Advertisement
Browse Subject Areas
?

Click through the PLOS taxonomy to find articles in your field.

For more information about PLOS Subject Areas, click here.

  • Loading metrics

Open Access

Peer-reviewed

Research Article

Effect of proprioceptive neuromuscular facilitation on patients with chronic ankle instability: A systematic review and meta-analysis

  • Yikun Yin ,

    Contributed equally to this work with: Yikun Yin, Jialin Wang, Qihan Lin

    Roles Conceptualization, Data curation, Formal analysis, Validation, Writing – original draft, Writing – review & editing

    Affiliation School of Sport Human Science, Beijing Sport University, Beijing, China

    ⨯
  • Jialin Wang ,

    Contributed equally to this work with: Yikun Yin, Jialin Wang, Qihan Lin

    Roles Conceptualization, Writing – original draft, Writing – review & editing

    1003723595@qq.com

    Affiliation Institute of Sports Medicine and Health, Chengdu Sport University, Chengdu, China

    ⨯
  • Qihan Lin ,

    Contributed equally to this work with: Yikun Yin, Jialin Wang, Qihan Lin

    Roles Formal analysis

    Affiliation College of Physical Education and Health, Longyan University, Longyan, China

    ⨯
  • Yinghang Luo,

    Roles Data curation, Formal analysis, Validation

    Affiliation School of Physical Education, Jining University, Jining, China

    ⨯
  • Yongsheng Liu,

    Roles Data curation

    Affiliation School of Physical Education, Jining University, Jining, China

    ⨯
  • Junzhi Sun

    Roles Writing – review & editing

    Affiliation Institute of Sports Medicine and Health, Chengdu Sport University, Chengdu, China

    ⨯

Abstract

Objective

This study conducts a rigorous meta-analysis of existing literature to rigorously examine the efficacy of Proprioceptive Neuromuscular Facilitation (PNF) in ameliorating functional deficits associated with Chronic Ankle Instability (CAI).

Methods

Literature searches were conducted in multiple databases including China National Knowledge Infrastructure (CNKI), VIP, Wanfang, China Biology Medicine disc (CBM), PubMed, EBSCO (Medline, CINAHL, SPORTDiscus, and Rehabilitation & Sports Medicine Source), Embase, ScienceDirect, ProQuest, Cochrane Library, and Web of Science for randomized controlled trials assessing the effects of Proprioceptive Neuromuscular Facilitation interventions on patients with Chronic Ankle Instability. The publication timeframe spanned from the inception of each database until April 10, 2024. Meta-analysis was performed using STATA 12 software on the included studies.

Results

① A total of 12 randomized controlled trials were included, encompassing 405 patients with Chronic Ankle Instability, demonstrating a generally high methodological quality of the literature.② Meta-analysis results indicate that compared to the control group, Proprioceptive Neuromuscular Facilitation (PNF) significantly enhanced the balance ability of patients with Chronic Ankle Instability as measured by the Y Balance Test (YBT) (Weighted Mean Difference (WMD) = 3.61, 95% CI [2.65, 4.56], z = 7.42, P<0.001) and the Star Excursion Balance Test (SEBT) (WMD = 5.50, 95% CI [3.80, 7.19], z = 6.36, P<0.001), with improvement in all eight directions of SEBT balance ability surpassing that of the control group (P<0.05); muscle strength around the ankle (SMD) = 0.19, 95% CI [0.03, 0.36], z = 2.26, P = 0.024), with both Plantar flexion and Dorsal flexion muscle strength improvements exceeding those of the control group (P<0.05); Visual Analog Scale (VAS) (WMD = -1.39, 95% CI [-1.72, -1.06], z = 8.23, P<0.001); Ankle instability questionnaire (WMD = 2.91, 95% CI [1.92, 3.89], z = 5.78, P<0.001).③Descriptive analysis results showed that the differences in Inversion Joint Position Sense and Dorsiflexion range of motion between the PNF and control groups were not statistically significant (P>0.05), however, the effects of PNF training persisted for a certain period even after cessation of treatment.

Conclusion

Proprioceptive Neuromuscular Facilitation (PNF) can significantly improve balance, muscle strength, and pain in patients with Chronic Ankle Instability (CAI). While PNF has shown improvements in joint position sense and dorsiflexion range of motion for CAI patients, with effects that remain for a period thereafter, these improvements were not significantly different when compared to the control group. Further research is required to substantiate these specific effects.

Citation: Yin Y, Wang J, Lin Q, Luo Y, Liu Y, Sun J (2025) Effect of proprioceptive neuromuscular facilitation on patients with chronic ankle instability: A systematic review and meta-analysis. PLoS ONE 20(1): e0311355. https://doi.org/10.1371/journal.pone.0311355

Editor: Renato S. Melo, UFPE: Universidade Federal de Pernambuco, BRAZIL

Received: June 21, 2024; Accepted: September 17, 2024; Published: January 9, 2025

Copyright: © 2025 Yin et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All data relevant to the study are included in the article or uploaded as supplementary information. The data supporting the findings of this study are provided in the supplemental material.

Funding: The author(s) received no specific funding for this work.

Competing interests: The authors have declared that no competing interests exist.

Introduction

Ankle sprain is a common musculoskeletal injury in sports [1], with up to 50% of patients with acute ankle sprain not seeking formal medical management. Repeated sprains can occur several months or years after the initial injury, developing into Chronic ankle instability (CAI) [2, 3]. CAI is characterized by a range of symptoms, which include reduced muscle strength in the area surrounding the ankle, delayed muscular activation, ligamentous laxity, compromised ankle stability, impaired proprioception, and restricted joint mobility [4]. Despite systematic rehabilitation attempts in the later stages, up to 70% of patients still exhibit various functional impairments within six months [5]. These deficiencies can significantly affect the physical activity levels and quality of life of individuals with CAI [6], potentially serving as principal risk factors for the early onset of post-traumatic osteoarthritis and joint degenerative diseases [7, 8]. Consequently, the rehabilitation of CAI patients has emerged as an important public health concern [9].

Current therapeutic approaches for CAI include both surgical and non-surgical interventions. The optimal surgical strategies and postoperative outcomes are subjects of ongoing debate [10, 11]. An increasing body of research and clinical practice underscores the manifest advantages of exercise-based non-surgical treatment in reducing the recurrence of ankle sprains and improving joint functionality in CAI patients [12]. Additionally, non-surgical treatments effectively circumvent the risks associated with surgery and reduce medical costs, thus garnering favor among patients and healthcare providers alike.

