The effectiveness of core stabilization exercise using ultrasound biofeedback on motor function, balance control, gait speed and activities of daily living in stroke patients

1.Introduction

Stroke is a major global health issue that causes a high death and morbidity rate [1]. Weakness, spasticity, and loss of balance on the hemiparetic side, which impacts activities of daily living (ADL) and the inability to maintain postural alignment, are common challenges associated with stroke [2]. Core instability is a common neuromusculoskeletal system impairment in stroke. During static and dynamic postural changes, the core stability is the primary critical location that enables the body to stay firm and modifies weight shifting [3]. Previous research has reported a decrease in motor function, asymmetry of the trunk during hemiplegic gait, significant weakening, and delayed activation of the gait muscles during gait [4]. Such irregular diaphragm functions may amend the instruction of intra-abdominal pressure (IAP) [5, 6]. This might lead to inadequate postural control and core stabilization during dynamic gait and motor function [6]. Movements such as running, jumping, and lifting impose a huge stress on the spine and cause an increase in intra-abdominal pressure (IAP). It is still unclear what this pressure increase’s purpose is. According to early theories, the pressure inside the belly cavity could help the lumbar spine bear some of its weight. These theories were developed on the theory that pressure created in the abdominal cavity applied a hydrostatic force on the diaphragm and the pelvic floor. It was believed that this force would lessen the spine’s compression force since it increased the spine’s tension and created a trunk extension moment [7]. Maintaining and moving in the standing position, stabilizing the body for everyday tasks, and regaining balance and stability are all possible due to trunk control function [8]. Furthermore, an increase in physical function levels and living quality standards is essential. It reduces their ability to maintain cooperative action, impairs their rib cage movement, and affects their trunk and respiratory muscles’ ability to maintain normal posture [9]. Breathing becomes less effective as a result of the dysfunctional trunk postures caused by the injured trunk muscles [10]. Generally speaking, the deep multifidus and deep abdominal muscles work together to stabilize the trunk [11]. Reduced trunk postural stability impedes stroke patients’ ability to regain their full mobility. Among patients with stroke, one of the best indicators of their functional prognosis is their capacity for unassisted sitting [12]. Frequently employed in a clinical context, the abdominal drawer-in maneuver (ADIM) selectively contracts the rectus abdominis (RA), transverse abdominis (TrA) muscle as well as internal oblique (IO), and external obliques (EO) more quickly than other superficial muscles to support the trunk [13, 14]. To do this, the transversus abdominis must be particularly engaged before the other abdominal muscles are activated. This method is crucial for maintaining the stability of spinal segments. Rather than using diaphragm movement, it is frequently utilized to increase the stability of the lumbar spine and pelvis by rebuilding the TrA and IO muscles [15]. Nevertheless, several laboratory studies have indicated that ADIM may have both positive and negative effects on the spine, potentially influencing the incidence of stroke, according to the existing systematic data [14].

To mitigate the ultrasound biofeedback core exercise (UBCE) in stroke, To transfer energy and produce coordinated force, proximal segment (core) stability must be achieved and connected to the fractured neighboring segment [5]. It has been determined that a noninvasive way to record the morphological characteristics and contraction thickness of muscles is real-time ultrasound biofeedback. It has been widely employed in research as well as therapeutic settings [16]. It has previously been shown that ultrasonic detection techniques are reliable for measuring muscle thickness and contraction [16]. The idea for normalizing the UBCE exercise originated in the field of developmental kinesiology [6]. The synchronized coactivation of the system’s deep and superficial muscles is a key component of the UBCE normalization procedure [9]. During deep inhalation, the deep muscular facilitation specifically involves the co-activation of the diaphragm, TrA-multifidus-pelvic floor as well as IO, and EO muscle, resulting in internal stability by using ultrasound biofeedback [9]. The superficial muscles are facilitated by the external core stabilization force, which is connected to the hip extensor muscles. To be more precise, the theory states that during the inspiration phase, After IAP is naturally generated by the deep core stability muscles (diaphragm-TrA/IO-multifidus-pelvic floor), it is further stabilized by reflexively coactivating the exterior core stabilizers (EO, rectus abdominis; RA, erector spinae; ES) [9]. Furthermore, in response to external perturbations and dynamic motions of the distal extremities section, the integrative internal and external core stabilization forces provide sufficient stability or moving forces in the proximal core segment [11]. However, Despite the important roles and large clinical benefits of the recommended core stabilization strategies, the therapeutic effectiveness and underlying motor control patterns and processes underpinning the UBCE and ADIM in stroke patients remain unknown. Therefore, this study aims to determine the therapeutic effectiveness of UBCE on motor function (Fugl-Meyer assessment; FMA), balance control (Time up and go; TUG), gait speed (10-meter walking test; 10MWT) and ADL (functional independent measure; FIM) in participants with stroke. We hypothesized that UBCE would demonstrate better motor function, balance control, gait speed, and ADL than ADIM.

