Changes in tendon blood circulation and heart rate variability after intermittent compression to patellar and Achilles tendons.

ABSTRACT

BACKGROUND: The purpose of this study was to compare changes in tendon blood circulation and heart rate variability after intermittent compression to the patellar and Achilles tendons. METHODS: Before the intermittent compression to tendons (3 min) and the recovery period (40 min), the blood volume and oxygen saturation of the patellar and Achilles tendons were measured using red laser lights. In addition, heart rate and ratio of low-frequency to high-frequency components of heart rate variability were measured. FINDINGS: Blood volume and oxygen saturation of patellar and Achilles tendons significantly increased after intermittent compression stimulation (both p ≤ 0.001). There were no differences in increases of blood volume (p = 0.575) and oxygen saturation (p = 0.055) between patellar and Achilles tendons. For both tendons treatments, heart rate (p = 0.698) and ratio of low-frequency to high-frequency components of heart rate variability (p = 0.518) did not change during the experimental period. In addition, the change in blood volume for Achilles tendon was significantly correlated with that in heart rate but not ratio of low-frequency to high-frequency components of heart rate variability, whereas the change in blood volume for patellar tendon was not significantly correlated with that in the heart rate or ratio of low-frequency to high-frequency components of heart rate variability,. INTERPRETATION: These results suggest that intermittent compression-induced changes in blood circulation were similar between patellar and Achilles tendons. In addition, the increase in blood volume after intermittent compression stimulation in the Achilles tendon would be related to the increased metabolism of the tendon.