PURPOSE: To compare the response of Heart Rate Variability (HRV) during induced stress as a psychophysiological stress indicator in Mexican college volleyball players.
METHODS: We evaluated 16 male college volleyball players (18 to 26 y). Psychophysiological assessment of stress consisted of 7 stages lasting 2 min each (baseline, exposed to a physiological stressor [unpleasant sounds], 1st rest, exposed to a cognitive stressor [mathematical task], 2nd rest, exposed to stressor emotional [talk about a stressful memory] and 3rd rest). It was done by a ProCompTM Infiniti Biofeedback System. Short-term HRV was obtained by a Blood Volume Pulse (BVP) Sensor and analyzed using time-domain: SDRR (standard deviation of RR intervals) and pNN50 (percentage of successive RR intervals that differ by more than 50 ms); and frequency-domain: HRV peak frequency, Very Low Frequency (VLF) total power, Low Frequency (LF) total power, High Frequency (HF) total power, VLF % power, LF % power and HF % power measurements. Statistical analysis was performed by repeated measures ANOVA and non-parametric Friedman test.
RESULTS: Significant differences in HRV were observed when we compared the seven stages of the assessment (with stress stimulus and without stress stimulus). During the COGNITIVE stage there was a difference with the BASELINE (p= .01) and EMOTIONAL (p= .004) stage in HRV peak frequency; in VLF% between PHYSIOLOGICAL and 1st REST (p= .01) stage; among the BASELINE and the EMOTIONAL (p= .04) stage on SDRR; and with pNN50 on COGNITIVE and 3rd REST (p= .02) stage. (Table 1)
.CONCLUSIONS: The results show significant changes in the variables associated with sympathetic activity in stages that had stressors compared to baseline and rests, which may indicate psychophysiological response to stress. These results support the idea of HRV is a useful psychophysiological stress indicator and maybe a helpful tool to identify and have better stress management in Mexican college athletes.
Table 1. Heart Rate Variability indicators comparison between each stage. | Baseline | Physiological | 1st Rest | Cognitive | 2nd Rest | Emotional | 3rd Rest |
| SDRR1 | 78.4 (58.3 - 92.4) a | 76.3 (67.5 - 110.5) | 91.6 (70.5 - 117.4) | 80.7 (62.4 - 114.6) | 89.9 (72.8 - 114.6) | 112.2 (62.9 - 155.5) a | 90.1 (68.8 - 115.5) |
| pNN502 | 20.4 (2.4) | 20.9 (2.6) | 19.2 (2.5) | 15.2 (2.2) b | 22.1 (2.2) | 17.4 (2.5) | 22.1 (2.5) b |
| HRVPF2 | 0.12 (0.01) c | 0.13 (0.01) d | 0.09 (0.01) | 0.07 (0.01) c,d | 0.13 (0.02) | 0.10 (0.01) | 0.11 (0.02) |
| VLFTP1 | 227 (86 - 444) | 130 (64 - 310) | 409 (198 - 608) | 254 (171 - 373 | 319 (140 - 555) | 399 (112 - 742) | 417 (122 - 651) |
| LFTP1 | 480 (308 -1015) | 604 (330 - 1160) | 609 (267 - 1490) | 850 (394 - 1673) | 508 (400 - 1439) | 924 (597 - 2735) | 506 (321 - 1442) |
| HFTP1 | 628 (378 - 1094) | 641 (273 - 935) | 681 (278 - 1055) | 473 (194 - 927) | 723 (210 - 1564) | 656 (321 - 2389) | 746 (304 - 1324) |
| VLF%1 | 16.8 (10.1 - 23.9) | 11.9 (4.1 - 17.7) e | 22.4 (12.2 - 27.8) e | 21.7 (11.3 - 29.4) | 15.6 (10.3 - 25.2) | 11.4 (6.1 - 18.9) | 18.9 (10.6 - 26.9) |
| LF%1 | 36.7 (24.7 - 51.6) | 41.8 (29.4 - 51.6) | 31.9 (26.5 - 55.9) | 48.6 (33.6 - 58.0) | 36.9 (27.1 - 56.0) | 47.9 (37.0 - 64.7) | 33.5 (25.1 - 49.9) |
| HF%2 | 43.9 (17.0) | 43.1 (20.4) | 37.9 (16.5) | 30.0 (12.8) | 40.7 (20.8) | 34.1 (16.2) | 40.2 (18.5) |
1 Non-normal distribution is expresed with Median (P25 - P75).
2 Normal distribution is expresed with Mean (SD). Same letters denote significant differences between the indicator of HRV during each stage (p<0.05). |
