Abstract
Objective
This study aimed to systematically evaluate the effect of Tai Chi on the balance function, mobility function, and gait function (including gait endurance, gait amplitude, and gait speed) of the lower limbs in patients with Parkinson's disease.
Methods
The “PICOS” principle was used to search seven English and six Chinese databases. Search for relevant studies published up to September 11, 2023, from the date of database creation. Two authors independently screened all eligible studies. The included studies were assessed for risk of bias based on the criteria outlined in Cochrane Handbook 5.1.0. Quantitative statistics and meta-analyses were conducted using Review Manager 5.4 software.
Results
Th 18 studies that met the inclusion criteria, 16 of which were included in the meta-analysis, included a sample of 963 cases from four countries. The meta-analysis revealed that Tai Chi was effective compared with conventional medication in improving balance function (MD = 2.06, 95% CI [1.35, 2.78], P < 0.00001, I2 =0%), mobility function (MD = − 1.59, 95% CI [− 2.28, − 0.91], P < 0.00001, I2 =14%), and gait speed (SMD =0.59, 95% [0.28, 0.91], P = 0.0002, I2 =29%). However, there was no significant improvement in gait endurance (SMD = 0.14, 95% CI [−0.41, 0.68], P =0.62, I2 = 0%) or gait amplitude (SMD =0.30 , 95% CI [− 0.00, 0.61], P = 0.05, I2 =0%). Compared with other exercise therapies, Tai Chi was significantly superior in improving balance function (MD = 3.05, 95% CI [1.94, 4.16], P <0.00001, I2 = 38%), mobility function (MD =−0.70, 95%CI [− 1.23, − 0.17], P = 0.01, I2 = 0%), and gait range (SMD = 0.36, 95% CI [0.14, 0.58], P = 0.002, I2 = 45%). However, the advantage of improving gait speed (SMD =0.00, 95% CI [− 0.28, 0.29], P = 0.98, I2 =0%) was uncertain.
Conclusion
Tai chi is a safe and effective rehabilitation intervention that can enhance the balance and mobility functions of the lower limbs in patients with Parkinson's disease.
Supplementary Information
The online version contains supplementary material available at 10.1186/s40001-024-02151-5.
Keywords: Tai Chi, Parkinson's disease, Lower limbs, Meta-analysis
Introduction
Parkinson's disease is a prevalent neurodegenerative disorder among middle-aged and older adults worldwide, and it is classified as a movement disorder [1]. The main pathological features of this disease are the degenerative loss of nigrostriatal dopaminergic neurons and the abnormal accumulation of Lewy vesicles [2, 3]. These pathological changes result in the abnormal conduction of neurotransmitters, specifically reduced dopamine levels. As Parkinson's disease progresses, patients gradually develop resting tremors, bradykinesia, abnormal muscle tone, and impaired balance. These symptoms increase the risk of falls and significantly affect their ability to carry out daily activities and quality of life [4]. Therefore, it is important to actively seek effective prevention and treatment. Currently, medications such as dopamine agonists and dopamine transferase inhibitors are considered the primary treatment approach for Parkinson's disease [3, 5]. However, despite their ability to control disease progression and alleviate symptoms, long-term use can lead to side effects, medication resistance, and dependence [6]. Furthermore, medication alone cannot alleviate all symptoms, such as dyskinesia, balance fluctuations, and gait abnormalities [7]. Therefore, additional complementary approaches are necessary. Due to the high prevalence and progressive nature of Parkinson's disease, as well as the limitations of current medications, the search for a safe and effective adjunctive therapy or alternative to medication to alleviate the limitations of existing treatments is of the utmost urgency [7].
