search for



Impact of Equine-Assisted Activities and Therapies on Gross Motor Function in Children with Cerebral Palsy: A Prospective Case Series
Korean J Sports Med 2024;42:12-22
Published online March 1, 2024;  https://doi.org/10.5763/kjsm.2024.42.1.12
© 2024 The Korean Society of Sports Medicine.

Su Jong Lee1, So Young Lee1,2, Jun Hwan Choi1,2, Mina Seok1, Sung Wook Song3, Hyun Jung Lee1,2

1Department of Rehabilitation Medicine, Jeju National University Hospital, Jeju, 2Department of Rehabilitation Medicine, Jeju National University College of Medicine, Jeju, 3Department of Emergency Medicine, Jeju National University College of Medicine, Jeju, Korea
Correspondence to: Hyun Jung Lee
Department of Rehabilitation Medicine, Jeju National University Hospital, Jeju National University College of Medicine, 15 Aran 13-gil, Jeju 63241, Korea
Tel: +82-64-717-1670, Fax: +82-64-717-1672, E-mail: sigano@jejunu.ac.kr
Received October 10, 2023; Revised January 4, 2024; Accepted January 23, 2024.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
 Abstract
Purpose: This study aimed to investigate the sustained effects of a 3-week equine-assisted activities and therapies (EAAT) program on motor function and muscle activity in children with cerebral palsy (CP).
Methods: Nine children with CP (aged 5–15 years, Gross Motor Function Classification System stages I–III) participated in the study. We assessed Gross Motor Function Measure-66 (GMFM-66) scores, Pediatric Balance Scale (PBS) scores, BioRescue static posturography (RM Ingenierie) findings, core-muscle activity, and body composition before, immediately after, and 3 months after EAAT.
Results: Of the nine included children, eight showed improvement in their GMFM-66 scores and six showed improvement in their PBS scores. No significant changes were observed in GMFM-66 and PBS scores immediately after the EAAT program compared to baseline. However, significant improvements were noted 3 months after EAAT in both GMFM-66 and PBS scores. Trunk skeletal muscle mass showed a significant increase immediately after EAAT. Balance, stability, and muscle activity during the gait cycle remained stable throughout the study.
Conclusion: This study suggests that a short-period EAAT program can lead to long-term improvements in gross motor function for children with CP.
Keywords : Cerebral palsy, Equine-assisted therapy, Rehabilitation, Postural balance
Introduction

Cerebral palsy (CP) is the most common cause of movement disorders in children, with a prevalence of 2 to 3 per 1,000 live births1. It is characterized by nonprogressive damage to the immature brain, leading to significant motor impairments, including disturbances in movement and posture2. These deficits often result in restricted daily activities, including gait function3.

Currently, neurodevelopmental and task-oriented approaches and robot-assisted walking therapy, are effectively used to treat the motor development of children with CP4,5. However, it is difficult to effectively engage children’s interests, as they are generally more focused on therapists in the treatment room, and they are also averse to repetitive training, which can lead to poor treatment compliance.

Equine-assisted activities and therapies (EAATs) are broad terms that involve any horse-related activities or therapies. EAATs integrate hippotherapy (an integrated therapeutic program) and therapeutic riding (derived from recreational activities). In the EAAT program, the therapist controls the horse to influence the rider’s posture, balance, coordination, strength, and sensorimotor systems, while the rider interacts with the horse and responds to the movement of the horse. Recently, EAATs have attracted attention as an alternative treatment to improve gross motor function in children with CP who have limited opportunities for leisure activities6. While the horse is walking, the child receives many impulses from the horse’s back; the child responds by trying to maintain their position on the horse to avoid falling7. Improvements in gross motor function, posture, lower limb spasticity, asymmetry, and gait function have been reported after EAAT, as well as an increase in core-muscle strength, limb muscle strength, and sense of balance through this process8,9.

However, although several studies have been conducted on the effects of EAAT on gross motor function, most have explored the immediate effects of EAAT10,11, and only a few have comprehensively reported the results of objective analyses, such as measuring balance ability and analyzing muscle activity using surface electromyography (EMG).

Therefore, this study aimed to investigate the effects of the short-term EAAT program on muscle activity, balance ability, and motor function quantitatively and qualitatively in nine cases of CP in children and to understand if their improvements, if any, persist beyond the treatment period. Our preliminary findings suggest the potential benefits of a short-period EAAT program on gross motor function in children with CP.

Methods

This study was approved by the Institutional Review Board and Ethics Committee of the Jeju National University Hospital (No. 2021-05-005-002). Informed consent was obtained from each participant or their guardians.

1. Participants

This study was conducted on nine children with CP who underwent EAAT between July 29, 2021 and August 14, 2021. The inclusion criteria were children aged 5 to 15 years with Gross Motor Function Classification System (GMFCS) stages I to III. The exclusion criteria were chemodenervation, such as Botulinum injection, received within the previous 6 months; selective dorsal rhizotomy performed within the previous 1 year; severe intellectual disability; uncontrolled convulsions; and vision or hearing impairment.

2. Equine-assisted activities and therapies program

EAATs were performed eight times (thrice a week) between July 29, 2021, and August 14, 2021. Between the first and second sessions, the participants handled the horses, including touching, feeding, grooming, and understanding how to approach the horses. Between the third and eighth sessions, the children rode the horses and learned basic riding postures, including actions such as starting and stopping, changing direction, turning, and navigating obstacles. In the program, the riding time per round was 30 minutes in total, and for the first 5 minutes after riding, a brief warm-up exercise was conducted, and time was allocated to interact with the horse. Five minutes before the end, a simple finishing exercise was performed while riding. Throughout the EAAT program, the guardian closely observed if the program was going well. If participants felt uncomfortable or were reluctant to participate in the EAAT, the program was discontinued with the guardian’s consent. Events such as a fall or unexpected outcomes were immediately reported to the persons in charge of this study.

3. Outcome measures

1) Gross Motor Function

The Gross Motor Function Measure (GMFM)—which has subsequent GMFM-88 and GMFM-66 versions12—is the most common evaluation tool to measure gross motor function over time for children aged 5 months to 16 years with disabilities. The GMFM-66 is a revised version of the GMFM-88 that uses Rasch analysis; in total, 22 of the original 88 items in the GMFM-88 were deleted to improve reliability and validity13.

2) Balance

The Pediatric Balance Scale (PBS) was used to evaluate balance ability. The PBS is a modified version of the Berg Balance Scale intended for pediatric use and has been proven effective in children with CP. It comprises 14 items, each scored on a scale of 0 to 4, with a maximum score of 5614.

To evaluate balance objectively, we utilized BioRescue static posturography (RM Ingenierie). This method has been used in previous studies on children with CP to measure various parameters of balance15,16. It provides excellent inter-rater and intra-rater reliability, especially in footprint area measurements17. During testing, children stood barefoot on the BioRescue force plate and the vertical pressure fluctuations in the heel and toes of both feet were measured. Balance ability was quantitatively calculated by obtaining weight distribution indices using BioRescue.

The weight distribution index (WDI) was maintained barefoot on the force plate. The pressure and surface area in contact with the foot were obtained from the left and right sides, and the ratio was determined by dividing the smaller value by the larger value. In cases of participants who required assistance while standing, the test was conducted by holding a bar mounted on the BioRescue system. The test was performed for 1 minute with eyes open and subsequently for 1 minute with eyes closed. An ideal state was considered when the child’s weight was evenly distributed on both sides and the WDI value was set to 1.

The limit of stability, which is an index of balance ability, was evaluated thereafter. The body was moved as far as possible in the direction of the arrow shown on a screen without moving the feet. Subsequently, when the arrow disappeared from the monitor, the body was moved back to its original position in preparation for the next balance exercise, also dictated by an arrow’s direction. Because each arrow’s direction was set differently, the area value for each direction was obtained. This enabled the investigation of the sectorization of balance problems regarding the original weight-bearing positions. Using the area values for each direction, the numerical values between each were calculated by dividing the smaller values by the larger values; this was done for the left and right and for the front and rear sides. The values of a limit of stability (left/right and front/back) indicate that the dynamic balance is equal on left/right and front/back when the value is 1. Values close to 1.0 indicate improved dynamic balance.

Lastly, stabilization capacity was evaluated to assess the ability to maintain postural and kinetic aptitude. The participant stood with both feet on the BioRescue force plate for 1 minutes, with eyes opened, to determine how the center of pressure shifted. The exercise was repeated with the participant’s eyes closed to assess how the center of pressure shifted under those conditions. The higher the stabilization capacity index, the more unstable the posture.

3) Surface electromyography

Surface EMG was performed to monitor changes in the activity of core muscles during the gait cycle, providing an objective measure of motor function changes in response to the EAAT in children with CP. Surface EMG allows for the most reliable assessment of muscle activation, as the magnitude values obtained from peak root mean square (RMS) are directly related to this factor18. Surface EMG was performed using a portable wireless eight-channel surface electromyograph–FREEEMG (BTS Bioengineering). The peak RMS of the bilateral paraspinal muscles at the L2 level, external oblique anterior, rectus femoris, and semi-tendinosus muscles was obtained through surface EMG during a single gait cycle. The motor points of the muscles were identified for electrode attachment, and the skin was cleaned with 70% alcohol to reduce bioimpedance. Data were analyzed and processed using SMART ANALYZER (BTS Bioengineering) and central core SMART DX (BTS Bioengineering).