Proprioceptive Neuromuscular Facilitation (PNF) is a rehabilitative training methodology that employs proprioceptive stimuli, such as stretching, joint compression, traction, and resistive actions, combined with spiral and diagonal movement patterns, to foster the restoration of motor function and enhance neuromuscular responsiveness [13]. PNF has been shown to relax muscles, alleviate pain, increase joint range of motion, strengthen muscular force, and improve stability, bodily coordination, and postural control. These benefits play a significant and positive role in maintaining or enhancing physical ability and facilitating post-activity fatigue recovery [14, 15].

Principally utilized in the rehabilitation following neural damage [16, 17], PNF has demonstrated efficacy in ameliorating motor function impairments resulting from neurological injuries [18]. It has also been applied in musculoskeletal rehabilitation, especially vital in the recuperation from conditions such as low back pain, rotator cuff injuries, and frozen shoulder [19–21]. Recently, PNF has been adapted to the rehabilitation of individuals with CAI, though its effects on balance and functional recovery remain controversial [22–24]. To comprehensively assess the impact of PNF in the rehabilitation of CAI, this study employs a Meta-analysis to synthesize and scrutinize the effectiveness of PNF interventions on CAI rehabilitation outcomes. This objective evaluation aims to reinforce the role of PNF in CAI recovery and provide a more substantiated basis for clinical practice.

Methods

Protocol and registration

This meta-analysis has been registered in the PROSPERO system evaluation database (CRD42024533915) and completed according to the PRISMA list [25]. Since all data in this study were derived from experimental articles without direct recruitment or collection of patient information, ethical approval or consent statements were not necessary.

Literature search

This meta-analysis retrieved databases such as China National Knowledge Infrastructure (CNKI), VIP, Wanfang, China Biomedical Literature Database (CBM), PubMed, EBSCO (Medline, CINAHL, SPORT Discus, Rehabilitation & Sports Medicine Source), Embase, Science Direct, ProQuest, Cochrane Library and Web of Science. The search time was set from the establishment of the database to April 2024, and the last search date was April 10, 2024. The search strategy involved a combination of subject words and free words, encompassing terms such as muscle stretching exercises, proprioceptive neuromuscular facilitation, PNF, PNF stretching, Proprioceptive Neuromuscular Facilitation Techniques, ankle sprain, ankle injury, ankle instability, chronic ankle instability, function ankle instability, CAI, FAI. Through the retrieval method of subject words combined with free words, manual retrieval is carried out and the references included in the literature are traced back to supplement and obtain more relevant documents. The retrieval strategy of the PubMed database is taken as an example (See Fig 1). (See S1 File. Tables for the complete search strategy of each database)

thumbnail
Download:
Fig 1. Search strategy terms of PubMed.

https://doi.org/10.1371/journal.pone.0311355.g001

Literature inclusion, exclusion criteria and outcome indicator

According to the PICOS principle, the inclusion, exclusion criteria and outcome indicator for the literature are as follows [26] (See Table 1):

thumbnail
Download:
Table 1. PICOS framework.

https://doi.org/10.1371/journal.pone.0311355.t001

Literature screening and information extraction

Literature screening and data extraction were conducted independently by two researchers (Yin and Luo), who would cross-verify their findings. In case of discrepancies, discussions would ensue or a third researcher (Liu) would be consulted for resolution. During the literature screening process, titles were first reviewed to eliminate any obviously irrelevant studies, followed by a more detailed examination of abstracts and full texts to determine their suitability for inclusion. Should it be necessary, contact would be made with the authors of the original studies via email or telephone to acquire any ambiguous information. Data extraction primarily encompassed the following aspects:①Basic information of the included studies, such as study titles, lead authors, and the publication year;②basic characteristics of the study participants, including the number of cases and age across groups;③detailed descriptions of the interventions;④key elements for the assessment of risk of bias;⑤ outcome measures and result data of interest.

(The names of the data extractors and the date of data extraction are in S2 File)

Assessment of risk of bias for study quality assessment

The quality assessment of the literature was independently conducted by two researchers (Lin and Luo), with cross-verification of results. In the event of a discrepancy in opinions, consultation with a third researcher (Liu) would be sought for resolution. Bias risk was independently evaluated using the second edition of the Cochrane Risk of Bias Tool (RoB2), which comprises five domains [27, 28]. The PEDro scale was utilized to assess the risk of bias and methodological quality of the included studies [29], with a scoring range of 0–10 points. Evaluation criteria dictated that one point be awarded for each of the items 2–11, with a total possible score of 10 points. Studies scoring ≥6 points are considered high quality, those with 4–5 points are deemed moderate quality, and scores of ≤3 are rated as low quality [30].

Statistical analysis

Statistical analyses were conducted using STATA.12 (Stata Corporation, College Station, TX, USA) to process the data metrics from the included studies. It can quickly and efficiently identify publication bias and accurately and reliably generate meta-analysis plots [31]. For continuous outcomes across all included studies, analysis was conducted using mean difference (MD) and 95% confidence interval (CI). When the units of measurement were identical, weighted mean difference (WMD) was selected as the measure of effect, while if the units of measurement varied, standard mean difference (SMD) was utilized as the measure of effect. Analysis was completed with a 95% confidence interval (CI). Heterogeneity in the data was assessed using chi-squared and I2 tests. An I2 of 0 indicates no inconsistency among the included studies, while a higher I2 value implies greater heterogeneity. A significance threshold for heterogeneity was set at P≤0.1 and I2>50%. For P>0.1 and I2<50%, a fixed-effects model was employed for the meta-analysis, whereas other scenarios utilized a random-effects model [32]. Studies with ≥5 entries underwent Egger’s test for publication bias and sensitivity analyses, with P<0.05 denoting statistical significance [33].

Results

Study selection and characteristics

Following the database search, an initial retrieval yielded 288 literatures, comprising 28 in Chinese and 260 in English, with no additional literature obtained through other channels. Subsequently, EndNote X9 was utilized to merge and remove duplicates, resulting in the exclusion of 152 redundant literatures. Titles and abstracts were reviewed, leading to the selection of 136 literatures. Full-text readings further narrowed the field to 32 literatures. According to the inclusion and exclusion criteria, ultimately 12 literatures were determined to be suitable for inclusion in the analysis [14, 22–24, 34–41] (The literature excluded after reading the full text is detailed in S3 File).

