DYNAMIC SHOULDER STRENGTH IN VARIOUS ELEVATION PLANES

INTRODUCTION: The objective assessment of shoulder strength is necessary to adequately predict a return to injury-free sport activities or strenuous activities. During most daily activities, the shoulder performs movements in various elevation planes and different modes of dynamic contraction. However, it appears that there has been no study of elevation plane movements, except for the sagittal plane and coronal plane. The purpose of this study was to establish a database of normal shoulder strength. More specifically, the study was performed to test the hypothesis that the mode of contraction (concentric and eccentric) and the plane of elevation would have significant effects on strength measurements of the shoulder joint. METHODS: Forty healthy young volunteers (20 men and 20 women) between 19 and 31 years of age with no history of upper extremity symptoms participated in this study. The Kin-Com isokinetic dynamometer (Chattanooga Corp., Chattanooga, TN) was used to measure elevation (abduction) and depression (adduction) strength of the shoulder in the 0° (sagittal plane), 30°, 60°, and 90° (frontal plane) of elevation, throughout the range of motion at eight angular velocities, 30°/sec to 240°/sec with steps of 30°/sec. Both concentric and eccentric tests of the dominant side were performed. The order of testing was random with respect to the elevation plane, velocity, and muscle contraction mode. MANOVA was used to analyze whether the strength ratios of elevation/depression differ with the plane of elevation, contraction mode and velocity. RESULTS: The strength ratios of elevation/depression depend on the plane of elevation, but not on the contraction mode and angular velocity. These values were greatest in the 60° plane of elevation and lowest in the 30° plane of elevation. In the 60° plane of elevation and frontal plane these strengths were greater in eccentric contraction than in concentric contraction. In contrast, in the sagittal plane and 30° plane of elevation these values were greater in concentric contraction than in eccentric contraction. There were significant differences in the plane of elevation and angular velocity, but no significance in gender and movement type, elevation or depression. CONCLUSIONS: In this study, the effect of elevation plane on shoulder strength was considered in addition to muscle contraction mode and angular velocity. In summary, this study demonstrated that the mode of contraction and planes of elevation have a significant influence on the strength measurement of the shoulder joint. Such information should be considered in functional evaluation and muscle conditioning in rehabilitation

IMAGE-BASED MODELING AND SIMULATION OF THE SHOULDER DURING BASEBALL PITCHING

The imaged-based modeling and simulation such as the virtual, interactive, musculoskeletal system (VIMS) software provides accurate muscle orientations and their relative moment arms. An imaged-based biomechanical model of upper extremity can be used for understanding of neuromuscular control and simulation of sports activities and surgery reconstruction after injuries. The relative movement of the skeletal segments cause a change of muscle orientation and its moment arm, and then affect the role of the muscle loading during the motion. This paper reviews studies in applying three-dimensional shoulder model for investigation of the multi-joint muscle function. An image based and graphic-enhanced, quantitative model of the musculoskeletal system would be utilized for dynamic shoulder analysis with accurate muscle line of action incorporating bone movement and muscle wrapping around the joint

Comparison of breast motion at different levels of support during physical activity

Optical tracking systems have been used in previous studies to capture the motion of the nude breast and breasts in bras, under the assumption that no breast-bra relative movement occurred within the bra. This study compared breast and bra movement through electromagnetic tracking and optical tracking systems to determine the relative breast movement occurring with different breast support and exercise-induced breast discomfort. Total of 30 female participants (mean age: 21.5 ± 2.3 years; cup sizes: A-F) were recruited and their movement at four different levels of breast support was recorded in two motion capture systems for further analysis and comparison. Significant differences between bra and breast vertical displacement were found at all support levels during periods of intense movement (r = 0.556; p < 0.05). Because the greatest bra displacement was observed when participants wore an everyday bra and the greatest breast displacement was observed when participants wore a crop-top bra, there was evident inconsistency in bra and breast motion and a high-impact sports bra was the most effective to reduce breast movement and discomfort among the four types of bras. An electromagnetic tracking system provided direct observation of the actual movement of the breasts, and an optical tracking system enabled us to monitor bra displacement. Significant differences were observed in bra and breast displacement during the intense movements included in this study. The results bring into question the assumption made in previous studies that no relative movement occurs within a breast support garment.This study is supported by Ministry of Science and Technology grants 103-2815-C-006-037-H and 105-2410-H-006-052, TAIWAN, and OT Motion Lab, Department of Occupational Therapy, National Cheng Kung University

Effect of the Kinesio tape to muscle activity and vertical jump performance in healthy inactive people

