activities such as walking and cycling are the two most common exercises performed for 
 maintaining good health or recovering conditiong1 .
previous studies have reported a decrease in blood pressure after 
 ground walking2 , 3 .
other studies have suggested there are improvements in the balance 
 and gait abilities , and muscle strength of stroke patients after stationary cycling exercise 
 or walking training in stroke patients1 , 4,5,6 .
in addition , a study demonstrated that 
 patients with diabetes who practiced 30 minutes walking for 3 months showed decreased blood 
 pressure and blood glucose levels , and physical changes such as improved muscle strength and 
 stability7 .
furthermore , another study 
 reported that patients who underwent pneumonectomy showed a decreased incidence of 
 complications , improved motor skills , and a decreased length of hospital stay when they 
 performed walking exercises for a specific amount of time and intensity8 . the recreational device , pedalo reha - bar , is becoming more popular .
this device is designed 
 for children , adults , and the elderly to enjoy recreation . however , a few countries are 
 using this device in rehabilitation .
thorpe and valvano utilized the device as an 
 intervention tool in order to investigate the effect of different types of feedback on motor 
 learning among children with cerebral palsy9 .
also , chen et al . analyzed the movement of healthy adults using the 
 pedalo reha - bar10 .
the pedalo reha - bar provides a weight shift between the lower limbs and allows movement 
 similar to walking .
thus , this device may be beneficial not only for healthy adults but also 
 for the elderly and disabled patients .
in addition , because the pedalo reha - bar was 
 originally designed for play or recreation , it could provide interest and motivation . 

although a few studies have been conducted on the pedalo reha - bar , the number of studies 
 conducted to analyze the movement and force while using the device is limited .
therefore , the present study aimed to investigate the electromyographic activities of the 
 lower extremity muscles while using the pedalo reha - bar , and compare them with the 
 electromyographic muscle activities while walking .
in the present study , healthy adult volunteers aged between 20 and 29 years from a 
 university were enrolled . the university message board was used for the recruitment of 
 volunteers , and subjects were enrolled if they fulfilled the inclusion criteria : healthy 
 adults without musculoskeletal , neuromuscular , cardiovascular , pulmonary , or integumentary 
 pathological conditions that might have affected physical performance .
the subjects included 2 male and 13 female healthy adults whose 
 mean age was 21.3 years , mean height was 162.1 cm , mean weight was 52.9 kg , and dominant 
 side was the right side , except one subject .
after the subjects had been interviewed to collect 
 general information ( gender , age , height , and weight ) , they participated in the experiment 
 in which surface emg signals were recorded while the subjects walked or performed pedalo 
 reha - bar riding . before the experiment , the maximum voluntary isometric contraction ( mvic ) 
 of five muscles ( rectus femoris , biceps femoris , tibialis anterior , soleus , and 
 gastrocnemius ) were measured .
measurements were taken in the sitting position for the rectus 
 femoris , soleus , and gastrocnemius in the standing position for the tibialis anterior and in 
 the prone position for the biceps femoris11 .
each muscle was measured for 10 seconds in three trials , with a 
 2-minute break between each trial .
mvic was calculated based on the 5 seconds of data , 
 between 3 to 7 seconds of the 10-second trial .
subjects were shown how to use the pedalo 
 reha - bar , and they were allowed to practice until they were comfortable with it . after a 
 10-minute break , emg electrodes were placed on the rectus femoris , biceps femoris , tibialis 
 anterior , soleus , and gastrocnemius .
the subjects were then asked to perform 20 steps on a 
 flat ground and 20 cycles on the pedalo reha - bar . for the pedalo
reha - bar riding , all 
 subjects began from the starting position on the pedalo reha - bar .
starting with the left 
 foot , in the raised position subjects were allowed to move at a comfortable speed for 20 
 cycles .
alternation from the left to the right foot was measured as one cycle . during the 
 pedalo
the mean emg 
 signals of three trials , the 10 seconds from 6 to 15 seconds of the 20-second period , were 
 used for the data analysis .
three trials of ground walking and pedalo reha - bar riding were 
 performed and the subjects were allowed to take a 5-minute break after each trial . in the present study , a surface emg system ( trigno wireless emg , delsys inc . , 
 boston , ma , usa ) was used to collect muscle activity data .
