pilates exercise is for making neutral spine position and involves various muscle exercises 
 for improving muscular strength , endurance , and flexibility .
it is known that the pilates 
 exercise has a positive effect on daily life , as it enhances balance and walking 
 capabilities1,2,3,4,5 .
since it can aid in the 
 development of deep muscles such as the erector spinae , transverse abdominis , and internal 
 oblique muscles , it has been frequently used as a rehabilitation exercise for stabilizing 
 the spine and reducing back pain6 , 7 . recently
, many researchers have utilized a modified form of pilates exercise involving 
 props for rehabilitation in the elderly and in patients with chronic stroke8,9,10,11 . 

it has been reported that this modified pilates exercise is safe compared with ordinary 
 pilates exercise .
therefore , it can be useful for those with poor physical function and limited mobility , 
 particularly as it can be done daily at home without the added difficulty of having to visit 
 a rehabilitation center .
bird and fell12 reported that pilates 
 exercise with props enhanced both the knee extensor and the ankle dorsiflexor muscles in 
 elderly participants .
other researchers have also reported that the improvement of muscular 
 strength , muscle endurance , and flexibility in the trunk and the lower extremities resulting 
 from performing pilates exercise can enhance static / dynamic balance , which is required for 
 gait in daily life and in particular , it has a positive effect on reducing the fall risk 
 factors2 , 3 , 
 13,14,15,16 .
the decrease in walking ability due to reduced lower limb neuromuscular function is an 
 important cause of falls in the elderly . with
falls being a major cause of mortality in the 
 elderly , and up to one - third of the elderly population experiencing at least one fall each 
 year17 , 18 , development of exercises and rehabilitation programs for the 
 elderly could be an important preventive measure for reducing the incidence of falls .
winter19 described gait as a dynamic 
 process for performing movements through high - level proprioceptive sense , neuromuscular 
 adjustment , and coordination among body segments and joints . in other words
, even if lower 
 limb muscular strength is improved , poor coordination between segments can affect the 
 ability to walk efficiently .
he also reported that excessive variability in walking or 
 improper coordination between segments and joints can also result in gait imbalance and 
 falls .
thus far , many gait - related studies in the elderly have used gait parameters or joint 
 kinematics in designing interventions to prevent potential falls .
it is , however , difficult 
 to confirm enhancement in neuromuscular adjustment or coordination with these variables . 

therefore , previous studies that examined the walking ability of elderly participants who 
 had undergone rehabilitative pilates exercise programs could not provide insight into the 
 fundamental mechanism of falls or gait imbalance .
inter - joint coordination is a method of investigating the coordination of two adjacent 
 joints during walking .
it is calculated through continuous relative phase ( crp ) as the phase 
 plane formed based on angle and angular velocity20 .
many researchers report that inter - joint coordination controls the 
 body s center of mass and can be expressed as the ability to maintain dynamic balance20,21,22 . unlike the traditional end - point 
 variability , which refers to the changes in each segment or joint movement , the variability 
 of inter - joint coordination indicates the variation in the pattern of performed movements . 

