Stroke is a disease that is accompanied by various neurological symptoms due to decreased cerebral function due to ischemia or hemorrhage of cerebral blood vessels [1]. Among them, the most prominent symptoms include asymmetrical posture and movement, and difficulties with weight bearing and movement during various movements [2,3]. Additionally, the ability to perform functional activities such as sit-to-stand is limited due to muscle weakness and decreased voluntary control [4]. Most patients suffering from stroke have symptoms of hemiplegia, which causes them to bear a lot of weight on the unaffected lower extremity, which breaks alignment, interferes with efficient muscle activity and weight transfer, and causes a decrease in balance ability [5].

Balance consists of static balance and dynamic balance. Static balance is the ability to maintain the center of gravity within the base of support while standing still, whereas dynamic balance is the ability to maintain the center of gravity within the base of support while shifting onés weight [6]. Asymmetrical problems between the unaffected side and the affected side increase the risk of falls by supporting 80% of the entire body on the unaffected side and reducing stability due to a decrease in balance ability in the standing position [7]. Additionally, motor function and balance are impaired, reducing mobility and causing gait dysfunction [8].

Gait is one of the activities that patients consider most important, and the importance of gait is already well known. Mauritz [9] and Perry [10] reported that stroke patients have impaired joint and muscle control required for normal walking, resulting in shorter step length and slower gait speed. Additionally, it was reported that the proportion of the stepping phase was relatively reduced, and the two-foot support phase was increased due to instability of the affected side [11]. Therefore, walking is one of the most important treatment goals in the rehabilitation of stroke patients.

The sit-to-stand movement of stroke patients is a movement that occurs before various activities of daily living, such as walking and climbing stairs [12], that is an activity that is performed more frequently than walking. Stroke patients perform standing movements abnormally and asymmetrically due to decreased balance and muscle weakness. Even if performed independently, the weight bearing ratio of the affected leg is less than 24-37%, and the muscle mobilization pattern is different from that of normal people [13-15]. As a result, it was reported that falls occur at a high frequency while performing sitting and standing movements [16]. One study found that exercises connecting the trunk and legs improved trunk control and facilitated weight transfer to the lower limbs [17]. Another study reported that weight-bearing exercises on the affected side leg and weight transfer training on both lower limbs enhanced balance control [18]. Based on these findings, it can be concluded that gait and sit-to-stand are closely related.

In a previous study, it was reported that when sit-to-stand training was applied to stroke patients with hemiplegia, balance ability, and muscle strength were improved, and task performance time was shortened [19,20]. A study reported that observing the participants’ center of pressure displayed on a monitor connected to two force plates and watching their training in real-time through a front mirror during sit-to-stand exercises, significantly improved the participants’ lower limb strength, balance, gait, and quality of life [20]. The other study showed that the asymmetry during sit-to-stand tasks in hemiplegic patients is influenced by foot position and that asymmetry can be modified depending on the position of the feet [21]. Kim et al. [22] reported that when patients with hemiplegia perform various activities, wearing a sandbag on the wrist on the affected side is more effective in rehabilitation than performing without it, and the application of the sandbag is incorporated into rehabilitation exercise programs. It was said that it has the potential to be applied in a variety of ways. Park et al. [23] reported that when stroke patients walked on a treadmill with 3 to 5% of the weight applied to the ankle on the affected side, the movement of the center of pressure was improved compared to stroke patients who did not apply weight. Lam et al. [24] proved that using leg weights equivalent to 5% of body weight can enhance functional ambulation. Lee et al. [25] reported that hemiplegia patients who put less weight on the affected leg while performing sit-to-stand activities had lower scores on Functional Independence measurement. It was reported in many studies that the group with weight loading applied to the ankle showed better improvement in gait ability compared to the group without weight loading [25]. Likewise, many studies using sandbags on stroke patients confirmed that they had a positive effect.

Many studies have been conducted on stroke patients using sit-to-stand and affected side weight bearing, and the results of sit-to-stand training for stroke patients have proven to have positive effects on balance and increased weight support on the affected side. While there are various studies on sit-to-stand exercises to improve weight distribution on the affected side, there is a lack of research on performing sit-to-stand exercises with weight loading applied to the affected side.

Therefore, in this study, we compared how the weight load applied to the affected side during sit-to-stand training using a sandbag affected the balance ability and walking ability of stroke patients and investigated their respective effects.

Fig. 1. Study flowchart. EG : sit-to-stand exercise using sandbag on the affected side ankle
CG : sit-to-stand exercise

1. Subjects

The research adhered to the Declaration of Helsinki guidelines and received approval from the Institutional Review Board of Daegu University (IRB no. 1040621-202301-HR-024). The randomized controlled trial was registered with the Clinical Research Information Service under Registration Number KCT0010052. This study was conducted on patients hospitalized after being diagnosed with stroke at D Rehabilitation Hospital in Daegu, Republic of Korea. G-power 3.1.9.7 was used to determine the number of participants for the study. To calculate the number of participants, the effect size of the weight-bearing affected foot (%), a tool for evaluating static balance ability, was taken from a similar type of RCT study. The effect size d was 1.31 [26], the significance level was .05, and the power (1-β error probability) was 95%, resulting in a total of 34 participants. Considering a dropout rate of 20%, the total number of participants was calculated to be 40.

The selection criteria are as follows. (1) A person diagnosed with stroke and suffering from hemiplegia [27], (2) Those with a score of 24 or higher on the Korean Mini-Mental State Examination (MMSE-K) [28], (3) A person who can stand up from a chair independently [27], (4) Those with a lower extremity score of G2 or lower on the Modified Ashworth Scale (MAS), (5) A person who does not have cognitive impairment and can smoothly carry out the therapist's instructions [26], (6) Those who can walk independently [28]. The exclusion criteria are those with diseases other than stroke.

2. Experimental Procedure

Our study followed the Consolidated Standards of Reporting Trials (CONSORT) guidelines [29] and utilized a prospective, single-blinded, controlled, randomized design. The participants were randomly distributed to either the experimental group (EG) or the control group (CG). We collected age, height, weight, gender, type of stroke, and affected side through interviews and a nursing information survey and randomly assigned to each group using www.randmizer.org. Subjects were recruited and classified for 3 weeks. After that, a period of 1 week was assigned pre- and post-intervention. For the EG, a sandbag of 5% of the body weight was applied to the affected side [23]. All groups were trained in 10 sets for 4 weeks, Three times a week, with 15 repetitions in each session [19,28,30]. Two physical therapists with physical therapist licenses carried out the entire process under the supervision of the chief investigator.

3. Intervention

The intervention has modified and revised previous research [19,28,30]. STSS used Template for Intervention Description and Replication (TIDieR) guidelines. The details of the program are described in Table 1. and Fig. 2. below. An international group of experts and stakeholders developed the Template for Intervention Description and Replication (TIDieR) checklist and guide to enhance the completeness of reporting and improve the replicability of interventions. This process included a literature review of relevant checklists and research, a Delphi survey of an international panel of experts to guide item selection, and a face-to-face panel meeting. The resulting TIDieR checklist consists of 12 items (brief name, why, what (materials), what (procedure), who provided, how, where, when and how much, tailoring, modifications, how well (planned), how well (actual)). This checklist is an extension of the CONSORT 2010 statement (item 5) and the SPIRIT 2013 statement (item 11). Although the checklist primarily focuses on trials, it is designed to be applicable across all evaluative study designs. The TIDieR checklist and guide aim to improve the reporting of interventions, assist authors in structuring their intervention descriptions, help reviewers and editors assess the completeness of descriptions, and make it easier for readers to utilize the information [31].

Table 1

details

Intervention Description and Replication (TIDieR) Guidelines
Brief name The STSS program.
Why	To improve balance and gait ability of stroke patients (EG, n = 18).
Materials	Previous study of Sit-to-stand exercise, trained by a therapist, chair, sandbags.
	The STSS program was performed 10 sets, 15 times per set, 3 times a week.
Procedures	Sit-to-stand training: Chairs without armrests and backrest were used, and the height was set according to the patient individual leg length. The angle of the hip joint and knee joint were set to 90 degrees, and about half of the thigh was in contact with the ground. The length of the thigh refers to the length from the greater trochanter of the femur to the joint line of the knee. The position was set so that two feet were comfortably positioned within 15 to 20cm and the person could look at the 3m in front. Both hands were placed lightly on the thighs, and the exercise was conducted while wearing shoes that one normally wears comfortably. Standing up was done at a speed that felt comfortable.
	Sandbag: The experimental group wore sandbags weighing 5% of body weight (Color-coded weight, Preston, USA) on the affected side.
Who	Skilled physical therapist with a license to become a physical therapist.
How	Independent exercise with supervision.
Where	In a treatment room.
How much	10 sets, 15 times per set (including 1 minute break time), 3 times a week for 4 weeks.
Tailoring	Referring to the study of Tung et al. [19], Liu et al. [26], Gray & Culham [27], Roy et al. [31], Rocha et al. [44].
Modifications	Modified and supplemented the study of Park et al. [23].
How planned Actual	Create an engagement record sheet to ensure that the intervention is complete.
	All subjects completed the STSS program.