The literature screening process and results are shown in Fig 2. According to the inclusion and exclusion criteria, a total of 12 literatures [14, 22–24, 34–41] were selected, encompassing 405 patients with CAI. Among these, six literatures [14, 22, 35–38] utilized PNF as the primary intervention in the experimental group. Four literatures reported the experimental group receiving PNF combined with core stability and conventional rehabilitation training [34, 39–41]. The control interventions included conventional rehabilitation training in four literatures [24, 34, 39, 40], no intervention in two literatures [14, 38], and bicycle training in two literatures [35, 36]. All included literatures were published in the last decade, accounting for 100% of the selection (2015 to 2023). Basic information about the included literature can be found in Table 2, and detailed characteristics of the included literature are presented in Table 3.

thumbnail
Download:
Fig 2. Study selection represented by PRISMA flowchart.

https://doi.org/10.1371/journal.pone.0311355.g002

thumbnail
Download:
Table 2. Basic information about the included literature.

https://doi.org/10.1371/journal.pone.0311355.t002

thumbnail
Download:
Table 3. Detailed characteristics of the included literature.

https://doi.org/10.1371/journal.pone.0311355.t003

Quality and risk of bias

For the 12 included literatures, bias risk was assessed using the second edition of the Cochrane Risk of Bias Tool (RoB2), with all articles deemed to be at low risk. According to the PEDro scoring system, all included articles were of medium to high quality (ranging from 5 to 10), with an average score of 6.9, indicating that the methodological quality of the studies included in the reports was high-quality. This suggests that the overall quality of the literature is high (See Fig 3/Table 4).

thumbnail
Download:
Fig 3. Risk of bias assessed using RoB 2 tool.

https://doi.org/10.1371/journal.pone.0311355.g003

thumbnail
Download:
Table 4. PEDro scale score of included literature.

https://doi.org/10.1371/journal.pone.0311355.t004

The Cochrane Risk of Bias Tool (RoB2) is detailed in S4 File.

Effect of PNF on balance

YBT: Three literatures involving 132 patients were included, reporting on the effect of PNF on CAI patients’ YBT scores. The data from these studies showed no heterogeneity: p = 0.412, I2 = 0%, hence a random-effects model was applied for analysis. The meta-analysis results indicated that PNF intervention led to a significant improvement in YBT scores compared to the control group (WMD = 3.61, 95%CI(2.65, 4.56), z = 7.42, P<0.001), suggesting statistically significant outcomes(See Fig 4).

thumbnail
Download:
Fig 4. Meta-analysis of the effect of PNF on Y balance test.

https://doi.org/10.1371/journal.pone.0311355.g004

SEBT: Four literatures, encompassing 144 patients, reported on the effect of PNF on CAI patients’ SEBT scores. The included studies showed significant heterogeneity: p = 0.00, I2 = 94.4%, therefore, a random-effects model was used for analysis. The meta-analysis results demonstrated that PNF intervention improved SEBT more effectively than the control group (WMD = 5.50, 95%CI (3.80, 7.19), z = 6.36, P<0.001), indicating statistically significant results (See Fig 5). Heterogeneity was substantially attributed to the study by Jiesong Y [23]; upon its exclusion, the remaining three articles showed no significant statistical heterogeneity: p = 0.092, I2 = 29.0%, and a fixed-effects model was applied; the meta-analysis indicated (WMD = 2.47, 95%CI(1.85, 3.09), z = 7.81, P<0.001) (The meta-graph on exclusion heterogeneity research is in S5 File). Further subgroup analysis of the eight directions of SEBT (Anterior (ANT), Anterolateral (ALAT), Anteromedial (AMED), Medial (MED), Posterior (POST), Lateral (LAT), Posterolateral (PLAT), and Posteromedial (PMED)) showed:①ANT (WMD = 1.96, 95%CI(0.42,3.49), P = 0.012);②ALAT (WMD = 1.90, 95%CI(0.47, 3.32), P = 0.009);③AMED (WMD = 3.44, 95%CI(1.21,5.67), P = 0.003);④MED (WMD = 2.93, 95%CI(1.18,4.68), P = 0.001);⑤POST (WMD = 3.12, 95%CI(0.88,5.36), P = 0.006)⑥LAT (WMD = 2.82, 95%CI(0.81,4.82), P = 0.006);⑦PLAT (WMD = 2.57, 95%CI(0.88,4.26), P = 0.003); ⑧PMED (WMD = 2.20, 95%CI(0.54, 3.87), P = 0.009). These assessments demonstrated that PNF intervention improved balance in all eight directions of the SEBT in subjects with Chronic Ankle Instability compared to the control group.

thumbnail
Download:
Fig 5. Meta-analysis of the effect of PNF on star excursion balance test.

https://doi.org/10.1371/journal.pone.0311355.g005

Effect of PNF on muscle strength

Muscle strength was assessed using both an isokinetic dynamometer and an isometric handheld dynamometer. The former was used to measure the relative peak torque of the muscles [42], whereas the latter evaluated the maximum peak force [14]. Higher values of relative peak torque and maximum peak force indicate greater muscle strength. Since the units of measurement for the two methods differ, the standardized mean difference (SMD) was chosen for data synthesis. Four literatures reported the effects of PNF on Muscle Strength, with no significant heterogeneity observed among the included studies: p = 0.075, I2 = 36.0%. Therefore, a fixed-effect model was applied for analysis. The results indicated that Muscle Strength improvements post-PNF intervention were superior to the control group (SMD = 0.19, 95%CI(0.03, 0.36), z = 2.26, p = 0.024), which is statistically significant. Subgroup analysis for muscle strength in the four directions of ankle movement showed the following: for Plantar flexion (SMD = 0.39, 95%CI(0.09,0.68), P = 0.010), Dorsal flexion (SMD = 0.33, 95%CI(0.04, 0.63), P = 0.026), Varus (SMD = 0.00, 95%CI(-0.40,0.40), P = 1.00), and Eversion (SMD = -0.24, 95%CI(-0.64,0.17), P = 0.249). The results demonstrate that PNF significantly improved Muscle Strength in the Plantar and Dorsal flexion for CAI patients compared to the control group, while no superior improvement was observed in the Varus and Eversion directions (see Fig 6).

thumbnail
Download:
Fig 6. Meta-analysis of the effect of PNF on muscle strength.

https://doi.org/10.1371/journal.pone.0311355.g006

Effect of PNF on self-assessment

VAS: Four literatures reported on the effects of PNF on VAS, with no heterogeneity observed among the included studies (p = 0.106, I2 = 51%). Therefore, a fixed-effects model was used for the analysis. The results demonstrated that the improvement in VAS following PNF intervention was superior to that of the control group (WMD = -1.39, 95% CI [-1.72, -1.06], z = 8.23, p<0.001), and the results were statistically significant (see Fig 7).