The Movement Disorder Society's Evidence-Based Medicine Group recommends the use of exercise therapy and physiotherapy as effective adjuncts to the treatment of Parkinson's disease, but there is currently no consensus on the specific form of exercise that should be used [8]. Tai Chi, which originated in traditional Chinese martial arts, is characterized by soft and fluid movements with an emphasis on breath control. When practiced, Tai Chi emphasizes the combination of body movements and deep diaphragmatic breathing to achieve a balance between the body and mind while promoting the flow of inner energy (the so-called qi in Chinese medicine) through body movements, breath control, and meditation [9]. Additionally, Tai Chi is considered to be a moderate-intensity aerobic exercise [10]. Participants typically perform the exercise in a semi-squatting position, which requires varying degrees of centripetal and centrifugal contractions, as well as fine joint control and muscle coordination [11]. Therefore, the long-term, consistent practice of Tai Chi can significantly enhance participants' leg muscle strength, improve balance, and enhance proprioception and walking function of the knee and ankle joints of the lower extremities, thereby reducing the risk of falls [12].
Previous studies have shown that Tai Chi training has demonstrated improvements in gait, balance, and motor function among patients with Parkinson's disease [13–16]. Furthermore, Li et al. [17] demonstrated that Tai Chi, as a non-pharmacological intervention, exhibited superiority over other exercise therapies in enhancing balance, decreasing fall occurrences, and reducing economic costs among patients with Parkinson's disease. However, there are inconsistencies in studies regarding the effect of Tai Chi on lower limb gait performance in patients with Parkinson's disease. A study conducted by Amano et al. [18] found that Tai Chi training was ineffective in improving postural control of lower limb gait in patients with Parkinson's disease. In addition, Hackney and Earhart found that Tai Chi did not confer a significant advantage in improving gait amplitude and speed in patients with Parkinson's disease compared to conventional medication [19]. Due to these discrepancies, this study will conduct a meta-analysis to comprehensively evaluate the true effect of Tai Chi on functional rehabilitation of the lower limbs in patients with Parkinson's disease. To our knowledge, previous studies have primarily compared the effects of Tai Chi with conventional medication therapy [2, 20, 21]. However, no study to date has examined the relationship between Tai Chi and other exercise therapies. Therefore, this study conducted a comprehensive synthesis and comparison of the effects of Tai Chi exercise with other exercise therapies based on existing literature.
Methods
The study followed the prescribed process outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) [22]. The literature search, comprehensive management, circular screening, inclusion, and exclusion criteria were developed based on the five specifications outlined in PICOS.
Search strategy
Searches were conducted in six English electronic databases (PubMed, Embase, Web of Science, Cochrane Library, Scopus, EBSCO) and five Chinese electronic databases (CNKI, Wipu, Wanfang, CBM, Baidu Scholar) using subject keywords and free words. Search for relevant studies published up to September 11, 2023, from the date of database creation. Additional searches were conducted in the National Library of Medicine (NLM) and the China Clinical Trial Registry (CTR) to include potential studies. Table 1 presents the specific process of combining the search strategies, while Table S1 of the Supplementary Material provides the search strategy for each database.
Table 1.
Search strategy for included studies
| steps | retrieval command | field |
|---|---|---|
| #1 | “Parkinson Disease” [Mesh] | Title/Abstract |
| #2 | “Idiopathic Parkinson's Disease” OR “Lewy Body Parkinson's Disease” OR “Parkinson's Disease, Idiopathic” OR “Parkinson's Disease, Lewy Body” OR “Parkinson Disease, Idiopathic” OR “Parkinson's Disease” OR “Idiopathic Parkinson Disease” OR “Lewy Body Parkinson Disease” OR “Primary Parkinsonism” OR “Parkinsonism, Primary” OR “Paralysis Agitans” | Title/Abstract |
| #3 | “Tai Ji” [Mesh] | Title/Abstract |
| #4 | “Tai-ji” OR “Tai Chi” OR “Chi, Tai” OR “Tai Ji Quan” OR “Ji Quan, Tai” OR “Quan, Tai Ji” OR “Taiji” OR “Taijiquan” OR “T'ai Chi” OR “Tai Chi Chuan” | Title/Abstract |
| #5 | randomized controlled trial OR randomized OR placebo | Title/Abstract |
| #6 | (#1 OR #2) AND (#3 OR #4) AND (#5) | Title/Abstract |
If the database advanced search does not have enough options, the search will only include keywords.