4) Muscle mass and body fat measurements

Total skeletal muscle mass, trunk skeletal muscle mass, and body fat mass were calculated using a body water meter (BWA 2.0; InBody Co., Ltd.). All evaluations were conducted before and within 1 to 2 months and 12 to 13 weeks after EAAT.

A well-trained physical therapist evaluated GMFM-66 scores, PBS scores, and BioRescue static posturography data, and a clinical technician evaluated surface EMG, muscle mass, and body fat measures. As the evaluator did not have access to the participants’ information, bias that may have occurred during the evaluation was minimized.

The collected data remained secure by allowing access only to the principal researcher. The computer used was password-protected to increase security.

4. Sample size

The sample size of nine participants was chosen based on the feasibility and availability of eligible individuals. The intent is to provide a descriptive and exploratory analysis of the intervention’s effects, acknowledging the limitations of generalizing from a small, non-random sample.

5. Statistical analyses

The children’s age, sex, height, weight, body mass index (BMI), type of CP, number of paralyzed sides, and GMFCS level were identified. Descriptive statistics were employed to detail individual changes over time. Furthermore, Supplementary Tables 1 and 2 have been included to provide additional detailed analyses, offering a comprehensive view of the data. The Wilcoxon signed-rank test was performed to compare the peak amplitude values of the GMFM-66 and PBS scores, WDI, surface EMG data, skeletal muscle mass, and body fat mass before and at 1–2 and 3 months after the EAAT program. A p-value of <0.05 indicated statistical significance. All statistical analyses were performed using STATA version 14 (Stata Corp.).

Results

Table 1 shows the baseline characteristics of the participants in this study, including six boys and three girls with ages ranging from 6 to 14 years. All nine participants had spastic CP; the three participants had unilateral paralysis, while six had bilateral paralysis. Four, three, and two participants had I, II, and III GMFCS stages, respectively.

Table 1 . Baseline characteristics of study participants

Case No.Age (yr)SexHeight (cm)Weight (kg)BMI (kg/m2)Type of CPParalyzed sideGMFCS
111Male1425326.28SpasticBilateral2
29Female1323721.24SpasticUnilateral1
314Male1705619.38SpasticUnilateral2
414Male1516126.75SpasticBilateral1
59Male1384624.15SpasticUnilateral1
68Female1142317.70SpasticBilateral3
76Male1112318.67SpasticBilateral2
811Male1303520.71SpasticBilateral3
98Female1262717.01SpasticBilateral1

BMI: body mass index, CP: cerebral palsy, GMFCS: Gross Motor Function Classification System.



Table 2 shows the GMFM-66 and PBS scores at baseline, immediately after the EAAT, and 3 months after the EAAT. The mean (standard deviation) GMFM-66 score was 70.556 (13.693), and the mean PBS score was 41.667 (16.454) at baseline. Case 9 was the only child whose GMFM-66 score decreased 3 months after EAAT compared to baseline. The rest of the children showed improvement in their scores in the 3 months after EAAT compared to baseline. In Case 3, there was no change in PBS scores at baseline, after EAAT, and 3 months after EAAT. In Cases 5 and 9, the PBS score was confirmed to decrease 3 months after EAAT compared to baseline. In Case 9, both GMFM-66 and PBS scores were observed to decrease. Case 5 showed the most improvement in the GMFM-66 score, and Case 1 showed the most improvement in the PBS score.

Table 2 . Motor function and balance ability measures at baseline, after EAAT, and 3 months after EAAT

Case No.GMFM-66PBS
BaselineAfter EAAT3 mo after EAATBaselineAfter EAAT3 mo after EAAT
159.659.160.9333738
288.089.792.1555556
389.781.992.1565656
477.580.080.9535455
576.080.084.0535252
654.155.956.9192023
765.666.067.4424545
852.353.653.671011
972.271.270.4504649

EAAT: equine-assisted activities and therapies, GMFM-66: Gross Motor Function Measure 66, PBS: Pediatric Balance Scale.



Table 3 summarizes the balance and stability values measured using the BioRescue system at baseline, immediately after the EAAT, and 3 months after the EAAT. Cases 1 and 6 showed signs of anxiety about using the BioRescue system; hence, they held the bar attached to the BioRescue system and performed the examination. Case 4 felt anxious only in the test that required their eyes to be closed; hence, they performed the examination while holding a bar and with their eyes closed. Cases 7 and 8 showed poor cooperation and anxiety; hence, the entire BioRescue examination was conducted with the examiner’s assistance, and the limit of stability test could not be performed. No statistically significant changes were observed in the balance and stability values in the Wilcoxon signed-rank test analysis (Supplementary Table 1).

Table 3 . Comparison of quantitative balance and stability function measures at baseline, after EAAT, and 3 months after EAAT

Case No.MeasurementWDI-area, eye openedWDI-area, eye closedLimit of stability, total surface areaStabilization capacity
Surface area with eye openSurface area with eye closedLength with eye openLength with eye closed
1Baseline0.9910.9123,3304,1927,022207.0178.2
After EAAT0.9761.000NT2,833388144.645.8
3 mo after0.9320.953NT6,1576,387171.6182.1
2Baseline0.8040.9172,2464125440.957.7
After EAAT0.8000.9171,62321831152.270.0
3 mo after0.9340.9257,504976738.041.4
3Baseline0.8350.79319,4517719036.338.0
After EAAT0.9740.87214,31411419535.841.5
3 mo after0.9680.92919,0709011636.429.2
4Baseline0.6850.6853,60120215628.423.6
After EAAT0.7960.7664,41717914934.422.4
3 mo after0.8210.7728,4262,928273201.943.8
5Baseline0.8210.6894,14649615158.155.2
After EAAT0.9330.9092,53224667253.6109.9
3 mo after0.8670.8243,2944232,16256.090.1
6Baseline0.8500.8766,3061,36936183.841.2
After EAAT0.7100.6423,07736023648.350.9
3 mo after0.8150.7951,7828010634.838.0
7Baseline1.0590.960NT6,3474,022245.2242.9
After EAAT0.9440.942NT2,4782,315179.9227.8
3 mo after0.9740.949NT5,91413,367320.4497.4
8Baseline1.0000.9551,121638230.729.5
After EAAT0.9550.9762,650683726.627.6
3 mo after0.9530.9241,10610317034.044.3
9Baseline0.8930.9578,9811,0031,154105.6135.9
After EAAT0.9300.9646,5451,7322,110142.5171.3
3 mo after0.9050.9795,7213,3922,216168.5185.8

EAAT: equine-assisted activities and therapies, WDI: weight distribution index, NT: not tested.



Table 4 summarizes the values of peak RMS applied to the bilateral paraspinal muscle, external oblique anterior muscle, rectus femoris, and semitendinosus during the gait cycle at baseline, immediately after the EAAT, and 3 months after the EAAT. Case 1 could not undergo surface EMG because of poor cooperation; thus, the results were analyzed using data of eight participants. No statistically significant changes were observed in the Wilcoxon signed-rank test analysis (Supplementary Table 2).

Table 4 . Comparison of peak RMS of core muscles during the gait cycle at baseline, after EAAT, and 3 months after EAAT

Case No.MeasurementPRMF-LstPRMF-LswPLMF-RstPLMF-RswPREOA-LstPREOA-LswPLEOA-RstPLEOA-RswPRRF-LstPRRF-LswPLRF-RstPLRF-RswPRST-LstPRST-LswPLST-RstPLST-Rsw
1BaselineNTNTNTNTNTNTNTNTNTNTNTNTNTNTNTNT
After EAAT36.98611.35738.94324.31543.76810.92628.22226.02337.87521.32437.58928.23025.23321.55015.2010.101
3 mo after35.17114.23928.68914.62712.33413.84121.96919.71747.46020.21927.99026.46668.8823.58042.00334.482
2Baseline45.50025.98045.78517.95934.33818.83996.11334.30255.51840.20373.34858.15763.42438.8130.0040.002
After EAAT27.52613.52255.63356.84533.51530.85062.77921.05754.43724.17344.22625.932118.98569.293294.34185.750
3 mo after51.85840.22351.51878.16576.54671.16864.39764.39762.89453.20195.193155.336159.78104.603153.83980.275
3Baseline39.22916.64549.10035.26791.50766.44972.146100.300172.64625.02328.88910.90951.92846.32069.14461.973
After EAAT37.64512.02128.92113.01449.88240.76440.91756.37941.44617.35935.03611.20254.67535.148123.14456.203
3 mo after44.88612.23335.90113.18839.92634.11768.35168.89879.53526.26037.24921.94528.09421.47755.30825.714
4Baseline34.48919.14723.73919.39316.5649.97025.26020.16676.47184.47232.15729.22526.4530.2320.0030.002
After EAAT24.79020.58522.04215.07212.15313.70315.38914.05721.58322.53829.94215.82251.60329.27271.68031.701
3 mo after22.98418.00730.47620.8329.8499.97523.84319.34330.71915.71919.93812.43851.87333.63138.78122.443
5Baseline28.69634.12553.67116.47761.56520.33935.31414.42634.80213.56754.66919.53895.732151.013153.726135.342
After EAAT33.81416.64143.99819.45063.38832.939113.503117.78437.38818.95837.61412.65276.60757.74485.53863.107
3 mo after58.16739.13545.38738.01242.25521.90818.65721.90573.12242.06958.56427.862147.09352.108181.87991.342
6Baseline72.32825.02459.75727.22228.36422.90148.27217.46120.46621.00426.73413.658184.642158.509161.530167.254
After EAAT84.13534.76783.46031.93332.85418.07654.14227.117255.73967.89630.65534.247211.988150.802176.339159.037
3 mo after78.43122.52173.18034.03833.59515.83161.56324.24118.61317.95544.89315.034139.57183.392125.64497.542
7Baseline67.32998.415106.29399.59948.50934.20138.93139.95536.56929.65717.05513.363107.82340.984170.285108.713
After EAAT147.55065.79698.29583.042104.123111.77268.19456.203149.84846.48659.79350.079172.339143.499151.014153.960
3 mo after118.01488.878120.307120.30748.13734.893135.30587.76267.92814.68733.93622.703128.18107.43370.01379.416
8Baseline63.18016.82259.67540.95227.22318.27036.65835.03190.44597.06097.98198.34748.54627.83927.20130.520
After EAAT50.05528.20686.026108.03146.69522.63693.536128.90684.44489.360134.452161.288100.87759.919108.163119.059
3 mo after47.81722.48967.87466.60966.84336.159290.34928.406170.33655.790137.24196.53460.52847.66290.39298.143
9Baseline98.56629.949108.098140.490108.00345.47342.34752.516221.07545.807115.93849.525212.64490.781397.178233.190
After EAAT110.37442.97992.70575.80971.22931.94537.83448.082125.41340.282196.27344.259148.574120.620269.434230.691
3 mo after46.5035.7440.0090.00334.47719.10277.53847.70678.73513.42972.37025.049306.242147.982393.286234.244

