在“Massage Therapy”文章的"Improved circulation and increased blood flow"中有提到：

When massaging, the therapist always moves in the direction of the heart; which is in the direction of circulation. This method works with the tiny veins that help move the blood towards the heart.

These tiny veins have valves that prevent the blood from “back flowing". It could be potentially harmful to massage away from the heart, thereby forcing the blood to flow pushing against these valves. Back flowing of the blood into these veins can cause the blood to pool thus producing varicose veins.

Massage warms the surface of the body by promoting circulation and delivering fresh oxygen and nutrients to the muscle tissue.

治疗师在进行按摩时，会往心臟的方向进行，有助于细微静脉中的血液往心臟方向移动。静脉中的阀门(Valves)可以防止血液的倒流，但若按摩的方式是逺离心臟的，造成血液推挤阀门的状况，会导致在静脉中产生血池，产生静脉曲张(Varicose Veins)的状况。此外，按摩可以增加身体表面的温度，促进血液循环，带给肌肉组织新鲜的氧气及养份。

在操作GRID因为会"来来回回"，所以有心血管疾病(高血压)、静脉曲张的人，在使用时就需要特别注意；而舒活棒的话，要控制方向是比较方便的，所以对于有心血管疾病、静脉曲张的人来说，或许会是个比较好的选择啰。

文章来源：山姆伯伯工作坊