This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) (12) guidelines. The protocol has been registered with the International Prospective Register for Systematic Reviews (PROSPERO; registration number CRD42021256958).

A systematic search was conducted on March 1, 2025, across the following electronic databases: PubMed, Web of Science, Embase, and the Cochrane Library. The search strategy utilized the following keywords: (“Parkinson’s disease” OR “idiopathic Parkinson’s disease” OR “Lewy body Parkinson’s disease” OR “paralysis agitans” OR “primary parkinsonism”) AND (“treadmill training”). Only full-text articles published in English were included in the search.

Two independent reviewers, Yin and Hu, screened the titles and abstracts of all retrieved records in a blinded manner. Any discrepancies were resolved by consulting a third reviewer, Li. Studies that met the screening criteria were subsequently evaluated in full text. All studies were included based on the following criteria:

Inclusion criteria: (1) Study design: randomized controlled trials (RCTs); (2) Population: Patients with Parkinson’s disease (Hoehn-Yahr stages I-III) aged ≥55 years; (3) Population: Disease duration ≥1 year, MMSE ≥24, and medically stable; (4) Intervention: conventional or body-weight-supported treadmill; (5) Comparison: Usual care, gait training, or standard comprehensive training; (6) Outcome: Includes UPDRS-III, BBS and TUG test, gait performance as assessed by 6MWT, 10MWT and quality of life as evaluated by PDQ-39.

Exclusion criteria: (1) Intervention: Combined with additional interventions; (2) Intervention: Short intervention duration (single or few sessions); (3) Comparison: Baseline data imbalance (Supplementary Table 1).

Data extraction was conducted independently by two reviewers, Yin and Hu. Any disagreements were resolved through discussion with a third reviewer, Li.

The extracted data included the following: (1) the general characteristics of each study (Authorship, Study design, Country, and Date of publication); (2) Characteristics of Participants (Age, Groups and Sample Size, Number of Men and Women, Parkinson’s Stage); (3) Characteristics of the intervention and control groups (treatment regimen, type of treadmill equipment): (4) Post-intervention quantitative data for the UPDRS-III, 6MWT, 10MWT, TUG, BBS, and PDQ-39, including mean and standard deviation.

Only data collected immediately after the intervention were included; no follow-up data were considered.

Two reviewers (Yin and Hu) independently assessed potential bias using an improved Cochrane Risk of Bias Tool across five domains: randomization, intended interventions, missing outcome data, measurement of the outcome, and selection of the reported result. Each domain was categorized into one of three levels: high risk of bias, cause for concern, or low risk of bias. The reviewers consulted a third author, Li, to resolve any discrepancies.

Statistical analyses were conducted using STATA version 15.1 (STATA Corp., College Station, TX, USA). The standardized mean difference (SMD) was employed to combine data, and Hedge’s g and 95% confidence intervals (CIs) served as effect size measures for continuous data. Heterogeneity among studies was evaluated using the χ² test. An I² ≤ 50% and p > 0.1 indicated no significant heterogeneity, while an I² > 50% and p < 0.1 indicated significant heterogeneity. Potential sources of heterogeneity were investigated through subgroup analysis, and publication bias was assessed using funnel plots and Egger’s test.

The initial search yielded 3,368 potential articles. Of these, 186 duplicates were excluded from the analysis. Additionally, 2,299 records were marked as ineligible by automation tools. After screening the titles and abstracts,98 studies were identified for further evaluation. Of these, 82 articles did not meet the inclusion criteria and were excluded from the study, leaving 16 studies for the meta-analysis (13–26) (Figure 1).

A total of 16 RCTs (2000–2022) involving 582 participants were included. The treadmill group comprised 274 participants, while the control group included 308 participants. The study populations were from Japan, Turkey, the United States, Australia, Italy, India, China, Brazil, Iran, and Germany. The majority of participants were elderly aged 60 and above, with Hoehn-Yahr stages ranging from I to III. The treadmill group underwent either treadmill training (TT) or body-weight-supported treadmill training (BWSTT), while the control group primarily engaged in routine activities, gait training, or comprehensive training. The intervention duration ranged from 2 to 10 weeks, with a frequency of 2–4 sessions per week, each lasting 25–45 min (As shown in Tables 1, 2).

The risk of bias assessment for the included studies indicated that out of the 16 RCT studies11 were considered to be at low risk of bias, 4 had somed some concerns and 1 had a high risk of bias (Figure 2, Supplementary Figure 2).

Parkinson’s disease (PD) is a prevalent neurodegenerative disorder characterized by motor dysfunction, impaired balance, and gait abnormalities, which significantly impact patients’ quality of life and independence (27). In recent years, treadmill training has emerged as an effective rehabilitation intervention, demonstrating potential benefits in enhancing motor function and functional capacity in individuals with Parkinson’s disease (28). However, there are still several methodological limitations (e.g., small sample sizes, inconsistent intervention protocols, etc.) and pressing research priorities (e.g., long-term outcome assessment and the optimization of individualized training protocols) in the field. Therefore, this study enhanced its quality through meta-analysis. The results of this meta-analysis indicate that treadmill training, particularly BWSTT, may positively impact lower extremity muscular endurance, cardiorespiratory fitness, functional mobility, and balance coordination in patients with Parkinson’s disease. This improvement may contribute to a reduced risk of falls and enhanced patient independence.

