Method for determining the physical and/or psychological state of a subject

#This application is the National Stage of PCT/EP2013/052573 filed on Feb. 8, 2013, which claims priority under 35 U.S.C. §119 of European Application Nos. 12154578.4 filed on Feb. 8, 2012, and 12154764.0 filed on Feb. 9, 2012, the disclosures of which are incorporated by reference. The international application under PCT article 21(2) was not published in English.

#The invention relates to a method for determination of the physical and/or psychological state of a subject, in that the heart rate variability (HRV) of the subject is subjected to analysis in the time domain, during which analysis at least one frequency distribution of interbeat intervals (IBI) recorded during at least one examination time period is investigated.

#In order to determine the physical and/or psychological state of a subject, it is known from the state of the art to determine the resting pulse or the pulse frequency—possibly at different respiratory defaults—and, in particular, to put the results obtained in this connection in relation to comparison values. Such methods can possibly yield guideline values with regard to the state or the performance capacity of a subject, but they prove to be comparatively complicated, because the conditions under which the determination is carried out can only be standardized with difficulty. Furthermore, the results of such methods are only meaningful with limitations, last but not least because an average heart rate is determined, but this only represents a result of the heart beats on which it is based.

#In the drawings, the object of the invention is explained in greater detail, as an example, using figures. These show:

#FIG. 1 a representation of RR interval lengths determined in a specific examination time period,

#FIG. 2 a histogram of the RR intervals according to the results in FIG. 1,

#For the sake of completeness, it should be mentioned that in the figures, RR intervals are investigated and represented, but that of course, it lies within the scope of the invention to also use other parameters and/or measurement methods for a determination of interbeat intervals.

#According to FIG. 1, the RR intervals of consecutive heart beats of a subject recorded during an examination time period 1 are shown graphically. In this connection, the time lengths 2 of the RR intervals that occur along the x axis of the examination time period 1 in seconds [s] are plotted in milliseconds [ms], and consecutive RR intervals are connected with one another by means of a straight line. For example, the representation according to FIG. 1 can thereby show the minimal and maximal RR interval 3 and 4 of a specific time period. A different representation, for example as an RR tachogram, is also possible, but is not shown.

#Likewise, a frequency distribution according to FIG. 2 can be derived from the values shown in FIG. 1. FIG. 2 represents a univariate statistical analysis in the time domain, in the form of a histogram 5, in which, for example, all the RR intervals that were determined during a specific time period are combined in 50 ms classes, whereby the x axis 6 characterizes the length of RR intervals in ms. The heights of these classes, shown as bars, result in accordance with the scaling of the y axis 7 and the number of RR intervals belonging to the class, in each instance, in this histogram. In this example, a modal value 8 can be recognized. The variation width of the lengths of the RR intervals can be derived from the number and height of the classes—for example also by means of evaluation as compared with comparison values. Such a histogram can be worked on further, for example in order to take the ratio of the densities of the modal distributions, particularly the integrals of these densities, into consideration; this is not shown in any detail in FIG. 2. If the frequency distribution shows merely one mode and an essentially normal, symmetrical density distribution—similar to a Gauss curve—one speaks of a comparatively good variability of the heart rates and a good state of a subject, in accordance with the state of the art.