The Effect of Local Pressure to the Knees on the Physiological and Psychological Responses of the Human Body

Abstract

The effect of local pressure to the knees on the physiological and psychological responses in the standing position and during light exercise were examined in this study in order to obtain data to design compression garments, such as elastic stockings, tights and knee supporters. Eight healthy women had cuff pressure applied to the knees at 0 mmHg, 10 mmHg, 20 mmHg, 30 mmHg and 40 mmHg, respectively for 20 minutes in a standing position. They then completed a 20-minute stepping exercise, followed by 10 minutes in a standing position under the same pressure conditions. The medial gastrocnemius muscle oxygenation (oxygenated blood volume in tissue [Oxy-Hb], deoxygenated blood volume in tissue [Deoxy-Hb], total blood volume in tissue [Total-Hb] and Oxygen Saturation [StO₂]), the skin blood flow and the skin temperature on the thigh, leg and toe, as well as pressure sensation and swelling sensation were measured.
The results showed that every physiological measurement was affected significantly by the change of posture and exercise. This is thought to be due to the change in the hydrostatic pressure in the lower extremities. The significant changes from standing to stepping are believed to be due to venous blood returning to the heart with the muscle pumping action in stepping.
Concerning the effects of local pressure intensity level on the knee on the medial gastrocnemius muscle oxygenation in the standing position, Deoxy-Hb increased, and StO₂ decreased significantly when a pressure of 40 mmHg was applied. These differences were greater than those reported by Dempoya et al. (2014) when 15 mmHg of pressure was applied to the knee in the supine position. The results suggested that the pressure levels of the compression garments should be different for night (lying) and for daily use (standing).
Both the skin blood flow in the toe and the skin temperature in the thigh decreased significantly at more than 20 mmHg which was lower than the 40 mmHg obtained in muscle oxygenation due to the difference of depth from the skin surface.
The pressure sensation increased significantly with pressure intensity, and the swelling sensation showed a tendency to be the lowest of all intensity levels, at 10 mmHg. In order to design compression garments for the lower extremities, high pressure more than 40 mmHg to the knees caused muscle oxygenation disorders, and more than at 20 mmHg of pressure negatively affected skin blood flow and skin temperature and caused a discomfort sensation. A low pressure of 10 mmHg to the knees can contribute to the comfort sensation without causing swelling.