RMS: root mean square, EAAT: equine-assisted activities and therapies, PRMF: peak RMS right multifidus, Lst: left stance, Lsw: left swing, PLMF: peak RMS left multifidus, Rst: right stance, Rsw: right swing, PREOA: peak RMS right external oblique anterior, PLEOA: peak RMS left external oblique anterior, PRRF: peak RMS right rectus femoris, PLRF: peak RMS left rectus femoris, PRST: peak RMS right semitendinosus, PLST: peak RMS left semitendinosus, NT: not tested.



Table 5 shows the skeletal muscle, trunk skeletal muscle, and body fat values at baseline, immediately after the EAAT, and 3 months after the EAAT. Case 3 had the highest skeletal muscle and trunk skeletal muscle values in the entire period. Case 4 had the highest body fat value in the entire period. Cases 5 and 8 showed increased trunk skeletal muscle values immediately after the EAAT.

Table 5 . Comparison of skeletal muscle and body fat values at baseline, after EAAT, and 3 months after EAAT

Case No.MeasurementSkeletal muscle (kg)Trunk skeletal muscle (kg)Body fat (%)
1Baseline17.216.120.4
After EAAT16.615.621.4
3 mo after17.016.020.9
2Baseline11.811.113.6
After EAAT11.710.413.5
3 mo after12.710.913.7
3Baseline28.222.46.5
After EAAT27.921.95.9
3 mo after28.521.49.5
4Baseline20.117.023.5
After EAAT20.316.623.1
3 mo after21.217.722.6
5Baseline14.812.417.5
After EAAT13.812.719.5
3 mo after13.912.620.1
6Baseline8.17.66.4
After EAAT8.17.66.0
3 mo after8.78.26.1
7Baseline6.38.19.2
After EAAT8.87.54.7
3 mo after7.27.09.2
8Baseline11.110.812.6
After EAAT11.010.912.8
3 mo after10.810.815.0
9Baseline9.89.16.8
After EAAT9.68.87.3
3 mo after9.89.08.9

EAAT: equine-assisted activities and therapies.


Discussion

This study investigated whether short-term EAAT had immediate effects as well as lasting effects on motor function in nine children with CP. After 3 months of EAAT, an increase in GMFM-66 scores was observed in eight cases, and an increase in PBS scores was seen in six cases, suggesting potential long-term improvements in gross motor and balance functions due to intensive, short-term EAAT.

While most participants showed improvement, Case 9 showed a decline in scores on GMFM, and Cases 4 and 9 showed a decline in scores on PBS at 3 months after EAAT; these score reductions were not large in magnitude. The children who showed a decrease in their scores had relatively good function with GMFCS 1 to 2 at baseline. Feelings of irritation and the lack of motivation during evaluation can greatly affect the results in children; in some children, evaluation was performed after other physical therapy, which may have affected the results.

Previous research has also reported improvements in gross motor function after EAAT. For instance, studies have found increased GMFM-66 scores after 16 EAAT sessions spread over 8 weeks. These studies had the advantage of consistent treatment schedules and control group comparisons10,11. The expected physical effects of the EAAT that would have led to improvement in gross motor function are as follows: rhythmic body movement through horseback riding, torso coordination in response to the movement of the horse that encourages appropriate participant balance and posture, and a wide spectrum of sensory and motor stimuli provided by the horses19,20. The slow, rhythmic movement of the horse promotes the development of the child’s paraspinal muscles, and the multifaceted swinging rhythm of the horse improves the child’s pelvic girdle. These promote the typical pelvis movements that occur during normal walking. Moreover, the EAATs have an entertaining effect and promote treatment compliance, resulting in improved participant balance, mobility, and posture21-24.

