Discussion The results of this study supported and contradicted the beforehand formulated hypotheses. Good reproducibility was found for measurements BAY 1895344 in vitro of HRV and RR. Measurements of HRV and RR had lower than moderate concurrent

validity for determining fatigue, as assessed with the CIS and the SHC subscale PN. The mean total CIS score of the subjects in this study is much higher than the mean total score of a healthy group, as reported by Vercoulen et al. (1999). This implies that the subjects in this study did indeed suffer from severe fatigue problems, as confirmed by the fact that 84% of the sample scored higher than the established cut-off point for chronic fatigue of >76 (Bultmann et al. 2000). Reeves et al. (2005) reported significantly lower scores on all eight subscales of the SF-36 in subjects with chronic fatigue syndrome, as compared to a healthy control group. Consistent differences between the SF-36 scores of patients with chronic fatigue syndrome and those of control subjects (Buchwald et al. 1996; Schmaling et al. 1998) have been found before and our subjects scored even lower on the four subscales of the SF-36 than did the fatigued subjects in Reeves et al. (2005). It is concluded that although we did

not include subjects with CFS criteria, they indeed suffered from substantial functional impairments and considerable fatigue levels. To our knowledge, for the first time, reproducibility of HRV and RR has been studied in a sample of subjects with prolonged fatigue problems. Earlier reproducibility studies have focused on healthy subjects and click here other kinds of patient populations (Carrasco et al. 2003; Marks and Lightfoot 1999; Pardo et al. 1996; Sandercock et al. 2004; Schroeder et al. 2004; Sinnreich et al. 1998; Tarkiainen et al. 2005). This study is a sequel to an earlier study that used the same device to measure HRV and RR in healthy subjects (Guijt et al. 2007). The measurement device generated reliable HRV and RR measurements in a sample of healthy

subjects and in a sample of subjects with prolonged fatigue complaints. This means that the Co2ntrol is a suitable device to distinguish between both healthy subjects and Olopatadine subjects with prolonged fatigue complaints. Both studies showed good agreement between repeated HRV and RR measurements. A number of interesting findings emerged from a comparison of the findings of the presents study with those of the earlier study, which evaluated the reliability of HRV and RR measurements with the Co2ntrol in healthy subjects (Guijt et al. 2007). As expected, the sample of healthy subjects in the earlier study showed higher SDNN and RMSSD values (HRV parameters) for cycling and MM-102 molecular weight reclining than did the fatigued subjects in this study. The findings for RR are even more interesting. The sample of fatigued participants in the present study showed lower RRs for both cycling and reclining than the healthy subjects had shown.