Journal 
Ⅰ. Introduction
Low back pain (LBP) is associated with neuromuscular disorders and disabilities in balance and movement. LBP can be a threat to the health system due to its negative impact on occupational conditions or daily activities. In addition, LBP may decrease proprioception due to deterioration of posture and balance ability.
Non-invasive therapies are available for LBP in a multidisciplinary approach to rehabilitation, including exercise (Sherman et al., 2011). However, several methodologies such as strength, endurance, and core training programs available for treating LBP seem to be weak because they ignore pain recognition, behavioral aspects, and knowledge of pain physiology (Gorji et al., 2022). Most of these rehabilitation methods focus only on strengthening spinal muscle, and research on the rehabilitation effects of central nervous system control and balance control is insufficient (Sigrist et al., 2013). Therefore, in LBP rehabilitation, it is important to improve balance ability through proprioception training that focuses on the control of the somatosensory system and the integration of motor output.
Balance or postural control can be defined as the ability to maintain a support base with minimal movement and the ability to perform tasks while maintaining a stable position (Daneshjoo et al., 2012). Balance is achieved through the dynamic integration of internal and external forces and factors related to the environment and regulation of balance depends on visual and proprioceptive sensory stimulation. Proprioception is a major component of the somatosensory system and provides the integration of sensory input, central processing, and motor output for postural control and balance abilities (Han et al., 2014). Proprioceptive deficits could be a potential damaging mechanism of LBP and cause pain through changes in lumbar spine motion (Newcomer et al., 2000).
Visual feedback is a representative stimulus for improving proprioception, and when a complex task is given, the training effect can be maximized according to the propensity (Sigrist et al., 2013). Simultaneous visual feedback favors motor learning because it promotes the automation of motor control (Timmermans et al., 2009). In addition, simultaneous feedback during early learning can prevent cognitive overload and improve learning on complex motor tasks (Wulf & Shea, 2002). Therefore, through visual feedback, it is possible to control the exercise load by itself and reduce the load on the body, thereby preventing damage caused by the exercise (Hides et al., 2008).
Eccentric training or combined concentric and eccentric training produces greater changes in neural activation and greater muscle hypertrophy (Narici et al., 2005). The goal of using eccentric and concentric contraction of training is to provide a sufficiently adjusted mechanical stimulus to overload skeletal muscle (Reeves et al., 2009). In skeletal muscles, this type of training is capable of producing much higher forces when they contract eccentrically compared with when they contract concentrically, in accordance with the force-velocity relation (Macaluso & De Vito, 2004). In relation to this, While many motion systems allow only a single resistance setting, pulley exercise training can efficiently utilize concentric and eccentric contraction using the power of an elastic cable (Nunez et al., 2019). In addition, using reactive forces through cables and pulleys, the intensity of the movement can be controlled by reducing the effects of gravity or by applying a greater load (Y. W. Kim et al., 2018). Because cable or pulley is free to exercise on various joint surfaces, it is also widely used to improve physical functions (Fernandez-Gonzalo et al., 2016).
Based on previous studies, the focus of this study was to investigate whether the efficiency of concentric and eccentric exercise through simultaneous visual feedback stimulation is related to changes in balance ability improvement, moving away from the existing rehabilitation method of LBP, which focused on improving muscle strength. In addition, based on the advantages of previous studies, we intend to investigate the effects on balance ability through visual feedback for proprioceptive enhancement and efficient concentric and eccentric contraction training using pulleys. Therefore, this study established the research purpose based on the hypothesis that there would be a significant change in the static and dynamic balance ability of patients with low back pain through a 4-week concentric and eccentric exercise program utilizing visual feedback.
