The decrease of the cranial rhythmic impulse during maximal physical exertion: an argument for the hypothesis of venomotion?

Abstract

A new hypothesis for the explanation of the origin of the cranial rhythmic impulse (CRI) is based on the principle of venomotricity. Research on this physiological phenomenon was carried out on bats more than 100 years ago and showed an automatic rhythm of approximately 10 cycles per min (cpm). In this study we will attempt to discover whether a brief physical peak effort has an influence on the CRI. We will assume that there is, in the case of maximal exertion, a brief shift of the CO2/O2volume ratio (RER), which serves as a measure for the energy consumption within the blood vessels. In analogy with this physiological phenomenon we would expect a decrease of the CRI. Three examiners (twice) palpated the cranium and the sacrum for the CRI as well as the vena femoralis for local vasomotion (LVMvf) on a group of healthy subjects (n=15). The examiners changed places during the examination, both before and after the exertion test performed by the subject. The study showed that the reproducibility of all measurements is exceptionally high and that there are no significant differences with respect to rhythm between the three measured locations on the body. The physical effort was determined by measuring the supplied physical strain within a certain time. The respiratory ratio (RER) was determined as the CO2/O2volume ratio in the bloodstream. Together with the values of lactic acid concentration these data were used as explanatory variables and compared to the outcome variables, i.e. the CRI of the cranium (CRI cranium), the CRI of the sacrum (CRI sacrum), cardiac pulse (CAP) and local vasomotion of the vena femoralis (LVMvf). It was found that for each of these research variables there was a significantly high difference associated with the exertion test. The experiment demonstrated that 20 min post-test, a maximal exertion test yields a significant decrease of the three measured rhythms of the CRI cranium, CRI sacrum and LVMvf, with an average reduction of 30%. This suggests that the common decrease probably points to a relation between ‘CRI’ and the decrease of O2concentration in the bloodstream. The CRI decreases after effort as a result of the simultaneously occurring reduced vasomotricity and does not show a proportional increase due to increased cardiac rhythm. As the three rhythms, CRI cranium, CRI sacrum and LVMvf, which were measured simultaneously, correspond both before and after the exertion test, and since all three rhythms decreased markedly following exertion, it is possible to hypothesize that venous vasomotricity is probably one of the forces behind CRI. Venomotricity is found in all the veins of the body, not only those in the cranium, for example in the vena porta, vena femoralis, vena poplitea, vena saphena magna etc.