Table 1.
Heart rate parameters obtained during consecutive days of maximal exercise testing.
| Variable | Controls Day 1 | ME/CFS Day 1 | Controls Day 2 | ME/CFS Day 2 | ‘Group’ effect value of p | ‘Time’ effect value of p | ‘Group’בTime’ interaction value of p |
|---|---|---|---|---|---|---|---|
| Supine | |||||||
| HR (bpm) | 69.5 (8.4) | 74.0 (12.1) | 70.1 (10.9) | 72.0 (12.0) | 0.471 | 0.607 | 0.350 |
| RR (ms) | 871.0 (98.7) | 846.1 (145.4) | 870.75 (128.5) | 847.8 (149.6) | 0.659 | 0.928 | 0.938 |
| LFP (ms2) | 616.3 (607.9) | 631.2 (737.6) | 710.9 (1171.9) | 602.3 (558.1) | 0.861 | 0.842 | 0.709 |
| HFP (ms2) | 207.1 (237.7) | 221.1 (194.3) | 272.3 (340.7) | 245.3 (305.4) | 0.949 | 0.271 | 0.609 |
| LF/HF | 4.66 (5.68) | 3.95 (3.56) | 4.35 (2.75) | 4.82 (5.29) | 0.935 | 0.783 | 0.551 |
| RMSSD (ms) | 21.0 (12.6) | 22.6 (10.3) | 23.5 (14.6) | 20.5 (10.2) | 0.877 | 0.872 | 0.141 |
| Seated | |||||||
| HR (bpm) | 80.0 (8.4) | 83.1 (12.3) | 80.2 (10.4) | 81.9 (11.3) | 0.556 | 0.812 | 0.740 |
| RR (ms) | 771.0 (81.4) | 753.3 (136.8) | 764.8 (99.2) | 767.4 (116.3) | 0.874 | 0.784 | 0.430 |
| LFP (ms2) | 365.5 (331.1) | 529.3 (429.0) | 332.7 (212.7) | 604.2 (557.6) | 0.199 | 0.688 | 0.308 |
| HFP (ms2) | 221.2 (321.2) | 428.1 (774.5) | 195.0 (265.6) | 223.6 (349.4) | 0.499 | 0.313 | 0.433 |
| LF/HF | 4.12 (3.50) | 5.64 (5.10) | 3.434 (3.771) | 6.73 (7.91) | 0.222 | 0.874 | 0.491 |
| RMSSD (ms) | 17.6 (9.1) | 20.7 (14.3) | 17.4 (9.0) | 18.8 (9.4) | 0.591 | 0.509 | 0.600 |
| Steady state | |||||||
| HR (bpm) | 100.6 (11.1) | 106.5 (12.6) | 101.0 (12.7) | 104.5 (14.2) | 0.331 | 0.716 | 0.556 |
| RR (ms) | 607.2 (70.9) | 594.8 (83.2) | 611.1 (77.8) | 590.9 (82.1) | 0.304 | 0.898 | 0.637 |
| rHRI (bpm/s) | 3.481 (3.21) | 2.315 (2.68) | 2.75 (2.10) | 2.09 (1.96) | 0.329 | 0.243 | 0.538 |
| RMSSD (ms) | 9.9 (5.7) | 8.4 (4.8) | 9.6 (6.1) | 7.8 (4.8) | 0.422 | 0.514 | 0.812 |
| AUC | 29447.9 (3095.1) | 31047.1 (4164.1) | 29386.5 (3665.3) | 29636.3 (2638.0) | 0.520 | 0.251 | 0.291 |
| Ventilatory threshold | |||||||
| HR (bpm) | 122.4 (13.2) | 124.0 (18.3) | 120.8 (14.2) | 117.4 (17.6) | 0.892 | 0.030 | 0.173 |
| Maximal exercise | |||||||
| HR (bpm) | 170.3 (10.0) | 167.8 (20.0) | 170.9 (11.0) | 167.0 (15.7) | 0.600 | 0.936 | 0.666 |
| AUC | 245324.3 (73468.9) | 236193.1 (155736.3) | 245790.6 (72822.6) | 220060.2 (127967.4) | 0.730 | 0.449 | 0.423 |
| HRR 1' (bpm) | 127.1 (15.4) | 134.6 (22.5) | 126.8 (15.1) | 130.0 (19.1) | 0.466 | 0.372 | 0.422 |
| HRR Δ1a (bpm) | 43.2 (7.9) | 33.2 (6.9)a | 44.1 (9.3) | 36.9 (8.8) | 0.007 | 0.151 | 0.373 |
Values are mean (SD), asignificant difference between ME/CFS and controls at Day 1 (p<0.05), ME/CFS, Myalgic Encephalomyelitis/Chronic Fatigue Syndrome; HR, heart rate; bpm, beats per minute; RR, interval between R waves; LFP, low frequency power from spectral analysis; HFP, high frequency power from spectral analysis; LF/HF, ratio between low frequency and high frequency power from spectral analysis; RMSSD, root-mean-square difference of successive normal R-R intervals from time-domain analysis; rHRI, maximal rate of increase in heart rate; sec, second; AUC, area under the curve for time (sec) vs HR (bpm); and HRR, post-exercise heart rate recovery.