Fig. 2. Sit-to-stand training using sandbags.

4. Measurement

We used a Gait checker (GhiWell Co., Ltd., Yangju, Republic of Korea) to measure static balance ability. This equipment uses a pressure sensor to measure the pressure between the sole of the foot, the human body, and the support. It collects weight distribution of affected side (%). We conducted the test three times and used the average value as the data.

Timed up and go test was used to measure the subject's dynamic balance ability. This test measures the time it takes to return to the point located 3 meters in front of you after sitting on a chair and then sit down again. The inter-rater reliability of this evaluation tool is r = .98. Intra-rater reliability is r = .99 [32]. We conducted the test three times and used the average value as the data [33].

To collect quantitative gait analysis data on the patient's pattern, GAITRite (CIR Systems Inc., Clifton, NJ, USA), whose reliability and validity for measuring spatiotemporal factors have been established through several studies, was used. It consists of a plate with a length of 5 meters, a height of 0.6 centimeters, and a width of 64 centimeters. Numerous sensors are positioned vertically every 1.27 centimeters. The test-retest reliability if this instrument is ICC = .72 ~ .94D [34]. This instrument collects gait speed (cm/s), cadence (steps/min), step length of the affected side (cm), and step length of the unaffected side (cm). The participants were placed 2 meters from the analyzer and asked to walk at a relaxed pace. We conducted the test three times and used the average value as the data [34].

5. Data analysis

We used the SPSS for Windows version 26.0 (IBM Corp., Armonk, NY, USA) statistical program. All data were described as mean ± standard deviation. A Kolmogorov-Smirnov test was used to test the homogeneity between the EG and the CG, and all data showed a normal distribution. A paired sample t-test was used to compare the results pre- and post-intervention within the group. An independent sample t-test was used to compare the preand post-intervention results between the two groups, and the statistical significance level was set at .05.

Cohens’ d formula was applied to determine the effect size for both within-group and between-group comparisons of the two groups. An effect size d of 0.2 indicates a small effect, 0.5 indicates a medium effect, and 0.8 indicates a large effect [35].

General characteristics consisted of age, height, and weight as shown in Table 2., and there were no significant differences between groups (p > .05).

Table 2

General characteristics (n = 36)

	EG (n = 18)	CG (n = 18)	t	p
Age (year)	61.22 ± 9.83	60.77 ± 6.44	.160	.874
Height (cm)	160.33 ± 5.23	160.38 ± 3.07	-.039	.966
Weight (kg)	60.55 ± 3.98	63.50 ± 5.11	-1.926	.062
Gender (Male/Female)	10/8	8/10
Type (Hemorrhage/Infarction)	5/13	8/10
Affected side (Right/Left)	9/9	9/9

Mean ± SD

EG: sit-to-stand exercise using sandbag on the affected side ankle

CG: sit-to-stand exercise

The results of comparing the weight distribution of the affected side in the EG and CG pre- and post-intervention and the comparison results between the groups are shown in t he t able b elow (Table 3.) . As a r esult of c omparing the EG and CG pre- and post-intervention, there was a significant difference in the results of the comparison preand post-intervention in both groups (p < .05, effect size d = 2.498, 1.383). There was no significant difference when comparing the EG and CG before the intervention (p > .05), but there was a significant difference when comparing the difference values pre- and post-intervention (p < .05).

Table 3

Comparison of balance ability

		Pre	Post	Changes	t	p (d)
Weight distribution (affected side, %)	EG	43.38 ± 1.64	47.49 ± 1.65	4.10 ± .79	-21.853	.000** (2.498)
	CG	44.05 ± 2.12	46.88 ± 1.97	2.83 ± .61	-19.388	.000** (1.383)
	t	-1.051		5.355
	p	.301		.000**
Timed Up and Go test (s)	EG	22.67 ± 5.12	18.33 ± 4.89	-4.34 ± .93	-19.736	.000** (.867)
	CG	22.87 ± 7.20	20.23 ± 6.96	-2.64 ± .78	-14.285	.000** (.373)
	t	-.097		-5.907
	p	.923		.000**

Mean ± SD

EG: sit-to-stand exercise using sandbag on the affected side ankle

CG: sit-to-stand exercise

*p < .05, **p < .001

d: effect size d

The results of comparing the pre- and post-intervention of the EG and CG on the TUG and the results of comparing the measurement values of the TUG between the groups are shown below (Table 3.). As a result of analyzing the TUG, there was a significant difference between the preand post-intervention evaluation results of the EG within the group (p < .05, effect size d = .867), and there were also significant differences between the pre- and post-intervention evaluation results of the CG (p < .05, effect size d = .373). There was no significant difference between the EG and the CG before the intervention (p > .05), but there was a significant difference in the difference values pre- and post-intervention (p < .05).

