Table 2.
Mean (SD) of the different chess problem for each group and intra and inter groups comparisons for heart rate variability and subjective perception.
| High performance group |
Low performance group |
|||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low level problem | Medium level problem | High level problem | Low level problem | Medium level problem | High level problem | Within group differencesa |
Differences between low and high performance groupsb | |||||
| High performance group | Low performance group | |||||||||||
| Low vs. high level | Medium vs. high level | Low vs. high level | Low level | Medium level | High level | |||||||
| Heart rate variability | ||||||||||||
| Mean HR | 78.16 (14.09) | 78.79 (15.71) | 80.55 (13.70) | 82.20 (11.44) | 84.10 (11.20) | 87.00 (11.07) | ns | ns | 0.037 | ns | ns | ns |
| SDNN | 70.58 (18.09) | 68.18 (17.24) | 67.28 (25.03) | 44.36 (12.74) | 46.45 (15.88) | 44.10 (17.02) | ns | ns | ns | 0.021 | 0.027 | ns |
| Pnn50 | 18.03 (14.68) | 19.44 (17.06) | 15.46 (15.92) | 3.76 (4.01) | 5.00 (7.14) | 3.65 (4.49) | ns | ns | ns | 0.021 | 0.027 | ns |
| RMSSD | 40.69 (19.02) | 42.01 (21.12) | 36.65 (20.37) | 20.65 (8.06) | 21.55 (9.48) | 18.61 (8.64) | ns | 0.037 | ns | 0.021 | 0.027 | ns |
| LF/HF | 4.12 (2.42) | 4.48 (2.62) | 3.95 (2.05) | 5.81 (3.73) | 5.83 (3.77) | 5.51 (4.90) | ns | ns | ns | ns | ns | ns |
| SampEn | 1.18 (0.42) | 1.19 (0.34) | 1.19 (0.22) | 1.04 (0.32) | 1.08 (0.25) | 0.90 (0.25) | ns | ns | ns | ns | ns | 0.041 |
| SD1 | 28.81 (13.47) | 29.76 (14.95) | 25.94 (14.42) | 14.76 (5.66) | 15.25 (6.73) | 13.16 (6.12) | ns | 0.037 | ns | 0.032 | ns | 0.027 |
| SD2 | 95.08 (23.56) | 78.26 (33.07) | 91.43 (32.77) | 61.56 (16.95) | 63.76 (21.79) | 60.89 (23.40) | ns | ns | ns | 0.032 | ns | ns |
| Subjective perception | ||||||||||||
| Stress | 1.75 (1.83) | 2.29 (1.60) | 5.38 (2.72) | 2.25 (1.58) | 4.13 (2.30) | 6.12 (2.80) | 0.004 | ns | 0.005 | ns | ns | ns |
| Difficulty | 1.75 (1.75) | 3.71 (1.70) | 8.13 (0.83) | 3.25 (2.38) | 5.38 (1.69) | 7.75 (1.16) | 0.002 | ns | 0.012 | ns | ns | ns |
| Complexity | 0.38 (1.06) | 0.86 (0.69) | 6.00 (2.56) | 4.25 (3.92) | 5.88 (2.75) | 6.88 (1.96) | 0.006 | ns | ns | 0.018 | 0.009 | ns |
ns: Non-significant; 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. aIntra group significant differences were detected using Friedman’s ANOVA by ranks. P-value was corrected using Dunn-Bonferroni adjustment. Only significant interactions between chess problems were reported. bDifferences between low and high performance groups in each difficulty level were detected using Mann–Whitney U-test. The alpha level of significance was adjusted by Benjamini–Hochberg procedure.