accordingly , the changes in the variability of inter - joint coordination are represented as 
 inherent properties of neuromuscular control , which determines the risk of injuries such as 
 falls23 .
therefore , the purpose of this study was to examine the effects of an 8-week modified 
 pilates exercise program on the variability of inter - joint coordination in the gait of 
 elderly participants .
twenty elderly participants were recruited for this study ( table 1table 1.general characteristics of the subjects ( n=20)training group ( n=10)control group ( n=10)gender5 males / 5 females7 males / 3 femalesage ( years)67.6 ( 2.4)68.1 ( 2.9)body mass ( kg)66.3 ( 11.3)68.0 ( 12.0)height ( cm)162.5 ( 8.6)164.9 ( 9.2)values are group means ( standard deviation ) . ) .
none of the participants had a history of orthopedic abnormalities within 
 the past year .
the selected participants were randomized into two groups of equal size  the 
 pilates exercise training group ( tg ) and the control group ( cg ) . during the intervention 
 period ,
the tg participated in pilates exercise training and received regular treatment at a 
 disabled rehabilitation center , while the cg received only regular treatment at the disabled 
 rehabilitation center .
the study protocol was approved by the university s institutional review board prior to 
 study commencement .
the pilates exercise used in this study was a mat - based pilates program . to ensure that 
 elderly participants could perform the exercise adequately ,
the intensity was modified , and 
 additional props such as balls , magic rings , and resistance bands were used .
the program was 
 conducted by two licensed pilates instructors three times a week for 8 weeks .
each session 
 lasted 60 minutes and comprised a warm - up exercise , the main exercise , and a cooldown 
 exercise .
eight sets were performed for each movement in this pilates training . for improving core 
 muscles stability ,
breathing exercises were conducted in a sitting posture before and after 
 all training sessions .
the mat - based pilates training program was composed of spine mobility 
 exercise , upper limb exercise , and lower limb strengthening exercise ; the detailed movements 
 for each part of the program were as follows : 1 ) for spine mobility exercise chin up and 
 down and seated forward and side spine stretches with a theraband ; 2 ) for upper limb 
 exercise , draw a sword and seated detoid lifts with a theraband ; and 3 ) for lower limb 
 strengthening exercise , side - lying top- and bottom - leg pulse - downs with a magic circle and 
 seated foot and ankle strengtheners with a theraband .
of note , unlike general mat - based 
 pilates training , the lower limb strengthening exercise included in this program helps to 
 strengthen the quadriceps , gluteus medius , adductor magnus , gastrocnemius , and anterior 
 tibialis .
a 3-d gait motion analysis with 8 infrared cameras was performed before and after the 
 exercise period . before the experiment
, the cameras were set around a 10  m gait path for 
 sufficient tracking redundancy and were calibrated using the nonlinear transformation 
 method . to identify lower limb movement and calculate inter - joint coordination variability 
 during walking , 16 reflective markers were attached to the lower body of the subjects . 

bilateral markers were placed on the iliac crest , posterior superior iliac spine , and 
 greater trochanter .
additional markers were placed on the sacrum , left lateral femoral 
 epicondyles , lateral malleolus , heel , 3rd metatarsal , and 5th metatarsal .
after sufficient warm - up , each 
 subject was asked to walk on the 10  m gait path at his or her preferred walking speed . 

subjects gait trials were captured into the host computer with 8 infrared cameras ( oqus 
 300 , sweden ) and five strides from the middle of the gait path were recorded .
gait was 
 captured at a sampling rate of 100  hz , and to reduce the random error from electronic 
 devices , a butterworth 4th order low - pass filter was used at a cutoff frequency of 6  hz . to obtain the crp ,
these variables were interpolated 100% such that 1% represented each moment of 
 the gait24 .
thereafter , to remove the 
 differences in amplitude and frequency among joints and to prevent the loss of data when the 
 angular velocity was 0 , the following two formulae were used to normalize the angle and 
 angular velocity from 1 to + 125 , 26 .
where , 
 i , normand i , norm represent 
 the normalized angle and angular velocity at ith sample , respectively .
max and  min represent 
 max and  min values during the analysis phase , respectively . after setting the phase plane formed based on the normalized angle (  ) and angular velocity 
 (  ) ,
the phase angle (  ) of each joint within the range of 0180 was calculated using the 
 right horizontal axis as the origin .
the two segments to be checked for inter - joint 
 coordination ( i.e. , the thigh and shank ) were then selected , and the difference between the 
 phase angles of the proximal and distal joints in each segment were used to calculate the 
 crp ( hip - knee , knee - ankle ) .
crpi 
 = i , proximal_segment - 
 i , distal_segment finally , inter - joint coordination variability was evaluated by using the deviation phase 
 ( dp ) , which was a mean value of the standard deviation calculated from each data point of 
 the crp . to evaluate the variability in single - joint coordination ,
an identical method was 
 used to calculate variability of angles of the ankle joint , knee joint , and hip joint in 
 terms of the mean standard deviation . to verify the effects of the pilates exercise on the variability of inter - joint 
 coordination in each subject s lower extremities ,
bonferroni correction was used as a post hoc test , as required . for all tests in this 

