Table 1.
Between group comparisons of the general characteristics, distribution of performance, and basal values of heart rate variability.
| Variables | High performance group | Low performance group | P-valuea |
|---|---|---|---|
| General characteristics | |||
| Sample Size | 8 | 8 | |
| Age | 27.63 (12.05) | 42.75 (10.55) | 0.038 |
| ELO | 1973 (161) | 1881 (172) | 0.234 |
| Distribution of performance: number of total correct problems for each group | |||
| Low level problem | 16 | 14 | 0.721 |
| Medium level problem | 16 | 7 | 0.002 |
| High level problem | 2 | 0 | 0.442 |
| Heart rate variability measures | |||
| Mean HR | 79.70 (26.23) | 78.17 (11.11) | 0.959 |
| SDNN | 60.05 (15.62) | 41.34 (14.94) | 0.644 |
| Pnn50 | 14.21 (15.61) | 4.30 (5.23) | 0.644 |
| rMSSD | 33.29 (19.04) | 20.79 (8.80) | 0.644 |
| LF/HF | 6.80 (8.66) | 4.81 (4.43) | 1.000 |
| SampEn | 1.10 (0.25) | 1.16 (0.19) | 1.000 |
| SD1 | 23.59 (13.46) | 14.71 (6.24) | 0.483 |
| SD2 | 81.34 (35.04) | 56.56 (20.21) | 0.798 |
ELO: ranking system of the World Chess Federation; HR: Heart Rate; SDNN: Standard deviation of all normal to normal RR intervals; pNN50: The percentage of intervals >50 ms different from preceding interval; RMSSD: Square root of the mean of the squares of successive RR interval differences; LF/HF: ratio Low Frequency (LF) (ms2)/ High Frequency (HF) (ms2); SampEn: Sample Entropy; SD1: Dispersion, standard deviation, of points perpendicular to the axis of line-of-identity in the Poincaré plot; SD2: Dispersion, standard deviation, of points along the axis of line-of-identity in the Poincaré plot. aDifferences between group were detected using Mann–Whitney U adjusted by Benjamini–Hochberg procedure.