Comparison of Effects of Core Stabilization Exercise according to Mirror Visual Feedback and Video Visual Feedback on Static and Dynamic Balance in College students with Low Back Pain

Ⅰ. Introduction

Everyone experiences low back pain (LBP) at least once in their lives (Lee, 2013). Low back pain is generally defined as muscle tension or stiffness pain localized between the costal margin and the inferior gluteal fold, regardless of leg pain. LBP is classified as non-specific pain, in which the physiopathological cause cannot be identified, and specific pain, mainly caused by hernia, fracture, osteoporosis, rheumatic disease, spinal arthrosis, infection, or cancer. Also, LBP is classified as acute for less than 6 weeks, subacute for between 6 weeks and 3 months, or chronic for more than 3 months based on the duration of the disease (Koes et al., 2006; Lippi & Mattiuzzi et al., 2020). The causes of LBP include muscle weakness due to lack of exercise and spinal instability due to improper posture (Choi, 2007; Park, 2001; Anthony, 1995). Conversely, LBP causes muscle atrophy, and muscle atrophy can reduce postural balance ability (Yang et al., 2004). In addition, various biopsychosocial factors lead to chronic LBP (CLBP) disorders (Kim et al., 2020; Steelman et al., 2018). In particular, students have a habit of sitting too long, maintaining uncomfortable postures for long periods of time, which results in high static muscle loads (Mozafari et al., 2015; Casas et al., 2016; Anggiat, et al., 2018). Students with LBP were unable to perform academic activities, which negatively impacts their LBP (Casas et al., 2016; Anggiat, et al., 2018). Long-term, severe LBP also impact the quality of life (QOL) of the college student population. The impact of CLBP on QOL, symptoms of depression and anxiety, impairment impairment in work and daily activities, and use of heath care increased with the severity of pain (Montgomery et al., 2016).

Core stabilization exercises have been suggested to improve LBP. Core stabilization exercises strengthen the lumbar muscles, restore the ability to control movement and muscles, and increase the stability of the back area (Hyung, 2008). Core stabilization exercises that strengthen deep muscles are correlated with the prevention of LBP (Yoon & Park, 2020), and are widely used as a lumbar stabilization exercise program for patients with LBP among musculoskeletal diseases (Moon et al., 2020). Core stabilization exercises performed on patients with CLBP can improve functional activities along with hospital-based treatment for pain reduction (Jung et al., 2020). Visual feedback for people suffering from chronic neck pain and CLBP is a novel approach based on an individual's perception of the painful area. In particular, visual feedback is an innovative therapeutic approach whose effectiveness has not yet been systematically reviewed for people with CLBP and chronic neck pain (Heinrich et al., 2020). It is very effective in motor learning to confirm the movements applied to the subject through visual stimulation (Schuett et al., 2008).

Action observation (AO) is an effective way to promote motor skill learning (Bähr et al., 2018), and feedback strategies that guide motor movements have been extensively studied to improve movement interaction (Cavalcanti et al., 2019). Feedback is divided into intrinsic feedback or sensory feedback and extrinsic feedback or augmented feedback depending on the source of information. The extrinsic feedback is used for motor learning (Sin et al., 2015). The extrinsic feedback includes current feedback, which provides information during motor performance, and knowledge of result and knowledge of performance, which provide information after the response is completed (Cynn et al., 2004). Among various feedback strategies, both intrinsic and extrinsic visual feedback can affect balance control, and extrinsic visual feedback can provide individuals with more information, such as knowledge of result and knowledge of performance, for balance control (Hung, 2022). Among various types of visual feedback, mirror visual therapy (MVF) is well known as mirror therapy and has been studied based on motor learning strategies (Bai et al., 2020) and is a pshychophysiological technique for the rehabilitation of people with chronic regional pain syndrome, stroke, and other types of motor disorder, with the aim of improving motor function or releasing pain (Reissig et al., 2015). A mirror is a source of visual information that allows one to see one's own form at any point in the movement, and enables self-analysis and self-correction (Lynch, 2006). Video visual feedback (VVF) is an effective educational tool (Halim et al., 2021; Cope et al., 2015) and improved an accuracy of self-assessments (Halim et al., 2021; Rizan, et al., 2015). The VVF is a more effective method than verbal feedback (Schoenmaker et al., 2023), and its use is increasing due to the advantages of video communication as remote technology develops (Eriksson et al., 2009).