Inclusion and exclusion criteria
The inclusion criteria for the study consisted of the following: (1) Participants: patients diagnosed with primary Parkinson’s disease and presenting Hoehn-Yahr Clinical Rating Scale scores ranging from I to IV who remained physically active. (2) Intervention group: participants receiving any form of Tai Chi intervention. (3) Control group: participants receiving conventional medication, placebo, or other forms of exercise therapy. (4) Outcome measures: lower limb balance function was assessed using the Berg balance scale (BBS), lower limb mobility function was evaluated with the time up and go test (TUGT), and lower limb gait function was measured through gait endurance, gait amplitude, and gait speed. (5) Study design: randomized controlled trial (RCT).
The exclusion criteria were as follows: (1) duplicated studies, qualitative studies, and studies with low relevance were excluded; (2) studies without eligible experimental and control groups were excluded; (3) studies with incomplete outcome indicators or insufficient data for extraction were excluded; (4) secondary studies, such as systematic reviews or meta-analyses, were excluded; (5) studies with interventions that were not eligible for the target group were excluded; and (6) studies for which the full text was not available were excluded.
Data extraction
Data from the included studies was extracted by two researchers (YLH and CYX) using a pre-designed extraction form. A third investigator (JPY) then reviewed the data. The data extracted from the included studies includes general details such as the first author, publication year, country, and location of the study. Additionally, study characteristics such as patient count, average age, illness duration, Hoehn-Yahr stage, and study design were recorded. Finally, interventions, including intervention duration, intervention specifics, and primary outcome measures assessing lower limb function, were also noted. The study's extracted data underwent meta-analysis, which included analyzing sample size, mean values, and standard deviation (SD) before and after testing in both the experimental and control groups. Data extraction was performed using GetData software when necessary, and in cases of incomplete reporting, the study authors were contacted.
Quality and risk of bias assessment
The quality of the included studies was evaluated independently by two researchers (YLH and CYX) using the latest version of the risk of bias assessment tool recommended by Cochrane 5.1. A third investigator (JPY) verified the results. Each item was scored as low risk, unclear, or high risk using the following criteria: (1) random sequence generation; (2) allocation concealment; (3) blinding of participants and personnel; (4) incomplete outcome data; (5) selective reporting; and (6) other biases. In case of any discrepancies in the assessment results, a meeting should be convened to discuss and compare the basis for the assessment [23].
Statistical analyses
Data integration and statistical analysis were performed using Review Manager 5.4 software. Heterogeneity was assessed using the I2 statistic. An I2 value of <50% indicated low statistical heterogeneity between studies, leading to the selection of the fixed-effects model for analysis. On the other hand, an I2 value of ≥50% indicated high heterogeneity, calling for the random-effects model [24]. For this meta-analysis, continuous variables were used, and the weighted mean difference (MD) was employed as the effect measure when the units of measurement were the same. However, in cases where the outcome indicators’ measurement methods or units varied significantly, standardized mean difference (SMD) was used [25]. Sensitivity analyses, such as N-fold cross-validation and subgroup investigations, were conducted to explore potential sources of heterogeneity among the study results. The pooled effect sizes were expressed as 95% confidence intervals (CI), with a significance level set at P ≤0.05.
Results
Search results
Based on the search strategy, an initial search of 13 Chinese and English databases yielded 743 documents, including 533 English documents 184 Chinese documents, and 26 registered studies. After removing duplicates using EndnoteX9.1, 539 relevant literature sources were identified. Following a review of their abstracts and titles, 384 papers were excluded. Exclusions were made for reasons such as meta-analyses, conference reports, non-human experiments, duplicates that could not be eliminated by the software, and papers irrelevant to the topic. Out of 155 papers identified for full-text analysis, 137 were excluded due to reasons including qualitative studies, incomplete or unextractable outcome data, non-Chinese core-type journals, and irrelevant outcome indicators. A systematic review was conducted, including a total of 18 directly relevant randomized controlled trials (RCTs). Of these, 16 RCTs were eligible for inclusion in the meta-analysis (Fig. 1).
Fig. 1.
