Ⅰ. INTRODUCTION

The pilates exercise program was developed based on the techniques of Joseph pilates (1880–1976) and is now considered a rehabilitation approach (Chang, 2000;Endleman & Critchley, 2008). Studies examining pilates as exercise and rehabilitation strategies have shown that pilates exercise programs are effective at core strengthening and rehabilitation intervention; thus, pilates programs are being applied in patient populations as well as among the general public (Di Lorenzo, 2011). The pilates exercise program has the characteristics of strengthening the abdominal, pelvic floor, and multifidus muscles while maintaining ideal spinal alignment and improving spinal stability by providing a stiffening mechanism to the spinal joint through the development of a simultaneous contraction method along with the muscles surrounding the spine (Muscolino & Cipriani, 2004;Schwab, Patel, Ungar, Farcy, & Lafage, 2010).

The alignment of the spinal column in an ideal standing posture minimizes muscle energy expenditure. The physiologic curvature of the spine in the sagittal plane, degree of vertebral straightness in the forehead plane, tension balance of the ligaments forming the spinal column, and proper contraction of the deep muscles of the torso allows for an efficient and painless standing posture (Schwab et al., 2010). On the contrary, abnormal postural alignment, when the degree of deviation and rotation in the sagittal, forehead, and horizontal planes of the spinal column exceeds the normal range (Lamartina & Berjano, 2014), reduces spinal column stability by negatively affecting spinal column alignment, resulting in mechanical changes in the muscles, tendons, and ligaments around the joints due to careless behavior, bad habits in daily life, and disease. If left untreated, it causes various spinal diseases such as neck and waist disc herniation (Christie, Kumar, & Warren, 1995;Lee, Nicholson, & Adams, 2004).

Spinal stabilization exercises have been actively performed to improve balance, posture, and limb function and are widely used for rehabilitation, but their methods are diverse and difficult to unify. However, the fact that core muscle strengthening contributes to spinal stabilization has already been demonstrated and is consistent with the exercise goal of strengthening the core muscles (Akuthota, Ferreiro, Moore, & Fredericson, 2008). pilates exercise programs aim to stabilize the spinal muscles through core muscle strengthening and promote health through proper posture (Lim, Poh, Low, & Wong, 2011).

While numerous studies have examined pilates exercise and the core muscles, studies of correct postural alignment are insufficient. Hence, this study investigated the effect of core training through pilates exercise on postural alignment in the sagittal and forehead planes. The hypothesis of this study assumed that a long term Pilates core training program would have a positive effect on postural alignment by strengthening the core muscles for stabilizing the spine. Therefore, this study aimed to investigate the effects of pilates-based long-term core training programs on postural alignment.

Ⅱ. Methods

This experimental study investigated the effects of pilates core exercise on body alignment by comparing the results before versus after intervention through the application of 16 weeks of pilates core exercises in adult women with abnormal body alignment as measured by the exbody^® analyzer.

1. Study participants

This study included adult women who were exercising at P pilates in Seoul, Korea. In the human body, the deviation between the gravitational line and the plumb line for each part indicates the measure of abnormal body alignment (Kendall et al., 2005). Therefore, in this study, the deviation of the participant's body alignment between the gravitational line and the plumb line was determined to be normal, and a deviation other than 0 was determined to be abnormal.

The participants were recruited through random sampling, and the exclusion criteria were as follows: 1) previous experience with pilates, 2) experience with other systematic exercise, and 3) body alignment within the normal range as measured by an exbody^® analyzer (exbody Inc., Seoul, Geumcheon, Korea). Eleven participants who did not meet the recruitment criteria above were excluded, while 20 participants who met the recruitment criteria were given an explanation of the study procedure and exercise method before providing written consent to participate.

2. Study design

The participants performed pilates core exercise intervention for 60 minutes a day three times a week for a total of 16 weeks. The body composition of each subject was assessed before the intervention. The participants performed the pilates core exercise intervention consisting of six core exercises according to the direction of one instructor, a physical therapist with more than 9 years of clinical experience, and a pilates lecturer. These interventions were performed for 16 weeks, followed by the same evaluation as before the intervention.

