the arm swing of humans during gait is a complex and natural movement of the joints and 
 limbs1 .
arm swing during gait minimizes 
 the increase of angular momentum and energy consumption , it has been reported that it also 
 increases stability during gait2 . arm 
 swing was first described as an indirect pendulum movement , which is a form of movement 
 between each joint during gait .
later , however , arm swing was described as being more than 
 just a pendulum movement , rather a direct movement involving muscular action of the 
 shoulders3 .
vleeming et al.4 suggested that a posterior oblique sling 
 links the hamstring , gluteus maximus , thoracolumbar fascia , and contralateral latissimus 
 dorsi , in sequence .
they also reported that the power of the posterior oblique sling muscle 
 is generated from the couple force of both the latissimus dorsi and gluteus maximus , and 
 that these muscles coordinate with each other in direct contraction affecting the 
 stabilization of the sacroiliac joint5 . 

therefore , the purpose of the present study was to identify the effects of different gait 
 speeds and low arm weight on the activities of the latissimus dorsi , gluteus medius , and 
 gluteus maximus muscles .
the subjects of this study were 14 young adult males who voluntarily consented to 
 participate in this study and had no disease history or any problem with walking .
their 
 average age , height and weight were 28.57  4.41  years , 174.51  6.62  cm and 73.81  
 9.14  kg , respectively .
ethical approval was obtained from inje university faculty of health 
 science human ethics committee , and the subjects provided their written informed consent to 
 participation prior to the commencement of the study .
surface emg was used to collect raw 
 emg data using a trigno wireless system ( delsys , boston , ma , usa ) .
the sampling rate of the 
 emg signal was 2,000 hz , and data was filtered using a band - pass of 20450  hz . the root mean 
 square ( rms ) was calculated .
three surface electrodes were placed on the following muscles ; 
 the latissimus dorsi ( lateral to the t9 spinous process over the muscle belly ) on the left 
 side , the gluteus medius ( proximaly one third of the distance between the iliac crest and 
 greater trochanter ) on the right side , gluteus maximus ( at the midpoint of a line running 
 from the last sacral vertebrae to the greater trochanter ) on the right side . the skin was 
 prepared before attaching the electrodes by shaving the area , and cleaning with 70% 
 isopropyl alcohol to reduce the skin impedance .
emg data were normalized using the maximum 
 voluntary isometric contraction ( mvic ) of each muscle , as measured by the manual muscle 
 test6 .
each mvic maneuver was performed 
 of 5 seconds and the average muscle activity for the middle 3 seconds of three trials was 
 used for normalization .
all participants walked at speeds of 3.5  km / h and 5.5  km / h , with and 
 without an arm weight on a treadmill for half a minute ( 2  2 design ) .
a 1  kg sand weight 
 was used for the arm weight ( sammons preston : usa ) .
the emg signal was collected for 30 
 seconds , and the first and last 5 seconds were discarded . during data collection ,
the spss ver.20.0 ( ibm , armonk , ny , usa ) statistical package was 
 used for statistical analyses .
repeated two - way anova was used to investigate differences in 
 muscle activities related to gait speed and the arm weight .
bonferroni s correction for 
 multiple comparison was used to investigate the differences between two - way anova . 

there were significant differences in the latissimus dorsi and gluteus maximus muscle 
 activities with change in gait speed and carrying of the arm weight ( p<0.05 ) , but there 
 were no significant differences in the muscle activities of the gluteus medius ( p>0.05 ) 
 ( table 1table 1 .
comparison of the muscle activities of the different gait speeds with and 
 without the arm weight ( unit : % mvic)no weightarm weightgait speed3.5  km / h5.5  km / h3.5  km / h5.5  km / hld11.3  6.915.3  10.3 * 12.3  7.7 * 16.4  10.4**gmed25.2  11.026.6  13.225.7  11.927.0  12.6gmax19.3  7.721.0  8.3 * 19.6  7.521.6  8.3**ld , latissimus dorsi ; gmed , gluteus medius ; gmax , gluteus maximus ) .
the present study investigated how muscle activities of the latissimus dorsi , gluteus 
 maximus , and gluteus medius are changed by different walking speeds and lower arm load 
 during treadmill gait .according to the results of the present study , at different gait 
 speeds , there were significant differences in the muscle activities of the latissimus dorsi 
 and gluteus maximus , and there were also significant differences in the presence of lower 
 arm load
. in general , change of gait speed occurs as passive arm swing changes into an 
 active one7 .
perry et al.1 also suggested that the angle of arm swing 
 increases as the gait speed increases .
ford et al.8 suggested that rotation of the trunk and pelvis decreases when the 
 arm swing is limited , and that the gait speed increases due to increased cooperation between 
 the upper and lower extremities when there is no limitation .
consequently , change of angle 
 of arm swing , due to increase in speed , affects the activity of the latissimus dorsi , which 
 belongs to the posterior oblique sling system , during gait .
this means that the role of arm 
 swing during gait can affect the movement of the legs , and it is consistent with the results 
 of the present study which suggest that muscle activity of the legs is affected by arm swing 
 increases .
lee et al.9 reported that there 
 was a more significant difference in gait speed , cadence and stride on the affected side 
 when a load of 1  kg was attached to the wrist than with no load or with load of 1.8  kg 
 attached to the wrist .
cavagnagh et al.10 
 suggested that the load of the arms plays an important role in arm swing during gait , and 
 that it represents changes in muscle activity which link the arms to the legs . in the 
 present study
, we demonstrated that there are some changes in muscle activities during gait 
 induced by different arm loads .
this means that as gait speed increased , gait and the lower 
 arm were affected through the latissimus dorsi and gluteus maximus which belong to the 
 posterior oblique sling system .
it also means that load on the arms plays a role in 
 resistance to increased muscle activity of arm swing regardless of gait speed .
therefore , 
 approaches utilizing walking speed and lower arm load during gait could provide therapeutic 
 methods influencing the muscle activities of the legs and trunk stability through the 
 posterior oblique sling system .
   [ purpose ] this study researched the effects of different gait speeds and lower arm 
 weight on the activities of the latissimus dorsi , gluteus medius , and gluteus maximus 
 muscles . [ subjects ] fourteen healthy adult men participated in this study . 
 [ methods ] all 
 the participants carried out walking on a treadmill at speeds of 3.5  km / h and 5.5  km / h for 
 half a minute . during treadmill gait , 
 electromyographic activity muscle was measured of 
 the latissimus dorsi , gluteus medius and gluteus maximus . 
 [ result ] there were significant 
 differences in the muscle activities due to changes in gait speed and lower arm load in 
 the latissimus dorsi and gluteus maximus , but there were no significant differences in the 
 muscle activities of the gluteus medius . 
 [ conclusion ] according to our results , arm swing 
 is related to increasing gait speed , and lower arm load is influences the muscle activity 
 of the lower extremities through the posterior oblique sling system . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION