# Effect of Blood Circulation in the Upper Limb after Flossing Strategy
## 4 Discussion  
The aim of our study was to determine the change in the blood supply to the musculus biceps brachii during and after compression therapy applied to the upper limb in the area of the shoulder joint by the flossing method. We noted a significant decrease in blood flow to musculus biceps brachii after flossing to the shoulder joint on the upper limb where flossing was applied, but there was also a statistically significant reduction of blood flow to the original value and a significant increase in blood flow to the opposite limb, i.e., the limb where flossing was not applied. In the available literature, the effect of flossing is related to the so-called sponge effect. The blood flow, initially markedly inhibited by occlusion, shows a marked increase after its elimination. It even reaches a level exceeding the inlet flow [11]. In our experiment, we expected that in accordance with the above assumption there would be a decrease in blood flow during the application and a subsequent increase in blood flow after the removal of compression. This principle was not confirmed in our experiment because the elevation time was statistically significantly longer than the depression time. The sponge effect is considered in the available literature as one of the basic effects that bring benefits in the application of flossing. It is assumed that the massive blood circulation, which occurs after reduced blood circulation during the application of flossing, is a key factor in the positive effect of this method. However, these considerations are only speculative, because the blood supply to the tissues when applied by flossing has not been studied so far. Our study is the first study to evaluate muscle blood flow during flossing, and our results showed a discrepancy between the expected effect and the actual effect. Future research should therefore focus more on the analysis of the physiological mechanisms of the flossing method, as it is still difficult to determine these mechanisms from the available literature. Our evaluation was performed on the biceps brachii muscle and therefore it will also be appropriate in the future for a similar evaluation to be performed on other muscles. We recorded a decrease in perfusion after two minutes of flossing application to 6.23 mmHg, which corresponds to an average of 23.47%. This may appear to be a dramatic decrease, as some studies [26] report 30 mmHg perfusion as a criterion for surgery in the ischemic disease of lower extremities (IDLE) or diabetes mellitus (DM). TcpO2 of 10 mmHg at rest is considered generally very critical. In contrast, [PERSON] [10] found the perfusion <30 mmHg even in healthy individuals. However, we must take into account that the studies above dealt mainly with long-term adverse conditions. In our case, it is significant tissue hypoxia but a very short-lived one. Even so, it is necessary to consider that due to the significant depression of perfusion after only two minutes of flossing tissue damage could occur, and results obtained by us correspond to the recommended application time, which is currently recommended at the length of 2 min. In view of the above, great caution is required when performing the flossing method, and the application time of 2 min appears to be marginal. An interesting finding was the relationship in blood supply to the right and left upper limbs, respectively, musculus biceps brachii on the arm where flossing was applied and on the side where it was not applied. On the upper limb, where flossing was applied, the values acquire statistically very significant changes. There will be a decrease in blood flow to 23.47% with subsequent elevation above the original level. While in the second minute the blood flow is 82%, in the fifth minute it already exceeds the input level and further rises to 116.88% at the end of the experiment. Blood flow to the upper limb, where flossing was not applied, is somewhat different.