3. Exercise program

The core exercises performed in this study were based on pilates and consisted of 10 minutes of warm-up, 40 minutes of main exercise, and 10 minutes of cool-down. A 30 seconds break was given between exercises and sets. Each exercise used in this study was taken from previous studies and then revised for its application in our participants (Endleman & Critchley, 2008;Kloubec, 2010).

The warm-up and cool-down exercises consisted of stretching movements. 1) spine(cervical, thoracic, lumbar), 2) upper limbs, and 3) lower limbs stretch <Table 1>. For each motion, a static stretching was applied. It was a method of stopping for 30 seconds within a range that does not cause pain with a stretching position that was increased by 10% or more from the end of the movement including flexion, extension, abduction, adduction, and rotation motions according to the synovial joint type.

The pilates core exercise program included six types of mat exercises without instruments: 1) hundreds, 2) roll-up, 3) leg-circle, 4) breaststroke prep, 5) leg full front, and 6) half roll back <Table 1><Figure 1>.

1) Hundreds

One set consists of five inhaled breaths and five exhaled breaths for a total of 10 breaths; the set is repeated 10 times for 100 breaths total. Go from posture A to B and then start. This is a movement method that stimulates the core while breathing and strengthens the core through breathing with 90-degree hip flexion in supine position and 90-degree knee flexion as the basic posture.

2) Roll-up and –down

This movement requires segmental movement of the spine by stimulating and contracting the core. It is performed during breathing, not apnea. A roll-up is where the trunk is flexed requiring sequential movement from the neck vertebrae to the thoracic and lumbar segments while maintaining 90 degrees of shoulder flexion and elbow extension in supine position; the roll-up is the reverse sequence performed to return to the first posture. The roll-down requires sequential movements using the lumbar, thoracic, and cervical segments.

3) Leg circle

After flexing the core in the lying position, fix the body while maintaining 90 degrees of hip flexion in one leg with knee extension and keeping the other leg on the floor. Perform a circumduction movement of the hip joint of the raised leg. Using the core muscles, the movement of the hip joint is allowed, and the movement of the torso is suppressed.

4) Breaststroke prep

After performing back extension in the prone position, return to the original position. Breathe while performing the exercise. The movement stimulates the spinal extensors by using the core muscles. Place the arms at the side of the pelvis in forearm pronation, elbow extension, and internal shoulder joint rotation.

5) Leg pull front

In this exercise, one leg is raised in the air in the push-up plus position with hip extension, knee extension, and ankle plantar flexion. The hip extensor is stimulated while the subject maintains body stability using the core muscles. The exercise is performed to the extent that lordosis does not occur in the waist.

6) Half roll back

The patient starts in the sitting position with the legs placed pelvis-width apart and the knees flexed to 90 degrees with the arms stretched out. Afterward, only the pelvic to lumbar segments are sequentially lowered and then raised back up using the core muscles so that the foot does not fall off the ground when lowering the body.

4. Measurement method

Here we used an exbody^® 9100 MOMI analyzer (exbody Inc., Korea) to measure body alignment while standing by attaching markers on the reference points on the front, back, and sides. Signal processing was performed using a software program. Participants performed static standing on exbody^® 9100 MOMI musculoskeletal analysis equipment for 10 seconds in the anterior, posterior, and lateral positions, respectively. The participants were allowed to stand in a natural position, and the measurements were taken three times.

In the anterior position, the markers were attached to the bilateral tragus, acromion, anterior superior iliac spine, center of the patella, tibial tuberosity, and center of the talocrural joint. The vertical height difference and horizontal degree of inclination that occurred on the forehead plane when the attached markers were connected were measured. In the posterior position, markers were attached to the inferior angle of the scapula, cervical vertebra 7, and lumbar vertebra 5 on the right and left. The degrees of horizontal and vertical inclinations on the forehead plane when the attached markers were connected were measured.