Flowchart of literature screening
Study characteristics
All 18 studies were randomized controlled trials that investigated the efficacy of Tai Chi in facilitating functional rehabilitation of the lower limb in patients diagnosed with Parkinson's disease. These studies were conducted between 2008 and 2022 in four countries: China, the United States, South Korea, and India. The sample sizes ranged from 8 to 62 cases, resulting in a total of 963 cases. The study participants' mean age ranged from 56 to 72 years, and the interventions lasted between 4 and 26 weeks. Each exercise session lasted 30 to 60 minutes. The control group received conventional medication and other exercise therapies, including qigong therapy, brisk walking, yoga, balance training, resistance training, stretching, and multimodal exercise training. Table 2 provides details of the experimental design of the included trials and information on the extraction of study outcomes.
Table 2.
Basic characteristics of the included studies
| Author year | Nations point | Sample (male/female) | Average age/year | Disease duration/year | Hoehn Yahr |
Intervention details | Span | Outcome indicator |
||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| C | T | C | T | C | T | C | T | |||||
| Suqiong Ji 2016 | China Hospital | 16 (8/8) | 16 (9/7) | 59.13 ± 11.22 | 56.06 ± 11.16 | 2.28 ± 1.18 | 2.09 ± 1.07 | 1–3 | M | M + T |
7F/W × 12W 60 min/F |
①③ |
| Fulin Lu 2017 | China Hospital | 8 (5/3) | 8 (5/3) | 68.20 ± 7.32 | 67.75 ± 6.84 | 2.02 ± 0.52 | 2.41 ± 0.48 | 1–2 | M | M + T | 5F/W × 8W 40–60 min/F | ① |
| Xihong Guan 2016 | China Hospital | 31 (17/14) | 31 (16/15) | 69.71 ± 4.13 | 70.23 ± 4.24 | 4.28 ± 3.25 | 4.43 ± 3.17 | 1–3 | M | M + T | 4F/W × 12W 60 min/F | ①②④⑤ |
| Xihong Guan 2018 | China Nursing Homes | 40 (21/19) | 40 (23/17) | 68.61 ± 6.22 | 69.46 ± 5.45 | 1.50 ± 0.32 | 1.52 ± 0.25 | \ | M | M + T | 4F/W × 24W 60 min/F | ①②④⑤ |
| Yi Zhu 2011 | China Communal | 20 (12/8) | 20(11/9) | 64.83 ± 9.29 | 63.35 ± 8.72 | 2.78 ± 2.29 | 2.72 ± 1.95 | 1–2 | M + W | M + T | 5F/W × 4W 30–45 min/F | ① |
| Xin Luan 2020 | China Hospital | 13 (6/7) | 13 (7/6) | 63.46 ± 4.33 | 64.08 ± 3.95 | \ | \ | 1–2.5 | M + S + W | M + T | 3F/W × 16W 60 min/F | ①②③ |
| Lin Li 2017 | China Hospital | 38 (20/18) | 42 (24/18) | 67.78 ± 5.36 | 65.25 ± 6.37 | 3.45 ± 0.88 | 3.73 ± 1.08 | 1–3 | M | M + T | 3F/W × 16W 60 min/F | ④⑤ |
| Guoqiang Chen 2016 | China Hospital | 15 (6/9) | 15 (7/8) | 68.2 ± 8.1 | 68.1 ± 8.2 | 4.6 ± 0.6 | 4.5 ± 0.7 | 3–4 | M + E | M + E + T | 7F/W × 8W 50–60 min/F | ② |
| Madeleine Hackney 2008 | American Hospital | 13 (10/3) | 13 (11/2) | 62.6 ± 10.2 | 64.9 ± 8.3 | 5.5 ± 3.3 | 8.7 ± 4.7 | 1.5–3 | M | T | 20F/10-13W 60 min/F | ①②③④⑤ |
