In contemporary society, computers are increasingly used to solve various tasks [1]. Nevertheless, prolonged computer use can lead to musculoskeletal disorders, particularly in the neck, lower back, shoulders, and upper back [2-4]. Hence, appropriate preventative measures are needed to prevent this.

Extended periods of sitting while working can cause frequent neck, upper back, and lower back pain because the position of the monitor and keyboard can affect these areas [5,6]. Incorrect posture leading to lower back pain can result in reduced balance ability compared to those without pain, particularly during challenging movements such as standing on one foot [7]. The pain can persist for years, causing disruptions in daily activities and impairing work efficiency [8]. Previous studies have shown that during computer use, pain occurs sequentially in the upper back, neck, and lower back and worsens with increased duration of usage [9].

Incorrect posture can trigger pain, and improper posture due to computer use can lead to excessive use of the trapezius muscles around the neck. This overuse increases tension in the upper trapezius region. Prolonged improper posture poses a risk of developing musculoskeletal problems [10,1]. In addition, continuous overactivation of the trapezius caused by incorrect posture adversely affects the respiratory function, leading to muscle dysfunction and, ultimately, respiratory impairment. If the issue persists for an extended period, it may develop into chronic pain, which can cause challenges in daily life and breathing [1,11,9].

Stretching is highlighted as a solution to these issues because it helps relax muscle tension, reduce pain, and improve functionality and quality of life [12,13]. Specifically, applying stretching to individuals with lower back pain can reduce pain and improve functionality and quality of life. Chest and lumbar stretching can increase the range of motion, enhancing the functional abilities in daily activities [14-16]. Stretching has been shown to help reduce pain, even in cases of back and neck pain [12,13]. These stretches can reduce acute and chronic pain, possibly related to the pain control mechanism [17].

Pilates methods, including stretching techniques, can significantly increase muscle activation and positively impact balance, flexibility, and cardiorespiratory capacity [18-21]. A study comparing the effectiveness of mat Pilates and equipment-based Pilates reported a similar significant decrease in pain in both groups [22]. A previous study applied equipment-based stretching methods and suggested that equipment-based Pilates could provide faster short-term effects [23].

A review of previous studies found that stretching has positive effects. On the other hand, there is a lack of research on the effects of Pilates stretching using equipment, especially in terms of quantitative data and follow-up studies examining the impact on balance, tension in the upper trapezius muscle, and forced vital capacity (FVC). Moreover, there is a lack of research on the effects of Pilates stretching using equipment, particularly in terms of quantitative data and follow-up studies examining the impact on balance, tension in the upper trapezius muscle, and FVC.

Validating this would demonstrate the clinical feasibility of Pilates equipment and contribute to the development of effective prevention and management strategies for back and spinal health. This study examined the impact of Pilates equipment-based stretching exercises on the balance control ability, tension in the upper trapezius muscle, and FVC in healthy adults.

1. Subjects

The required sample size of the study was calculated to be 14 participants using G*Power 3.1.9.7 (Heine Heinrich University, Düsseldorf, Germany) based on correlation analysis, assuming a significance level (α) of .05, power of .80, and effect size of .6, as per previous studies. Eighteen participants were recruited to account for potential dropout rates during the experiment (Table 1).

Table 1

General subject characteristics (n = 18)

Variable	Mean ± SD
Age (year)	22.00 ± 2.22
Height (cm)	172.56 ± 5.03
Weight (kg)	75.67 ± 14.21

SD, standard deviation

The selection criteria for the study participants are as follows: 1) adults aged 20 and above, 2) individuals without significant impairments in vision or somatosensory perception that could affect the experiment, 3) individuals without abdominal or lower back pain that could influence the experiment during its execution, 4) individuals not taking medication that affects muscle tone and with a BMI > 30kg/m², and 5) right-handed individuals

2. Intervention

This study examined the effects of two stretching devices on back and spine muscles. The first device, the Advanced Split (Motion Care Company, Korea) (Fig. 1), was used to stretch the overall back muscles. The participants performed protraction and retraction movements of the scapula using this device in a supine position. They were instructed to exhale and inhale during the protraction and retraction movements, respectively. The second device used in the study was the Whole-body Spineback (Motion Care Company, Korea) (Fig. 2). The device was applied to stretch the spine and anterior trunk muscles. The participants laid their torso back, inhaled, and, during this process, performed eccentric contraction of the rectus abdominis muscle for five seconds to stably support the spine. After lying flat on the device and arching the spine into a 'C' shape, the patient exhaled and was instructed to slowly rise by contracting the rectus abdominis muscle. Each stretching session consisted of three sets of 12 repetitions, with one minute of rest between sets. The total stretching time was 20 minutes. All exercises were performed after providing detailed training to the participants in advance.

