Comparison between Fast Fourier Transform and Autoregressive Model on Analysis of Autonomic Nervous Function after Food Intake in Women

Purpose: Heart rate variability (HRV) is acknowledged as a useful tool to estimate autonomic function. Fast Fourier transform (FFT) and autoregressive model (AR) are used for power spectral analysis of HRV. However, there is little evidence of agreement between FFT and AR in relation to HRV following food intake in females. In the present study, we applied both FFT and AR after food intake during the follicular and luteal phases, and compared raw low-frequency (LF) and high- frequency (HF) powers, and LF/HF ratio obtained with the two power-spectral analytical methods. Methods: All subjects participated in two sessions: follicular phase session and luteal phase session. In each session, R-R intervals were continuously recorded before and after meals, and power spectral analysis of heart rate variability was performed. We analyzed low-frequency power (LF: 0.04 - 0.15 Hz) and high-frequency power (HF: 0.15 - 0.40 Hz) by using FFT and AR. LF and HF power were computed for each 30 sec, 1 min, 2.5 min, and 5 min of the 5-min R-R data before meal intake and at 20, 40, 60 and 80 min after meal intake. The LF/HF ratio was calculated as an index of sympathovagal balance. Results: In the present study, after 30 sec and 1 min of segment analysis, there was little interchangeability between AR and FFT in LF, HF, and LF/HF ratio in both follicular and luteal phases. In 2.5 min or 5 min of segment analysis, there was interchangeability between FFT and AR in LF and HF, but not in the LF/HF ratio in both follicular and luteal phases. Additionally, FFT underestimated HRV compared with AR, and the extent of underestimation increased with increasing AR value. Conclusion: FFT underestimated HRV compared with AR, and FFT correlated poorly with AR when the analysis segment was shortened.

Relationship among Eating Behavior, Effortful Control, and Working Memory in Female Young Adults

The management of eating behavior plays an important role in health maintenance. In this study, we investigated the relationship between eating behavior and effortful control in female young adults. Participants completed the questionnaire measures of effortful control and eating behaviors and Stroop cognitive interference task. The results showed that restrained eating was positively correlated with activation control;emotional eating was negatively correlated with inhibitory control and attentional control;external eating was negatively correlated with inhibitory, activation, and attentional control. The scores for activation control and restrained eating were higher for participants with a low Stroop error rate than for those with a high Stroop error rate. These results indicate that restrained eating has a different association with effortful control than doing emotional and external eating.

Relationship between the Existence of Exercise Partners and Exercise Habits in University Students in Japan

We investigated the relationships between the existence of exercise partners and exercise habits among Japanese university students. Subjects were 650 university students (539 males, 111 females;age range 18 - 27 years). They responded to an anonymous questionnaire asking about current and past exercise habits, preference for exercise (i.e., like or dislike of exercise), and the existence of one or more exercise partners. In the results, the existence of exercise partners had a significant association with exercise habits at each school stage in both genders. Exercise preference had a significant association with exercise habits during high school in both genders;during primary and middle school, however, this association was significant only in males. In males, exercise habits and the preference for exercising in high school affected current exercise habits. In females, only exercise habits in high school affected current exercise habits. Our results suggest that the existence of one or more exercise partners is important for the practice of exercise, as well as the preference for exercise. They also suggest that continuity of exercise habits is different between males and females.

The Relationships among Perception of Body Image, a Desire for Thinness, and Dieting Behavior in Young Females in Japan

The aim of this study was to investigate the relationship among body image perceptions, a desire for thinness, and dieting behavior in young females in Japan. The subjects were 302 Japanese female university students (age 19.9 ± 1.4 years). An anonymous, self-administered questionnaire survey was conducted between July and August 2011. The questionnaire clarified the subjects’ physical status, perception about personal body shape, desired body shape, the time frame when they first thought about body shape dieting, exercise habits, and eating behaviors. The results revealed that many of the underweight or normal weight subjects perceived themselves as obese, and often the reasons for the perception of obesity were comparisons with others or with themselves in the past. The scores of EAT-26 in those who perceived themselves as obese were higher than the scores in those who did not. Those who perceived themselves as obese had a desire to become slim, were concerned about body shape at an early age, were concerned about dieting, had dieting experience, and were willing to increase daily exercise. These results indicated that incorrect perceptions about body shape have connection to a desire for thinness and dieting behavior.