| Zhang T-Y 2015 | China Hospital | 20 (11/9) | 20 (13/7) | 64.35 ± 10.53 | 66 ± 11.80 | 4.85 ± 3.72 | 6.80 ± 5.43 | 1–3 | E | T |
2F/W × 12W 60 min/F |
①②④⑤ |
| Gloria Vergara Diaz 2018 | American Hospital | 16 (7/9) | 16 (9/7) | 62 ± 7.77 | 65.7 ± 3.86 | 2.9 ± 2.20 | 2.9 ± 2.38 | 1–2.5 | M | T | 2F/W × 26W 60 min/F | ② |
| Gen Li 2022 | China Hospital | 31 (22/9) 32 (19/13) | 32 (17/15) | 61.9 ± 5.64 61.9 ± 6.76 | 62.7 ± 5.51 | 3.82 ± 1.87 4.32 ± 2.46 | 5.91 ± 4.01 | 1–2.5 | M/W | T | 12 M | ①②④⑤ |
| Arva Khuzema 2020 | India Hospital | 9 (6/3) 9 (7/2) | 9 (6/3) | 68.11 ± 4.23 70.89 ± 6.01 | 72 ± 5.22 | 6.20 ± 1.67 5.23 ± 3.13 | 5.67 ± 2.33 | 2.5–3 | Y/B | T | 7F/W × 8W 30–40 min/F | ①② |
| Hye-Jung Choi 2013 | South Korea Hospital | 9 | 11 | 65.54 ± 6.80 | 60.81 ± 7.60 | 5.2 ± 2.7 | 5.2 ± 2.7 | 1–2 | M | T | 3F/W × 12W 60 min/F | ②③ |
| Qiang Gao 2014 | China Hospital | 39(27/12) | 37(23/14) | 68.28 ± 8.53 | 69.54 ± 7.32 | 8.37 ± 8.24 | 9.15 ± 8.58 | \ | M | M + T | 3F/W × 12W 60 min/F | ①② |
| Shinichi Amano 2013 | American University | 9(7/2) 9(7/2) | 12(7/5) 15(7/8) | 68 ± 7 66 ± 7 | 64 ± 13 66 ± 11 | 12 ± 7 5 ± 3 | 7 ± 7 5 ± 3 | \ | Q/M | T | 3F/W × 16W 60 min/F | ④⑤ |
| Mingjin ZHU 2020 | China Hospital | 22(13/9) | 19(12/7) | 67.77 ± 1.72 | 68.53 ± 1.90 | 4.00 ± 0.39 | 4.68 ± 0.43 | 1–3 | E | T | 3F/W × 12W 40–50 min/F | ② |
| Fuzhong Li 2012 | American Hospital | 65(38/27) 65(39/26) | 65(45/20) | 69 ± 8 69 ± 9 | 68 ± 9 | 8 ± 9 6 ± 5 | 8 ± 9 | 1–4 | R/S | T | 2F/W × 24W 60 min/F | ②④⑤ |
T = Tai Chi group; C = Control group; R = Resistance training; S = Stretching training; E = Multi-modal exercise training; Q = Qigong therapy; W = Walking exercise; Y = Yoga exercise; B = Balance exercise; M = Conventional medication; F = Frequency; W = Week; M = Month. Outcome indicators: ① Berg Balance Scale (BBS); ② Timed Up and Go Test (TUGT); ③ Six-Minute Walk Test (6-MWT); ④ gait amplitude; ⑤ gait speed
Risk of bias
Two investigators (YLH and CYX) conducted an independent risk assessment for the 18 included studies using the Cochrane 5.1 recommended risk of bias assessment tool [26]. The sensitivity analysis identified that two studies were the primary contributors to the high heterogeneity in the data [4, 19]. Two studies were excluded from the meta-analysis due to differences in measurement methodology and a high occurrence of sample shedding during the experimental period. This was done to ensure a more objective analysis of the efficacy of Tai Chi for functional rehabilitation of the lower limbs in Parkinson's disease patients. Therefore, a total of 16 randomized controlled trials were included in the meta-analysis. Figs. 2 and 3 display the results of the risk of bias assessment.
Fig. 2.
Risk of bias graph
Fig. 3.
Risk of bias summary
Lower limb balance function
The Berg Balance Scale (BBS) is a test used to evaluate lower limb balance function. It has been shown to have strong validity and reliability in patients with Parkinson's disease. Higher BBS scores indicate improved lower limb balance [7]. The meta-analysis demonstrated a significant increase in BBS scores among the Tai Chi group compared with the conventional medication group [13–15, 27–29] (fixed-effects model: MD =2.06, 95% CI [1.35, 2.78], P <0.00001, I2 =0%). Furthermore, in comparison with other exercise therapies, Tai Chi showed a greater improvement in BBS scores [16, 27, 30–33] (random-effects model: MD =2.72, 95% CI [0.98, 4.47], P =0.002, I2 =60%) (Supplementary Material, Figure S1). A sensitivity analysis was conducted, which excluded a lower-quality study, and the pooled results indicated that the study findings remained unchanged. Additionally, the statistical heterogeneity was decreased (fixed-effects model: MD = 3.05, 95% CI [1.94, 416], P <0.00001, I2 =38% ). As a result, lower-quality studies were excluded from the final analysis (Fig. 4). The results suggest that Tai Chi has a positive impact on rehabilitating lower limb balance function in patients with Parkinson's disease.
Fig. 4.
Effect of Tai Chi on lower limb balance function in patients with Parkinson's disease
Lower limb mobility function
The Timed Up and Go Test (TUGT) is used to evaluate lower limb mobility function in Parkinson's disease patients. It measures the time taken for patients to transition from a seated position to standing, walking, and turning. Lower TUGT scores indicate improved lower limb mobility function in Parkinson's disease patients [34]. The meta-analysis showed a significant decrease in TUGT scores for the Tai Chi group compared with the conventional medication group [13, 14, 27, 28, 35, 36] (fixed-effects model: MD =− 1.59, 95% CI [− 2.28, − 0.91], P <0.0001, I2 =14%) and other exercise therapy groups [16, 17, 27, 30, 33] (fixed-effects model: MD =− 0.70, 95% CI [− 1.23, − 0.17], P =0.01, I2 =0%). This result suggests that Tai Chi significantly improves lower limb mobility in patients with Parkinson's disease (Fig. 5).
Fig. 5.
Effect of Tai Chi on lower limb mobility function in patients with Parkinson's disease
Lower limb gait function
To evaluate lower limb gait function in people with Parkinson's disease, gait endurance (measured by the 6 MWT), gait amplitude, and gait speed were chosen as indicators. According to the meta-analysis, the Tai Chi group achieved better results in gait speed compared with those receiving conventional medication [13, 14, 18, 27, 37] (fixed-effects model: SMD =0.59, 95% CI [0.28, 0.91], P =0.0002, I2 =29%). However, no significant difference was observed between the Tai Chi group and conventional medication for gait endurance [15, 36] (fixed-effects model: SMD =0.14, 95% CI [− 0.41, 0.68], P =0.62, I2 =0%) and gait amplitude [13, 14, 18, 27, 37] (fixed-effects model: SMD =0.30, 95% CI [− 0.00, 0.61], P =0.05, I2 =0%) (Fig. 6).
Fig. 6.
Effect of Tai Chi on gait function in patients with Parkinson's disease compared with conventional medication
Compared with other exercise therapies [17, 18, 27, 33], Tai Chi has shown a significant advantage in improving gait amplitude in people with Parkinson's disease (fixed-effects model: SMD =0.36, 95% CI [0.14, 0.58], P = 0.002, I2 =45%). However, its impact on gait speed remains uncertain (fixed-effects model: SMD =0.00, 95% CI [− 0.28, 0.29], P =0.98, I2 =0%) (Fig. 7). Regarding gait endurance, only one article among the included studies compared Tai Chi with other exercise therapies [16]. The Cochrane Handbook guidelines recommend combining two similar control groups for a single comparison. Since this criterion was not met, the study was not included in the meta-analysis.
Fig. 7.
Effect of Tai Chi on gait function in patients with Parkinson's disease compared with other exercise therapies
Sensitivity analysis
In order to test the reliability of the results, a switched combined effect model, N-fold cross-validation, and the one-by-one investigation method were used for each of the comparisons to monitor the influence of individual studies on heterogeneity and the overall effect estimate. Based on the results of the one-by-one investigation, the studies conducted by Lin Li et al. [37] and Gen Li et al. [27] had a significant impact on the functional outcome of lower limb gait (Supplementary Material, Figure S2, Figure S3). One possible reason for this result could be the disparity in the duration of the intervention, as Gen Li et al. [27] did not specify the duration of their intervention.
