouts consisted of 6-minute at 85% of the subject’s ventilation threshold. Firstly, multiple-trial and multiple-breath data were processed using traditional methods. As well, data were fit using a mono-exponential model to derive tau. Data for all levels of multiple-trial and multiple-breath methods were compared to an 8-trial and 13-breath average, respectively. Reduction in error from the 3-trial average and a 3-breath average represented ∼68% and ∼70% of total error reduction, respectively. Tau tended to increase with increasing breath averaging and decrease with increasing trial averaging. There is negligible benefit to averaging more than 3 repeat trials in VO2 kinetics research. Breath averaging beyond 3-breaths artificially increases tau.

The Time Course of Oxygen Uptake, Aerobic Capacity and Emg during Two Months of Moderate Interval Endurance Training (A Case Study)

Research background and hypothesis. The low-moderate-intensity continuous endurance training improved body composition, aerobic capacity and overall health-related parameters in healthy persons. However, we could not find publications about the effect of moderate interval aerobic endurance training (IET) on body composition, 2 OV& kinetics, aerobic capacity and EMG parameters. Research aim. The main purpose of this study was to examine the effect of interval endurance training (IET) on oxygen uptake kinetics, aerobic capacity, body composition and EMG parameters. Research methods. A 26-year-old, sedentary obese female (stature – 1.80 m; weight – 99.2 kg; VO 2 max – 37.2 ml/kg -1 /min -1 ) was involved in two-month moderate interval endurance training (IET). The subject performed three training sessions a week separated by one or two days of rest. The initial intensity of training was 90% of the first ventilation threshold (VT1). The VT1 and second ventilation threshold (VT2) ware estimated after completion of incremental running test until exhaustion on a LE 200 CE treadmill (VIASYS, Germany). Research results. We determined that after two months IET subject’ body mass decreased by 10%, the training had an effect on aerobic capacity parameters as well. The running speed at VT1 and VT2 increased by 8.1% and 10.2% respectively after the two-month IET programme. The heart rate (165.9 beats/min -1 ) and oxygen uptake (2.583 l/min -1 ) significantly decreased respectively (150.4 beats/min -1 ) (2.285 l/min -1 ) after IET period compared with pre-training testing. To indicate the total muscle activity we measured integrated EMG (iEMG) and root mean square (RMS). We also determined changes on EMG parameters after four, six and eight weeks IET.Discussion and conclusions. Two-month moderate interval endurance training has significant effect on aerobic capacity, anthropometrics, EMG parameters and VO 2 kinetics.Keywords: ventilatory thresholds, maximal oxygen uptake, EMG root mean square.

Reproducibility of short-term food intake and subjective appetite scores after a glucose preload, ventilation threshold, and body composition in boys

The objective of these studies was to assess the reproducibility of (i) short-term food intake (FI) and subjective appetite following a glucose preload, (ii) ventilation threshold (VT) and subjective appetite after short-duration exercise, and (iii) body composition assessed by bioelectrical impedance (BIA). On two separate weekend mornings, boys (n = 11; aged 9–14 years) received drinks containing 50 g glucose made up to 250 mL with water 2 h after a standardized breakfast. FI from a pizza meal was measured 30 min later. Subjective appetite was measured before and after the glucose loads and the VT measures. VTs were measured on 2 weekday evenings, 1 week apart. BIA was measured during the FI assessment sessions. Short-term FI after the glucose preload was highly reproducible. Mean energy intake was 925 ± 139 kcal on the first day and 988 ± 147 kcal on the second day (coefficient of repeatability (CR) = 259 kcal; intra-class correlation coefficient (ICC) = 0.96). Moderate reproducibility of the average appetite score was found at 30 min (CR = 24 mm; ICC = 0.82). Subjective appetite was increased similarly by short-duration exercise on both days (CR = 19 mm). Absolute VT was more highly reproducible (CR = 359 mL O2·min–1, ICC = 0.85) than VT expressed on the basis of body weight (CR = 8.0 mL O2·kg–1·min–1, ICC = 0.59). Fat mass (FM) estimated from BIA was highly reproducible (CR = 2.7 kg, ICC = 0.95), but underestimated FM compared with skinfolds. In conclusion, FI and subjective appetite scores in response to glucose preloads, VT, subjective appetite after short-duration exercise, and estimates of FM from BIA are reproducible in boys.