摘要：Diurnal rhythms of the mean R-R interval and the coefficient of variation (CV) of R-R intervals in eleven young Thoroughbred horses (2-year-old) were examined by periodic analysis to see whether the periodicity of the rhythms change with growing and physical training. On the diurnal rhythm of the mean R-R interval, a single spectrum (14.5 hr-19.3 hr periodicity) was extracted and the power, amplitude and the middle estimating static of rhythm (MESOR) of this periodicity increased with growing and physical training. On the other hand, two periodicities (14.5 hr-15.8 hr and 5.6 hr-7.5 hr periodicity) were found in the diurnal rhythm of the R-R interval variability but no alteration with growing and physical training was recognized. This suggests that the diurnal rhythm of the mean R-R interval and that of the R-R interval variability are extracted and reflect the different factors affecting autonomic nervous activity. Monitoring the diurnal rhythm of the R-R interval, furthermore, may enable us to understand the progression of growing and physical training effects.
