There are two main reasons why people use compression socks for running:
- Blood Flow: The veins are responsible for returning blood to the heart. As the calves are well below the heart, the blood can pool in the legs (calves) due to gravity. This equates to less venus (vein) return of blood to the heart and therefore, less oxygen is distributed to working muscles. The theory of compression socks is that by squeezing the calves, it enhances venus return, thus increasing running performance.
- Muscle Vibration: When running, the calf muscles (as well as other muscles) vibrate upon foot impact and therefore a theory is that this vibration causes fatigue and delayed onset muscle soreness.
Based on several studies, the jury is still out in regard to venus return, however, a recent study seems to demonstrate that calf sleeves reduce muscle activation of calf muscles and therefore may postpone muscle fatigue. More specifically, this study shows that calf muscle activity decreased between 4-16% at various running speeds, with the largest decrease occurring while running at 6.3 mph.