thumbnail
Download:
Fig 7. Meta-analysis of the effect of PNF on VAS.

https://doi.org/10.1371/journal.pone.0311355.g007

Ankle Instability Questionnaire: Seven literatures involving 310 patients were included to assess the effect of PNF on the Ankle Instability Questionnaire in patients with chronic ankle instability (CAI). There was heterogeneity among the included studies (p = 0.069, I2 = 48.6%), so a random-effects model was used for the analysis. The meta-analysis results indicated that PNF intervention significantly improved the Ankle Instability Questionnaire scores compared to the control group (WMD = 2.91, 95% CI [1 92, 3.89], z = 5.78, p<0.001) (see Fig 8). The study by Alahmari KA [38] contributed significantly to the heterogeneity. Upon exclusion of this literature, the remaining six literatures showed no statistical heterogeneity (p = 0.781, I2 = 0%), and a fixed-effects model was then used for the analysis. The meta-analysis results demonstrated a significant improvement in the Ankle Instability Questionnaire scores with PNF intervention (WMD = 3.36, 95% CI [2.70, 4.02], z = 9.95, p<0.001) (The meta-graph on exclusion heterogeneity research is in S5 File).

thumbnail
Download:
Fig 8. Meta-analysis of the effect of PNF on Ankle instability questionnaire.

https://doi.org/10.1371/journal.pone.0311355.g008

Descriptive analysis results

Effect of PNF on inversion joint position sense.

Only two literatures reported on the effects of PNF on Inversion Joint Position Sense, which did not meet the criteria for a meta-analysis, thus descriptive analysis was used. Research by Linhua X and Mengfan S, et al. [34, 40] found that after a period of PNF training in patients with CAI, the difference in Inversion Joint Position Sense between the experimental group and the control group was not statistically significant (P>0.05).

Effect of PNF on Dorsiflexion range of motion.

Only two literatures reported on the effects of PNF on the Dorsiflexion range of motion, which did not meet the criteria for a meta-analysis, thus a descriptive analysis was employed. Research conducted by Lazarou L, et al. [37] found that after 4 weeks of PNF training for CAI patients, and a study by Alahmari K A, et al. [38] which provided training for CAI patients four times a week over a continuous three-week period, improvements in Dorsiflexion range of motion were not superior to the control group. However, follow-up results from both studies demonstrated that the effectiveness of PNF training was maintained for some time even after the cessation of treatment.

Publication bias.

Egger’s test was utilized to analyze publication bias for the following indicators: the Ankle Instability Questionnaire, Plantar Flexion Muscle Strength, and Dorsal Flexion Muscle Strength. Results revealed no significant publication bias for these indicators, with the Ankle Instability Questionnaire (t = -0.15, P = 0.889, P>0.05), Plantar Flexion (t = -2.56, P = 0.083, P>0.05), and Dorsal Flexion (t = -0.47, P = 0.669, P>0.05) (Publication bias is in the S6 File).

Discussion

Chronic Ankle Instability (CAI) is defined as the structural or functional alterations in the ankle and surrounding joint tissues due to recurrent sprains [43], resulting in sensations of instability, movement restrictions, intermittent pain, muscle weakness around the ankle, ligament laxity, and other functional impairments [44], severely impacting the physical health and quality of life of active individuals. Thus, the main objectives of the intervention are to enhance the muscle strength surrounding the ankle, improve proprioception, and better balance capabilities. From an evidence-based medicine perspective, this study incorporates 12 literatures, covering a total of 405 CAI patients. The meta-analysis results reveal that proprioceptive neuromuscular facilitation techniques significantly improve balance, muscle strength, and joint position sense, and alleviate pain in patients with CAI.

Chronic Ankle Instability (CAI) often manifests as abnormalities in postural control to varying degrees [45]. After an initial ankle sprain, the anterior talofibular ligament, posterior talofibular ligament, and calcaneofibular ligament may become lax to varying extents, or even partially torn, leading to damage of proprioceptors that perceive joint speed and position during movement [46]. This results in abnormal transmission of postural control pathway information, subsequently causing postural control disorders and a decline in balance [47]. The Y Balance Test (YBT, ICC = 0.88–0.99) [48] and the Star Excursion Balance Test (SEBT, ICC = 0.85–0.96) [49] are dynamic tests requiring strength, flexibility, and proprioception. They are commonly used to assess dynamic body balance capabilities and lower limb dynamic postural control in patients with CAI [50]. Meta-analysis results indicate that PNF shows a significant advantage over conventional training in improving postural control abilities in patients with CAI (P<0.05). The results suggest that PNF techniques can improve lower limb postural control, aligning with previous findings [23, 38]. PNF techniques often involve dynamic stretching, joint compression, traction, and isometric contractions, which stimulate joint proprioceptors, increase neuronal excitability and conduction velocity, and improve the efficiency of neuromuscular conduction pathways, thereby enhancing motor control [51]. Furthermore, PNF techniques, through repetitive and complex multi-planar movements, involvement and coordination of multiple joints, muscle groups, and sensory inputs (visual, tactile, and proprioceptive feedback), stimulate the sensory processing centers in the brain and spinal cord. This improves the synergy and synchrony between muscles, strengthens the feedback regulation loop of the nervous system, and enhances the central nervous system’s perception and response capabilities to movement [52, 53].

Muscle strength is foundational for maintaining postural control and balance stability. During high-intensity activities such as walking, running, and jumping, robust muscle strength can effectively buffer the ground reaction forces [54]. Patients with CAI commonly exhibit a decrease in muscle strength during inversion and eversion of the ankle, as well as prolonged muscle response times [55]. If this persists, it can lead to muscle strength asymmetry. Asymmetry often results in excessive muscle compensation and increases the risk of recurrent sports injuries [56]. Therefore, strengthening the muscle strength around the ankle is key to preventing the recurrence of ankle sprains. Meta-analysis results demonstrate that PNF has a significant advantage over conventional training in improving the muscle strength around the ankle in CAI patients, with particularly noticeable improvements in Plantar flexion and Dorsal flexion (P<0.05). Specific movement patterns in PNF techniques, such as the D2 pattern, and the use of Hold-Relax, rhythmic stabilization (RS), and combination of isotonics (COI), can thoroughly activate and strengthen the musculature surrounding the ankle joint [57]. The repetitive static and dynamic exercises along spiral diagonals in PNF techniques not only stimulate the muscles and intra-articular receptors but also activate the motor-evoked potentials in the prefrontal cortex of the brain [58]. This increases the electromyographic signal output, encouraging the recruitment of more neuromuscular units, enhancing the rate and synchronicity of muscle fiber recruitment, and activating the coordination of the ankle’s surrounding musculature (such as the peroneal muscle group, tibialis anterior, and triceps surae). This helps maintain joint stability during prolonged activities [37]. Compared to other interventions, PNF training also involves additional sensory stimuli (tactile, visual, or verbal) to better facilitate neuromuscular responses and enhance the subject’s neural control of the muscles [59].