2.Method

3.Results

4.Discussion

In this study, stroke patients’ motor function, balance control, gait speed, and ADL were examined in relation to the therapeutic benefits of the UBCE. The UBCE group considerably outperformed the ADIM group in terms of motor function, balance control, gait speed, and ADLs, supporting our hypothesis. Significantly, compared to the ADIM group, the UBCE group showed clinically more significant improvements in motor function, balance control, gait speed, and ADL in stroke survivors.

According to FMA analysis, UBCE had a higher impact than ADIM (38.12%), which is consistent with other studies that looked at how UBCE affected stroke patients’ motor abilities. Chen et al. (2020) informed an improved FMA score following 48 sessions of core muscle stability training (23.58%) when compared to the control group in 180 stroke patients with hemiplegia [25]. Park et al (2022) stated an improvement in FMA score in 38 patients with ischemic and hemorrhagic stroke after 48 sessions of core muscle stability exercise with music-combined rehabilitation training (29.81%) compared to conventional rehabilitation exercise combined with trunk muscle control [26]. These results were consistent with previous studies that shown increased co-activation (1.2:1) of the muscle around the trunk during lifting activities in those without symptoms, which is associated with IO-multifidus muscle chain stability [27]. This discovery seems to reprogram UBCE breathing rhythm. Furthermore, it is known that an increase in IAP produces “relative stiffness,” or the control of the spine that is necessary for functional activities. It has been demonstrated that isolated diaphragm contraction, even in the absence of back and abdominal muscle activity, increases IAP and aids in spinal control [27]. During dynamic hip movement, such as in the UBCE, these anterior muscular oblique chains may be counterbalanced by the posterior chain muscles to make the complete spinal segment upright and stabilize the movement of externally (negative) stabilizing forces [27]. The distal section moves on an anatomical foundation from the core. To keep the spine stable, core stability requires the capacity to control trunk motion over the pelvis and legs. It was anticipated that adding core stability would increase stability and enable better force production and control over lower leg movement [28]. However, the patient’s abnormal flexion synergy may be connected to the significant decline in upper extremity function. One of the main things influencing patients’ neuroplasticity and motor rehabilitation is abnormal upper extremity flexion synergy. The daily motor repertoire may include maladaptive strategies as a result of abnormal upper extremity flexion synergy. When trying to improve movement, compensatory movement methods can be exceedingly frustrating for both the patient and the therapist to relearn [29].

Balance analysis demonstrated a superior effect of UBCE (27.48%) compared to ADIM. These results support previous research that examined the balanced clinical effects of UBCE in stroke. Chen et al. (2020) described an improved balance score following 48 sessions of core muscle stability training (32.50%) when compared to the control group of 180 stroke patients with hemiplegia [25]. The capacity to synchronize vestibular organs, muscles, tendons, joints, and visual impulses is known as balance ability. It is the fundamental idea that people should maintain their posture and execute technical moves correctly. After a stroke, aberrant muscle tone, strength, and motor control challenges are caused by disturbances in the motor or sensory pathways, which ultimately lead to balance problems [25]. The ability of people with hemiplegia from brain infarction to walk and perform their everyday activities is dependent on the balancing function. The ability to sustain the same muscle conditions in the trunk and pelvis during an exercise, offer a stable foundation for upper and lower limb movement, and synchronize the force of the two muscles to optimize power production, transfer, and control is known as core stabilization [5]. Core stability exercise may improve the body’s ability to coordinate, communicate, balance, regulate, and integrate the power production of each muscle group [15]. Consequently, scientists have worked to create techniques that would improve core stability and strength. Core stability training has gained a lot of attention in the area of rehabilitative medicine [11]. Patients recovering from strokes may find that core stability training helps them walk and live more independently, which will facilitate their reintegration into society and family [11]. In order to attain an objective that necessitates an upright posture, balance is a complex process that involves the planning and execution of movement as well as the processing and integration of sensory information. Strokes can impact the different postural control systems or the interplay between these systems. The loss of balance following a stroke can be caused by a variety of circumstances, including weakness on one side of the body, loss of sensation in the affected side, especially the leg, brain injury, lack of attention, perceptual issues, vision problems, dizziness or vertigo, and pharmaceutical side effects [30].

