[Purpose] This study investigated the parameters that characterize the knee, hip, and pelvic kinematics during a single-leg squat in preoperative anterior cruciate ligament rupture injury. [Participants and Methods] Overall, 15 patients with unilateral anterior cruciate ligament deficiency were enrolled in this study. For each single-leg squat, data from two-dimensional video cameras and three-dimensional motion analysis were collected. Measurement indices included the articular angles of the knee, hip, and trunk. The anterior cruciate ligament-injured leg was compared with the uninjured leg. [Results] The maximum knee valgus and flexion angles during a single-leg squat were smaller in the injured leg than in the uninjured leg. During the single-leg squat, the effect of “compensatory mechanisms” appeared as knee valgus and flexion movements. In particular, the knee valgus angle decreased in the anterior cruciate ligament-injured leg compared to that in the uninjured leg. [Conclusion] This phenomenon suggests that it is possible to utilize recurrence prevention training for anterior cruciate ligament injury.

Pectoralis minor tightness has been thought to affect the scapular position. Despite the wide implementation of doorway stretch in clinical practice owing to its apparent effectiveness in stretching the pectoralis minor, limited studies have investigated its influence on the glenohumeral rotational range of motion (ROM). This study aimed to examine the acute effects of doorway stretch on the glenohumeral rotational ROM and the correlation between the scapular position and ROM. In total, 34 male high-school baseball players participated in this study. Outcomes included the pectoralis minor muscle length, glenohumeral rotational ROM, and scapular position. The distance between the sternocostal joint of rib 4 and the coracoid process was measured as the pectoralis minor length. Internal and external rotation ROM with the shoulder abducted at 90° were measured. The scapular position was defined by the following two measurements: the distance between the surface and the posterolateral corner of the acromion as well as the scapular index. The participants performed doorway stretch by abducting and externally rotating the shoulder at 90° and flexing the elbow at 90°. The outcomes were compared before and after stretching. Furthermore, the correlation between these changes was investigated. Pectoralis minor muscle length and glenohumeral internal rotation ROM was significantly higher after stretching than before, and the scapular position also significantly changed (P < .01 for both). A moderate correlation was found between the degree of change in the glenohumeral internal rotational ROM and scapular position (r = 0.44, P < .01). Our results indicated that doorway stretch significantly increased the pectoralis minor muscle length and glenohumeral internal rotation ROM and significantly altered the scapular position. Furthermore, a significant correlation between the degree of change in the scapular position and glenohumeral internal rotation ROM was observed. These results suggest that doorway stretch could be beneficial for improving the scapular position and glenohumeral internal rotation ROM, which are considered the cause of throwing injuries. Furthermore, the glenohumeral ROM may be affected by the scapular position.

Background: Non-specific lower back pain is a common medically and economically impactful condition that affects patients’ quality of life. Purpose: This study aimed to determine the relationship between thoracic expansion and spinal curvature angle during trunk extension in healthy participants. Results: The participants comprised 24 men aged 18–21 years. The measurement items included the lateral and longitudinal diameters of the thorax, measured at the level of the xiphoid process and 10th rib, and spinal curvature angle, measured in the upright posture and trunk extension position. The difference in thoracic expansion levels during trunk extension tended to be greater in the lower thorax than in the upper thorax, with the lateral diameter higher than the longitudinal diameter. The inferior thoracic and lumbar curvatures increased with trunk extension. Regarding the relationship between the difference in thoracic expansion and the amount of change in the spinal curvature, the difference in the expiratory lateral diameter of the lower thorax during trunk extension was positively correlated with the superior thoracic curvature during trunk extension. Conclusions: These results indicate that expansion of the lower thoracic lateral diameter increased the thoracic curvature during trunk extension exercises. Consequently, the lumbar curvature may be suppressed. Reduced lower thorax flexibility may enhance lumbar curvature during trunk extension. Therefore, flexibility of the lower lateral thoracic diameter may be a factor when preventing lower back pain. KEY WORDS: Thorax, Lateral Diameter, Longitudinal Diameter, Trunk Extension, Chest Griping.