Fig. 1. Spine stretching (A): Starting position (B): Coronal oblique view of the ending position (C): Horizontal view of Ending position.

Fig. 2. Back stretching (A): Starting position (B): Ending position

3. Measures

1) Balance Control Ability

The study used the Tetrax system (Tetrax, Sunlight Medical Ltd., Israel) to evaluate the balance control ability. The system comprised four force transmission plates measuring the variations in vertical pressure originating from the toes and heels, as well as vibrations transmitted to the feet. The participants were assessed barefoot and asked to stand on the device while looking forward to assess the fall risk. The measurements were conducted while maintaining balance in two conditions: eyes open (Eye Open, EO) and eyes closed (Eye Close, EC) for 32 seconds each. Tetrax provided the stability and weight distribution indices. The stability index (ST) measured the degree of posture sway through four force transmission plates located on the front and back of the feet. The weight distribution index refers to the weight distribution of identical plates. Lower values for both indices indicate more stable conditions.

2) Respiratory Volume

The study used a spirometer (Pony FX, A-M System, Italy) to measure the respiratory volume. The device was operated according to the technical specifications outlined by the American Thoracic Society and the European Respiratory Society. The participants wore a nose clip and received training to sit upright during the measurement process. The measurements commenced after ensuring that the participants had understood and practiced sufficiently and had rested adequately. The measurement method involved taking a maximal inhalation followed by a maximal exhalation for six seconds [24]. The measured values of a one-second respiratory volume divided by the total respiratory volume and the total respiratory volume were examined.

3) Myotone

This study evaluated the muscle tension in the left upper trapezius muscle trigger point on the non-dominant side using MyotonPRO (Myoton AS, Estonia). The participants sat in a chair with their hands on their knees and facing forward [25]. The muscle tension was assessed by positioning the probe tip vertically on the trigger point and measuring three times at 15-second intervals to derive the mean value. Five impulses were applied with a force of .4 Newton for each measurement to measure the muscle tone (Hz) [26]. Before the measurement, the most sensitive trigger point on the participant was identified and marked with a non-toxic washable ink pen. A rest period of five minutes was allowed before the measurement to minimize the potential influence of pain from trigger point stimulation on muscle tension assessment.

4. Ethics Approval

The Institutional Bioethics Committee of Sunmoon University approved this study (SM-202311-034-3).

5. Statistical Analysis

SPSS for Windows (version 22.0) was used to analyze the data in this study. The normality was assessed using a normality test. One-way repeated measures analysis of variance (ANOVA) was conducted to determine the differences according to the intervention period (before, after, and follow-up), and a Fisher's LSD (least significant difference) test was used for post-hoc comparisons. The level of statistical significance was set to α = .05.

After stretching, the changes in balance control ability were examined; only significant differences in stability typical eye open (ST_EC) were observed (p < .05). A significant decrease in stretching was observed after compared to before, and a significant difference was also observed between the follow-up and post-exercise values (p < .05, Table 2). This indicates a return to the pre-stretching value in follow-up. Significant differences in the upper trapezius muscle tone and FVC (p < .05) were observed after stretching. Post-stretching resulted in a significant decrease in the upper trapezius muscle tone compared to pre-stretching (p < .05, Table 3). The FVC was significantly higher in the post and follow-up measurements compared to the pre-stretching measurement. Furthermore, a significant difference was observed between the follow-up and post-measurements (p < .05, Table 3).

Table 2

Changes in balance control after stretching

	pre	post	Follow-up	F	p	effect size(η2)
WDI_EO	3.44 ± 1.35	3.79 ± 1.18	3.74 ± 1.47	2.56	.092	.131
WDI_EC	3.79 ± 1.17	4.25 ± 1.05	4.04 ± 1.54	2.23	.115	.060
ST_EO	15.42 ± 2.29	15.93 ± 4.201	5.32 ± 2.87	.26	.770	.015
ST_EC	17.98 ± 3.04b	17.12 ± 2.54ac	17.90 ± 2.11b	3.89	.025*	.100

*p < .05 (Mean ± SD), EO: eye open, EC: eye close, WDI: weight distribution index, ST: stability index, a Statistically different from pre, b Statistically different from post, c Statistically different from Follow-up.

Table 3

Changes in upper trapezius muscle tone and FVC after stretching

	pre	post	Follow-up	F	p	effect size(η2)
Upper Trapezius muscle tone(Hz)	24.89 ± 1.17b	24.32 ± 1.55a	24.48 ± 1.50	4.47	.015*	.113
FVC	4.65 ± 1.41bc	5.12 ± .52a	4.97 ± 1.11a	4.56	.014*	.115

*p < .05 (Mean ± SD), FVC: Forced vital capacity, a Statistically different from pre, b Statistically different from post, c Statistically different from Follow-up.

