Effect of consecutive matches on heart rate variability in elite volleyball players

The objective of this study was to observe and determine changes in HRV parameters in volleyball players during the Mexican national professional volleyball league. Heart rate was monitored in 12 athletes (age 22.60 +/- 3.4) for four months during weekends (Saturdays and Sundays). Three measures were taken during each match-day: the first at rest (REST), the second in the afternoon after the matches of the first day (R2), and the third after the matches of the second day (R4). Data were analyzed with ANOVA and the Bonferroni method. We found a difference between REST and R2 and R4 in SDNN (98.66 +/- 62.50 vs. 50.35 +/- 26.33 ms, p < .001; 59.24 +/- 22.11, p < .001 for R2 and R4 respectively), rMSSD (43.49 +/- 34.60 vs. 24.33 +/- 18.89,p < .05; 28.44 +/- 16.70, p < .05 for R2 and R4, respectively), pNN50 (30.37 +/- 21.47% vs. 12.09 +/- 16.56,p < .001; 13.30 +/- 13.64,p < .001 for R2 and R4 respectively), SDI (45.84 +/- 30.17 ms vs. 22.83 +/- 17.30, p < .001; 28.01 +/- 14.94,p < .01 for R2 and R4, respectively) and SD2 (123.18 +/- 53.67 ms vs. 65.58 +/- 32.42. p < .001; 79.06 +/- 28.33, p < .001 for R2 and R4, respectively). There were no significant differences between R2 and R4. These results show that heart rate variability helps determine changes after several matches in sympathetic and parasympathetic modulation in volleyball players, and that this provides information on athletes' physical performance.