Ⅱ. Methods
1. participants
In this study, subjects were recruited through the study recruitment notice for patients with LBP living in Yeo-ju city. The criteria for recruiting the subjects included those who had experienced back pain for more than 3 months, those who were not currently being treated for back pain in other rehabilitation institutions, those who perceived pain intensity ranging between mild and moderate (less than 65 mm on the Visual Analog Scale of pain from 0mm to 100mm). The exclusion criteria included those with cognitive impairment, communication, and visual or hearing impairments. In addition, those who have had musculoskeletal surgery in the shoulder or spine, those with a history of trauma, fracture, or presence of scar tissue at the lumbar region, those who is incapable of performing a training program due to a disability in balance ability due to a cause other than back pain, and those who had neurological lesions due to sensory or motor palsy were excluded from this study. Based on the results of Lee et al (2015), the number of subjects was calculated by G*Power analysis with 0.05 type Ⅰ error, 0.774 effect size, and 10% loss rate. A type Ⅰ error is incorrectly concluding that there is a difference when there actually is no difference, and effect size is a numerical value that quantifies how strongly a phenomenon intended for research actually appears. Initially, seventy-one subjects were recruited for the study; however, eleven patients who had surgical experience or had severe pain levels during the screening process and six subjects who withdrew from the study voluntarily during the study were excluded. In total, fifty-four participants were selected as subjects and were randomly assigned to the visual feedback based eccentric pulley training (VF-EPT, n=18) group, the eccentric pulley training (EPT, n=18) group, or the eccentric pulley training (ET, n=18) group. The subjects were comprised of 29 men and 25 women. This study adhered to the Helsinki Declaration principles and was approved by the Institutional Review Board of Sahmyook University (IRB No. 2-7001793-AB-N-012019025HR). All participants provided written consent to participate. The general characteristics of the participants who participated in this study are as follows(Table 1).
Table 1
Characteristics of subjects (N=54)
VF-EPTG : Visual feedback based eccentric pulley training group
EPTG : Eccentric pulley training group
ETG : Eccentric training group
BMI : Body mass index
| Variable | VF-EPTG (n=18) |
EPTG (n=18) |
ETG (n=18) |
χ2/F(p) |
|---|---|---|---|---|
| Gender (male/Female) |
9/9 | 10/8 | 10/8 | 0.146(.930) |
| Age (years) | 19.22±0.55 | 19.22±0.73 | 19.44±0.62 | 0.731(.486) |
| Height (cm) | 166.67±8.30 | 169.67±7.59 | 168.72±6.19 | 1.431(.248) |
| Weight (kg) | 63.61±12.10 | 68.83±14.30 | 73.39±19.47 | 1.771(.180) |
| BMI(㎏/㎡) | 23.01±2.80 | 23.91±4.87 | 25.58±5.62 | 1.460(.242) |
2. outcome measurements
1) Static balance test
As a static balance test, the Single Leg Standing Test (SLST) was used. The SLST is the most commonly used static balance test and was performed because it is easily applicable to patients with LBP (Springer et al., 2007). SLST has high reliability with high intra-clinician reliability (ICC=0.820-0.830) (Schaafsma et al., 2003). The subjects were instructed to stand on one leg and maintain a single-leg position for as long as possible. The SLST measures duration in seconds, with longer holding times indicating superior static balance ability. The measurement was performed on both the dominant and non-dominant leg, with eyes open and then with eyes closed (Kawai et al., 2018). In terms of posture control, the dominant leg refers to the side with superior ability to maintain body stability or control body position in space (Arunee et al., 2023). The arms were crossed to each other on the chest and were instructed not to fall off the trunk. When the feet were lifted off the floor, the testing procedure and time began, and a digital stopwatch was used to measure the time when the feet were lifted off the floor to maintain 90°of hip joint flexion and 90°of knee joint flexion (Chomiak et al., 2015). The measurement was terminated when the raised foot was placed on the floor or the arm was moved or fell off the chest. The test was terminated after a maximum of 60 seconds, and each leg was tested 3 times unless the subject performed perfectly in the previous trials (Saito et al., 2019). During the shift between the legs, participants were provided a rest period. A maximum of three trials was recorded and analyzed (Springer et al., 2007).
2) Dynamic balance test
Dynamic balance ability was measured using a Star Excursion Balance Test (SEBT). SEBT is an easy-to-apply, inexpensive, and reliable tool used to verify balance ability as a means of evaluating dynamic postural control, so it was used because it was applicable to LBP (Ness et al., 2015). SEBT has high reliability with high intra-clinician reliability (ICC=0.860-0.920) (Gribble et al., 2013). SEBT was performed in three directions. By fixing 3 strips of tape in units of 0.5 cm to the floor, a tape was defined as the direction of anterior (ANT) arrival as facing the vertex, and 2 additional strips of tape were fixed to the vertex at 135° (Ness et al., 2015). It was defined as the direction of reaching posterior medial (PM) and posterior lateral (PL). The foot starting position was defined as the anterior boundary of the second toe at the intersection of the three reaching direction lines of SEBT. The starting position of the reach foot was defined as the area next to the posture limb in the weightless posture. Participants had a 2-minute rest period before the official test and included 3 test attempts for each lower limb for each of the ANT, PM, and PL reach directions. The recording of the measurements normalized the excursion distance in each direction by dividing the reach by the participant’s leg length and multiplying the percentage score by 100 (the normalized maximum excursion distance) (Gribble et al., 2013).
3. Experimental procedures
1) Eccentric pulley training device
The eccentric pulley exercise program was conducted using a smart pulley device (Ronfic, Busan, Korea) (Figure 1). This device is freely available for the pulley length and concentric and eccentric resistances can be easily adjusted via electronic pads. The smart pulley evaluation equipment is an exercise equipment capable of training and evaluation with a width of 1.6 meter, a length of 0.8 meter and a height of 2.3 meter. The pulley cable can be extended up to 5 meter in length, and the height of the lever connecting the pulley can be adjusted. The monitor attached to the pulley device was 30 cm wide and 20 cm tall display with a resolution of 1280x720. On the screen that receives visual feedback, the maximum speed, average speed, average force, and maximum force that occur during the exercise were represented in a graph so that the subject can receive real-time feedback for each part and period.
2) Eccentric pulley training program
The 4-week training program was based on 6 exercises: pelvic mobilization (A), trunk rotation (B), squat & trunk rotation (C), single-leg deadlift (D), seated lat pull down (E), and 4-point kneeling reach (F) (Cholewicki & VanVliet, 2002;Ebben, 2009) (Figure 2). The warm-up program performed pelvic mobilization for 5 minutes and the cool-down program consisted of 5 minutes with a 4-point kneeling reach. Trunk rotation, squat & trunk rotation, single-leg deadlift, and seated lat pull down motion were performed for 20 minutes as the main exercise. For six identical exercise, VF-EPT group received visual feedback on his workout on a monitor installed on the front of the exercise machine. However, EPT exercised without looking at the monitor and without visual feedback. On the other hand, the ET group trained the same movements without using pulley exercise equipment. Instead of using a pulley device, the ET group performed the same motion using the theraband. Because of this, the ET group did not receive visual feedback, and the eccentric load was not arbitrarily adjusted. The exercise program was conducted for 30 minutes, 3 times/week, for 4 weeks. Between the training, a 1-minute rest was allowed. The intensity of exercise was established progressive overload exercise was performed based on the 60% maximal voluntary contractions (Robinson et al., 1992). Two sets of 15 sessions were performed per exercise movement within a given time. During the training process, the training manager was present to ensure the safety of the subject, and training was performed after checking the conditions of the subjects to consider the fatigue.
4. Statistical analysis
The SPSS version 21.0 statistical software (IBM, Chicago, IL, USA, 2018) was used to analyze the descriptive statistics and general characteristics. A one-way ANOVA was used to compare the differences between groups regarding the pre and post changes in static and dynamic balance ability after 4 weeks of the exercise program. A post-hoc analysis was performed with the Duncan method. In addition, a homogeneity test was conducted on the measurement results to verify the differences in pre-measurement values for balance ability between groups. A paired t-test was performed to observe for changes before and after the training. All values were presented as the mean and standard deviation. Statistical significance was at p<0.05.
