, 2012). When considered with other athletic kinase inhibitor Cabozantinib performance variables, changes in RMSSD throughout training and competition periods may indicate quality of physical adaptation, such as over-fatigue or increases in fitness (Cipryan et al., 2010; Oliveira et al., 2012; Tian et al., 2012). Additionally, it has been suggested that the RMSSD may be the preferred parameter for longitudinal athlete monitoring due to its easy calculation and interpretation (Plews et al., 2013) as well as its reduced sensitivity to breathing frequency compared to spectral measures (Pentilla et al., 2001; Saboul et al., 2013). This is particularly important when considering that field tools such as ithlete? are intended for athlete use with unsupervised data collection.

The prospect of a smart phone HRV application is attractive to coaches due to it being user friendly, affordable and time efficient. Therefore, it has potential for being utilized in field settings as an HRV monitoring tool among sports teams. Unfortunately, there are no available studies that have examined the accuracy of the ithlete? receiver and chest-strap hardware for determining HRV. This research is warranted as the merit of any field parameter depends on validity statistics when compared to laboratory derived measures. Therefore, the purpose of this investigation was to cross-validate the ithlete? HRV smart phone application with an ECG for determining ultra-short-term RMSSD. Technology for acquiring heart rate data in the field has advanced considerably over time.

Therefore, it is reasonable to hypothesize that the smart phone application with a heart rate strap and an ECG receiver will accurately reflect laboratory-derived HRV measures. Material and Methods Participants Twenty-five male (n = 17) and female (n = 8) college students from the University��s Exercise Science program volunteered for this study. Descriptive statistics for the participants are shown in Table 1. Acquisition of the data occurred between the hours of 8:00 am and 12:00 pm on week days in the Human Performance Laboratory. Volunteers were told to report to the lab in a fasted state and to avoid the consumption of stimulants (e.g. coffee). Only healthy individuals were included in this study. Those with a heart condition, illness or prescription medication were excluded.

All subjects provided written informed consent after being given a detailed account of the investigation, potential risks and were told that they may withdraw their participation at any time. The experimental protocol was granted ethical approval by the associated University��s Institutional Review Board. Table 1 Descriptive statistics (mean �� SD) of the studied sample Procedures For the ithlete?, each subject was fitted with a heart rate transmitter Cilengitide and an elastic strap (Non-Coded Polar T-31, Polar Electro Oy, Kemple, Finland) fastened securely around the upper thorax at the level of the xiphoid process.