Conversely, studies by Žalienė et al.23 and Davis et al.24 did not report consistent improvements in motor function after EAAT, possibly owing to inconsistent treatment durations among participants and the absence of a control group. Additionally, the 1-week gap between EAAT sessions in these studies may have been too long to provide improvements in muscle strength or balance23,24. In particular, the study of Žalienė et al.23, similar to ours, involved an intensive EAAT program over a short-term period (10 sessions in 2 weeks) for the beginner group. Similar to our study, their study did not show immediate improvement in gross motor function.

Most previous studies have compared the effects before and immediately after the EAAT10,11,23-25. Unlike previous studies focusing on immediate posttreatment effects, our study contributes new insights into the long-term impacts of EAAT, an aspect not extensively explored before.

Although caution is needed in interpreting the results owing to the small sample size inherent to a case series, this study demonstrated improvements in gross motor function in more than half of the cases, allowing for the consideration of several reasons underlying the long-term effects of such short-term, intensive EAAT. Through the EAAT, core-muscle engagement gradually increased in participants, and the amount of movement in daily life increased; this appears to be a long-term effect, as it was observed 3 months after the EAAT. Improved self-confidence is also thought to be a long-term effect of the EAAT. This increase in self-confidence triggers a child’s willingness to explore and learn new motor activities. To confirm these suppositions, it is important to develop a method to quantitatively assess the physical activity of participants with CP both during and after the EAAT using a wearable device such as a smartwatch.

During the riding time, lateral flexion, extension, and rotation occur in the participants’ back, which reduce the spasticity of the back, pelvis, and lower limbs8,23,25 and can also improve energy expenditure26 and muscle symmetry8. Lower limb spasticity and thigh adductors’ asymmetry cause a lack of pelvic and trunk dissociation. Therefore, this improvement is meaningful, as it reduces the strength imbalance and disturbance of the torso muscles23. Accordingly, gross motor function is expected to improve even after 3 months of the EAAT in children with CP.

When performing the BioRescue examination, some participants required assistance, such as holding the examiner’s hands or a bar attached to the BioRescue equipment, owing to feelings of anxiety and fear of falling. This inconsistency in providing assistance was considered a limitation, as it was not uniformly applied to all patients, and might have led to a lack of consistency in the BioRescue test results, warranting greater caution in their interpretation. However, the observed increase in PBS scores in many children suggests that more substantial and significant results could be achieved in more quantitative tests like the BioRescue, particularly in future studies with a larger sample size. In addition, as reported in a previous study27, the number and duration of EAAT sessions in this study might not have been sufficient to achieve statistical significance. This highlights the importance of considering session frequency and duration in future EAAT research to fully assess its effectiveness.

Muscle activity, as measured through surface EMG, did not demonstrate a consistent increasing or decreasing trend. Notably, one child was unable to undergo the test, and even when the Wilcoxon analysis was conducted on data from the remaining eight participants, no significant results were obtained (Supplementary Table 2). Previous studies23,28,29 have reported inconsistent results regarding whether the EAAT improves muscle strength and gait parameters. This inconsistency may partly stem from the inherent limitations of using surface EMG for measuring balance and stability. The variability in attachment sites and the method’s poor repeatability can lead to challenges in drawing precise comparisons and firm conclusions about real improvements in balance, particularly in a longitudinal study design. These factors underline the complexity of assessing the true impact of EAAT on muscle activity and balance over time.

The observed changes in skeletal muscle and body fat following EAAT, as shown in Table 5, provide interesting insights, albeit without statistical significance. As with previous research on the neuromuscular effects of EAAT30, we observed a tendency for both skeletal muscle and body fat levels to increase after EAAT. However, these changes did not reach statistical significance across all cases (Supplementary Table 3). This absence of significant findings may be due to the small sample size, underscoring the necessity for larger-scale studies.