Gait speed analysis demonstrated a superior effect of UBCE (20.48%) than ADIM. These results support previous research that inspected the gait speed effectiveness of UBCE in hemiplegic participants. Jung et al (2016) reported an improvement in gait speed after 20 sessions of core stability training (16.09%) compared to a control group in 24 hemiplegic stroke patients [31]. It implies that dynamic balance and gait speed may be enhanced by extra trunk exercises targeted at enhancing rotation of the upper and lower trunk as well as lateral flexion. It suggests that a deficit in any of the core stability exercises distorts the muscle’s capacity to maintain balance and spinal stability, which harms community ambulation [32]. Additionally reinforced by this concept is the conception of the “core” as a box with the abdominals in the front, the diaphragm as the roof, the pelvic floor and hip girdle muscles as the bottom, and the paraspinal and gluteal muscles in the rear [32, 33]. The upper and lower trunks move in unison and opposing directions along the vertical axis during a typical gait cycle. In healthy individuals, the maximum mobility in the frontal plane trunk function is reached at the toe of the sagittal plane trunk function, which peaks near each heel strike [34]. Trunk function is said to be crucial for hemiplegic gait. Muscle imbalance after a stroke significantly changes trunk motions. The trunk deficits are opposite to the extremities and bilateral [35]. During the swing phase, core strengthening enhanced center of gravity transfer and posterior pelvic tilt. It has been established that the transverse abdominis helps the body become ready for contralateral weight redistribution. Research indicates that muscles in the trunk, particularly the multifidus and TrA, contract before muscles in the upper and lower limbs. Additionally, it is thought that this feed-forward activation pattern of the core muscles contributes to more accurate limb control during locomotion and offers a more solid neuromuscular basis for muscular movement [6].

ADL analysis demonstrated a superior effect of UBCE (37.15%) than the ADIM group. These results support a previous study that observed the gait speed effectiveness of UBCE in stroke participants. Haruyama et al. (2016) reported an improvement in ADL function in 32 participants with stroke after 16 sessions of a conventional therapy program with 400 min of core stabilization (25.40%) compared to the traditional physical therapy program alone [37]. In stroke hemiplegia, deep abdominal muscle activity is preserved. Hence, stroke victims can co-contract the trunk’s global muscles while activating their core [37]. Regarding the intervention in this research, The program was created with the primary objective of improving core stability through the activation of the local core muscles [37]. As a result, we discovered that balance and mobility were enhanced by trunk stabilization due to core stability training [37]. This outcome was in parallel with the study by Cabanas-Valdés et al. (2017) on the intervention impact of improved core stability [38]. In contrast to our protocol, their core stability training included workouts of the local core muscles and consisted of bridge, reaching, and selected trunk or pelvic movement activities [39]. Although an intervention effect using core stability training as a supplemental training was requested, our protocol, which engages the local muscles of the core, revealed advantages without further training. Recent studies have shown that progressive programs have an effect and are useful in core stability exercises [34, 35]. As a result, we created a unique progressive program for workouts including core stability. In terms of the protocol content, we sought to create a more targeted protocol than those found in earlier research by choosing a few specific training modalities. Most of the workouts were done while sitting upwards. It is safe and simple to use core stability training in a therapeutic context, and it proved beneficial when upright, and anti-gravity position compared to laying [40, 41]. Several authors have shown that using ultrasound as a biofeedback technique can improve the deep core muscles’ preferential activation in stroke patients. The ability of the lumbar multifidus muscle to contract preferentially was found to be substantially correlated with the muscle’s capacity to recuperate, function, and maintain contraction during a restricted number of treatment sessions [16].

A limitation of this research was its small sample size for both groups due to the complications in employing patients at risk of falling. Consequently, even if the clinical outcome of the measurement data showed encouraging UBCE benefits, doctors should proceed with care when interpreting these results. Another limitation was that the anterior superficial and deep chain muscles and IAP were not measured. Therefore, more study is required to create an advanced sensor and motion magnetic resonance imaging (MRI) in order to accurately detect the motor control of the chain muscles that underlie dynamic hip or limb movement.

5.Conclusion

This study shows that stroke patients in UBCE had better treatment outcomes than those in ADIM. Our unique findings offer encouraging empirical proof that, when it comes to neuromuscular chain control, UBCE-based rehabilitation is more coordinated, balanced, well-moved, and fastened than ADIM. As such, it might be utilized as a substitute exercise for core stability. Important clinical insights on stroke rehabilitation are offered by this research.