Balance plays an important role in daily life as it is necessary for our activities such as maintaining stable posture, performing physical exercises, and responding appropriately to various stimuli (Wang et al., 2022; Pollock et al., 2000). Maintaining balance is closely related to vision, equilibrium, proprioception, and lower extremity muscle stability (Russo et al., 2008), and asymmetric gait patterns may appear due to spinal instability caused by changes in muscle strength due to LBP (Kang & Jeong., 2013). Interventions using visual feedback on trunk movements in patients with LBP have been shown to improve proprioception (Alemanno et al., 2019).

Core stabilization exercise programs for patients with CLBP improved functional activities, which could relieve pain and contribute to a stable role in functional activities including daily living abilities (Park, 2012). Core stabilization exercise reduced the pain index of patients with CLBP and significantly increased lumbar stabilization balance ability (Jeon, 2021). In addition, core stabilization exercise contributed to trunk stability as it significantly improved static and dynamic balance ability after exercise (Choi et al., 2018). And mat Pilates exercise including core stabilization exercise with visual feedback using a mirror significantly increased static and dynamic balance ability in patients with chronic stroke (Lim et al., 2019).

Although there have been many studies on core stabilization exercise programs for people with LBP and studies on core stabilization using visual feedback, there are most studies on the presence or absence of visual feedback and on targeted neurological patients performing core stabilization exercises with visual feedback. The results of these studies have limitations in utilizing them according to the type visual feedback for musculoskeletal disorders and in applying them to musculoskeletal disorders such as LBP. Therefore, the purpose of this study was to perform core stabilization exercises using MVF and VVF to college students with LBP in their 20s and compare the effect of theses visual feedback types on static and dynamic balance.

Ⅱ. Methods

3. Study procedure

1) Study design

In this study, 20 people with mild LBP who fully understood the purpose and content of the experiment and agreed to the research informed consent form participate. To select subjects with mild LBP, ODI-K questionnaire was used, and their physical characteristics were measured. Among them, 10 were randomly divided into a mirror visual feedback (MVF) group and 10 were divided into a video visual feedback (VVF) group.

The core stabilization exercise program with visual feedback using mirrors and images was conducted for 30 minutes, three times a week for four weeks. The face-to-face method was applied once out of the three times a week, and the non-face-to-face method was applied twice a week. In the non-face-to-face exercise, the subject filmed the exercise video from the side and the researcher provided feedback. The MVF group exercised while checking their postural alignment with a full-length mirror at the side, and the VVF group exercised while watching video materials on their personal devices (Choi & Yoon, 2020). Each group measured static and dynamic balance before and after exercise.

2) Measurement methods

(1) ODI

ODI was used to select subjects who met the criteria for LBP. ODI was developed as a patient-centered and patient-life evaluation method. It is a clinical evaluation tool expressed as a percentage of the estimated disability and consists of 10 items: pain, personal management, lifting, walking, sitting, standing, sleeping, sex life, social life, and traveling (Pekkanen et al., 2011; Davidson, 2008). In this study, nine items were surveyed except for the section eight – sex life. The reliability of K-ODI is .9168 (Cronbach’s α=.9168), the reliability coefficient for each annotation is .7 or higher (r>.7), and the test-retest reliability coefficient of K-ODI is .9331 (test-retest reliability, r=.93) (Jeon et al., 2005).

(2) Balance

Static balance ability and dynamic balance ability were measured using a balance trainer BT4. The reliability of the BT4 is excellent reliability (ICC=.77-.94) (Granacher et al., 2011). For static balance ability, the Romberg test with eyes open and eyes closed was used. The measurement posture was one-leg stance posture with the non-dominant foot with barefoot and then stand as stable as possible with the other leg with 30 degrees of knee flexion. The measurement time was measured for 30 seconds both with eyes open and eyes closed (Chae et al., 2018). The non-dominant foot was defined as the opposite foot that kicked a ball (Chowning et al., 2021).

For dynamic balance ability, a test of the limits of stability (LOS) was used. The LOS is measured the maximum limit of voluntary movement that can be maintained by measuring the extent to which the center of pressure moves in the forward, backward, left, and right directions from a two-leg stance posture (Kang et al., 2014). The subject kept two-leg stance posture with his bare feet aligned with the gradations on the platform and was able to recognize his own degree of inclination while watching the real-time target on the monitor. The subject performed movements in which they tilted their bodies as much as possible in the forward, backward, left, and right directions for 8 seconds each (Chae et al., 2018).

