Researchers have investigated whether ultra-short-term (UST) heart rate variability values can replace traditional 5-minute values in clinical and optimal performance settings. Concurrent validity is the extent to which the results of a measurement correspond to a previously validated assessment of the same construct. Several studies either failed to specify their concurrent validity criteria or used an inappropriate statistical test. The authors proposed a rigorous standard and demonstrated that artifacted resting ultra-short-term heart rate variability values can achieve strong concurrent validity for diverse time-domain, frequency-domain, and nonlinear measurements in healthy undergraduates. Based on these findings, resting baselines as brief as 1 minute should be sufficient to measure heart rate, the standard deviation of the interbeat interval for normal beats (SDNN), and the square root of the mean squared difference of adjacent NN intervals (RMSSD) in clinical, optimal performance, and personal health assessment with individuals who resemble Truman State University undergraduates.