Cardiac autonomic functions derived from short-term heart rate variability recordings associated with heart rate recovery after treadmill exercise test in young individuals.
Analysis of short-term heart rate variability (HRV) may provide useful information about autonomic nervous control of heart rate recovery. We studied 495 individuals (273 men), age range 19-85 years, submitted to treadmill exercise tests and short-term HRV evaluations over time (standard deviation of the normal-to-normal interval [SDNN], the square root of the mean squared differences of successive normal-to-normal intervals [RMSSD], the number of interval differences of successive normal-to-normal intervals greater than 50 ms [NN50 count], the proportion derived by dividing NN50 count by the total number of normal-to-normal intervals [pNN50]) and frequency (low-frequency power [LF], high-frequency power [HF], total power) domains. Among 495 patients, 106 patients (68 men) were elderly (age ≥ 65 years). Male gender and hypertension were significantly higher in elderly patients. The young patients had higher HRR after exercise. HRR at 4 min (54 ± 13 vs 60 ± 12 beats/min; P = 0.003) was the most significant predictor for positive exercise test result. In the young group, both time domain measures (SDNN: correlation coefficient 0.34, P < 0.001; RMSSD: correlation coefficient 0.37, P < 0.001) and frequency domain measures (LF: correlation coefficient 0.21, P < 0.001; HF: correlation coefficient 0.13, P = 0.01; total power: correlation coefficient 0.22, P < 0.001) were significantly associated with HRR at 4 min. HRR at 4 min was significantly associated with short-term HRV of time and frequency domains in young individuals, but not elderly ones, receiving treadmill exercise test.
Division of Cardiology, Department of Internal Medicine, National Cheng Kung University Hospital, 138 Sheng-Li Road, Tainan, 704, Taiwan.
Ju-Yi
JY
Chen
Yungling Leo
YL
Lee
Wei-Chuan
WC
Tsai
Cheng-Han
CH
Lee
Po-Sheng
PS
Chen
Yi-Heng
YH
Li
Liang-Miin
LM
Tsai
Jyh-Hong
JH
Chen
Li-Jen
LJ
Lin
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D001341:Autonomic Nervous System / Q000502:physiology*; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D004562:Electrocardiography; D015444:Exercise; D005080:Exercise Test; D005260:Female; D006321:Heart / Q000294:innervation*; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D020127:Recovery of Function; D013624:Taiwan; D013997:Time Factors; D055815:Young Adult