The Effect of Blood Flow Restriction on Muscle Weaknesses and Changes in Gait pattern

PURPOSE: To examine whether the blood flow restriction prevents weakness of muscle strength and change of gait pattern induced by immobilization and non-weight bearing in lower extremity. METHODS: Seven healthy Japanese adults (4 males and 3 females, age: 22.0 ± 0.8 yrs) participated in this study. The left ankle of all subjects was immobilized by a cast for two weeks. They were also instructed to use crutches during locomotion to impose non-weight bearing situation on lower extremity for the period. Our earlier study has demonstrated that a combination of a casting on ankle with use of crutches provides muscle weaknesses in lower extremity. During the experimental period, subjects were divided into two groups as follows: a blood flow restriction (RBF) group (application of external compressive force of 200 mmHg for 5 min followed by 3 min of rest, repeated five times in a single session, two sessions per day for 14d) and a control (CON) group (no intervention). After the experimental period, the changes in knee extensor-flexor muscle strength of angular speeds of 60 and 180 deg·s-1 under concentric contraction (CC60 and 180) and eccentric contraction (EC60 and 180), thigh/leg circumferences, and gait patterns were evaluated. RESULTS: In knee extensor torques, the percent changes in the CON and RBF groups were CC60: -15.0 ± 4.6 % vs. -11.5 ± 2.1 %, CC180: -6.8 ± 4.4 % vs. -10.5 ± 1.7 %, EC60: -19.9 ± 7.2 % vs. -5.4 ± 6.4 % (p<0.05) and EC180: -17.8 ± 4.6 % vs. -6.5 ± 8.6 % (p<0.05). In knee flexor torques, the percent changes in the CON and RBF groups were CC60: -9.7 ± 10.3 % vs. -11.8 ± 6.8 %, CC180: -6.7 ± 1.0 % vs. -7.7 ± 3.6 %, EC60: -16.1 ± 7.7 % vs. 2.6 ± 7.3 % (p<0.05) and EC180: -8.1 ± 4.5 % vs. 0.8 ± 6.7 %. In the RBF group, those were CC60:, CC180:, EC60: and. The percent changes in circumferences were thigh: -1.5 ± 1.1 % and leg: -1.9 ± 1.0 % in the CON group and thigh: -0.2 ± 0.9 % and leg: -0.1 ± 1.3 % in the RBF group. The gait cycle was delayed and the amplitude in vertical and mediolateral direction were smaller in the CON group. CONCLUSIONS: The blood flow restriction partially diminishes the muscle weakness and changes of gait pattern induced by immobilization with non-weight bearing in lower extremity.