The purposes of this study were to demonstrate the transition of heart rate variability (HRV) during trials in the field and to examine the relationship between peak frequency of high-frequency band (HF) and stride frequency. Ten healthy long-distance college female runners (age 19-21 years) performed a 3000 m realistic time trial. The time-series power spectrum analysis by maximum entropy method was used to evaluate cardiac autonomic nervous activity during the race. Cross-correlation coefficients were calculated to estimate the degree of linear co-ordination between the central peak frequency of HF and stride frequency. Just after starting, the decrease in HF (0.15-1.00 Hz) and a transient increase of low-frequency band (LF)/HF were found. After that, the HF remained at a low level and LF/HF decreased sharply. These findings suggested that the parasympathetic activity was suppressed and sympathetic activity increased just after starting, and the sympathetic activity reached the saturated level according to continuation of high-intensity exercise. In spite of the significant decrease of HRV during trials, peak frequency of HF could be differentiated clearly. The cross-correlation coefficient of peak frequency of HF and stride frequency was from 0.703 to 0.868. This finding indicated that exercise rhythm reflected HRV during high-intensity running in the field.

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The purpose of this study was to examine the timing of recovery of the high-frequency (HF) component of heart rate variability (HRV) after exercise in female distance runners using frequency analysis of HRV. Twenty-two female young (nϭ11; YG) and middle-aged (nϭ11; MG) distance runners participated in this study. The two groups performed incremental cycle exercise with progressive intensity until exhaustion. The R-R intervals were processed by the maximum entropy method for determination of HF power on successive 7-second segments of 70 seconds of the recovery period. In the YG, the HF power of the second 7-sec segment showed significantly higher values than the 7 sec before cessation of exercise (pϽ0.005), whereas the MG exhibited significantly higher values in the third segment (pϽ0.005). The YG indicated significantly higher HF power than the MG in the fifth segment (pϽ0.0045). These findings suggested the occurrence of parasympathetic reactivation at an earlier period compared to the previous findings. Multiple influences of various factors including the subjects' characteristics to HF recovery were suggested. However, the detection of the timing of HF recovery despite the duration of sharp change in HR indicated that HRV was an effective evaluation technique for determination of autonomic control immediately after exercise.

The present study investigated the relationship between psychophysiological state and clutch or choking performance during golf putting under pressure. Ten males and 13 females who were high-level competitive amateur golfers performed 25 putts under control and pressure conditions. State-Trait Anxiety Inventory-Y1 (STAI-Y1), heart rate variability (HRV), and putting scores were measured. Participants whose performance improved under the pressure condition compared to the control condition were defined as clutch performers and all others were defined as choking performers. Change ratios between the pressure and control conditions for each variable were calculated and compared between clutch and choking performers. There was a significant difference in the change ratio of the low frequency (LF) component of HRV such that LF HRV decreased under the pressure condition compared with the control condition only in choking performers. Thus, LF HRV may be associated with improved fine motor control, such as golf putting, under pressure circumstances.

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