The objective of this study was to verify the usefulness of a “parallel link type human ankle rehabilitation assistive device” (PHARAD) that we developed for prevention of deep vein thrombosis (DVT). We evaluated the blood flow (BF)-promoting effect of passive and active (with and without load) ankle exercises performed using the PHARAD, by comparing BF before and after exercise. Ten healthy male adults were recruited. Each subject performed 3-minute passive, active (without load), and active loaded ankle exercise, as well as walking. The ankle exercise consisted of plantar flexion/dorsiflexion (P/D) and rotation motion. BF was measured at the medial head of the gastrocnemius muscle (MG) and the vastus medialis muscle (VM). BF was calculated from the rate of increase in total hemoglobin concentration during venous occlusion. During all the exercises, BF measured at both muscles increased significantly compared to resting level (p<0.05). In passive P/D, BFs in MG/VM increased to 154.5±66.2%/146.4±55.4% of the resting levels. In passive rotation motion, the corresponding BFs increased to 183.6±91.9%/144.3±63.0% of the resting levels. The BF-promoting effects (MG/VM) of passive P/D were 51.2%/105.7% of active (without load) exercise and 53.3%/56.4% of walking. In active loaded P/D, BFs at MG/VM increased to 239.2±71.1%/182.8±132.6% of the resting levels. In active loaded rotation motion, the corresponding BFs increased to 286.3±148.6%and 208.7±130.5% of the resting levels. The BF-promoting effects (MG/VM) of active loaded P/D were 131.3%/177.3% of active (without load) exercise and 182.2%/132.2% of walking. There were no significant differences in passive, active (without load) and active loaded exercises with respect to the BF-promoting effects of P/D and rotation motion. These results suggest the following:1) Passive and active loaded exercises using PHARAD significantly increase BF compared to the resting level. 2) Passive exercise has the potential to prevent DVT. 3) Active loaded exercise is more effective than walking in promoting BF. 4) P/D and rotation motion have the same level of BF-promoting effect. 4)does not suggest the superiority of PHARAD that can perform rotation exercise, but 1)-3)suggest the usefulness of PHARAD for DVT prevention.