For the lateral position, only the right side was measured, and the markers were attached on the right behind the temporomandibular joint, center of the shoulder, tubercle of the iliac crest, and greater trochanter, in front of the fibular head, and just in front of the lateral malleolus. The differences in horizontal distance and degree of inclination compared with the vertical line on the sagittal plane when the markers were connected were measured <Figure 2>.

5. Analysis method

The collected data were analyzed using SPSS ver. 18.0 (SPSS Inc., Chicago, IL, USA) by calculating the mean and standard deviation of all items. The Kolmogorov- Smirnov test was used to test for data normality, and the results showed that all continuous variables were distributed normally. The difference between the preand post-intervention was measured using the paired t-test. For all items, the statistical significance level was α = .05.

Ⅲ. RESULTS

1. Participants’ General Characteristics

Mean age, mean height, mean body weight, body mass index, and body alignment of the participants in this study are shown in <Table 2>.

2. Before versus After Intervention in the Anterior Position

The markers were attached to the left and right tragus, acromion, anterior superior iliac spine, center of the patella, tibial tuberosity, and center of the talocrural joint, and the two dots were connected. As a result of comparing the vertical height difference and the horizontal inclination between two points before versus after the intervention, the height difference and the horizontal inclination were significantly decreased after the intervention (p < 0.05)<Table 3>.

3. Before versus After Intervention in the Posterior Standing Position

The horizontal inclination from the left to right inferior angle of the scapula and the degree of inclination when cervical vertebra 7 and lumbar vertebra 5 were connected were compared before versus after the intervention. The horizontal inclination was significantly reduced to almost horizontal (p < 0.05), while the vertical inclination was also decreased to almost vertical (p < 0.05) <Table 3>.

4. Before versus After Intervention in the Lateral Standing Position

The markers were attached right behind the temporomandibular joint, center of the shoulder, tubercle of the iliac crest, and greater trochanter, in front of the fibular head, and just in front of the lateral malleolus and were then connected. The differences in horizontal distance and vertical inclination that occurred compared with the vertical line were measured to examine the inclination of the shoulder and the front and back of the pelvis as well as the degree of knee flexion before versus after the intervention. The inclination in the pelvis was significantly reduced after the intervention (p < 0.05), while there was no statistically significant difference between the degree of knee flexion and the degree of shoulder inclination before versus after the intervention (p < 0.05)<Table 3>.

Ⅳ. DISCUSSION

The purpose of this study was to investigate the change of posture alignment through the pilates exercise which has an emphasis on the core muscles. The exercise method of this study was based on the method introduced by Muscolino & Cipriani (2004). According to this study, pilates exercise affects pelvic posture, stretches the vertebrae, and affects the tone and structural integrity of the abdominopelvic cavity (Muscolino & Amp; Cipriani, 2004). Endleman & Critchley (2008) found through ultrasound imaging that pilates activated the transverse and intramedullary muscles (Endleman & Critchley, 2008). Based on previous studies, the present study aimed to investigate how the participants’ anterior, posterior, and lateral alignments changed with the application of the pilates core strengthening exercise program before versus after the intervention.

After the reference points were fixed for alignment, markers were attached to the anterior, posterior, and lateral positions and alignment was compared before versus after the interventions using the exbody^® 9100 MOMI musculoskeletal analysis equipment. First, for the anterior position, in which the makers were attached to the tragus, acromion, anterior superior iliac spine, center of the patella, tibial tuberosity, and center of the talocrural joint to compare the differences in vertical heights and horizontal inclination between the left and right sides, the differences in height and horizontal inclination were significantly reduced after the application of the pilates core-strengthening exercise. If the vertical difference in height and horizontal inclination degree is close to zero, the right and left sides are symmetrical; after the pilates core strengthening exercise, the difference in the left and right shoulder horizontal, pelvic horizontal, knee horizontal, and ankle horizontal angles in the forehead plane all approached 0, suggesting a positive effect on the left–right body balance.