there was a significant increase in the hip - knee dp value for the tg after the pilates 
 training had been completed .
this increase was also significant when compared with that in 
 the cg ( table 1 , p<0.05 ) .
however , there was 
 no significant difference in the knee - ankle dp value ( table 2table 2.variability of inter - joint coordination of the training and control groups 
 between exercise periodsmean  sdtg ( n=10)cg ( n=10)hip - knee dp ( )pre12.51  3.0912.26  4.06post20.01  7.34 11.66  6.61knee - ankle dp ( )pre23.26  13.2524.22  13.88post24.77  5.9125.53  12.19tg : modified pilates training group ;
values are shown as the group 
 mean  standard deviation . significant difference between before and after 
 pilates training .
there was no significant difference in the joint variability of the ankle , knee , and hip 
 joints between the tg and cg , either before or after the intervention period ( table 3table 3.variability of lower extremity joint angular positions of the training and 
 control groups between exercise periodsmean  sdtg ( n=10)cg ( n=10)hip sd ( )pre1.30  0.281.50  0.75post1.47  0.601.50  0.80knee sd ( )pre1.94  0.422.12  1.15post2.24  0.682.14  1.53ankle sd ( )pre1.08  0.201.20  0.51post1.33  0.241.25  0.38tg : modified pilates training group ; cg : control group , p>0.05 ) .
this study examined the influence of a modified pilates training program on changes in the 
 variability of inter - joint coordination during walking in elderly participants .
according to this 
 concept , low variability indicates a stable performance while performing motions aimed at 
 achieving certain movements .
arutyunyan et al.27 and hausdorff28 
 reported that the gait of healthy adults tends to demonstrate lower variability than that of 
 the elderly , and this is also true of performance of higher - level athletes compared to 
 lower - level athletes .
accordingly , research on biomechanics and motor control has used this 
 variability as a marker of performance level29 , 30 . unlike the variability described above , in the dynamic system theory , coordinative 
 variability is considered diverse coordination patterns that appear while performing tasks 
 rather than essentially good or bad of the performance31 , 32 , or is considered to 
 present the adaptability required for adjusting movements22 , 33 .
generally , increased 
 coordinative variability is interpreted as enhanced adjustment of coordination patterns 
 required for adapting to new movement patterns or maintaining particular movements25 , 34 . on the other hand , decreased coordinative variability can explain 
 the causes of injuries or diseases that occur when the decrease in coordinative variability 
 reaches a decisive point22 , 33 .
arutyunyan et al.27 reported that the 
 performance of higher - level athletes indicates low variability and high coordinative 
 variability compared with that of lower - level athletes and that this signifies that higher 
 coordinative variability allows diverse coordination patterns among segments or joints for 
 achieving particular movements .
in addition , seay et al.34 emphasized the connection between the diversity of coordination 
 patterns and risk of injuries in their report , as their  no injury history 
, there was no significant difference in lower extremity joint variability 
 between the intervention and control groups ( table 
 3 , p>0.05 ) , but significantly increased hip - knee coordinative variability was 
 found in the tg compared with the cg ( table 1 , 
 p<0.05 ) .
our results are consistent with previous studies on inter - joint coordination for 
 preventing and reducing the risk of falls during walking in elderly participants35 , 36 .
these studies also reported that elderly participants had 
 significantly reduced hip - knee coordinative variability compared with that of healthy adults 
 and that the higher the hip - knee coordinative variability , the more neuromuscular control 
 strategies were shown during walking . in our study , the pilates exercise group revealed an increase in hip - knee coordinative 
 variability , while joint variability remained unchanged .
this may be because the pilates 
 exercise developed the deep muscles , which may have helped to improve the flexibility of the 
 pelvis and hip joints1,2,3,4 , 
 7 .
this also suggests that more diverse 
 coordination patterns are gained while maintaining the variability of the joint angular 
 position . in conclusion
, our study has demonstrated that an 8-week modified pilates exercise program 
 can have a positive impact on the gait of elderly participants , potentially by enhancing 
 neuromuscular adjustment , which may have positive implications for reducing their fall 
 risk .
 [ purpose ] this study aimed to examine the effects of an 8-week modified pilates program 
 on the variability of inter - joint coordination in the elderly during walking . 
 [ subjects 
 and methods ] twenty elderly participants with no recent history of orthopedic 
 abnormalities ( age , 67.9  2.7  years ; height , 163.7  8.9  cm ; weight , 67.1  11.6  kg ) were 
 recruited for this study and randomly allocated to a modified pilates exercise group or a 
 control group . 
 three - dimensional motion analysis was performed on both groups to evaluate 
 the effects of the pilates exercise . 
 [ results ] there was no significant difference in the 
 joint variability of the ankle , knee , and hip joints between the groups , both before 
 training and after training 
 . however , there was a significant increase in the hip - knee 
 deviation phase value in the exercise group after the program was completed , and this 
 increase was also significant when compared with that in the control group . 
 [ conclusion ] 
 this study has demonstrated that an 8-week modified pilates exercise program can have a 
 positive impact on the gait of elderly participants , potentially by enhancing 
 neuromuscular adjustment , which may have positive implications for reducing their fall 
 risk . 
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION