Kentaro Sasaki

Experimental Joint Immobilization and Remobilization in the Rats

[Purpose] The purpose of our study was to clarify temporal effects on restrictions to range of motion and the histopathological changes of joint components after joint immobilization in a rat knee-contracture model. [Subjects] Fifty-four male Wistar rats were randomly divided into two groups: a fixation group, and a control group. [Methods] In the fixation group, unilateral knee joints were immobilized at full flexion using a plaster cast for 4 weeks. At four weeks the animals were randomly divided into six subgroups, corresponding to the time of examination after cast removal: 0, 4, 8, 16, 24, and 32 weeks. For comparison, control group animals of corresponding age were also examined. [Results] Although movement restrictions of the knee joint had completely recovered 6 weeks after the cast removal, cartilage and synovial membrane structures did not completely recover. [Conclusion] These findings have not previously been reported, and as they form an addition to the fundamental scientific foundations of physical therapy, further research must examine these findings from a variety of perspectives.

Characteristics of Postural Sway during Quiet Standing Before and After the Occurrence of Neurogenic Intermittent Claudication in Female Patients with Degenerative Lumbar Spinal Canal Stenosis

[Purpose] This study investigated the effect of neurological symptoms and/or signs after the occurrence of neurogenic intermittent claudication (NC) on postural sway during quiet standing of patients with lumbar spinal canal stenosis (LSS). [Subjects and Methods] Thirty-two female patients with LSS at the L4/5 level were studied. We measured the path of center of foot pressure (COP) during quiet standing with eyes open for 30u2005s using a stabilometer before and after the occurrence of NC. [Results] The total path length of COP (LC) and area surrounded by the outline of the path of COP (AC) significantly increased after NC. Body mass index (BMI) correlated with both the NC rate (after NC/before NC) of LC and that of AC. The average lateral COP displacement from the center of the base of support (COPRL) before NC was located on the asymptomatic side from the center of the base of support in 29 of 32 patients. After NC, COPRL moved to the symptomatic side in 31 patients. [Conclusion] These results suggest that patients with LSS are at risk of falling after NC, especially those with high BMI.

The temporal relationship of thresholds between muscle activity and ventilation during bicycle ramp exercise in community dwelling elderly males

[Purpose] To compare the appearance time of the ventilatory threshold point and the electromyographic threshold in the activity of the vastus lateralis, rectus femoris, biceps femoris long head and gastrocnemius lateral head muscles during ramp cycling exercise in elderly males. [Subjects and Methods] Eleven community dwelling elderly males participated in this study. Subjects performed exercise testing with an expiratory gas analyzer and surface electromyography to evaluate the tested muscle activities during ramp exercise. [Results] The electromyographic threshold for rectus femoris was not valid because the slope after electromyographic threshold was not significant as compared to that before electromyographic threshold. The slope of the regression line for vastus lateralis was significantly decreased after electromyographic threshold while biceps femoris and gastrocnemius were increased. The electromyographic threshold appearance times for vastus lateralis and gastrocnemius were significantly earlier than ventilatory threshold point. There were no difference in electromyographic threshold appearance times among three muscles. [Conclusion] These results suggest that the increase in the slope of the regression line after electromyographic threshold for vastus lateralis was decreased, possibly indicating to postpone muscular fatigue resulting from the activation of biceps femoris and gastrocnemius as biarticular antagonists. This recruitment pattern might be an elderly-specific strategy.