CAI patients have a high recurrence rate and are often overlooked in everyday settings. Regularly conducting subjective assessments and descriptions of CAI patients using ankle function scales to judge pain, loss of control, and motor function status can help understand the effectiveness of CAI rehabilitation and the implementation and improvement of rehabilitation strategies [60]. Currently, there is still a lack of a "gold standard" for evaluating CAI scales. Researchers make subjective judgments about CAI using various scales developed to evaluate ankle function, and there is no unified standard for the reliability and validity of these scales [61]. The functional scales used in the included studies of this article, namely AJFAT (ICC = 0.94), FADI (ICC = 0.84), and CAIT (ICC = 0.95), all show good internal reliability. The meta-analysis results revealed that ankle joint function significantly improved following CAI intervention through PNF training (P<0.05); PNF can effectively alleviate the sensation of pain around the ankle in CAI patients(p<0.001). This may be attributed to the fact that PNF training, through dynamic movements and isometric contractions, promotes blood circulation around the ankle joint, accelerating the repair and regeneration of damaged tissues, thereby reducing inflammation and associated pain [62]. PNF can alleviate pain, help patients avoid discomfort during movement and daily activities, improve joint function and quality of life, and reduce the risk of secondary injuries.

Joint Position Sense refers to the ability to perceive joint positions, which is essential for executing precise movements, maintaining correct posture and balance, and preventing excessive joint extension or injury [63]. In CAI patients, repeated ankle sprains can lead to the impairment of internal sensors (such as muscle spindles, Golgi tendon organs, and joint receptors), resulting in abnormal ankle proprioception [64]. The results of this study indicate that PNF can improve the Joint Position Sense in CAI patients, but its effectiveness is not superior to conventional intervention measures. A meta-analysis conducted by AKASAKI H et al. [65] on the effects of PNF on joint position sense showed that PNF did not provide significant advantages, which is consistent with the results of this study. CAI patients often experience anterior displacement of the talus after a sprain, which can prevent effective posterior sliding during movement, leading to an inability to achieve a stable closed position of the joint and limiting dorsiflexion activity [66]. The study results show that PNF can improve dorsiflexion mobility in CAI patients, though not superior to the control group, it is noteworthy that the improvement effects can be maintained for a certain period after PNF training.

Study limitations

The limitations of this meta-analysis include: ① Only 12 literatures were included, with a relatively small data sample size, and bias analysis was not conducted, which may affect the conclusions; ② Only two of the included studies conducted follow-ups after the training, the remaining nine did not follow up on the intervention effects;③ The experimental designs of the included studies, assessment indicators, and subject characteristics varied, which impacted the reference value of the results; ④ The control groups lacked a unified standard, affecting the accuracy of the results.

Conclusions

In conclusion, the current meta-analysis demonstrates that proprioceptive neuromuscular facilitation (PNF) significantly enhances balance, and muscle strength, and alleviates pain in patients with Chronic Ankle Instability (CAI). PNF has been observed to improve joint position sense and dorsiflexion range of motion among CAI patients, with sustained effects observed for a period following the intervention. In clinical treatment, PNF training is recommended for improving pain, balance ability, and muscle strength in patients with CAI. However, additional therapeutic approaches should be incorporated if patients with CAI experience significant mobility limitations.

For future research directions, we propose the following: (1) To optimize research protocols and experimental designs by using PNF as the sole variable in the experimental group, and including other interventions, either without PNF or with sham PNF, in the control group to determine the combined effects of PNF and other interventions; (2) To increase the sample size and conduct medium- and long-term follow-ups on CAI patients treated with PNF to assess whether the improvements are sustained over time; (3) To further conduct high-quality randomized clinical trials in clinical settings to provide more evidence-based support for clinical application.

Acknowledgments

We express our gratitude to all professors and colleagues for their unwavering support throughout this project. We also extend our sincere appreciation to the reviewers for their rigorous evaluation of our work and their invaluable recommendations for further improvement.

