Background: Testosterone has been related to improved acute neuromuscular performance in athletic populations. It is our contention that testosterone may also contribute to improved volitional motivation and, when monitored longitudinally, may provide one proxy marker for readiness to perform. Methods: Twelve female netball players provided saliva samples prior to five standardized training sessions in which they completed a maximal-distance medicine ball throw, and then 3 sets of bench press and then back squat using a self-selected load perceived to equal a 3-repetition maximum load. Additional repetitions were encouraged when possible and total voluntary workload was calculated from the product of the load lifted and repetitions performed. Results: Relative salivary testosterone levels as a group were correlated with bench press (r = 0.8399; p = 0.0007) and squat (r = 0.6703; p = 0.0171) self-selected workload, as well as maximal medicine ball throw performance (r = 0.7062; p = 0.0103). Conclusions: Individual salivary testosterone, when viewed relatively over time, demonstrated strong relationships with self-selected workloads during an in-season training period in female netball players. As such, daily variations in testosterone may provide information regarding voluntary training motivation and readiness to perform in elite athletic populations. Psychological and behavioral aspects of testosterone may have the potential to enhance training adaptation by complementing the known anabolic and permissive properties of testosterone.
The aim of the present study was to assess the criterion validity, relative reliability and level of agreement ofPolar® RS800CX heart rate monitor measuring inter-beat intervals (IBIs), compared to simultaneously recordedelectrocardiogram (ECG) in dogs.Methods: Five continuous minutes of simultaneously recorded IBIs from Polar® RS800CX and Cardiostore ECG in11 adult healthy dogs maintaining standing position were analyzed. Polar® data was statistically compared toECG data to assess for systematic differences between the methods. Three different methods for handling missingIBI data were used. Criterion validities were calculated by intraclass correlation coefficients (ICCs) and corresponding95% confidence intervals (CIs). Relative reliabilities and levels of agreement were calculated by ICCsand the Bland and Altman analysis for repeated measurements per subject.Results: Correlation coefficients between IBI data from ECG and Polar® RS800CX varied between 0.73 and 0.84depending on how missing values were handled. Polar® was over- and underestimating IBI data compared toECG. The mean difference in log transformed (base10) IBI data was 0.8%, and 93.2% of the values were withinthe limits of agreement. Internally excluding three subjects presenting IBI series containing more than 5% erroneousIBIs resulted in ICCs between 0.97 and 0.99. Bland and Altman analysis (n = 8) showed mean differencewas 1.8 ms, and 98.5% of the IBI values were plotted inside limits of agreement.Conclusion: This study showed that Polar® systematically biased recorded IBI series and that it was fundamentalto detect measurement errors. For Polar® RS800CX heart rate monitor to be used interchangeably to ECG, byshowing excellent criterion validity and reliable IBI measures in group and individual samples, only less than5% of artifacts could be accepted.
Abstract
The aim of the present study was to assess criterion validity, and relative and absolute reliability of Polar® RS800CX heart rate monitor, compared to simultaneously recorded electrocardiogram (ECG) data, in measuring heart rate of dogs during standing position and at trot on a treadmill.
Methods
Heart beats from Polar® RS800CX and Cardiostore ECG were recorded simultaneously during seven continuous minutes in standing position and at trot, in 10 adult healthy dogs. Polar® data was statistically compared to ECG data for a variety of mean beats per minute (BPM), standard deviation and confidence interval. Criterion validity was calculated by Pearson product moment correlation method and intraclass correlation coefficient (ICC2.1). Relative and absolute reliability were calculated by ICC2.1, the Bland and Altman analysis and standard error of measurement (SEM and SEM%).
Results
The correlation, criterion validity, between Polar® and ECG data in standing position was r = 0.99 (p < 0.0005) and at trot r = 0.97 (p < 0.0005). Polar® data was not significantly different from ECG data. Mean difference between ECG and uncorrected Polar® data was − 0.6 BPM in standing position and − 0.6 BPM at trot. Polar® was over- and underestimating ECG data. SEM and SEM% in standing were ± 2.6 BPM and 3.0%, at trot ± 3.8 BPM and 3.1%, indicating that measurement errors were low.
Conclusion
This study showed that the criterion validity and the instrument reliability were excellent in Polar® RS800CX heart rate measuring system. The equipment seemed to be valid and reliable in measuring BPM in the dogs studied during submaximal cardiovascular conditions such as in standing position and at trot on a treadmill.