This study has some limitations. First, the sample size was small. Although the GMFM-66 score was set as the primary outcome at the research planning stage, and the sample size was calculated to recruit an adequate number of participants, this seemed insufficient to obtain significant results for the secondary outcomes, including the balance index, stability index, muscle activities, and muscle amount. Second, the inclusion of participants receiving other treatments introduces potential confounding factors that may impact the interpretation of the effectiveness of the EAAT. Third, owing to the small sample size, it was impossible to analyze subgroups according to the GMFCS stage and age. Children with originally good GMFCS stages may benefit more from the EAAT, even if they are of the same spastic type9,14, and younger children have a higher potential for improvement than older children14. There was no control group to compare the effectiveness of the EAAT with conventional treatment. Future studies might benefit from the inclusion of larger and more diverse cohorts to validate these preliminary findings and explore subgroup responses more thoroughly. Fourth, in the EAAT, each horse’s movement, communication between children and horses, children’s adaptability, and horses’ adaptability are different, affecting the treatment effect on children. However, these traits are difficult to control, as they are distinct to each individual and horse. To address this limitation, comparing EAAT, horse-simulator exercise, and general treatment control groups may determine which treatment is more effective for gross motor function. Lastly, the technical challenges with surface EMG, such as variable electrode placement, highlight the need for more standardized methods to ensure the reliability of muscle-activity measurements.

Nevertheless, the strength of this study is that objective results were obtained by quantitatively analyzing surface muscle activity, balance, and muscle mass and evaluating the GMFM-66 and PBS scores in children with CP. Moreover, as the function and objective indicators 3 months after the end of treatment were presented, it demonstrated that the effect of the EAAT could be helpful in the long term. While a case series provides preliminary insights rather than conclusive evidence, this case series serves as a valuable starting point for exploring the effects of EAAT. To build on these findings, future studies should consider larger and more diverse cohorts and should incorporate randomized control groups.

In conclusion, our preliminary findings suggest that short-term EAAT might have potential as an intervention for long-term motor improvement in children with CP. Further researches with larger sample sizes and more diverse cohorts are needed to validate these results.

Supplementary Materials

Supplementary Materials can be found at https://doi.org/10.5763/kjsm.2024.42.1.12.

kjsm-42-1-12-supple.pdf
Acknowledgments

This work was supported by a research grant from Jeju National University Hospital (Jeju, Korea) in 2021. The funding body had no involvement in the study design; collection, management, analysis, and interpretation of data; or the decision to submit for publication.

Conflict of Interest

No potential conflict of interest relevant to this article was reported.

Author Contributions

Conceptualization, Funding acquisition: HJL. Methodology: HJL, SWS. Formal analysis: SJL, SWS, HJL. Project administration: all authors. Visualization: SWS, MSS. Writing–original draft: SJL HJL. Writing–review & editing: all authors.