Publication bias
The scatter of the funnel plot in this study was mainly concentrated towards the center and top, with several studies falling near the null line at the bottom of the plot, all of which exhibited close to symmetrical distributions (Supplementary Material, Figure S4). Therefore, it can be concluded that there is no significant risk of publication bias [38].
Discussion
Main finding of this study
This study is the first to use meta-analysis to compare the effectiveness of Tai Chi with other treatments in improving functional rehabilitation of the lower limbs in patients with Parkinson’s disease. The results suggest that Tai Chi is an effective complementary and alternative therapy to improve balance function, mobility function and gait function in the lower limbs of patients with Parkinson’s disease. When Tai Chi was compared with conventional medication, it showed positive effects on improving balance function, mobility function, and gait speed, but there was insufficient evidence to support or refute its value for gait endurance and gait amplitude. When compared to other exercise therapies, Tai Chi showed significant advantages in improving balance function, mobility function, and gait amplitude, but there is insufficient evidence to determine whether it is superior to other exercise therapies for gait speed.
Balance function and mobility function
Tai Chi serves as both an internal and external exercise and plays an important role in improving motor control and muscle coordination in the lower limbs of individuals with Parkinson's disease, achieved through slow and smooth movements and by matching the characteristics of breathing. Tai Chi training emphasizes the constant shifting of the body's center of gravity between the two feet, facilitating the body's equilibrium by adjusting the support surface [39, 40]. When compared to traditional exercise regimens, Tai Chi might yield superior advantages for individuals diagnosed with Parkinson’s disease [41]. Tai Chi encompasses a variety of multidimensional exercises encompassing endurance, flexibility, and neuromuscular coordination, along with numerous cognitive elements like body awareness, concentration, and meditation incorporated within its training [41, 42]. Tai Chi training can enhance muscle strength in the lower limbs of Parkinson’s disease patients and improve concentration and stability during weight shifting [43, 44]. In contrast, some other forms of exercise may focus on only one aspect of rehabilitation. In addition, Tai Chi is thought to have anti-inflammatory and antioxidant properties that help to reduce inflammation, apoptosis, and neuronal loss. Some studies have found an association between Parkinson's disease and the accumulation of α-synuclein [45, 46]. Tai Chi exercises have been shown to reduce α-synuclein levels by reducing inflammatory responses, apoptosis, and neuronal loss [45, 46]. Therefore, it is expected that Tai Chi exercise will attenuate the inflammatory response and mitochondrial dysfunction in people with Parkinson's disease while improving stability and coordination during exercise performance.
We conducted a systematic review and analyzed data from 14 clinical trials [13–17, 27–33, 35, 36]. We found that Tai Chi, as an adjunctive therapy, had a positive impact on rehabilitating balance and mobility functions of the lower limbs in patients with Parkinson’s disease. Our findings align with previous studies, and the systematic reviews by Yu et al. [2] and Zhu et al. [21] have also affirmed the effectiveness of Tai Chi in improving balance and mobility functions in patients with Parkinson’s disease. However, their research methods primarily compared Tai Chi with conventional medication. Although this traditional approach allowed for an assessment of the independent effects of Tai Chi, it failed to adequately consider other variables and factors that might influence the outcome. In addition, there was a high degree of heterogeneity in the results of Yu et al. [2] and Zhu et al. [21]. Our systematic review provided a more detailed subgroup analysis of Tai Chi with other treatments while ensuring lower heterogeneity. The combined results suggest that Tai Chi is more effective than conventional medication and other exercise therapies in improving the balance and mobility functions of the lower limbs in patients with Parkinson’s disease.
