because horseback riding has long been known to be an excellent full - body exercise around 
 the world , it has been widely used not only for body exercise and mind training but also for 
 rehabilitation exercise and therapy for various disabilities1 . despite the many advantages of horseback riding as a recreational and sporting activity , it 
 has not been very popular in south korea due to the high cost and space limitations . much 
 attention thus has been paid to horseback riding simulators that can be used in indoor 
 spaces at any time as a new type of exercise tool that allows the general public to enjoy 
 the physical and mental benefits of horseback riding2 . a previous also found that both real and simulated horseback riding 
 showed significant effects on trunk and leg muscles3 , and muscle activity during horseback riding simulator exercises 
 significantly activated muscles for full - body muscle development and postural control2 . janura et al.4 reported that horseback riding simulator exercises were closely 
 correlated with endurance , agility , coordination , flexibility , balance , and aerobic and 
 anaerobic capacity and that horseback riding training devices or horseback riding simulator 
 training ( which utilizes similar motions as real horseback riding ) can affect balance and 
 postural control in individuals with disabilities . although previous studies have been conducted to examine improvements in muscle strength of 
 the legs , body balance , and flexibility during horseback riding simulator exercises , few 
 studies have been done on the effects on leg muscles according to changes in arm posture . thus , this study aimed to determine the effects of horseback riding simulator exercise on 
 the muscle activities of the lower extremities according to changes in arm posture . this study selected 30 healthy subjects ( fifteen males and fifteen females ) who were 
 19  years old and attending y university in chungbuk , south korea . the selection criteria 
 were no abnormal health problems and no lesions in the lower extremities in the last six 
 months . subjects were given information about the purpose and methods of the study prior to 
 the experiment ; they gave voluntary consent to participate in the experiment and signed a 
 consent form , in accordance with the ethical standards of the declaration of helsinki . mean 
 age , mean height , and mean weight of the subjects were 19.80.6  years , 169.49.0  cm , and 
 61.48.7  kg , respectively . subjects performed a full - body exercise program to gain the full - body effects of the 
 horseback riding simulator exercise device ( frtis , seoul , south korea ) . there were two 
 positions for the arms : a posture in which the handle of the exercise device was held ( p1 ) 
 and a posture in which the arms were crossed and both hands were put on the shoulders ( p2 ) . 
 to prevent subjects from falling while riding , two assistants who were trained to stop the 
 device automatically kept an eye on the subjects . to prevent subjects from becoming physically fatigued , the p1 exercise was performed in the morning , while the p2 exercise was 
 done in the afternoon . the horseback riding simulator device was similar to actual horse size , and exercise 
 intensity could be adjusted by controlling saddle movement , speed , and range . actual equine 
 motions were reproduced mechanically with a 3,350 rpm motor that reciprocated 190 times 
 per  min , generating short and fast three - dimensional figure-8 movements . in order to measure changes in muscle activity , electromyography ( mp150 ; biopac systems 
 inc . , santa barbara , ca , usa ) was used , while the surface electrodes were attached to the 
 transverse rectus femoris ( rf ) , the biceps femoris ( bf ) , and the hip adductors ( has ) . data 
 were collected for five  min ; data obtained during the first one  min and last one  min were 
 excluded , so only data from the middle three  min were used . the average value of the emg 
 signal of the subject was presented as a percentage of the maximum voluntary isometric 
 contraction ( % mvic ) . a nonparametric paired sample test was used in this study to determine differences in 
 muscle activities in the lower extremities with respect to the two different arm postures . the significance level  was set to 0.05 to test the significance level statistically , and 
 spss version 12.0 for windows was used to process the data statistically . the study results showed that p2 had higher muscle activity in the has than p1 ( p<0.05 ) 
 ( table 1table 1.comparison of muscle activities of the rf , bf , and has in the lower extremities 
 according to changes in arm posture ( unit : % ) musclep1p2rf13.0  10.715.7  10.7bf13.6  17.514.6  9.2has30.0  18.037.4  19.2**rf : rectus femoris ; bf : biceps femoris ; ha : hip adductors ; p1 : posture 1 ; p2 : posture 
 2 . rf : rectus femoris ; bf : biceps femoris ; ha : hip adductors ; p1 : posture 1 ; p2 : posture 
 2 . horseback riding is an exercise that improves muscle control through improvements in muscle 
 strength achieved by coordinating one s body movements with those of the horse to maintain 
 posture . westerling5 reported that static 
 muscle contraction increases when riding on a horse that is running slowly . kim et al.6 reported that balance , gait , 
 and daily living activities were improved significantly after training with horseback riding 
 exercises for six weeks in patients who had suffered stroke . back and kim7 conducted a study on horseback riding 
 simulation training for eight weeks with stroke patients and reported improvements in 
 balance capabilities as well as the thickness of abdominal muscles . lee et al.8 reported that indoor horseback riding 
 exercise significantly improved muscle activities in the rectus femoris and adductor longus 
 in normal adults . back et al.2 reported 
 that exercises performed by 40 normal adults using a horseback riding simulator increased 
 muscle activity in the biceps brachii , transverse abdominis , abdominal oblique , and adductor 
 longus muscles compared with jogging . the current study showed that p2 resulted in higher muscle activity in the has than p1 . the 
 above result is consistent with a study by winter et al.9 in which difficulty due to changes in posture could disturb or 
 stimulate the vestibular system , disturbance due to changes in posture could affect postural 
 agitation , and increased postural agitation contributed to postural control through 
 neuromuscular control of the appropriate legs . furthermore , amiridis et al.10 measured changes in muscle action 
 potential according to postural change in 20 subjects in a youth group and 19 subjects in an 
 elderly group ; both groups showed increased postural sway due to the effect of narrowing the 
 base of support . le bozec et al.11 
 reported that the postural control mechanism in the trunk is activated prior to ( or 
 simultaneously with ) movements of limbs and that this mechanism plays a role in stabilizing 
 the trunk against an unstable force , thereby providing the stability needed for connections 
 between postural body segments in the presents study , the posture in which the arms were 
 crossed and both hands were placed and putting both hands on the shoulders activated the hip 
 adductor muscles in the lower extremities to compensate for the unstable postural changes of 
 the trunk when a continuous three - dimensional movement pattern was applied during horseback 
 riding exercises . the limitations of this study include the fact that the results can not be generalized to 
 all ages because the study utilized a small number of subjects who were all 19  years of age ; 
 furthermore , study results may vary depending on particular physical traits or personal 
 daily habits and activities .
[ purpose ] this study aimed to determine the effects of horseback riding simulator 
 exercise on the muscle activities of the lower extremities according to changes in arm 
 posture . 
 [ subjects ] the subjects of this study were 30 normal adult males and females . 
 [ methods ] the horseback riding simulator exercise used a horseback riding simulator 
 device ; two arm postures were used , posture 1 ( holding the handle of the device ) and 
 posture 2 ( crossing both arms , with both hands on the shoulders ) . 
 electromyography was 
 used to compare the muscle activities of the rectus femoris , biceps femoris , and hip 
 adductors in the lower extremities . 
 [ results ] posture 2 had significantly higher muscle 
 activity than posture 1 . 
 [ conclusion ] posture 2 , which entailed crossing both arms with 
 both hands on the shoulders , was an effective intervention for improved muscle activity in 
 the hip adductors .