The results of comparing the step length of the affected side within the EG and CG pre- and post- intervention, and the step length of the affected side between the EG and CG are as follows (Table 4.). There was a significant difference in the step length of the affected side between the EG and CG pre- and post-intervention (p < .05, effect size d = .546, .407). There was no significant difference between the EG and CG before the intervention (p > .05), and there was no significant difference in the difference value after the intervention (p > .05).

Table 4

Comparison of affected side step length (unit: cm)

	Pre	Post	Changes	t	p (d)
EG	34.42 ± 5.36	37.39 ± 5.51	2.97 ± .58	-21.376	.000** (.546)
CG	34.51 ± 6.88	37.25 ± 6.57	2.73 ± .91	-12.767	.000** (.407)
t	-.043		.913
p	.966		.368

Mean ± SD

EG: sit-to-stand exercise using sandbag on the affected side ankle

CG: sit-to-stand exercise

*p < .05, **p < .001

d: effect size d

The results of comparing the step length of the unaffected side within the EG and CG pre- and post-intervention, as well as the step length of the unaffected side between groups, are as follows (Table 5.). There was a significant difference in the step length of the EG and CG pre- and post-intervention (p < .05, effect size d = 1.007, .481). As a result of comparing the step length of the unaffected side between the EG and CG before the intervention, there was no significant difference (p > .05), but there was a significant difference in the difference value after the intervention (p < .05).

Table 5

Comparison of unaffected side step length (unit: cm)

	Pre	Post	Changes	t	p (d)
EG	27.48 ± 7.05	34.51 ± 6.91	7.02 ± 2.16	-13.804	.000** (1.007)
CG	28.12 ± 8.73	32.51 ± 9.50	4.38 ± 2.10	-8.841	.000** (.481)
t	-.239		3.711
p	.812		.001*

Mean ± SD

EG: sit-to-stand exercise using sandbag on the affected side ankle

CG: sit-to-stand exercise

*p < .05, **p < .001

d: effect size d

The results of comparing the gait speed of the EG and CG pre- and post-intervention, as well as the gait speed between groups, are as follows (Table 6.). When comparing gait speed within the groups pre- and post-intervention, there was a significant difference between both the EG and CG (p < .05, effect size d = .329, .332). There was no significant difference in gait speed between the groups before the intervention (p > .05), and there was no significant difference in the difference value after the intervention (p > .05).

Table 6

Comparison of gait speed (unit: cm/s)

	Pre	Post	Changes	t	p (d)
EG	42.60 ± 17.28	48.42 ± 18.08	5.82 ± 3.26	-7.583	.000** (.329)
CG	42.82 ± 14.06	47.47 ± 13.98	4.65 ± 2.53	-7.786	.000** (.332)
t	-.043		1.210
p	.966		.235

Mean ± SD

EG: sit-to-stand exercise using sandbag on the affected side ankle

CG: sit-to-stand exercise

*p < .05, **p < .001

d: effect size d

The results of comparing the cadence between the EG and CG pre- and post-intervention, and the results of comparing the cadence between groups are shown below (Table 7.). When comparing the cadence pre- and post-intervention within both the EG and CG, there was a significant difference (p < .05, effect size d = .262, .266), When comparing the cadence between the two groups before the intervention, there was no significant difference (p > .05), and when comparing the difference values after the intervention, there was no significant difference (p > .05).

Table 7

Comparison of cadence (unit: steps/min)

	Pre	Post	Changes	t	p (d)
EG	71.47 ± 20.06	76.72 ± 19.99	5.24 ± 1.08	-20.501	.000** (.262)
CG	69.45 ± 22.57	75.40 ± 22.21	5.95 ± 1.02	-24.648	.000** (.266)
t	.285		-2.021
p	.778		.051

Mean ± SD

EG: sit-to-stand exercise using sandbag on the affected side ankle

CG: sit-to-stand exercise

*p < .05, **p < .001

d: effect size d

While sandbags could be applied to the wrist and trunk, previous studies have shown that weight loading on the wrist and trunk does not significantly affected side lower limb movement [36]. Therefore, weight loading was applied to the ankle.