Gait function
Currently, there is controversy regarding the effectiveness of Tai Chi in improving gait function, including gait endurance, amplitude, and speed, in patients with Parkinson's disease. Early studies suggest that Tai Chi training significantly improves lower limb extensor-flexor muscle coordination and gait amplitude and speed in patients with Parkinson's disease [13, 14]. However, several studies have reported that Tai Chi training is ineffective in improving gait speed and amplitude in patients with Parkinson's disease [17–19, 27]. In a randomized controlled trial comparing tai chi with other exercise therapies, Gen Li et al. [27] found tai chi to be superior to brisk walking in improving balance and stride length. Fuzhong Li et al. [17] also found tai chi to be superior to resistance training for stride length and functional stretching. The results of our meta-analysis indicated that Tai Chi was more effective than conventional medication in improving gait speed and superior to other exercise therapies in improving gait amplitude. However, our positive results were not consistent with those of the systematic review by Yang et al. [9]. Yang and his colleagues concluded, based on 2 randomized controlled trials [18, 19], that tai chi showed no beneficial effects in improving gait speed or gait length compared with the no-intervention group, and it did not outperform other active therapies in terms of gait speed and gait length when compared with those therapies. Objective evidence distinguishes our review from previous literature. Our review included more new studies, and we ensured the reliability of the findings by choosing randomized controlled trials for all our meta-analyses. Therefore, our systematic review provides strong evidence that tai chi improves the motor function of the lower limbs in patients with Parkinson's disease.
In our systematic review, we found that variations in the results of gait function studies may be due to differences in intervention modalities and measurement techniques. Firstly, in terms of intervention modalities, some studies implemented the 24-step Tai Chi [13, 14], while others implemented the first eight movements of Yang-style Tai Chi [17, 18]. These different Tai Chi movements involve different degrees of limb and trunk activation, which may lead to different study results. Secondly, in terms of measurement techniques, some studies have used the widely used clinical approach of Footprint Analysis Method to assess gait [13, 14], while others have used the GAITRite system from a biomechanical perspective to collect gait data [17–19, 27]. These different measurement methods may have different influences on the assessment of gait performance. In our review of the literature, we found that studies using the Footprint Analysis Method tended to support the beneficial effects of Tai Chi, whereas those using the GAITRite System failed to demonstrate such effects. Therefore, we suggest that future research should actively explore an alternative, more objective measure to comprehensively assess the effects of Tai Chi on gait performance in Parkinson's disease patients. Due to incomplete reporting in some studies, we had difficulty determining the most effective Tai Chi practice style for gait performance in Parkinson's disease patients.
Limitations
While this study provides innovative findings, there are some limitations. Firstly, variations in factors such as study population, research methodology, Tai Chi delivery format, and the time interval between studies may have contributed to differences in the combined results. Secondly, despite our efforts to include a substantial body of relevant literature, it is plausible that certain studies may have been inadvertently omitted due to publication bias and limitations associated with language restrictions. Finally, within the scope of the literature that we reviewed, a paucity of studies were identified that investigated the efficacy of Tai Chi in improving gait endurance in patients with Parkinson’s disease. Furthermore, out of the limited number of viable studies, only one compares Tai Chi with other exercise therapies. Therefore, it is important to exercise caution when interpreting the results of specific studies.
Conclusions
This study provides evidence supporting the effectiveness of Tai Chi in improving lower limb motor function in patients with Parkinson’s disease. Therefore, we recommend the use of Tai Chi as a complementary and alternative therapy in clinical practice, particularly for enhancing lower limb balance function and mobility function in patients with Parkinson’s disease. However, there is limited information available on the benefits of Tai Chi for improving gait function, including gait endurance, gait amplitude, and gait speed. Therefore, more large-scale, high-quality studies are necessary to validate these findings in the future.
Supplementary Information
Acknowledgements
Not applicable.
Author contributions
Conceived the idea: LJL, JPY; collected data: LJL, YLH, CYX; extraction of the data: YLH, CYX, JPY; the risk of bias assessment: YLH, CYX, JPY; analyzed and interpreted data: LJL, YLH, CYX, JPY; wrote the first draft: LJL, JPY; key revisions to important contents of the manuscript: LJL, JPY, CCL; conducted meta-analyses: LJL. All authors approved the final manuscript before submitting.
Funding
This work was supported by grants from the National Social Science Foundation of China (20BTY068).
Availability of data and materials
No datasets were generated or analysed during the current study.
Declarations
Ethics approval consent to participate
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Lijie Lou and Chunyu Xiang contributed equally to this work.
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Supplementary Materials
Data Availability Statement
No datasets were generated or analysed during the current study.