Table 4. The overall average values and values for successful and unsuccessful performances in different heart rate variability and direct current potential variables for four elite international long jump athletes in a 16-week period that included the qualification for and competition at the 2016 Olympic Games. OVERALL SUCCESSFUL PERFORMANCES UNSUCCESSFUL PERFORMANCES p f2 Effect size LnRMSSD 1.83 ± 0.22 1.80 ± 0.26 1.99 ± 0.12 0.06 0.20 Moderate LnRMSSD %CV 8.04 ± 4.80 9.38 ± 6.60 4.71 ± 3.37 0.11 0.08 Small RR 1000 ± 167 1034 ± 92.7 1091 ± 116 0.32 0.05 Small LnRMSSD:RR (x10-3) 1.86 ± 0.24 1.75 ± 0.25 1.83 ± 0.12 0.37 0.05 Small LnRMSSD-7 1.84 ± 0.16 1.81 ± 0.13 1.99 ± 0.13 <0.01** 0.19 Moderate LnRMSSD:RR-7 (x10-3) 1.86 ± 0.16 1.81 ± 0.06 1.77 ± 0.13 0.59 0.01 Trivial DC 11.8 ± 15.1 19.3 ± 9.03 19.5 ± 10.7 0.71 0.01 Trivial DC-7 11.3 ± 11.2 15.4 ± 7.48 16.9 ± 7.51 0.48 0.01 Trivial LnRMSSD - natural logarithm of the square of the mean sum of the squared differences between R-R intervals, LnRMSSD %CV - LnRMSSD coefficient of variation, LnRMSSD:RR - LnRMSSD to R-R interval ratio, LnRMSSD-7 – LnRMSSD averaged over 7 days, LnRMSSD:RR-7 - LnRMSSD:RR averaged over 7 days, DC – direct current potential, DC-7 – direct current potential averaged over 7 days, * - p<0.05, f2 – Cohen’s marginal effect size.