Both groups showed a significant increase in the weight distribution of the affected side, which is an evaluation tool for static balance ability. The weight of the sandbag positively influences various activities by increasing foot-floor contact area and providing stability. In a study by Kim et al. [37] patients suffering from hemiplegia due to stroke reported that when they performed various activities while wearing sandbags, the effectiveness of rehabilitation treatment was higher than when they performed without them. It was also said that sandbags have the potential to be used in a variety of ways during the rehabilitation treatment process.

In the TUG conducted to analyze dynamic balance ability, both the EG and CG significantly improved. When comparing the pre-intervention measurement values of the two groups, there was no significant difference, but when comparing the difference values pre- and post-intervention, the EG's measurement values were significantly higher. It is believed that the intervention in this study increased the amount of weight supported on the affected side, thereby reducing asymmetry and improving balance ability, resulting in positive effect. A study by Kim Hyun-seong et al. [38] also reported that the static and dynamic balance abilities of stroke patients were significantly improved due to sit-to-stand training, like in this study. Additionally, given that the five-time sit-to-stand test is an evaluation tool that evaluates lower extremity strength, dynamic balance, and fall risk, sit-to-stand training is considered an effective fall prevention training [39]. Therefore, STSS is recommended for patients at risk of falling.

There were significant differences between the EG and CG in the step length of the affected side, step length of the unaffected side, gait speed, and cadence measured for the gait ability test. This is shown to be due to the increased weight support ratio on the affected side and the improvement in balance ability. The step length of the unaffected side in the EG significantly improved compared to the CG. It is thought that the results in this study were obtained by performing the movement using a strategy of supporting a large amount of body weight on the unaffected side leg. In a study by Lee et al. [40], because of gait training using sandbags, it was reported that the balance and gait ability of the weight-bearing group significantly improved compared to the no-load group and it was effective in improving functional activities. Therefore, the study by Lee et al. [40] supports this study. Additionally, Yang [41] reported that gait training while holding dumbbells in hand or wearing sandbags on ankles increases exercise efficiency and reduces boredom. Auble et al. [42] reported that applying weight load increases the efficiency and intensity of exercise and increases the amount of exercise compared to time. A study by Lee [43] reported that gait training using weight bearing in stroke patients with hemiplegia had a positive effect on temporal and spatial changes in gait ability. In previous studies, various studies were conducted to reduce disuse of the affected side and increase weight distribution by applying weight bearing to the affected side. This study applied the benefits derived from previous research to sit-to-stand exercise. It is thought to be a study that proved that a simple method such as this study can achieve the effect of reducing non-use of the affected side during sit-to-stand training.

In this study, STSS on the affected ankle significantly improved both balance and gait ability compared to the group that performed training without wearing a sandbag. Through research, it has been proven that performing training with a sandbag worn on the ankle of the affected side has a more positive effect on the balance and gait of stroke patients than simply performing sit-to-stand training. It is a good method to enhance the effectiveness of exercise in a simple way without anyonés help by using easily obtainable and inexpensive sandbags. Therefore, it is recommended that patients suffering from hemiplegia due to stroke perform STSS on the affected sidés ankle.

This study has several limitations. First, since the weight load was only applied to the ankle, it was not possible to determine how it would differ if applied to other areas. Second, the sandbag was not used as a weight that fits 5% of the subject's body weight, but an approximate weight was used. Third, although the weight difference between the two groups is not significant, it is substantial enough to potentially act as a variable that could influence the study results. Furthermore, electromyography tests are needed to identify the factors that improved balance and gait abilities. Follow-up evaluations are also necessary to confirm the sustainability of the treatment effects.

This study serves as a foundational resource that addresses these limitations and suggests directions for future research. Future studies should apply various weights to different areas.

The group that performed STSS on the affected ankle significantly improved both balance and gait ability. Through research, it has been proven that performing training with a sandbag worn on the ankle of the affected side has a more positive effect on the balance and gait of stroke patients than simply performing sit-to-stand training. Therefore, it is recommended that patients suffering from hemiplegia due to stroke wear a sandbag on the affected side ankle and perform sit-to-stand training. This intervention is also recommended for individuals at risk of falling.

This study is a summary of Sim Geon-woo’s master’s degree thesis (2023).