Linear and non-linear parameters of heart rate variability during static and dynamic exercise in a high-performance dinghy sailor.

The analysis of heart rate variability (HRV) is recognized as a powerful non-invasive tool to evaluate the influence of autonomic nervous system on the heart and the heart-brain interaction. It is well-known that relatively high HRV is correlated to health condition while low HRV corresponds to cardiovascular disease or could be caused by mental stress, depression or exercise. In order to investigate heart-brain interaction we compare linear and non linear parameters calculated from HRV signals recorded in the same subject at similar heart rate (HR) values, during two different conditions, i.e. static exercise during sailing and dynamic exercise on cycloergometer. In the study, performed in one high-performance would class dinghy sailor, the HR was recorded at rest and during the two types of exercise. For the analysis, tachogram tracts with similar HR values were considered. The power spectral densities in very-low, low (LF) and high (HF) frequency bands were evaluated as well as the LF/HF ratio, the two standard deviations (SD1 and SD2) of the Poincaré plot, the beta values and the fractal dimension (FD). The results indicate a decrease of HRV, LF, HF, SD1 and SD2 parameters, as well as an increase of beta and FD during both types of exercise compared to rest. However, the higher values of LF, LF/HF ratio and SD2 as well as the lower value of FD in upwind sailing in comparison to dynamic exercise on cycloergometer, at similar HR, suggest a different sympatho-vagal modulation on cardiac function and therefore a different heart-brain interaction in these isometric and isotonic exercises.