Second, for the posterior position, when the horizontal inclination of the inferior angle of the bilateral scapulae and the angle difference between the vertical line and the inclination in the line connecting cervical vertebra 7 and lumbar vertebra 5 were compared, the horizontal inclination in the inferior angle of the scapula was nearly horizontal after the application of pilates core strengthening exercise, while the inclination in the line between the cervical and lumbar vertebrae was nearly vertical. As the values of the horizontal and vertical inclinations approach 0, the lines are horizontal and vertical, respectively, indicating that the corestrengthening pilates exercise had a positive effect on the horizontal and vertical alignment of the body in the forehead plane.

Third, for the lateral position, the markers attached to the straight gravity line passing through the middle of the head bone and right behind the temporomandibular joint; at the center of the shoulder, tubercle of the iliac crest, and greater trochanter; in front of the fibular head; and just in front of the lateral malleolus were connected. The resulting differences in horizontal difference and vertical inclination were measured to compare the difference in shoulder inclination, front and back inclination of the pelvis, and degree of knee flexion before and after the intervention, and a significant reduction was observed in the front and back inclination of the pelvis after application of the core-strengthening pilates exercise. There was no significant change in shoulder inclination or knee flexion angle before versus after the intervention, which was contradictory to the assumption that the core-strengthening pilates exercise improves balance in the sagittal plane and positively affects the overall vertical alignment of the body. Nonetheless, only the pelvic posture was affected in a positive way, with the horizontal distance difference and the vertical inclination approaching zero, consistent with a neutral pelvic posture since the intervening exercise focuses on the core.

Overall, the postural alignments in the forehead and sagittal planes were more consistent with the ideal posture after than before the pilates core exercise intervention, while the bilateral symmetry was more symmetrical after the intervention. The pilates exercise had a positive effect on body alignment, consistent with the findings of Muscolino & Cipriani (2004), who reported that pilates movement affects the thoracic and abdominopelvic cavities, increasing the pressure of each cavity to stabilize the core and affect posture (Muscolino & Cipriani, 2004). The increase in abdominal pressure is caused by strong contractions of the abdominal muscles. The contraction of the abdominal muscles control the rotation of the trunk to maintain body alignment correctly and contribute to stability (Gibbons, & Comerford 2001;Neumann, 2010 ; Sahmann, 2002). Kloubec (2010) confirmed that after 12 weeks of pilates exercise intervention, height was significantly increased compared to pre-intervention because it affected the structural alignment of the spine and affected body alignment (Kloubec, 2010). In addition to the mechanical changes of the muscles, tendons, and ligaments around the spinal joints, stabilization of the spine by proper adjustment of the intraabdominal pressure creates efficient body alignment (Frank, Kobesova, & Kolar, 2013). pilates exercises are simple and repetitive and can be performed with little flexibility. Because it is an exercise to improve dynamic posture control, balance, and joint movement around a low back–pelvic–hip complex to improve the muscular endurance of the pelvis and trunk as well as the abdominal, waist, hip, and thigh muscles (Kloubec, 2010), it has the same goal as the spinal stabilization exercise used for rehabilitation and uses a similar exercise method, which is believed to positively affect body alignment. Therefore, pilates core exercise has a positive effect on the ideal spinal alignment process by adjusting the intraabdominal pressure to achieve spinal stabilization.

This study aimed to investigate the effects of the pilates core exercise on postural alignment. However, there were limitations in that it is difficult to generalize the results to the public because of the small number of participants including only adult women. Therefore, more comprehensive studies with a greater number of participants including male participants should be conducted in the future.

Ⅴ. CONCLUSION

The purpose of this study was to investigate the effect of a 16-week pilates core exercise program on the postural alignment of adult women with abnormal posture. A comparison of the postural alignment with the ideal postural alignment as described in the literature was performed of the anterior, posterior, and lateral positions. When the results were compared before versus after the intervention, the postural alignment was closer to the ideal after the application of the pilates core exercise program compared to before the intervention in the forehead and sagittal planes. We found that asymmetry on the left and the right sides was significantly decreased. Our findings suggest that the pilates core exercise had a positive effect on postural alignment due to structural changes in the spine. pilates is an exercise method easily available to the public that can be performed with relatively little impact from the surrounding environment. The clinical significance is that it can be performed by the general public with incorrect postural alignment.