Table 3.
Heart rate variability measurements during the 24 hr following the HIIE sessions or the no-exercise control session
| Variable | 24-Hr period | Nighttime period | Daytime period | ||||||
|---|---|---|---|---|---|---|---|---|---|
|
|
|
|
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| CON | Land-based HIIE | Water-based HIIE | CON | Land-based HIIE | Water-based HIIE | CON | Land-based HIIE | Water-based HIIE | |
| HR (beats/min) | 74.4±6.4 | 78.4±6.4† | 78.6±7.5†† | 60.1±5.4 | 62.3±2.8 | 62.6±5.2 | 84.1±9.0 | 87.5±10.3 | 85.6±12.7 |
|
| |||||||||
| R interval (msec) | 856.0±77.3 | 809.7±64.1† | 813.4±82.4†† | 1,034.0±98.2 | 981.5±43.9† | 990.6±83.8†† | 740.3±84.2 | 712.1±90.9 | 731.7±113.9 |
|
| |||||||||
| SDNN (msec) | 197.1±32.0 | 180.2±25.4 | 189.2±45.1 | 156.5±45.0 | 118.9±25.6 | 145.7±45.4 | 120.5±32.4 | 108.6±45.7 | 106.0±37.3 |
|
| |||||||||
| pNN50 (%) | 26.6±8.4 | 21.0±7.1†† | 22.2±10.2†† | 47.1±12.5 | 39.3±10.7† | 41.9±13.8† | 12.6±7.0 | 10.6±8.1 | 13.1±12.7 |
|
| |||||||||
| RMSSD (msec) | 68.1±19.5 | 54.3±16.3†† | 60.4±24† | 88.7±23.1 | 70.4±18.0† | 80.2±29.7 | 43.6±13.7 | 37.6±20.7 | 40.9±23.7 |
|
| |||||||||
| lnHF (msec2) | 7.3±0.5 | 6.9±0.5†† | 7.0±0.6†† | 7.8±0.5 | 7.4±0.6† | 7.6±0.6 | 6.2±0.6 | 5.8±0.8 | 5.9±1.0 |
|
| |||||||||
| lnLF (msec2) | 7.4±0.4 | 7.1±0.4†† | 7.2±0.5†† | 7.5±0.6 | 7.2±0.6† | 7.3±0.6† | 6.9±0.3 | 6.8±0.5 | 6.8±0.6 |
|
| |||||||||
| lnVLF (msec2) | 8.8±0.3 | 8.6±0.3† | 8.6±0.4† | 8.8±0.4 | 8.4±0.4† | 8.6±0.5 | 8.0±0.5 | 7.8±0.6 | 7.8±0.7 |
|
| |||||||||
| lnTP (msec2) | 9.2±0.3 | 8.9±0.3†† | 9.0±0.4† | 9.3±0.4 | 8.9±0.5† | 9.1±0.5† | 8.5±0.5 | 8.2±0.6 | 8.2±0.7 |
|
| |||||||||
| LF/HF ratio | 1.1±0.3 | 1.3±0.3† | 1.2±0.3 | 0.8±0.3 | 0.9±0.3 | 0.8±0.3 | 2.1±0.8 | 2.8±1.0† | 2.7±1.0 |
|
| |||||||||
| SD1 (msec) | 48.1±13.8 | 38.4±11.5†† | 42.7±17.0† | 62.7±16.3 | 49.8±12.8† | 56.7±21.0 | 30.8±9.7 | 26.6±14.6 | 28.9±16.8 |
|
| |||||||||
| SD2 (msec) | 274.4±44.4 | 251.8±34.8 | 263.9±62.3 | 211.7±63.1 | 160.6±34.3 | 197.9±61.3 | 167.5±45.2 | 151.1±63.1 | 146.9±50.7 |
|
| |||||||||
| SD2/SD1 | 6.0±1.4 | 6.9±1.4†† | 6.6±1.8† | 3.5±0.9 | 3.3±0.5 | 3.6±0.5 | 5.6±1.2 | 6.0±1.3 | 5.7±1.5 |
Values are presented as mean±standard deviation.
HIIE, high-intensity interval exercise; CON, no-exercise control; HR, heart rate; SDNN, standard deviation of all RR intervals; pNN50, percentage of consecutive RR intervals that differ by >50 msec; RMSSD, root mean square of differences of successive RR intervals; lnHF, logarithm high frequency; lnLF, logarithm low frequency; lnVLF, logarithm very low frequency; lnTP, logarithm total power; LF/HF ratio, ratio of absolute LF power to HF power; SD1, the standard deviation of the distance of each point from the y=x-axis; SD2, the standard deviation of each point from the y=x+average RR interval; SD2/SD1, ratio of SD2 to SD1.
P<0.05 and
P<0.01 to between-group comparison (vs. CON).