Table 1. Correlation (r) matrix of elite volleyball referees’ cardiac responses with cardiac responses. HR pre-match HR post-match Ø HR during the match HRV pre-match HRV post-match Ø HRV during the match HR pre-match 1.00 0.78 *** 0.77 *** -0.53 *** -0.42 ** -0.63 *** HR post-match 0.78 *** 1.00 0.82 *** -0.46 ** -0.49 *** -0.59 *** Ø HR during the match 0.77 *** 0.82 *** 1.00 -0.57 *** -0.35 -0.72 *** HRV pre-match -0.53 *** -0.46 ** -0.57 *** 1.00 0.81 *** 0.74 *** HRV post-match -0.42 ** -0.49 *** -0.35 0.81 *** 1.00 0.61 *** Ø HRV during the match -0.63 *** -0.59 *** -0.72 *** 0.74 *** 0.61 *** 1.00 ** and *** indicate p < 0.01 and 0.001 respectively.