Ⅲ. Results
1. Static balance
The results of the open-eyed and SLST are shown in (Table 2). The results of the open-eyed SLST with lifting the dominant leg of the EPT group decreased significantly four weeks later (p<0.05). However, VF-EPT and ET group were no statistically significant decrease and no statistically significant differences were found between the groups before and after training. When the non-dominant leg lifted, no statistically significant training effect was found in all groups, no difference between groups was found.
The results of closed-eyed SLST are shown in (Table 2). When the dominant and non-dominant leg lifted, no statistically significant training effect was found in all groups, and no significantly difference between groups was found.
Table 2
Comparison of single leg standing balance ability
VF-EPTG : Visual feedback based eccentric pulley training group
EPTG : Eccentric pulley training group
ETG : Eccentric training group
Dom lift : Eye dominant leg lift
Non-dom lift : Eye non-dominant leg lift
| VF-EPTG (n=18) |
EPTG (n=18) |
ETG (n=18) |
F(p) | Effect Size(n2) | |
|---|---|---|---|---|---|
| Open-eyed dom lift (s) | |||||
| pre-test | 53.79±12.50 | 56.84±9.60 | 52.06±14.72 | ||
| post-test | 56.25±8.65 | 48.48±15.69 | 49.43±18.50 | ||
| Post-Pre | 2.46±12.95 | -8.36±14.40 | -2.39±12.51 | 2.982(.060) | 0.10 |
| t(p) | 0.805(.432) | -2.463(.025) | -0.810(.429) | ||
| Effect Size (d) | 0.19 | 0.58 | 0.19 | ||
| Open-eyed non-dom lift (s) | |||||
| pre-test | 57.83±9.19 | 52.53±15.03 | 52.31±17.07 | ||
| post-test | 53.64±12.60 | 45.40±17.59 | 49.43±18.50 | ||
| Post-Pre | -4.19±12.20 | -7.13±20.35 | -3.18±16.32 | 0.274(.762) | 0.01 |
| t(p) | -1.459(.163) | -1.486(.156) | -0.827(.420) | ||
| Effect Size (d) | 0.34 | 0.35 | 0.20 | ||
| Closed–eyed dom lift (s) | |||||
| pre-test | 21.40±15.62 | 20.66±14.93 | 18.71±14.25 | ||
| post-test | 17.80±14.73 | 17.20±15.71 | 20.88±21.21 | ||
| Post-Pre | -3.60±14.61 | -3.46±10.86 | 2.17±14.01 | 1.109(.338) | 0.04 |
| t(p) | -1.046(.310) | -1.350(.195) | 0.657(.520) | ||
| Effect Size (d) | 0.25 | 0.32 | 0.15 | ||
| Closed–eyed non-dom lift (s) | |||||
| pre-test | 19.82±12.25 | 19.31±16.22 | 18.13±18.98 | ||
| post-test | 22.12±16.45 | 15.50±17.09 | 19.42±18.84 | ||
| Post-Pre | 2.30±15.36 | -3.81±17.46 | 1.29±14.33 | 0.776(.465) | 0.03 |
| t(p) | 0.636(.533) | -0.925(.368) | 0.383(.706) | ||
| Effect Size (d) | 0.15 | 0.22 | 0.09 |
2. Dynamic balance
1) Anterior dynamic balance
The results for right leg reaching in the anterior direction values SEBT are shown in (Table 3). The maximum SEBT of statistically significant difference was found in the comparison between groups (p<0.05). As a result of the post hoc test, a difference was observed between the VF-EPT and the EPT group (p<0.05), and VF-EPT and the ET group (p<0.05). In addition, the VF-EPT group increased significantly by 8.81% on the Rt side after training (p<0.05) The EPT and ET group were no significantly changed.
The mean SEBT of statistically significant difference was found in the comparison between groups (p<0.05). As a result of the post hoc test, a difference was observed between the VF-EPT and the EPT group (p<0.05), and the VF-EPT and the ET group (p<0.05). Furthermore, the VF-EPT group increased significantly by 7.57% on the Rt side after training (p<0.05). The EPT group were no significantly changed. The ET group decreased significantly (p<0.05).