We first analyzed the impact of treadmill training on the enhancement of overall motor abilities in patients with Parkinson’s disease, using the UPDRS III score as a primary index to assess motor function. The results indicated that treadmill training significantly reduced the UPDRS III score compared to conventional training; however, there was a high degree of heterogeneity (I² > 50%). To further investigate the source of this heterogeneity, we conducted a subgroup analysis, categorizing treadmill training into conventional and BWSTT groups. The findings revealed that the BWSTT group significantly reduced the UPDRS III score, accompanied by a notable decrease in heterogeneity. In contrast, the conventional treadmill group did not demonstrate a significant difference in the improvement of the UPDRS III score when compared to conventional therapy. These results suggest that BWSTT is more effective than conventional therapy in enhancing the overall motor function of patients with Parkinson’s disease, while the effects of conventional treadmill training are comparable to those of conventional therapy. By reviewing and analyzing the literature, it appears that the weight-loss treadmill is more effective at reducing the load on the lower limbs during walking (29). This reduction may facilitate walking training for patients, decrease their fear of falling, and boost their motivation and confidence in participating in such training (30). Additionally, it may enhance sensory feedback and promote neuroplasticity by stimulating the motor cortex (31), and such effects could be further augmented by integrating advanced technologies like robotic-assisted gait training and virtual reality tools (32).

This study first assessed the ability of patients with Parkinson’s disease to engage in moderate-intensity exercise over extended periods, as an indicator of their muscular endurance and cardiorespiratory fitness, using the 6-MWT. The results showed that treadmill training significantly increased the walking distance in the 6-MWT compared to conventional rehabilitation methods. Furthermore, the study evaluated short-term walking speed, balance, and functional mobility using the 10-MWT. Treadmill training was associated with a significant improvement in walking speed compared to standard approaches, with the effects of BWSTT appearing even more pronounced.

This study focused on assessing the balance abilities of patients with Parkinson’s disease using BBS. The results indicated that the therapeutic effects of treadmill training and traditional conventional training were comparable in enhancing the balance of these patients. Even after further categorizing treadmill training into conventional and weight-loss groups, the treatment effects in each group remained similar to those observed with conventional routine training. Balance improvements depend not only on lower limb strength but also on sensory systems like proprioception, vision, and vestibular functions (33). As Lena et al. note, rehabilitation interventions target these systems to enhance balance in Parkinson’s disease (34). While treadmill training can effectively enhance gait and lower limb strength, the stimulation of other sensory systems, such as the visual and vestibular systems, may be more limited (35), though recent VR-based interventions have shown promising improvements in these areas (36).

The TUG is utilized to evaluate the functional mobility of patients with Parkinson’s disease. It primarily measures the time required for patients to perform a series of movements, including standing up, walking, turning around, and sitting down, all within a brief period. Analyses revealed no significant difference between treadmill training and traditional conventional training in reducing TUG times. Possible explanations for this finding may include the following: treadmill training primarily focuses on enhancing gait and walking ability, which may have a limited impact on dynamic balance (e.g., turning and one-legged standing) (37). Additionally, the existing literature on this topic is sparse, and the small sample sizes may contribute to a deviation of the results from reality.

Finally, this study utilized the PDQ-39 to assess the quality of life in patients with Parkinson’s disease. The results indicated that treadmill training was comparable to traditional conventional training in enhancing patients’ quality of life. It is hypothesized that this outcome may be attributed to the limited research literature related to this indicator and the insufficient sample size, which may have led to some deviation from the actual results.

This systematic review and meta-analysis offers several advantages:

(1) The substantial number of included studies, the extensive sample size, and the diverse range of countries involved more accurately highlight the advantages of treadmill training over traditional conventional training in enhancing motor function in patients with Parkinson’s disease; (2) Revealed that BWSTT may have superior therapeutic effects; (3) No publication bias was identified in the included studies; (4) revealed potential shortcomings of treadmill training in stimulating the visual and vestibular balance systems; (5) highlighted the potential limitations of treadmill training in enhancing dynamic balance (e.g., turning and one-legged standing; (6) demonstrated the potential benefits of treadmill training in enhancing muscular endurance and short-term walking speed.

This study has several limitations: (1) The study population primarily consists of elderly individuals, which may limit the applicability of the findings to other demographic groups; (2) Regarding the two indicators, TUG test and PDQ-39, the literature included and the sample sizes are relatively small, potentially introducing bias into the results. Further research is necessary to enhance and validate these findings; (3) There are potential shortcomings in the discussion of treadmill training, which are based on a review of the literature. Future experiments should be designed to verify these results; (4) Treadmill training currently lacks a standardized treatment protocol.

Future research should focus on the following areas: First, efforts should be directed toward further enhancing the treadmill to better meet patients’ needs for visual stimulation and dynamic balance functions, such as turning and one-legged standing. While some studies have started to explore this area, the current research remains insufficient in both breadth and depth. Second, to address the limitations of the small sample size in the current study, future research should include larger cohorts or consider multicenter collaborations to enhance statistical power. it is essential to design large-scale randomized controlled trials to establish standardized protocols. Additionally, research that addresses the humanistic aspects of patient care, such as quality of life, should be incorporated.

Moreover, when considering the practical implementation of treadmill training programs in community or rural settings, it is important to acknowledge several potential barriers. These may include limited access to specialized equipment, a lack of trained professionals, and financial constraints. In rural areas, transportation issues could also pose significant challenges, making it difficult for patients to attend regular sessions. To overcome these obstacles, strategies such as community-based initiatives, telemedicine solutions, and the development of more cost-effective training equipment could enhance the feasibility and effectiveness of treadmill training for Parkinson’s disease patients in these settings, especially when combined with customizable features such as self-selected speeds and immersive VR environments, which have shown clinical benefits (38).