Table 1.
Demographic characteristics and outcome measures before the six-minute walk test of the COVID-19 group and the healthy group.
| COVID-19 Group (n = 37) |
Healthy Group (n = 37) |
t Value | p-Value | |
|---|---|---|---|---|
| Demographics | ||||
| Age (year) | 41.35 ± 15.12 | 38.97 ± 14.51 | 0.69 | 0.49 |
| Height (cm) | 163.83 ± 8.47 | 163.98 ± 8.43 | −0.08 | 0.94 |
| Weight (kg) | 69.03 ± 10.54 | 70 ± 9.52 | −0.42 | 0.68 |
| BMI (kg/m2) | 25.66 ± 3.14 | 25.95 ± 2.54 | −0.45 | 0.65 |
| Gender (Male) | 37 | 37 | - | - |
| Time since COVID infection (month) | 6.24 ± 1.38 | - | - | - |
| Average HR (bpm) | 90.51 ± 10.59 | 80.11 ± 6.29 | 5.14 | p < 0.001 |
| Time domain measures of HRV | ||||
| MeanRR (ms) | 696.4 ± 89.34 | 672.04 ± 75.91 | 1.26 | 0.21 |
| RMSSD (ms) | 22.61 ± 12.48 | 20.31 ± 7.8 | 0.95 | 0.34 |
| Ln RMSSD (ms) | 2.92 ± 0.67 | 2.96 ± 0.64 | −0.29 | 0.77 |
| SDNN (ms) | 39.12 ± 16.73 | 58.91 ± 19.11 | −4.74 | p < 0.001 |
| pNN50 (%) | 6.1 ± 8.82 | 1.05 ± 0.89 | 3.47 | p < 0.001 |
| Frequency domain measures of HRV | ||||
| Total Power (ms2) | 621.35 ± 622.46 | 160.8 ± 66.49 | 4.48 | p < 0.001 |
| Ln Total Power (ms2) | 5.92 ± 1.15 | 5.02 ± 1.2 | 3.26 | p < 0.001 |
| LF (ms2) | 422.18 ± 461.24 | 75.26 ± 16.57 | 4.57 | p < 0.001 |
| HF (ms2) | 198.05 ± 195.15 | 44.73 ± 9.84 | 4.77 | p < 0.001 |
| VLF (ms2) | 55.57 ± 12.57 | 36.68 ± 7.93 | 7.73 | p < 0.001 |
| Ln LF (ms2) | 5.47 ± 1.27 | 4.29 ± 0.41 | 5.36 | p < 0.001 |
| Ln HF (ms2) | 4.63 ± 1.35 | 3.78 ± 0.35 | 3.69 | p < 0.001 |
| LF nu | 67.41 ± 18.86 | 43.49 ± 18.63 | 5.49 | p < 0.001 |
| HF nu | 13.79 ± 15.36 | 22.08 ± 6.3 | −3.04 | p < 0.001 |
| LF/HF | 3.5 ± 3.65 | 1.45 ± 0.54 | 3.38 | p < 0.001 |
| Blood Pressure | ||||
| Systolic | 131.41 ± 12.64 | 131.49 ± 14.36 | −0.03 | 0.98 |
| Diastolic | 86.19 ± 10.04 | 85.81 ± 11.23 | 0.15 | 0.88 |
HR—Heart rate; HRV—Heart rate variability; MeanRR—mean RR normal-to-normal interval; RMSSD—root mean square of successive differences between adjacent RR intervals; SDNN—standard deviation of normal-to-normal intervals; PNN50—proportion of NN50 (number of pairs of successive normal-to-normal intervals that differ by more than 50 ms) divided by the total number of normal-to-normal intervals); LF—low frequency spectral power; HF—high frequency spectral power; LF/HF—ratio of low frequency and high frequency spectral power; nu—normalized units; Ln—natural logarithm.