Relationships between the Munich Chronotype questionnaire index and time at minimum core temperature

Abstract

ABSTRACT The purpose of this study was to examine the correlation between the Munich ChronoType Questionnaire (MCTQ) index and time at minimum core temperature. Nine athletes were requested to answer the MCTQ questionnaire and monitor their core temperature during night. In the MCTQ, the midpoint of sleep on free day, which is corrected for sleep debt accumulated during the workweek (MSFsc), was calculated. The core temperature was monitored using a telemetric system with an ingestible capsule-type sensor. The correlation between the MSFsc and the time at the lowest core temperature was examined. The range of MSFsc and time at minimum core temperature were 2.54–7.75 (mean ±SE: 4.54 ± 0.52, 95%CI: 3.52–5.55) and 3:43–7:41 (mean ±SE: 5:24 ± 0:32, 95%CI: 4:21–6:27), respectively. Four participants with their MSFsc later than 4.96 showed times at minimum core temperature later than 6:00. A significant correlation between the MSFsc and time at minimum core temperature was observed, with a very high correlation coefficient (r = 0.86, p < 0.01). These results suggest that the MSFsc may be useful to find athletes who have a better chance to advance their circadian rhythmicity for morning competitions.