The results for left leg reaching in the anterior direction values SEBT are shown in (Table 3). The maximum SEBT of statistically significant difference was found in the comparison between groups (p<0.05). As a result of the post hoc test, a difference was observed between the VF-EPT and the ET group (p<0.05). In addition, the VF-EPT group increased significantly by 12.32% on the Lt side after training (p<0.05) The EPT and ET group were no significantly changed.
The mean SEBT of statistically significant difference was found in the comparison between groups (p<0.05). As a result of the post hoc test, a difference was observed between the VF-EPT and the ET group (p<0.05). Furthermore, the VF-EPT group increased significantly by 7.78% on the Lt side after training (p<0.05). The EPT and ET group were no significantly changed.
Table 3
Comparison of anterior SEBT balance ability
VF-EPTG : Visual feedback based eccentric pulley training group
EPTG : Eccentric pulley training group
ETG : Eccentric training group
ANT : Anterior
Rt : Right
Lt : Left
| VF-EPTG (n=18), (A) |
EPTG (n=18), (B) |
ETG (n=18), (C) |
F(p) post-hoc |
Effect Size(n2) | |
|---|---|---|---|---|---|
| Rt ANT max (%) | |||||
| pre-test | 67.76±10.72 | 69.06±7.75 | 70.06±12.05 | ||
| post-test | 73.73±10.15 | 67.65±9.68 | 66.32±13.43 | ||
| Post-Pre | 5.97±3.55 | -1.41±9.89 | -3.74±8.87 | 7.340(.002) A｜B, C |
0.22 |
| t(p) | 7.128(<.001) | -0.607(.552) | -1.789(.091) | ||
| Effect Size (d) | 1.68 | -0.14 | -0.42 | ||
| Rt ANT mean (%) | |||||
| pre-test | 66.68±11.52 | 66.28±7.98 | 67.63±10.47 | ||
| post-test | 71.73±9.27 | 64.45±9.90 | 62.87±13.12 | ||
| Post-Pre | 5.04±5.18 | -1.83±9.34 | -4.76±8.29 | 7.480(.001) A｜B, C |
0.23 |
| t(p) | 4.128(.001) | -0.829(.418) | -2.437(.026) | ||
| Effect Size | 0.97 | 0.20 | 0.57 | ||
| Lt ANT max (%) | |||||
| pre-test | 66.62±9.99 | 68.08±7.26 | 69.96±10.73 | ||
| post-test | 74.83±9.83 | 67.62±8.58 | 66.83±12.08 | ||
| Post-Pre | 8.21±11.84 | -0.46±9.43 | -3.13±7.42 | 6.687(.003) A, B｜C |
0.21 |
| t(p) | 2.944(.009) | -0.207(.838) | -1.790(.091) | ||
| Effect Size | 0.69 | 0.05 | 0.42 | ||
| Lt ANT mean (%) | |||||
| pre-test | 66.41±10.52 | 64.58±9.07 | 66.81±11.39 | ||
| post-test | 71.58±9.68 | 65.02±8.65 | 63.71±11.04 | ||
| Post-Pre | 5.17±8.91 | 0.44±9.56 | -3.10±8.16 | 3.918(.026) A, B｜C |
0.23 |
| t(p) | 2.462(.025) | 0.195(.847) | -1.613(.125) | ||
| Effect Size | 0.58 | 0.05 | 0.38 |
2) posteriolateral dynamic balance
The results of right leg reaching in the posteriolateral direction SEBT are shown in (Table 4). The maximum SEBT of statistically significant difference was found in the comparison between groups (p<0.05). As a result of the post hoc test, a difference was observed between the VF-EPT and the EPT group (p<0.05), and the VF-EPT and the ET group (p<0.05). In addition, the VF-EPT group increased significantly by 10.74% on the Rt side after training (p<0.05). The EPT and ET group were no significantly changed.
