Table 2.
Heart rate variability
| Variable | Younger Men | MA/O Men with Low T | MA/O Men with Normal T | P Value |
|---|---|---|---|---|
| N | 6 | 10 | 10 | |
| SDNN, ms | 57.6 ± 30.2 | 28.9 ± 8.9 | 43.1 ± 25.2 | 0.067 |
| RMSSD, ms | 59.5 ± 43.3 | 28.7 ± 9.9 | 49.1 ± 31.1 | 0.135 |
| LF power, ms2a | 695 [378–2,529] | 357 [143–611] | 180 [120–1,049] | 0.366 |
| HF power, ms2a | 1,258 [434–3,653] | 165 [128–349]* | 925 [142–2,581] | 0.041 |
| LF/HFa | 0.69 [0.33–1.60] | 1.80 [0.42–1.80] | 0.42 [0.28–1.33] | 0.229 |
Data are means ± SD or median [interquartile range]. HF, high frequency; LF, low frequency; MA/O, middle-aged/older; RMSSD, root mean square of successive differences between normal heartbeats; SDNN, standard deviation of normal-to-normal R-R intervals; T, testosterone. Boldface indicates significant main effect. aNonnormally distributed data. *P < 0.05 compared with younger men.