References

  1. 1. Picot B, Fourchet F, Lopes R, Rauline G, Freiha K, D’Hooghe P, et al. Low Ankle-GO Score While Returning to Sport After Lateral Ankle Sprain Leads to a 9-fold Increased Risk of Recurrence: A Two-year Prospective Cohort Study. Sports medicine—open. 2024;10(1):23. Epub 2024/03/08. pmid:38453775; PubMed Central PMCID: PMC10920508.
  2. 2. Whalan M, Lovell R, McCunn R, Sampson JA. The incidence and burden of time loss injury in Australian men’s sub-elite football (soccer): A single season prospective cohort study. Journal of science and medicine in sport. 2019;22(1):42–7. Epub 2018/06/10. pmid:29884595.
  3. 3. Terada M, Kosik KB, McCann RS, Drinkard C, Gribble PA. Corticospinal activity during a single-leg stance in people with chronic ankle instability. Journal of sport and health science. 2022;11(1):58–66. Epub 2020/09/01. pmid:32866712; PubMed Central PMCID: PMC8847849.
  4. 4. Gribble PA, Delahunt E, Bleakley C, Caulfield B, Docherty C, Fourchet F, et al. Selection criteria for patients with chronic ankle instability in controlled research: a position statement of the International Ankle Consortium. British journal of sports medicine. 2014;48(13):1014–8. Epub 2013/11/21. pmid:24255768.
  5. 5. Delahunt E, Bleakley CM, Bossard DS, Caulfield BM, Docherty CL, Doherty C, et al. Clinical assessment of acute lateral ankle sprain injuries (ROAST): 2019 consensus statement and recommendations of the International Ankle Consortium. British journal of sports medicine. 2018;52(20):1304–10. Epub 2018/06/11. pmid:29886432.
  6. 6. Hubbard-Turner T, Wikstrom EA, Guderian S, Turner MJ. An Acute Lateral Ankle Sprain Significantly Decreases Physical Activity across the Lifespan. Journal of sports science & medicine. 2015;14(3):556–61. Epub 2015/09/04. pmid:26336342; PubMed Central PMCID: PMC4541119.
  7. 7. Gribble PA, Kleis RE, Simon JE, Vela LI, Thomas AC. Differences in health-related quality of life among patients after ankle injury. Frontiers in sports and active living. 2022;4:909921. Epub 2022/08/23. pmid:35992155; PubMed Central PMCID: PMC9382240.
  8. 8. Houston MN, Hoch JM, Hoch MC. College Athletes With Ankle Sprain History Exhibit Greater Fear-Avoidance Beliefs. Journal of sport rehabilitation. 2018;27(5):419–23. Epub 2017/06/13. pmid:28605298.
  9. 9. Thompson C, Schabrun S, Romero R, Bialocerkowski A, van Dieen J, Marshall P. Factors Contributing to Chronic Ankle Instability: A Systematic Review and Meta-Analysis of Systematic Reviews. Sports medicine (Auckland, NZ). 2018;48(1):189–205. Epub 2017/09/10. pmid:28887759.
  10. 10. Guelfi M, Zamperetti M, Pantalone A, Usuelli FG, Salini V, Oliva XM. Open and arthroscopic lateral ligament repair for treatment of chronic ankle instability: A systematic review. Foot and ankle surgery: official journal of the European Society of Foot and Ankle Surgeons. 2018;24(1):11–8. Epub 2018/02/08. pmid:29413768.
  11. 11. Robbins JB, Stahel SA, Morris RP, Jupiter DC, Chen J, Panchbhavi VK. Radiographic Anatomy of the Lateral Ankle Ligament Complex: A Cadaveric Study. Foot & ankle international. 2024;45(2):179–87. Epub 2023/11/23. pmid:37994643; PubMed Central PMCID: PMC10860354.
  12. 12. Doherty C, Delahunt E, Caulfield B, Hertel J, Ryan J, Bleakley C. The incidence and prevalence of ankle sprain injury: a systematic review and meta-analysis of prospective epidemiological studies. Sports medicine (Auckland, NZ). 2014;44(1):123–40. Epub 2013/10/10. pmid:24105612.
  13. 13. Hindle KB, Whitcomb TJ, Briggs WO, Hong J. Proprioceptive Neuromuscular Facilitation (PNF): Its Mechanisms and Effects on Range of Motion and Muscular Function. Journal of human kinetics. 2012;31:105–13. Epub 2013/03/15. pmid:23487249; PubMed Central PMCID: PMC3588663.
  14. 14. Hall EA, Docherty CL, Simon J, Kingma JJ, Klossner JC. Strength-training protocols to improve deficits in participants with chronic ankle instability: a randomized controlled trial. Journal of athletic training. 2015;50(1):36–44. Epub 2014/11/05. pmid:25365134; PubMed Central PMCID: PMC4299733.
  15. 15. Lial L, Moreira R, Correia L, Andrade A, Pereira AC, Lira R, et al. Proprioceptive neuromuscular facilitation increases alpha absolute power in the dorsolateral prefrontal cortex and superior parietal cortex. Somatosensory & motor research. 2017;34(3):204–12. Epub 2017/11/04. pmid:29096587.
  16. 16. Boob MA, Kovela RK. Effectiveness of Pelvic Proprioceptive Neuromuscular Facilitation Techniques on Balance and Gait Parameters in Chronic Stroke Patients: A Randomized Clinical Trial. Cureus. 2022;14(10):e30630. Epub 2022/11/26. pmid:36426303; PubMed Central PMCID: PMC9682972.
  17. 17. Sharma A, Saxena A. Combined Effect of Pelvic Proprioceptive Neuromuscular Facilitation with Core Strengthening on Trunk Control, Balance, and Gait in Paraplegia. International journal of applied & basic medical research. 2023;13(4):263–5. Epub 2024/01/17. pmid:38229730; PubMed Central PMCID: PMC10789460.
  18. 18. Gunning E, Uszynski MK. Effectiveness of the Proprioceptive Neuromuscular Facilitation Method on Gait Parameters in Patients With Stroke: A Systematic Review. Archives of physical medicine and rehabilitation. 2019;100(5):980–6. Epub 2018/12/26. pmid:30582917.
  19. 19. Arcanjo FL, Martins JVP, Moté P, Leporace G, Oliveira DA, Sousa CS, et al. Proprioceptive neuromuscular facilitation training reduces pain and disability in individuals with chronic low back pain: A systematic review and meta-analysis. Complementary therapies in clinical practice. 2022;46:101505. Epub 2021/12/03. pmid:34852989.
  20. 20. Lin P, Yang M, Huang D, Lin H, Wang J, Zhong C, et al. Effect of proprioceptive neuromuscular facilitation technique on the treatment of frozen shoulder: a pilot randomized controlled trial. BMC musculoskeletal disorders. 2022;23(1):367. Epub 2022/04/22. pmid:35443651; PubMed Central PMCID: PMC9020070.
  21. 21. Junji C, XU G, Liu X, Simao X. Effects of PNF Training on Functional Recovery of Sports Rotator Cuff Injury. Journal of Medical Biomechanics. 2022;37(01):174–9.
  22. 22. Yuduo L, Xianglin W. Comparison of effects of proprioceptive neuromuscular facilitation and whole body vibration training on functional ankle instability. Chin J Rehabil Theory Pract. 2022;28(07):776–82.