References
  1. Surveillance of Cerebral Palsy in Europe. Surveillance of cerebral palsy in Europe: a collaboration of cerebral palsy surveys and registers. Surveillance of Cerebral Palsy in Europe (SCPE). Dev Med Child Neurol 2000;42:816-24.
    CrossRef
  2. Bax M, Goldstein M, Rosenbaum P, et al. Proposed definition and classification of cerebral palsy, April 2005. Dev Med Child Neurol 2005;47:571-6.
    Pubmed CrossRef
  3. Sanger TD, Delgado MR, Gaebler-Spira D, Hallett M, Mink JW; Task Force on Childhood Motor Disorders. Classification and definition of disorders causing hypertonia in childhood. Pediatrics 2003;111:e89-97.
    Pubmed CrossRef
  4. Butler C, Darrah J. Effects of neurodevelopmental treatment (NDT) for cerebral palsy: an AACPDM evidence report. Dev Med Child Neurol 2001;43:778-90.
    Pubmed CrossRef
  5. Horak FB. Motor control models underlying neurologic rehabilitation of posture in children. Karger Publishers; 1992. p. 21-30.
    CrossRef
  6. Ahn B, Joung YS, Kwon JY, et al. Effects of equine-assisted activities on attention and quality of life in children with cerebral palsy in a randomized trial: examining the comorbidity with attention-deficit/hyperactivity disorder. BMC Pediatr 2021;21:135.
    Pubmed KoreaMed CrossRef
  7. Debuse D, Gibb C, Chandler C. Effects of hippotherapy on people with cerebral palsy from the users' perspective: a qualitative study. Physiother Theory Pract 2009;25:174-92.
    Pubmed CrossRef
  8. McGibbon NH, Benda W, Duncan BR, Silkwood-Sherer D. Immediate and long-term effects of hippotherapy on symmetry of adductor muscle activity and functional ability in children with spastic cerebral palsy. Arch Phys Med Rehabil 2009;90:966-74.
    Pubmed CrossRef
  9. Tseng SH, Chen HC, Tam KW. Systematic review and meta-analysis of the effect of equine assisted activities and therapies on gross motor outcome in children with cerebral palsy. Disabil Rehabil 2013;35:89-99.
    Pubmed CrossRef
  10. Kwon JY, Chang HJ, Yi SH, Lee JY, Shin HY, Kim YH. Effect of hippotherapy on gross motor function in children with cerebral palsy: a randomized controlled trial. J Altern Complement Med 2015;21:15-21.
    Pubmed CrossRef
  11. Park ES, Rha DW, Shin JS, Kim S, Jung S. Effects of hippotherapy on gross motor function and functional performance of children with cerebral palsy. Yonsei Med J 2014;55:1736-42.
    Pubmed KoreaMed CrossRef
  12. Russell DJ, Rosenbaum P, Wright M, Avery LM. Gross Motor Function Measure (GMFM-66 & GMFM-88) user’s manual. 3rd ed. Mac Keith Press; 2021.
    CrossRef
  13. Lundkvist Josenby A, Jarnlo GB, Gummesson C, Nordmark E. Longitudinal construct validity of the GMFM-88 total score and goal total score and the GMFM-66 score in a 5-year follow-up study. Phys Ther 2009;89:342-50.
    Pubmed CrossRef
  14. Chen CL, Shen IH, Chen CY, Wu CY, Liu WY, Chung CY. Validity, responsiveness, minimal detectable change, and minimal clinically important change of Pediatric Balance Scale in children with cerebral palsy. Res Dev Disabil 2013;34:916-22.
    Pubmed CrossRef
  15. Han YG, Lee SW, Yun CK. The immediate influence of various whole-body vibration frequency on balance and walking ability in children with cerebral palsy: a pilot study. J Exerc Rehabil 2019;15:597-602.
    Pubmed KoreaMed CrossRef
  16. Lee NY, Lee EJ, Kwon HY. The effects of dual-task training on balance and gross motor function in children with spastic diplegia. J Exerc Rehabil 2021;17:21-7.
    Pubmed KoreaMed CrossRef
  17. Kim MK, Kim SG, Shin YJ, Choi EH, Choe YW. The relationship between anterior pelvic tilt and gait, balance in patient with chronic stroke. J Phys Ther Sci 2018;30:27-30.
    Pubmed KoreaMed CrossRef
  18. Kallenberg LA, Hermens HJ. Behaviour of motor unit action potential rate, estimated from surface EMG, as a measure of muscle activation level. J Neuroeng Rehabil 2006;3:15.
    Pubmed KoreaMed CrossRef
  19. Kim KJ. Relationships between gross motor capacity and neuromusculoskeletal function in children with cerebral palsy after short-term intensive therapy. J Korean Phys Ther 2018;30:90-5.
    CrossRef
  20. Bertoti DB. Effect of therapeutic horseback riding on posture in children with cerebral palsy. Phys Ther 1988;68:1505-12.
    Pubmed CrossRef
  21. Meregillano G. Hippotherapy. Phys Med Rehabil Clin N Am 2004;15:843-54.
    Pubmed CrossRef
  22. Silkwood-Sherer DJ, Killian CB, Long TM, Martin KS. Hippotherapy: an intervention to habilitate balance deficits in children with movement disorders: a clinical trial. Phys Ther 2012;92:707-17.
    Pubmed CrossRef
  23. 탐alien휊 L, Mockevi훾ien휊 D, Kreivinien휊 B, Razbadauskas A, Kleiva 탐, Kirkutis A. Short-term and long-term effects of riding for children with cerebral palsy gross motor functions. Biomed Res Int 2018;2018:4190249.
  24. Davis E, Davies B, Wolfe R, et al. A randomized controlled trial of the impact of therapeutic horse riding on the quality of life, health, and function of children with cerebral palsy. Dev Med Child Neurol 2009;51:111-9.
    Pubmed CrossRef
  25. Lechner HE, Feldhaus S, Gudmundsen L, et al. The short-term effect of hippotherapy on spasticity in patients with spinal cord injury. Spinal Cord 2003;41:502-5.
    Pubmed CrossRef
  26. McGibbon NH, Andrade CK, Widener G, Cintas HL. Effect of an equine-movement therapy program on gait, energy expenditure, and motor function in children with spastic cerebral palsy: a pilot study. Dev Med Child Neurol 1998;40:754-62.
    Pubmed CrossRef
  27. Cho WS, Cho SH. Effects of mechanical horseback riding exercise on static balance of patient with chronic stroke. J Korea Acad-Ind Coop Soc 2015;16:1981-8.
    CrossRef
  28. Honkavaara M, Rintala P. The influence of short term, intensive hippotherapy on gait in children with cerebral palsy. EUJAPA 2010;3:29-36.
    CrossRef
  29. Low S, Collins G, Dhagat C, Hanes P, Adams J, Fischbach R. Therapeutic horseback riding: its effects on gait and gross motor function in children with cerebral palsy. Sci Educ J Ther Riding 2005;11:12-24.
  30. Bravo Gonçalves Junior JR, Fernandes de Oliveira AG, Cardoso SA, Jacob KG, Boas Magalhães LV. Neuromuscular activation analysis of the trunk muscles during hippotherapy sessions. J Bodyw Mov Ther 2020;24:235-41.
    CrossRef