prior to attaching the electrodes , skin impedance 
 was reduced by shaving excess body hair , gently scrubbing the skin with sandpaper , and 
 wiping the skin with alcohol swabs .
the emg electrodes were placed on the rectus femoris , 
 biceps femoris , tibialis anterior , soleus , and gastrocnemius , on both sides of the body . in 
 total ,
the emg electrodes were placed according to seniam 
 ( surface emg for noninvasive assessment of muscles ) guidelines12 .
the electrodes were placed at the midpoint of the line 
 from the anterior spina iliaca superior to the superior part of the patella for the rectus 
 femoris , at the medial position on the line between the ischial tuberosity and the lateral 
 epicondyle of the tibia for the biceps femoris , at one - third the distance between the tip of 
 the fibula and the tip of the medial malleolus for the tibialis anterior , at two - thirds the 
 distance on the line between the medial condyles of the femur to the medial malleolus for 
 the soleus , and at the one - third the distance on the line between the head of the fibula and 
 the heel for the gastrocnemius .
a 60 hz high - pass filter and a 10 
 hz low - pass filter were applied ( all filters , zero - lag 4th order butterworth ) .
the root mean 
 square ( rms ) value of the raw emg data was calculated .
the emg data of each muscle was 
 normalized by calculating the rms of the 5-second mvic of the muscle .
the emg data collected 
 during the ground walking and the pedalo reha - bar riding were expressed as % mvic .
spss 18.0 ( ibm corporation , endicott , ny , usa ) was used for the statistical analysis .
data 
 were analyzed using the paired t - test for the comparison of values between walking and the 
 pedalo reha - bar riding .
the electromyographic activities of each muscle measured during ground walking and pedalo 
 reha - bar riding are summarized in table 
 1table 1.comparison of emg data between walking and pedalo ridingmusclessidewalkingpedalo ridingrectus femoris ( % ) right4459*left3755*biceps femoris ( % ) right1920left2123tibialis anterior ( % ) right1815left2016*soleus ( % ) right5144left6345*gastrocnemius ( % ) right4036left5854the values are presented as % mvic . *
significant difference between the two tasks , p<0.05 .. significant differences were observed between ground walking and the pedalo 
 reha - bar riding in the electromyographic activities of the rectus femoris , left tibialis 
 anterior , and left soleus ( p<0.05 ) .
the electromyographic activity of the right rectus 
 femoris showed a significant difference between ground walking and pedalo reha - bar riding 
 ( 44% vs. 59% , respectively ) .
moreover , the left rectus femoris showed a electromyographic 
 activity of 37% during ground walking and 55% during pedalo reha - bar riding .
meanwhile , the 
 left tibialis anterior showed a electromyographic activity of 20% while ground walking and 
 16% while pedalo reha - bar riding , and the left soleus showed electromyographic activities of 
 63% and 45% , respectively , indicating a significant decrease in electromyographic activity 
 during the pedalo reha - bar riding .
in the present study , the electromyographic activities of the lower extremity muscles 
 during pedalo reha - bar riding were recorded and compared with those of ground walking .
the 
 results show that the rectus femoris on both sides demonstrated a significant increase in 
 electromyographic activity during the pedalo reha - bar riding compared to ground walking . 
 however , the electromyographic activities of the left tibialis anterior and left soleus 
 decreased during the pedalo reha - bar riding compared to ground walking .
romkes et al . reported that masai walking , which is walking slowly with short strides , 
 elicited maximum activity in the tibialis anterior in the toe off and swing phases , and the 
 gastrocnemius at mid stance compared to normal walking with ordinary shoes13 .
kim et al . reported that as the load 
 increases , the soleus and tibialis anterior showed increased activity compared to the other 
 muscles14 .
reported that 
 the rectus femoris , vastus medialis , vastus lateralis , biceps femoris , gastrocnemius , 
 tibialis anterior , and soleus showed increased activities while walking , and even greater 
 muscle activities were observed in the rectus femoris , vastus medialis , vastus lateralis , 
 and biceps femoris when the muscles were tensed while stepping over an obstacle15 .
miller et al . used the step - and - go cycle 
 as a three - wheel cycle that repeats vertical motion to investigate the muscle activity of 
 the power levels in the three different stages between standing and sitting16 .