3) Exercise program

The core stabilization exercise program was modified and supplemented from previous studies (Jeon, 2021; Kim, 2021; Ifeyinwa et al., 2021; Kwon et al., 2019; Lee et al., 2019), and consisted of a total of 30 minutes, five minutes of warm-up exercise, 20 minutes of main exercise, and five minutes of cool-down exercise. Stretching exercises were performed as warm-up exercises (Jeon, 2021), and abdominal breathing was performed as cool-down exercises (Choi, 2018). The main exercise was consisted of five exercises: bridge exercise, dead bug exercise, bird dog exercise (Lee, 2019), crunch exercise, and leg raise exercise (Ifeyinwa et al., 2021). To prevent the subjects from adapting, the difficulty was adjusted. Two sets were performed in the 1st and 2nd weeks, and three sets were performed in 3rd and 4th weeks with an increased number of repetitions (Kwon et al., 2019) (Table 1).

Table 1.

Core exercise program (for four weeks)

Ⅲ. Results

1. General characteristics of the subjects

The subjects of this study were 20 people with mild LBP (ODI (%) = 9.10±4.72). In the MVF group, mean age was 21.60±3.20 years, mean height was 169.14±7.42 cm, mean weight was 68.09±11.03 kg, mean BMI was 23.96±4.76 kg/m², and mean ODI was 7.99±3.50 %. In the VVF group, mean age was 20.10±1.96 years, mean height was 172.74±5.37 cm, mean weight was 76.35±14.06 kg, mean BMI was 25.48±3.99 kg/m², and mean ODI was 7.99±3.50 %. Homogeneity was demonstrated in gender, age, height, BMI, and ODI (Table 2).

Table 2.

General characteristics of the subjects(n=20)

2. Balance

1) Static balance

As a result of comparing static balance between groups, in the eyes open, the 90% confidence elliptical area (C90 area), which is the range of movement of center of pressure, in the MVF group was significantly lower than in the VVF group (p<.05). The trace length in the MVF group was significantly higher than in the VVF group (p<.05). In the eyes closed, the C90 area and the trace length in the MVF group was significantly higher than in the VVF group (p<.05).

As a result of comparing static balance within each group, in the eyes open, the C90 area and trace length in both the MVF group and the VVF group showed significant decreases after exercise compared to before exercise (p<.05). In the eyes-closed state, the C90 area and trace length in both the MVF group and the VVF group showed significant decreases after exercise compared to before exercise (p<.05) (Table 3).

Table 3.

Result of change of static balance

2) Dynamic balance

As a result of comparing dynamic balance between groups, no significant difference was found in Forward, Rearward, Leftward, and Rightward for both groups.

As a result of comparing static balance within each group, no significant difference was found in Forward, Rearward, Leftward, and Rightward for both groups (Table 4).

Table 4.

Result of change of dynamic balance

Ⅳ. Discussion

Core stabilization exercises maximize the mobility and stability of the spine (Brill and Couzen, 2002). Core stabilization exercises can be applied to patients with various diseases and improve muscle strength, balance, back pain reduction, and walking ability, allowing them to live a better life (Choi et al., 2012). In addition, lumbar stabilization exercises with visual feedback have a correlation with the prevention of back pain and exercise rehabilitation (Yoon & Park, 2020). In this study, 20 college students with LBP in their 20s were divided into the MVF group and the VVF group and they performed a core stabilization exercise program for 30 minutes, three times a week, for four weeks, once face-to-face and twice non-face-to-face, to compare the effects of these visual feedback types on static and dynamic balance.

Ⅴ. Conclusion

This study compared the effects of core stabilization exercises using MVF and VVF on static and dynamic balance in adults in their 20s with mild LBP by applying face-to-face and non-face-to-face methods.

In the results of the comparison of static balance between groups, the C90 area with eyes open in the MVF group was significantly lower than in the VVF group. And the trace length with eyes open and the C90 area and trace length with eyes closed in MVF group was significantly higher than in the VVF group. In the results of comparing static balance within groups, there was significant differences in the C90 area and the Trace length with the eyes open and eyes closed in both MVF group and MVF group. In the result of the comparison of dynamic balance between and within groups, there was no significant difference in either group.

These results suggest that both MVF and VVF through face-to-face and non-face-to-face methods can improve the subject's static balance. And MVF can increase brain interaction and reduce movement errors by providing real-time visual feedback by observing one's own movements. MVF can improve motor performance and be more effective than video visual feedback in increasing static balance of college students with LBP.

Acknowledgments

Funding for this paper was provided by Namseoul University year 2024.

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