Background and Study Aim. The aim of this research is to create a non-invasive and easy to apply in practice approach to determine the anaerobic threshold based only on measurement of the pulmonary ventilation and the hearth rate. It uses proportions, with which these variables were changed during a maximal incremental test. Material and Methods. Twenty athletes from the national rowing team of Bulgaria with average age of 17.5 years were tested. Participants performed a one-time graded incremental exercise test to exhaustion on a rowing ergometer. The proposed new approach for determining the anaerobic threshold is related to detecting the power. Thus, one curve (obtained from differences in percentages of hearth rate and pulmonary ventilation) crosses the other one (obtained from pulmonary ventilation in percentages). The crossing point corresponds to the anaerobic threshold. This approach was compared with two methods determining the lactate threshold, by blood lactate measurement. Results. The Shapiro-Wilk test results indicated, that the samples of the heart rate of the compared methods have a normal or close to the normal distribution. The Fisher's F-test demonstrated, that the standard deviations of the samples do not differ significantly two by two at ɑ=0.05. The Bland&Altman test presented, that the 95% of all measurement data points lie within the confidence interval limit for each of the comparisons made between the new approach and two methods. Conclusions. Our proposed approach is non-invasive and can be easily applied in the field conditions, without using gas-analysing devices. In addition, it is reliable, reproducible and comparable to the accepted for “Gold Standard” methods for determination of anaerobic threshold with 95% statistical significance.

Background and Study Aim. The aim of this study is to verify the X-method for determining the second anaerobic threshold in rowers.Material and Methods. Twelve male athletes from the national rowing team of Bulgaria were tested. Participants performed a one-time graded incremental exercise test to exhaustion on a rowing ergometer. The workload were conducted on rowing ergometer system Concept 2, and spirometry system Clark C5. We obtained ventilatory indices, intensity and heart rate bred-by-bred for each participant, for each test stage. The anaerobic threshold was determined by two methods: 1) by the localization of the respiratory compensation point visually, after polynomial regression analysis of the trends for the dynamics of the ventilatory variables related to time and 2) by the X-method using the change in the ratio between heart rate and pulmonary ventilation. We compared the heart rate corresponding to the anaerobic threshold determined by both methods.Results. We found similar values for heart rate at the respiratory compensation point and the anaerobic threshold determined by the X-method for each of the investigated. The Shapiro-Wilk test showed a normal distribution of the two samples with a significance level of α = 0.05. Thus, the t-test for two paired samples showed a p-value of 0.202 at α = 0.05. We found a correlation coefficient r = 0.973 between the heart rate at the anaerobic threshold (determined by X-method) and the heart rate at the anaerobic threshold (detected at the respiratory compensation point). The Blant-Altman analysis showed that 95% of the points in the scatter plot lie within the confidence interval.Conclusions. The two methods give similar results and can be applied alternatively in the investigation of rowers in the age group 18.3 ± 1.07 years. The X-method always gives a reliable intersection point, which in our studies is close to the second anaerobic threshold. Comparative studies are also needed in other contingents for the wider use of the X-method.

Background and Study Aim. To investigate how bilateral pedaling asymmetries change at exercises with different levels of intensity. Material and Methods. Eight students of cycling, average age 25.4 years, were investigated. In the experiment, we recorded the pedal force of the right and left legs during three consecutive exercises of different intensity 35%, 55% and 85% respectively.  To quantify the difference in physical parameters of pedaling between the left and right legs, we used two approaches that complement each other in the analysis of bilateral asymmetry. One approach involved determining an asymmetry index, and other was statistical analysis. Results. The Student's t-test indicated that the difference between the power samples for the left and right pedals decreased at 85% exercise intensity vs. 55% with a statistical significance of α = 0.05. The bilateral asymmetry in most cases decreased or in two cases remained unchanged. The cases where there was no statistically significant difference between the power samples for both legs at 85% and 55% intensity levels had the lowest asymmetry index. Conclusions. The bilateral pedaling asymmetry is reduced at 85% exercise intensity compared to the 55% one. The reduction in asymmetry index ranges from 1% to 14.1%, Combining the asymmetry index and the Student's t-test can increase the informativeness of pedaling power data when analyzing bilateral asymmetry.