  23. 23. Jiesong Y, Changyan L, Zhuangzhuang Z. Effect of proprioceptive neuromuscular facilitation technique on functional ankle instability. Journal of Nantong University (Medical Sciences). 2023;43(01):63–6.
  24. 24. Renyi , Wang C, Yaohua Z. Effect of proprioceptive neuromuscular facilitation combined with neuromuscular electrical stimulation on chronic ankle instability. Chin J Rehabil Theory Pract. 2023;29(07):750–5.
  25. 25. Moher D, Shamseer L, Clarke M, Ghersi D, Liberati A, Petticrew M, et al. Preferred reporting items for systematic review and meta-analysis protocols (PRISMA-P) 2015 statement. Systematic reviews. 2015;4(1):1. Epub 2015/01/03. pmid:25554246; PubMed Central PMCID: PMC4320440.
  26. 26. Schardt C, Adams MB, Owens T, Keitz S, Fontelo P. Utilization of the PICO framework to improve searching PubMed for clinical questions. BMC medical informatics and decision making. 2007;7:16. Epub 2007/06/19. pmid:17573961; PubMed Central PMCID: PMC1904193.
  27. 27. Sterne JAC, Savović J, Page MJ, Elbers RG, Blencowe NS, Boutron I, et al. RoB 2: a revised tool for assessing risk of bias in randomised trials. BMJ (Clinical research ed). 2019;366:l4898. Epub 2019/08/30. pmid:31462531.
  28. 28. Higgins JP, Altman DG, Gøtzsche PC, Jüni P, Moher D, Oxman AD, et al. The Cochrane Collaboration’s tool for assessing risk of bias in randomised trials. BMJ (Clinical research ed). 2011;343:d5928. Epub 2011/10/20. pmid:22008217; PubMed Central PMCID: PMC3196245 at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare support from the Cochrane Collaboration for the development and evaluation of the tool described; they have no financial relationships with any organisations that might have an interest in the submitted work in the previous three years and no other relationships or activities that could appear to have influenced the submitted work.
  29. 29. Maher CG, Sherrington C, Herbert RD, Moseley AM, Elkins M. Reliability of the PEDro scale for rating quality of randomized controlled trials. Physical therapy. 2003;83(8):713–21. Epub 2003/07/29. pmid:12882612.
  30. 30. de Morton NA. The PEDro scale is a valid measure of the methodological quality of clinical trials: a demographic study. The Australian journal of physiotherapy. 2009;55(2):129–33. Epub 2009/05/26. pmid:19463084.
  31. 31. Chaimani A, Mavridis D, Salanti G. A hands-on practical tutorial on performing meta-analysis with Stata. Evidence-based mental health. 2014;17(4):111–6. Epub 2014/10/08. pmid:25288685.
  32. 32. Cochrane M, Mitchell E, Hollingworth W, Crawley E, Trépel D. Cost-effectiveness of Interventions for Chronic Fatigue Syndrome or Myalgic Encephalomyelitis: A Systematic Review of Economic Evaluations. Applied health economics and health policy. 2021;19(4):473–86. Epub 2021/03/02. pmid:33646528; PubMed Central PMCID: PMC7917957 included in the narrative synthesis. Madeleine Cochrane, Eileen Mitchell, William Hollingworth, Esther Crawley, and Dominic Trépel have no other conflicts of interest or competing interests.
  33. 33. Irwig L, Macaskill P, Berry G, Glasziou P. Bias in meta-analysis detected by a simple, graphical test. Graphical test is itself biased. BMJ (Clinical research ed). 1998;316(7129):470; author reply -1. Epub 1998/03/11. pmid:9492687; PubMed Central PMCID: PMC2665595.
  34. 34. Mengfan S, Sheng H. Proprioceptive neuromuseular facilitation combined with core stability training can help relieve functional ankle instability. Chin J Phys Med Rehabil. 2017;39(11):834–8.
  35. 35. Hall EA, Chomistek AK, Kingma JJ, Docherty CL. Balance- and Strength-Training Protocols to Improve Chronic Ankle Instability Deficits, Part II: Assessing Patient-Reported Outcome Measures. Journal of athletic training. 2018;53(6):578–83. Epub 2018/07/12. pmid:29995462; PubMed Central PMCID: PMC6089028.
  36. 36. Hall EA, Chomistek AK, Kingma JJ, Docherty CL. Balance- and Strength-Training Protocols to Improve Chronic Ankle Instability Deficits, Part I: Assessing Clinical Outcome Measures. Journal of athletic training. 2018;53(6):568–77. Epub 2018/07/06. pmid:29975573; PubMed Central PMCID: PMC6089027.
  37. 37. Lazarou L, Kofotolis N, Pafis G, Kellis E. Effects of two proprioceptive training programs on ankle range of motion, pain, functional and balance performance in individuals with ankle sprain. Journal of back and musculoskeletal rehabilitation. 2018;31(3):437–46. Epub 2017/09/28. pmid:28946541.
  38. 38. Alahmari KA, Silvian P, Ahmad I, Reddy RS, Tedla JS, Kakaraparthi VN, et al. Effectiveness of Low-Frequency Stimulation in Proprioceptive Neuromuscular Facilitation Techniques for Post Ankle Sprain Balance and Proprioception in Adults: A Randomized Controlled Trial. BioMed research international. 2020;2020:9012930. Epub 2020/10/09. pmid:33029528; PubMed Central PMCID: PMC7532422.
  39. 39. Xuepeng X, Benping S. Study on the Application Effect of Proprioceptive Nerve Promotion Technique Combined with Core Stability Training on Patients with Functional Ankle Instability. Reflex therapy and rehabilitation medicine. 2020;1(20):158–60,63.
  40. 40. Linhua X. Effect of PNF Technology Combined with Core Stability Training on the Functional Rehabilitation of Lower Limbs in Patients with Functional Ankle Instability. Reflex therapy and rehabilitation medicine. 2021;(17).
  41. 41. Min P, Zhi W, Guan-jie L. Clinical efficacy of proprioceptive neuromuscular facilitation plus core stabilization training in patients with functional ankle instability. JOURNAL OF GUANGDONG MEDICAL UNIVERSITY. 2019;37(05):554–6.
  42. 42. Cain MS, Ban RJ, Chen YP, Geil MD, Goerger BM, Linens SW. Four-Week Ankle-Rehabilitation Programs in Adolescent Athletes With Chronic Ankle Instability. Journal of athletic training. 2020;55(8):801–10. Epub 2020/06/25. pmid:32577737; PubMed Central PMCID: PMC7462179.
  43. 43. Xiaojian S, Hanjia , Yu L, Xueqiang W, Peijie C. Research progress on pathological mechanism, evaluation and diagnosis of chronic ankle instability. Chin J Sports Med. 2019;38(09):816–24.
