NIRS Analysis of the Metabolic Effects Induced by Local Mechanical Vibrations

Mechanical vibration application is common in clinical practice due to the efficacy induced by these stimuli on the human body. Local vibration (LV) application is increasingly used because it allows applying and act only where needed, focusing the treatment on the selected body segment. The aim of this study was to detect and analyze the metabolic effects induced by LV on the brachial bicep muscle by means of an oximeter. This device monitors tissue and muscle oxygenation using NIRS (Near Infrared Spectroscopy) and is able to determine the concentration of haemoglobin and oxygen saturation in the tissue. An experimental device for LV application was used to generate the vibrations. We divided our study in different levels of analysis to investigate what happens at systemic and metabolic level. In the first step we investigated the effects induced by LV application, by measuring blood pressure, heart rate, oxygen saturation and temperature. These data confirmed that the effects induced by LV application are actually localized, as we only observed a temperature increase in the limited area. In the second step to study the metabolic behaviour we analyzed total haemoglobin [THC], deoxygenate haemoglobin [Hb], oxygenate haemoglobin [HbO2] and oxygen saturation (% ox) in the tissues with the oximeter. The results of the measurements obtained using the oximeter during vibration application, have shown a variation of concentrations. In particular an increase of oxygenate haemoglobin was shown, probably caused by an increased muscle activity and/or a rise in local temperature detected during the application. To show that the results obtained don’t depend on the temperature increase during vibration, another experiment was performed. The results through a statistic analysis showed that the metabolic changes detected by the oximeter are primarily due to the application of vibration treatment.