COMPARATIVE ANALYSIS OF MUSCLE ACTIVITIES DURING RESISTANCE EXERCISES USING VARIABLE AND ELASTIC LOADS

Over the last few decades, many resistance training devices and methods have been deve'loped for the purpose of increasing strength~ One of the most popular devices being used is variable resistance training (VRT) device (Baechle & Groves, 1992). This type of exercise machines has a major advantage that, by altering the shapes of cams, the resistance profiles at different joint positions can match the strength curve (maximum torque-angle curve) of a joint motion. Despite this advantage, the method has not been perfected and there are arguments against its effectiveness (Garhammer, 1989; Ward, 1993). The major disadvantages of this device are the relatively high cost and large space required. The elastic band exercise device such as elastic tubing is getting popular in recent years, especially in rehabilitation settings. To a certain extent, an elastic exercise device has characteristics similar to a variable resistance-training device. The major advantages of this device are its safety, inexpensiveness, and compact design. To evaluate the stresses placed on different upper arm muscles during a biceps curl using selected home exercise devices, it was the purpose of this study to examine the electromyographic (EMG) activities of the pectoralis major, biceps brachii, triceps brachii, and brachioradialis muscles during biceps curls using a VRT device and an elastic tubing

ESTIMATING LUMBAR SPINAL LOADS DURING A GOLF SWING USING AN EMG-ASSISTED OPTIMIZATION MODEL APPROACH

This study estimated the lumbar spinal loads at L4-L5 level during a golf swing using musculoskeletal modeling techniques. Data were collected from five college golfers. Four S-VHS camcorders and two force plates were used to obtain 3-D kinetics and kinematics of the golfer’s motion and 10 surface electrodes were used to record the activity of selected lower trunk muscles. The EMG-assisted optimization model was used to estimate lower trunk muscle forces. The results demonstrate that the L4-L5 motion segment is subjected to considerable compressive (4,300 N), antero-posterior (A/P) shear (882 N), and medio-lateral (M/L) shear loads (-252 N) during a golf swing. The repetitive changing direction of the shear load during a golf swing may increase the chance of fatigue fracture of pars interarticularis. The results also suggest that a golf swing with shortened backswing and follow-through may reduce the risk of back injury

COMPARATIVE GAIT ANALYSIS BETWEEN CHILDREN WITH AUTISM AND AGE MATCHED CONTROLS

There are very few studies that have analyzed the gait of children with autism. The purpose of this study was to investigate gait of children with autism using temporal-spatial variables. Fifteen children with autism and fifteen age matched typically developing children walked 3 times on the GAITRite® system. Dependent variables were statistically analyzed using independent samples t-tests with Bonferroni adjustments. Results show a reduction in cadence, gait velocity, step length and an increase in step width for the children with autism. In conclusion, our results suggest that the children with autism have abnormal gait compared to age matched controls

BIOMECHANICAL ANALYSIS A SEQENCE OF ANGULAR VELOCITY AND COORDINATED MUSCLES ACTIVITY DURING BASEBALL HITTING

The purpose of this study was to analyse a sequence of rotations and coordinated muscles activities of upper body. Using kinematic and EMG data from 3 recreational university baseball players participating in this study, we computed the angular velocity of trunk, pelvis, bat and trunk-pelvis rotation angle and PMT of upper body muscles. Trunkpelvis rotation angle was 22 ° before the bat-ball contact. The pelvis, trunk, and bat showed a sequence of angular velocity beginning with the hip, followed by the trunk, and end tip of the bat. Additionally, PMT of upper body muscles generated right pectoralis major(1.03 sec.), right external oblique(1.11 sec.), left thoracloumbar fasci(1.12 sec.), left external oblique(1.13 sec.), right latissimus dorsi(1.15 sec.), left latissimus dorsi(1.16 sec.), right thoracloumbar fascia(1.16 sec.), left pectoralis major(1.25 sec.), on at a time during baseball hitting motion. PMT of upper body muscles were related to the shifting and rotating of body segment and this action can be considered the coordinated muscle activities of upper body

THE ANALYSIS OF OCULAR MOVEMENT FOR THE DYNAMIC POSTURAL CONTROL OF TURN MOTION ON THE BALANCE BEAM

This study demonstrated the importance of dynamic postural balancing and ocular movement in a turn motion on the balance beam using a manufactured wireless EOG measuring system with three female gymnasts. This study found that among the dynamic postural control variables, angular displacement and ocular movement were closely related. During a turn motion, the ocular movement was in opposite direction of the angular displacement of head and trunk along the medio-lateral axis. This resulted from the gymnast’s effort to stare at the end of the balance beam or the front in order to keep balance. The change of angular displacement of head around the medio-lateral axis and vertical axis was in opposite direction of the ocular movement. When the motion was successful, the gymnasts performed a spotting motion

ELECTROMYOGRAPHICAL ANALYSIS OF TRUNK MUSCLE ACTIVITIES DURING A GOLF SWING

The purposes of this study were to describe and compare the activation patterns of the trunk muscles during a golf swing using surface electromyographic (EMG) techniques. Five male collegiate golfers were the subjects. The golf swing was broken into five phases using the critical instants identified from video recordings. Wilcoxon signed ranks tests were used to test for significant differences (12 < .05) in average and peak normalized EMG values between the left and right muscles for each phase. The significant bilateral differences in muscle activation were only found in the average and peak rectus abdominus (acceleration phase), external oblique (acceleration and early follow-through phases), and erector spinae (late follow-through phase). The trunk muscles were highly active in the follow-through phases which may indicate the hyperextension of the trunk, which leads to lower back injury