This study examined the effects of Pilates equipment-based back and spine stretching on the balance control ability, upper trapezius muscle tension, and FVC in adults in their 20s. The evaluations were conducted before, immediately after, and at a follow-up one week later. Regarding the balance control ability, significant results were observed only with the eyes closed (EC) after stretching. Immediately after stretching, a significant decrease in the ST was noted, which returned to the pre-stretching level at the Follow-up one week later.

An increase in ST indicates poorer balance control ability and vice versa [27]. This decrease in ST is consistent with studies reporting that Pilates activates core muscles such as the rectus abdominis, internal oblique, and multifidus, leading to improved core strength and stability. Furthermore, a previous study reported that Pilates could enhance postural alignment, positively impacting balance and stability [28]. Evidence suggests that obstructing visual input enhances the function of other sensory systems, resulting in notable improvements in balance because balance relies on the integration of visual, proprioceptive, and vestibular inputs. For the insignificant post-measurement outcomes, elucidating the correlation regarding post-measurement results is challenging because most studies primarily investigated the short-term effects of stretching. Therefore, one study conducted post-measurements excluding the immediate effects of stretching, but the results were not statistically significant [29]. Based on these findings, stretching may not exert an influence other than immediate effects, aligning with the lack of significant effects observed when comparing outcomes one week later in this study. On the other hand, considering the immediate effects where ST decreased, it can be inferred that balance control ability improved. Hence, incorporating regular stretching routines or combining stretching with strength and balance training may be necessary to maintain these improvements over a longer period. Future studies could examine the long-term effects of such combined interventions to sustain improvements in balance control.

A notable reduction in muscle tension in the upper trapezius was observed after stretching. Although not statistically significant at the one-week follow-up, the values were lower than the pre-intervention measurement. Muscle tension is the tension level in relaxed muscles, defined as the resistance the examiner felt when passively stretching the muscles at rest. This contributes to movement and postural alignment and has been shown to enhance the quality of life [30]. Previous studies have shown that reducing muscle tension and pain can improve the quality of life [12,13].

As muscle tension decreases, pain is relieved and daily comfort is improved. Nevertheless, this is only a temporary stretching effect and does not correct posture, so the pain will likely return within 24 hours [27]. The post-measurements in this study were conducted one week later. During this time, individuals may have maintained incorrect postures in their daily activities, leading to a return to the initial state [1,10]. Considering that muscle tension affects postural alignment, reducing muscle tension during daily activities is likely to have a positive impact on postural alignment.

The FVC was significantly higher after stretching and at the one-week follow-up than the pre-intervention measurement. The increase in FVC observed immediately after stretching was partially maintained even one week later. This result is consistent with previous studies showing that excessive activation of the upper trapezius muscle causes respiratory dysfunction due to the muscle dysfunction [11]. Stretching overactive muscles can lower muscle tension, affecting the breathing rate. In the post-evaluation, muscle tension recovered to a similar level to the initial value but was lower than the initial value. These results suggest that decreased muscle tension affects the respiratory function, and significant changes in total lung capacity can be observed.

According to a report, stretching can increase lung capacity by affecting the maximum force of the primary inspiratory muscle and its associated muscle length [31]. Therefore, stretching is believed to lower muscle tension and affect the muscle length, resulting in a change in total lung capacity. Stretching methods should be considered to improve the respiratory function because they can increase the total lung capacity by allowing the surrounding muscles to expand more than usual through stretching.

The study limitations included a small sample size and a short intervention period, which may affect the generalizability of the findings. In addition, the study only included healthy young adults, limiting the applicability of the results to other populations, such as individuals with musculoskeletal issues related to prolonged computer use, including neck, back, shoulder, and upper body issues. As the use of computers continues to increase with advances in automation and robotics in the workplace, future research will be needed to explore the long-term effects of such interventions in a broader and more diverse population. Studies with larger sample sizes and longer intervention periods, including individuals experiencing musculoskeletal problems from prolonged computer use, will be needed to validate these findings and assess the long-term impact of Pilates-based stretching on balance and musculoskeletal health.

The use of Pilates equipment for stretching the back and spine led to an improvement in the stability index of balance control ability under closed-eye conditions. In addition, a significant decrease in tension in the upper trapezius muscle was noted. A noteworthy enhancement in the FVC was observed, and this increase in lung capacity persisted even after one week. The study results provide evidence and foundational data supporting the relaxation of muscle tension and increased lung capacity through Pilates equipment-based stretching of the back and spine.

This study was supported by the Daegu University, 2023 (Grant No. 2023-0006).

The authors declare no conflicts of interest related to this study.