BACKGROUND: Elastic taping applied on the triceps surae has been commonly used to improve the performance of lower extremities. However, little objective evidence has been documented. The purpose of this study was to investigate the effect of elastic taping on the triceps surae during a maximal vertical jump. It was hypothesized that elastic taping to the triceps surae would increase muscle activity and cause positive effect to jump height. METHODS: Thirty-one healthy adults (19 males and 12 females with mean age, body weight and height for 25.3 ± 3.8 years old, 64.1 ± 6.2 kg, and 169.4 ± 7.3 cm, respectively) were recruited. All participants performed vertical jump tests prior to (without taping) and during elastic taping. Two elastic tapes, Kinesio tape and Mplacebo tape from two different manufacturers, were applied to the participants, respectively. RESULTS: The results showed that the vertical ground reaction force increased when Kinesio tape was applied even when the height of jump remained about constant. However, the height of the jump decreased, and there was no difference on the vertical ground reaction force in Mplacebo taping group. Although the EMG activity of medial gastrocnemius tended to increase in Kinesio taping group, we did not see differences in EMG activity for the medial gastrocnemius, tibialis anterior and soleus muscles in either group. CONCLUSIONS: Based on the varied effects of Kinesio tape and Mplacebo tape, different intervention technique was suggested for specific purpose during vertical jump movement. Mplacebo tape was demanded for the benefits of stabilization, protection, and the restriction of motion at the ankle joint. On the other hand, the findings may implicate benefits for medial gastrocnemius muscle strength and push-off force when using Kinesio tape

THE CENTER OF MASS TRAJECTORY DURING FIXED-STANCE PUSH HANDS MOVEMENTS OF TAI CHI CHUAN

The purpose of this study was to investigate how Tai Chi Chuan (TCC) skills affect the whole body center of mass (COM) during Tai Chi Chuan fixed-stance push hands movement. Four TCC experts with push hands movement experience for 10.3±1.7 years and four TCC beginners with 2.5±1.3-year experience were recruited in this study. Three-dimensional kinematics data of the TCC fixed-stance push hands movements were collected and COM displacement and velocity during the movements were analyzed. The patterns of the COM between two groups during the push hands movement cycle were similar, but the COM displacement and velocity were different. Our investigation reveals that the experience-related differences in whole body COM transfers are reflected in the push hands movement cycle

EVALUATION OF ELBOW AND FOREARM MOTION BETWEEN SIDEARM AND OVERHAND PITCHING

This study is to analyze the differences in kinematics, electromyography (EMG) and ultrasonography between two types of pitchers. We intend to observe and simulate the muscles around glenohumeral and elbow joints in different pitching motions and hope to discover the connections and differences in between. 12 pitchers from the top level were recruited. Larger elbow flexion was found in sidearm pitchers during the acceleration phase. Decrease of the distance of nerve to medial epicondyle was also found as the elbow moved to a more flexed position. More anterior translation of the ulnar nerve might occur during acceleration phase. Slightly lower flexor carpi radialis (FCR) activity was displayed in sidearm pitchers, showing that FCR might play a less crucial role in protecting medial elbow by providing less varus torque

Comparison of breast motion at different levels of support during physical activity

Optical tracking systems have been used in previous studies to capture the motion of the nude breast and breasts in bras, under the assumption that no breast-bra relative movement occurred within the bra. This study compared breast and bra movement through electromagnetic tracking and optical tracking systems to determine the relative breast movement occurring with different breast support and exercise-induced breast discomfort. Total of 30 female participants (mean age: 21.5 ± 2.3 years; cup sizes: A-F) were recruited and their movement at four different levels of breast support was recorded in two motion capture systems for further analysis and comparison. Significant differences between bra and breast vertical displacement were found at all support levels during periods of intense movement (r = 0.556; p < 0.05). Because the greatest bra displacement was observed when participants wore an everyday bra and the greatest breast displacement was observed when participants wore a crop-top bra, there was evident inconsistency in bra and breast motion and a high-impact sports bra was the most effective to reduce breast movement and discomfort among the four types of bras. An electromagnetic tracking system provided direct observation of the actual movement of the breasts, and an optical tracking system enabled us to monitor bra displacement. Significant differences were observed in bra and breast displacement during the intense movements included in this study. The results bring into question the assumption made in previous studies that no relative movement occurs within a breast support garment

The effects of rear-wheel camber on the kinematics of upper extremity during wheelchair propulsion

BACKGROUND: The rear-wheel camber, defined as the inclination of the rear wheels, is usually used in wheelchair sports, but it is becoming increasingly employed in daily propulsion. Although the rear-wheel camber can increase stability, it alters physiological performance during propulsion. The purpose of the study is to investigate the effects of rear-wheel cambers on temporal-spatial parameters, joint angles, and propulsion patterns. METHODS: Twelve inexperienced subjects (22.3±1.6 yr) participated in the study. None had musculoskeletal disorders in their upper extremities. An eight-camera motion capture system was used to collect the three-dimensional trajectory data of markers attached to the wheelchair-user system during propulsion. All participants propelled the same wheelchair, which had an instrumented wheel with cambers of 0°, 9°, and 15°, respectively, at an average velocity of 1 m/s. RESULTS: The results show that the rear-wheel camber significantly affects the average acceleration, maximum end angle, trunk movement, elbow joint movement, wrist joint movement, and propulsion pattern. The effects are especially significant between 0° and 15°. For a 15° camber, the average acceleration and joint peak angles significantly increased (p < 0.01). A single loop pattern (SLOP) was adopted by most of the subjects. CONCLUSIONS: The rear-wheel camber affects propulsion patterns and joint range of motion. When choosing a wheelchair with camber adjustment, the increase of joint movements and the base of support should be taken into consideration