The mean SEBT of statistically significant difference was found in the comparison between groups (p<0.05). As a result of the post hoc test, a difference was observed between the VF-EPT and the EPT group (p<0.05), and the VF-EPT and the ET group (p<0.05). Furthermore, the VF-EPT group increased significantly by 11.99% on the Rt side after training (p<0.05). The EPT and ET group were no significantly changed.
The results of the reaching with the left leg in the posteriolateral direction SEBT are shown in (Table 4). The maximum SEBT of tatistically significant difference was found in the comparison between groups (p<0.05). As a result of the post hoc test, a difference was observed between the VF-EPT and the ET group (p<0.05). In addition, the VF-EPT group increased significantly by 11.92% on the Lt side after training (p<0.05). The EPT group and ET group were no significantly changed.
The mean SEBT of statistically significant difference was found in the comparison between groups (p<0.05). As a result of the post hoc test, a difference was observed between the VF-EPT and the ET group (p<0.05). Furthermore, the VF-EPT group increased significantly by 12.30% on the Lt side after training (p<0.05). The EPT and ET group were no significantly changed.
Table 4
Comparison of posteriolateral SEBT balance ability
VF-EPTG : Visual feedback based eccentric pulley training group
EPTG : Eccentric pulley training group
ETG : Eccentric training group
PL : Posteriolateral
Rt : Right
Lt : Left
| VF-EPTG (n=18), (A) |
EPTG (n=18), (B) |
ETG (n=18), (C) |
F(p) post-hoc |
Effect Size(n2) | |
|---|---|---|---|---|---|
| Rt PL max (%) | |||||
| pre-test | 67.05±10.23 | 69.24±11.96 | 65.62±16.23 | ||
| post-test | 74.25±8.30 | 69.81±12.98 | 67.33±15.51 | ||
| Post-Pre | 7.20±4.90 | 0.57±9.93 | 1.72±9.26 | 3.257(.047) A｜B, C |
0.11 |
| t(p) | 6.237(<.001) | 0.245(.810) | 0.786(.442) | ||
| Effect Size (d) | 1.47 | 0.06 | 0.19 | ||
| Rt PL mean (%) | |||||
| pre-test | 63.62±10.54 | 66.98±11.12 | 63.58±15.45 | ||
| post-test | 71.25±9.01 | 67.95±12.58 | 65.16±15.11 | ||
| Post-Pre | 7.63±5.87 | 0.97±9.49 | 1.59±9.04 | 3.545(.036) A｜B, C |
0.12 |
| t(p) | 5.511(<.001) | 0.433(.670) | 0.745(.466) | ||
| Effect Size (d) | 1.30 | 0.10 | 0.18 | ||
| Lt PL max (%) | |||||
| pre-test | 70.13±12.07 | 68.05±9.52 | 66.77±15.35 | ||
| post-test | 78.49±10.36 | 70.42±11.55 | 68.06±14.87 | ||
| Post-Pre | 8.36±8.74 | 2.37±9.44 | 1.29±10.38 | 3.404(.041) A, B｜C |
0.12 |
| t(p) | 6.179(<.001) | 1.066(.301) | 0.529(.604) | ||
| Effect Size (d) | 1.46 | 0.25 | 0.12 | ||
| Lt PL mean (%) | |||||
| pre-test | 66.69±11.23 | 64.88±11.04 | 64.15±15.27 | ||
| post-test | 74.89±9.13 | 67.17±11.14 | 63.81±14.03 | ||
| Post-Pre | 8.20±10.01 | 2.28±9.66 | -0.34±10.76 | 3.342(.043) A, B｜C |
0.12 |
| t(p) | 3.475(.003) | 1.003(.330) | -0.134(.895) | ||
| Effect Size (d) | 0.82 | 0.24 | 0.03 |
3) posteriomedial dynamic balance
Dynamic balance ability with right leg reaching in the posteriomedial direction of the SEBT are shown in (Table 5). The maximum SEBT of statistically significant difference was found in the comparison between groups (p<0.05). As a result of the post hoc test, a difference was observed between the VF-EPT and the ET group (p<0.05). In addition, the VF-EPT group increased significantly by 9.55% on the Rt side after training (p<0.05). The EPT group and ET group were no significantly changed.
The mean SEBT of statistically significant difference was found in the comparison between groups (p<0.05). As a result of the post hoc test, a difference was observed between the VF-EPT and the ET group (p<0.05). Furthermore, the VF-EPT group increased significantly by 8.86% on the Rt side after training (p<0.05). The EPT and ET group were no significantly changed.
The results of left leg reaching in the posteriomedial direction on the SEBT are shown in (Table 5). The maximum SEBT of statistically significant difference was found in the comparison between groups (p<0.05). As a result of the post hoc test, a difference was observed between the VF-EPT and the ET group (p<0.05). In addition, the VF-EPT group increased significantly by 10.10% on the Lt side after training (p<0.05). The EPT group and ET group were no significantly changed.
The mean SEBT of the VF-EPT group increased significantly by 8.47% on the Lt side after training (p<0.05). The EPT and ET group were no significantly changed and a statistically significant difference was no found in the comparison between groups.
Table 5
Comparison of posteriomedial SEBT balance ability
VF-EPTG : Visual feedback based eccentric pulley training group
EPTG : Eccentric pulley training group
ETG : Eccentric training group
PM : Posteriomedial
Rt : Right
Lt : Left
| VF-EPTG (n=18), (A) |
EPTG (n=18), (B) |
ETG (n=18), (C) |
F(p) post-hoc |
Effect Size(n2) | |
|---|---|---|---|---|---|
| Rt PM max (%) | |||||
| pre-test | 64.70±11.43 | 66.24±11.34 | 62.31±15.32 | ||
| post-test | 70.88±11.11 | 65.71±11.49 | 63.15±13.96 | ||
| Post-Pre | 6.19±3.79 | -0.54±11.11 | 0.84±7.32 | 3.564(.036) A, B｜C |
0.12 |
| t(p) | 6.940(<.001) | -0.204(.841) | 0.488(.632) | ||
| Effect Size (d) | 1.64 | 0.05 | 0.12 | ||
| Rt PM mean (%) | |||||
| pre-test | 61.38±10.29 | 63.85±10.64 | 59.90±14.88 | ||
| post-test | 66.82±9.35 | 63.53±11.65 | 60.17±13.79 | ||
| Post-Pre | 5.45±4.57 | -0.31±9.99 | 0.27±6.87 | 3.234(.048) A, B｜C |
0.11 |
| t(p) | 5.063(<.001) | -0.132(.896) | 0.169(.868) | ||
| Effect Size (d) | 1.19 | 0.03 | 0.04 | ||
| Lt PM max (%) | |||||
| pre-test | 66.76±11.11 | 67.31±9.89 | 65.13±14.35 | ||
| post-test | 73.50±11.33 | 68.38±10.37 | 65.31±12.60 | ||
| Post-Pre | 6.74±4.91 | 1.07±9.40 | 0.18±8.88 | 3.575(.035) A, B｜C |
0.12 |
| t(p) | 5.825(<.001) | 0.483(.635) | 0.087(.932) | ||
| Effect Size (d) | 1.37 | 0.11 | 0.02 | ||
| Lt PM mean (%) | |||||
| pre-test | 63.91±9.97 | 63.66±10.71 | 61.41±14.41 | ||
| post-test | 69.32±9.85 | 65.42±9.79 | 62.26±11.75 | ||
| Post-Pre | 5.41±4.84 | 1.76±9.41 | 0.84±10.18 | 1.457(.243) | 0.05 |
| t(p) | 4.740(<.001) | 0.797(.437) | 0.352(.729) | ||
| Effect Size (d) | 1.12 | 0.19 | 0.08 |
Ⅳ. Discussion
In this study, we tried to confirm changes in static and dynamic balance ability by constructing a proprioceptive sensory-centered training program to improve LBP balance ability through eccentric pulley training using visual feedback. Data analysis revealed no significant changes in static balance for any group. In contrast, dynamic balance demonstrated significant enhancement only in the VF-EPT group, yielding significant differences between the groups.