they reported that standing with the 
 lowest power level elicited major muscle activities in the gluteus maximus , vastus medialis , 
 vastus lateralis , rectus femoris , and tibialis anterior16 .
moreover , the study by lopes et al . , which was not relevant to 
 this study because the subjects performed recumbent pedaling and upright pedaling , indicated 
 that only the rectus femoris was activated during upright pedaling17 .
the pedalo reha - bar used in the present study was not the 
 same device as that used in the studies of miller et al . and lopes et al . , but it has 
 sufficient similarity for comparison . the increased activity of the rectus femoris reported 
 in the previous studies16 , 17 may support the findings of the present study . in the 
 present study ,
electromyographic activity of the rectus femoris was greater during the 
 pedalo reha - bar riding than during ground walking .
this result , as previous studies showed , 
 indicates that the rectus femoris is used to propel the body forward in the upright 
 position .
that is , cycling uses the rectus femoris to push the pedals forward while sitting 
 down and during knee extension , and the pedalo reha - bar uses a similar motion to perform the 
 knee - extension position , which requires more force to be applied by the rectus femoris .
previous studies of muscle activities while riding and bicycling have reported rectus 
 femoris activation16 , 17 . in this study ,
although it is different from a bicycle , the pedalo reha - bar 
 may induce similar muscle activation , but via a different method and position of using the 
 device .
in addition , the present study compared the emg data obtained during the pedalo 
 reha - bar riding and those obtained during ground walking .
thus , the results from the present 
 study alone can not confirm the similarity between the pedalo reha - bar and a bicycle . 

therefore , follow - up studies are required to compare muscle activities between pedalo 
 reha - bar riding and bicycle riding .
the present study showed the electromyographic activities of the tibialis anterior and 
 soleus decreased while using the pedalo reha - bar compared to their values during ground 
 walking .
this may be due to the propulsion characteristics of the pedalo reha - bar , which 
 uses the knee and hip joints , rather than the ankle , in the standing position .
although no 
 direct investigation was conducted , the angle of the ankle joint did not change much while 
 pedalo reha - bar riding .
moreover , ground walking requires tibialis anterior activation at 
 heel strike and soleus activation at heel off , rather than a powerful knee extension18 , 19 . the present study confirmed that walking and pedalo reha - bar riding 
 utilize different types of muscles .
in particular , pedalo reha - bar riding has a positive 
 influence on electromyographic activation of the rectus femoris .
furthermore , the pedalo 
 reha - bar may be used as an exercise device for neuromuscular activation of the lower 
 extremities , especially the rectus femoris .
the results suggest that the pedalo reha - bar may 
 be utilized as an optional device for exercise or recreation . however , the present study had 
 a few limitations .
first , the number of subjects was small and the subjects were limited to 
 those in their twenties .
, 
 electromyographic activities of only a few muscles in the lower extremity were recorded . 

thus , future studies should include analysis of other muscles , such as core muscles , motion 
 analysis , and recording of electromyographic activities of muscles while pedalo reha - bar 
 riding . through such studies ,
the pedalo reha - bar can be suggested as an optional device for 
 exercise or recreation .
 [ purpose ] to analyze the electromyographic ( emg ) activities of several lower extremity 
 muscles during ground walking and pedaling using the pedalo reha - bar device . 
 [ subjects and 
 methods ] fifteen healthy adults aged 2029 year participated in this study . 
 the subjects 
 surface emg signals while walking and pedalo reha - bar riding were recorded . 
 the subjects 
 performed 20 steps on flat ground and 20 cycles on the pedalo reha - bar . during the tasks , 
 emg signals of the rectus femoris , 
 biceps femoris , tibialis anterior , soleus , and 
 gastrocnemius within a 20-second period were recorded . 
 the mean emg signals within the 10 
 seconds from 6 to 15 seconds were used for the data analysis . 
 [ results ] there was a 
 significant increase in the bilateral use of the rectus femoris and a significant decrease 
 in the use of the left tibialis anterior and left soleus in pedaling using the pedalo 
 reha - bar device compared to ground walking . 
 [ conclusion ] level walking and the pedalo 
 reha - bar riding utilize different types of muscles activities . 
 these results suggest that 
 pedalo reha - bar riding may be used for neuromuscular activation , especially of the rectus 
 femoris . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION