Yukio Urabe

Alignment control exercise changes lower extremity movement during stop movements in female basketball players

This study was intended to evaluate a short-term intervention designed to improve the lower extremity alignment with neutral position during stop movements of female basketball players when performing a quick-stop jump shot. In this study, 20 healthy female college basketball players (mean age 20.5 years) participated. The authors monitored two groups for 4 weeks: one which trained (n=10) and one which did not train (n=10). The exercise program emphasized the neutral position of lower extremities for dynamic alignment control; the players avoided the valgus position with their knees. Kinematics analysis with a lower extremity angle in the stop action was performed using three digital video cameras and analyzed using software. Following the intervention exercise program, each subject was re-evaluated at two and four weeks to determine changes in movement patterns during the sink shot task. Two-way analysis of variance models were used to determine differences at pre-intervention, at mid-term, and post-intervention. After the 2-week intervention, the trained athletes group made basketball shots with greater change of the lower extremity motion pattern during the stop action than did non-trained athletes (p<0.05). However, no significant differences were found between other data of the 2-week and 4-week intervention groups. Results of this study show that two weeks of training can improve the dynamic alignment control of the lower extremities, as measured using the alignment angle of the coronal plane and the torsion angle of horizontal plane during a stop action.

Glenohumeral, Scapular, and Thoracic Angles at Maximum Shoulder External Rotation in Throwing

Background Because a majority of throwing injuries occur near the maximum external rotation (MER) of the throwing shoulder, sports medicine practitioners and researchers have paid special attention to the shoulder kinematics at the MER in throwing. However, little is known about the individual kinematics of the glenohumeral, scapulothoracic, and thoracic joints at the MER. Purpose To demonstrate the glenohumeral, scapulothoracic, and thoracic joint movements and their contribution to the MER in throwing for baseball players. Study Design Descriptive laboratory study. Methods We collected throwing motion data for 20 collegiate baseball players by using 3 high-speed cameras and established 3-dimensional coordinates of each landmark with a direct linear translation method. We then obtained the MER of the shoulder complex, the external rotation angle of the glenohumeral joint, the posterior tipping angle of the scapula, and the thoracic extension angles at the MER in throwing. Results The mean (± standard deviation) value of the MER was 144.2° ± 11.0°. The mean (± standard deviation) values of the glenohumeral external rotation, the scapular posterior tipping, and the thoracic extension angles at the MER were 105.7° ± 15.5°, 23.5° ± 13.9°, and 8.9° ± 7.3°, respectively. Conclusion Our results indicate that not only the glenohumeral joint movement but also the scapular and thoracic movements make major contributions to the MER angle. Clinical Relevance To better understand the pathomechanics of the shoulder complex in throwing, we need to take into account the individual contributions of the glenohumeral, scapulothoracic, and thoracic extension movements to the MER.

Characteristics of trunk lean motion during walking in patients with symptomatic knee osteoarthritis

OBJECTIVEnTrunk lean motion on the frontal plane shifts the pressure across the medial-lateral cartilage of the stance limbs knee. The purpose of this study was to investigate trunk lean motion during walking in patients with knee osteoarthritis.nnnMATERIALS AND METHODSnThe study involved five healthy normal controls and 12 patients with symptoms of knee osteoarthritis (six with unilateral and six with bilateral). The trunk lean angle and the direction during one stride cycle of walking were calculated using a three-dimensional gait analysis.nnnRESULTSnThere was no significant difference between the three groups (normal, unilateral knee OA, and bilateral knee OA group). However, patients with bilateral limb knee osteoarthritis displayed a tendency to lean their trunk toward the swing side.nnnCONCLUSIONnThis study determined that bilateral OA patients exhibit the characteristic gait which may progress knee OA.

The common mechanisms of anterior cruciate ligament injuries in judo: a retrospective analysis

Background Although high prevalence of anterior cruciate ligament injuries (ACL) in judokas has been reported, there has been very little research concerning events preceding the injury. Objective To determine the common situations and mechanisms of ACL injury in judo. Methods A total of 43 cases of ACL injuries that had occurred during judo competition or practice were investigated, using questionnaires with interviews conducted by a single certified athletic trainer who has 20 years of judo experience to obtain information regarding the situation and mechanism in which the ACL injury occurred. Results The number of ACL injuries when the participants grip style was different from the style of the opponent (ie, kenka-yotsu style) (28 cases) was significantly greater than when the participants grip style was the same as that of the opponent (ie, ai-yotsu style) (15 cases; p<0.001). The number of ACL injuries was significantly higher when the participant was attacked by the opponent than when counterattacked or when attempting the attack (p<0.001). In addition, being attacked with osoto-gari was revealed as the leading cause of ACL injury incidence among the participants (16.8%). Conclusions Grip style may be associated with ACL injury occurrence in judo. In addition, direct contact due to the opponents attack may be a common mechanism for ACL injuries in judo.

EMG Analysis of Lower Extremity Muscles in Three Different Squat Exercises

The purpose of this study was to come across an exercise that increases the Hamstring contraction levels so that it may protect the anterior cruciate ligament (ACL). Previous studies have postulated that changing the projection of the center of gravity behind the feet will decrease the translation of the tibia, therefore protect the ACL. Muscle activity of the quadriceps, hamstring and soleus muscles in healthy subjects was measured with an EMG during three different squat tasks with differences of support of body weight and the center of gravity. The subjects were nine healthy female recreational athletes with no history of any pathological knee condition or musculoskeletal system disorder. There was no significant difference in the activities of the four muscles (Vastus Medialis; Hamstring: Semitendinosus and Biceps Femoris; and Soleus); and there was a similar pattern in the activity between those muscles in the exercises. In addition, VM values were considerably higher than the Hamstring and soleus activity levels. There was no significant difference between one squat from another and among the phases (0-30°, 30-60° or 60-90°) of knee flexion. These results suggest that even when changing the projection of the center of gravity, the activity of the quadriceps is high compared to the hamstring and soleus muscles.

How long can joint position sense be retained in memory by young healthy subjects

[Purpose] The aim of the present study was to investigate how long joint position sense (JPS) can be retained in memory. [Subjects] Eleven healthy subjects (5 men and 6 women) were enrolled in this study. [Methods] Subjects memorized a specific joint position visually, and then they were asked to reproduce without visual aid the position at 3 different time intervals: immediately, 5 minutes post-memorization, and 30 minutes post-memorization. [Results] Differences in JPS between time intervals of immediate and 30 minutes post-memorization were statistically significant with the exception of knee flexion at 60° with a 5u2005kg load. Differences in reproduced JPS between time intervals of immediately and 5 minutes post-memorization were not statistically significant. [Conclusions] The results suggest that JPS can be retained in memory for approximately 5 minutes.

Relationships between jumping height and power, force and velocity during one-legged vertical jumps

[Purpose] To determine the deficit in one-legged vertical jumping ability and to clarify the relationships between maximum jumping height and maximum power, force and velocity during one-legged vertical jumps after anterior cruciate ligament reconstruction (ACL-R) compared with healthy subjects. [Subjects] Twenty-five healthy subjects (10 males and 15 females) and 32 ACL-R patients (18 males and 14 females) participated in this study. [Methods] The isokinetic quadriceps femoris strength and one-legged vertical jumping ability evaluated by the height, power, force and velocity were measured in all subjects. [Results] The maximum height of the one-legged vertical jumps was only significantly correlated with the maximum force in the healthy subjects (p < 0.05). In contrast, for the involved and uninvolved legs in the ACL-R patients, the maximum jumping height was significantly correlated with the maximum power, force and velocity during one-legged vertical jumps (p < 0.05). [Conclusions] These findings suggest the importance of a knee strategy during one-legged vertical jumps for rehabilitation after ACL-R. Assessment of the jumping ability after ACL-R may be determined by the maximum power instead of the maximum jumping height.

The correlation between whole body reaction time and the onset timing of lower extremity muscles during landing

Background Quickness can be shown as whole body reaction time (WBRT) by measuring how quickly they can react for a stimulus. In addition, it is said that the onset timing of muscles contribute to stabilise joints and to prevent injury during the movement. Objective The purpose of this study is to clarify the correlation between WBRT and the onset timing of muscles during landing. Design Randomisation study. Setting Youth sports. Participants 15 healthy female college students volunteered in this study. Intervention WBRT was defined as the duration from light stimulus to the both feet apart from the floor. The onset timing of muscles were measured by bilateral landing from the 40 cm height box with the electromyography (EMG). EMG data were collected from vastus medialis (VM), vastus lateralis (VL), semimembranosus (SM) and biceps femoris (BF). The onset timing of the muscle was visually identified as the first point, which was the EMG amplitude of 100 ms after the start of landing movement that exceeded the mean baseline activity by three SD. The definition of the baseline was set as the EMG amplitude of the 100 ms after the toe-off from the box. Main outcome measurements The hypothesis was that there were the correlation between WBRT and the onset timing of muscles. Results The mean±SD of WBRT was 331.8±45.6 ms. VM onset timing during landing was 243.7±78.3 ms, VL was 259.6±75.5 ms, SM was 191.7±86.2 ms, BF was 237.5±73.8 ms. There were correlations between WBRT and SM and BF onset timings (p<0.05). Conclusion This study identified the correlation between WBRT and SM and BF onset timing. It might be possible to make SM and BF onset timing occur faster by reacting to certain stimulus faster.