Balance ability is being able to maintain the center of gravity on the support and plays an important role in various physical and daily activities, as well as in the basic movements of the human body (Sihvonen et al., 2004). Numerous clinical test can be used to confirm the performance of the main types of balance (dynamic anticipatory, reactionary postural control, and static postural control) (Springer et al., 2007). In this study, the dynamic balance ability was confirmed through the SEBT measurement, which can measure the balance ability of LBP patients with high reliability, and the static balance ability was investigated through the SLST measurement. Static balance is trained to enhance stability and dynamic balance is trained for stability-based functionality (Daneshjoo et al., 2012). Dynamic balance places greater demands on balance and neuromuscular control systems (Gribble et al., 2013).
Increasing strength through strength training is not guaranteed to improve balance ability (Zemkova et al., 2017). The comparison of adaptation identified through balance and strength training emphasized that only the balance training group improved postural stability (Granacher et al., 2006). This means that balance ability can be improved by training focused on balance ability including specific elements. The importance of learning to train visual signal and sensory input in the neurologically intact parts of the body has been reported to assist with balance (Sayenko et al., 2010). Furthermore, training experiences that improve joint strength, neuromuscular coordination, proprioception, vision, and range of motion can also be mechanisms to improve balance. This study also confirmed the improvement of dynamic balance ability through selective balance ability training using visual feedback.
Our study results were different according to the dynamic balance ability and the static balance ability. Dynamic balance was assessed using bilateral leg reach tests. The results revealed significant between-group differences in the anterior, posteromedial, and posterolateral directions. Furthermore, a statistically significant post-training improvement was observed exclusively within the visual feedback training group. Previous literature demonstrates that exercise integrated with visual feedback facilitates the restoration of neuromuscular function, proprioception, and kinesthetic awareness in patients with low back pain, while also enhancing refined spinal control mechanisms. This is considered to have clinical significance in that the improvement of proprioception using visual feedback has a positive effect on dynamic balance ability and postural control in LBP.
In a previous study, the dynamic balance ability of stroke patients through visual feedback training was found to be different according to the period, however, dynamic balance ability improved after training (Lee et al., 2015). This can be interpreted that the purpose of visual feedback training is not selective physical training but selective training affected by the exercise program (Cameirao Monica et al., 2012). In addition, in previous studies, it was confirmed that dynamic balance ability improved when exercise rehabilitation including pain neuroscience education was performed on LBP for 8 weeks (Gorji et al., 2022). As a result, balance training in this study improved neuromuscular facilitation, which improved dynamic balance by suppressing spinal reflex excitability, such as muscle stretch reflex and improved agonist-antagonist muscle coordination by dynamic balance improved mechanism.
However, the static balance did not show a statistically significant difference in all evaluations. The fact that there was no change in static balance ability is thought to be because visual feedback has a great effect on dynamic balance ability, and the influence of the construction program implemented in this study was low. In addition, The static balance result is thought to be due to the high average value of the subjects before training.
Our study set the visual feedback-based training period to 4 weeks. This referenced the training period of previous studies to improve balance ability for LBP (Sihvonen et al., 2004). However, the short follow-up period had limitations, and the long-term effects of eccentric pulley exercise using visual feedback on patients with LBP remain to be determined in future studies. The findings of this study have limited generalizability due to the small sample size and the fact that participants were primarily young adults around the age. To enhance the external validity of these results, further research involving a larger cohort of middle-aged patients, who represent a more typical chronic LBP population, is required. However, despite these limitations, it can be used as basic research data to confirm the training effect of eccentric pulley training based on visual feedback by comparing balance ability of the three groups.
Ⅴ. Conclusion
This study investigated the effect of visual feedback-based eccentric pulley training on static and dynamic balance ability in patients with LBP. As a results, the dynamic balance showed to improve due to the impact of visual feedback-based eccentric pulley training. Various rehabilitation training programs need to be developed through the wide application of visual feedback as a therapeutic intervention to restore function in LBP. This study will be useful as basic data for the diversification of rehabilitation methods through the application of specialized visual feedback programs.