  44. 44. Yuying S, Liang P, Wei L1, Keqiang L, Ying Z, Jun L. Research Progress of Integrative Neuromuscular Training for the Rehabilitation and Prevention of Chronic Ankle Instability. CHINA SPORT SCIENCE AND TECHNOLOGY. 2023;59(07):47–52.
  45. 45. Yikun Y, Jialin W, Chaoming W, Junzhi S. Effect of Joint mobilization treatment for chronic ankle instability function recovery: A meta-analysis. Chinese Journal of Tissue Engineering Research. 2022;26(33):5407–12.
  46. 46. Ziaei Ziabari E, Lubberts B, Chiou D, Razi M, Haghpanahi M, Ashkani-Esfahani S, et al. Biomechanics Following Anatomic Lateral Ligament Repair of Chronic Ankle Instability: A Systematic Review. The Journal of foot and ankle surgery: official publication of the American College of Foot and Ankle Surgeons. 2021;60(4):762–9. Epub 2021/03/14. pmid:33712375.
  47. 47. Kawabata S, Ozone K, Minegishi Y, Oka Y, Terada H, Takasu C, et al. Chronic Ankle Joint Instability Induces Ankle Sensorimotor Dysfunction: A Controlled Laboratory Study. The American journal of sports medicine. 2024;52(3):739–49. Epub 2024/01/28. pmid:38279796.
  48. 48. Shaffer SW, Teyhen DS, Lorenson CL, Warren RL, Koreerat CM, Straseske CA, et al. Y-balance test: a reliability study involving multiple raters. Military medicine. 2013;178(11):1264–70. Epub 2013/11/05. pmid:24183777.
  49. 49. Olmsted LC, Carcia CR, Hertel J, Shultz SJ. Efficacy of the Star Excursion Balance Tests in Detecting Reach Deficits in Subjects With Chronic Ankle Instability. Journal of athletic training. 2002;37(4):501–6. Epub 2003/08/26. pmid:12937574; PubMed Central PMCID: PMC164384.
  50. 50. Plisky PJ, Gorman PP, Butler RJ, Kiesel KB, Underwood FB, Elkins B. The reliability of an instrumented device for measuring components of the star excursion balance test. North American journal of sports physical therapy: NAJSPT. 2009;4(2):92–9. Epub 2009/05/01. pmid:21509114; PubMed Central PMCID: PMC2953327.
  51. 51. Lee JH, Park SJ, Na SS. The effect of proprioceptive neuromuscular facilitation therapy on pain and function. Journal of physical therapy science. 2013;25(6):713–6. Epub 2013/11/22. pmid:24259836; PubMed Central PMCID: PMC3804994.
  52. 52. Guiu-Tula FX, Cabanas-Valdés R, Sitjà-Rabert M, Urrútia G, Gómara-Toldrà N. The Efficacy of the proprioceptive neuromuscular facilitation (PNF) approach in stroke rehabilitation to improve basic activities of daily living and quality of life: a systematic review and meta-analysis protocol. BMJ open. 2017;7(12):e016739. Epub 2017/12/14. pmid:29233831; PubMed Central PMCID: PMC5728303.
  53. 53. Areeudomwong P, Buttagat V. Comparison of Core Stabilisation Exercise and Proprioceptive Neuromuscular Facilitation Training on Pain-related and Neuromuscular Response Outcomes for Chronic Low Back Pain: A Randomised Controlled Trial. The Malaysian journal of medical sciences: MJMS. 2019;26(6):77–89. Epub 2020/01/08. pmid:31908589; PubMed Central PMCID: PMC6939725.
  54. 54. Liu K, Delaney AN, Kaminski TW. A review of the role of lower-leg strength measurements in ankle sprain and chronic ankle instability populations. Sports biomechanics. 2022;21(4):562–75. Epub 2021/05/04. pmid:33938376.
  55. 55. Mendez-Rebolledo G, Guzmán-Venegas R, Cruz-Montecinos C, Watanabe K, Calatayud J, Martinez-Valdes E. Individuals with chronic ankle instability show altered regional activation of the peroneus longus muscle during ankle eversion. Scandinavian journal of medicine & science in sports. 2024;34(1):e14535. Epub 2023/11/14. pmid:37957808.
  56. 56. Tashiro T, Maeda N, Sasadai J, Kotoshiba S, Sakai S, Suzuki Y, et al. Tensiomyographic Neuromuscular Response of the Peroneus Longus and Tibialis Anterior with Chronic Ankle Instability. Healthcare (Basel, Switzerland). 2021;9(6). Epub 2021/07/03. pmid:34200684; PubMed Central PMCID: PMC8230383.
  57. 57. Gao P, Tang F, Liu W, Mo Y. The effects of proprioceptive neuromuscular facilitation in treating chronic low back pain: A systematic review and meta-analysis. Journal of back and musculoskeletal rehabilitation. 2022;35(1):21–33. Epub 2021/07/13. pmid:34250930.
  58. 58. Medeiros DM, Martini TF. Chronic effect of different types of stretching on ankle dorsiflexion range of motion: Systematic review and meta-analysis. Foot (Edinburgh, Scotland). 2018;34:28–35. Epub 2017/12/11. pmid:29223884.
  59. 59. Alexandre de Assis IS, Luvizutto GJ, Bruno ACM, Sande de Souza LAP. The Proprioceptive Neuromuscular Facilitation Concept in Parkinson Disease: A Systematic Review and Meta-Analysis. Journal of chiropractic medicine. 2020;19(3):181–7. Epub 2020/12/29. pmid:33362441; PubMed Central PMCID: PMC7750824.
  60. 60. Yan Y, Dong-mei L, Hui L, Bing Y. Advance in Mechanism and Self-reported Measures of Functional Ankle Instability (review). Chin J Rehabil Theory Pract. 2018;24(06):671–7.
  61. 61. Donahue M, Simon J, Docherty CL. Critical review of self-reported functional ankle instability measures. Foot & ankle international. 2011;32(12):1140–6. Epub 2012/03/03. pmid:22381198.
  62. 62. Song Q, Shen P, Mao M, Sun W, Zhang C, Li L. Proprioceptive neuromuscular facilitation improves pain and descending mechanics among elderly with knee osteoarthritis. Scandinavian journal of medicine & science in sports. 2020;30(9):1655–63. Epub 2020/05/15. pmid:32407583.
  63. 63. Proske U, Gandevia SC. The proprioceptive senses: their roles in signaling body shape, body position and movement, and muscle force. Physiological reviews. 2012;92(4):1651–97. Epub 2012/10/18. pmid:23073629.
  64. 64. Xue X, Ma T, Li Q, Song Y, Hua Y. Chronic ankle instability is associated with proprioception deficits: A systematic review and meta-analysis. Journal of sport and health science. 2021;10(2):182–91. Epub 2020/10/06. pmid:33017672; PubMed Central PMCID: PMC7987558.
  65. 65. Takasaki H, Okubo Y, Okuyama S. The Effect of Proprioceptive Neuromuscular Facilitation on Joint Position Sense: A Systematic Review. Journal of sport rehabilitation. 2020;29(4):488–97. Epub 2019/05/17. pmid:31094655.
  66. 66. Wang L, Yu G, Zhang X, Wang YZ, Chen YP. Relationship between ankle pain, range of motion, strength and balance in individuals with functional ankle instability: a cross-sectional study. BMC musculoskeletal disorders. 2023;24(1):955. Epub 2023/12/09. pmid:38066472; PubMed Central PMCID: PMC10704625.