Effect of Taichi exercise on balance, lower limb muscle strength, and proprioception in older with mild Parkinson’s disease

DENGGUI CHENG1, LAN LEI2

1Department of Neurosurgery, the Third Affiliated Hospital of Zunyi Medical University / the First People’s Hospital of Zunyi, Guizhou, China; 2Human Movement Science, Sichuan Sports College, Sichuan, China.

Summary. Background. The impact of Taichi as a supplementary exercise for enhancing balance, lower limb strength, and proprioception in older individuals with mild Parkinson’s disease beyond standard rehabilitation needs further validation. Objective. This study examines the additional effects of Taichi on balance, lower limb strength, and proprioception in older individuals with mild PD, in conjunction with conventional rehabilitation. Methods. Forty-three participants with mild PD were randomly assigned to a Taichi group (TG, n = 22) or a Control group (CG, n = 21). Both groups received standard rehabilitation, while the TG also completed a 12-week Taichi program. Assessments of balance (Berg Balance Scale, BBS), fall efficacy (Modified Falls Efficacy Scale, MFES), lower limb strength, and proprioception were conducted at baseline and post-intervention. Results. Compared to baseline, the CG showed an increase of 7.5% in BBS scores (p = 0.026, η² = 0.118) and 24.4% in MFES scores (p = 0.002, η² = 0.208) by the 12th week. The TG exhibited an increase of 17.2% in BBS scores (p <0.001, η² = 0.460) and 59.3% in MFES scores (p <0.001, η² = 0.656) by the 12th week, along with a 16.1% increase in knee extension peak torque (60°/s) (p = 0.007, η² = 0.159). The ankle plantar flexion peak torque (60°/s) increased by 35.0% (p = 0.001, η² = 0.226). The knee flexion proprioceptive threshold decreased by 13.2% (p = 0.136, η² = 0.052), and the extension proprioceptive threshold decreased by 7.7% (p = 0.384, η² = 0.018). At the 12th week, the TG’s BBS and MFES scores were higher than those of the CG (p = 0.001, η² = 0.235; p <0.001, η² = 0.278), and the knee extension peak torque (60°/s) was greater than that of the CG (p = 0.015, η² = 0.136). Conclusion. Supplementing conventional rehabilitation with Taichi exercise can further enhance balance and fall efficacy in older individuals with mild PD, and increase the peak torque of knee extensor and ankle plantar flexor muscles. Although there is some improvement in knee flexion and extension proprioception, it is not statistically significant.

Key words. Taichi, mild Parkinson’s disease, older, muscle strength, proprioception.

Effetto dell’esercizio di Taichi su equilibrio, forza muscolare degli arti inferiori e propriocezione negli anziani con malattia di Parkinson lieve

Riassunto. Background. L’efficacia del Taichi come esercizio complementare per migliorare l’equilibrio, la forza degli arti inferiori e la propriocezione negli anziani affetti da malattia di Parkinson lieve, oltre alla riabilitazione standard, richiede ulteriori evidenze. Obiettivo. Questo studio analizza gli effetti aggiuntivi del Taichi sull’equilibrio, la forza degli arti inferiori e la propriocezione in soggetti anziani con malattia di Parkinson lieve (PD), in associazione con la riabilitazione convenzionale. Metodi. Quarantatré partecipanti con PD lieve sono stati assegnati in modo casuale a un gruppo Taichi (TG, n = 22) o a un gruppo di controllo (CG, n = 21). Entrambi i gruppi hanno seguito un programma di riabilitazione standard, mentre il TG ha partecipato anche a un programma di Taichi della durata di 12 settimane. Le valutazioni dell’equilibrio (Berg Balance Scale, BBS), dell’efficacia nella prevenzione delle cadute (Modified Falls Efficacy Scale, MFES), della forza degli arti inferiori e della propriocezione sono state effettuate all’inizio e al termine dell’intervento. Risultati. Rispetto al basale, al termine delle 12 settimane il CG ha mostrato un aumento del 7,5% nei punteggi BBS (p = 0,026, η² = 0,118) e del 24,4% nei punteggi MFES (p = 0,002, η² = 0,208). Il TG ha evidenziato un incremento del 17,2% nei punteggi BBS (p <0,001, η² = 0,460) e del 59,3% nei punteggi MFES (p <0,001, η² = 0,656), oltre a un aumento del 16,1% nella coppia di picco dell’estensione del ginocchio (60°/s) (p = 0,007, η² = 0,159). La coppia di picco della flessione plantare della caviglia (60°/s) è aumentata del 35,0% (p = 0,001, η² = 0,226). La soglia propriocettiva della flessione del ginocchio è diminuita del 13,2% (p = 0,136, η² = 0,052), mentre quella dell’estensione è diminuita del 7,7% (p = 0,384, η² = 0,018). Alla dodicesima settimana, i punteggi BBS e MFES del TG erano significativamente superiori a quelli del CG (p = 0,001, η² = 0,235; p <0,001, η² = 0,278), così come la coppia di picco dell’estensione del ginocchio (60°/s) (p = 0,015, η² = 0,136). Conclusione. L’integrazione dell’esercizio Taichi alla riabilitazione convenzionale può migliorare ulteriormente l’equilibrio e la fiducia nella prevenzione delle cadute negli anziani con PD lieve, oltre ad aumentare la forza massimale dei muscoli estensori del ginocchio e flessori plantari della caviglia. Sebbene si osservino miglioramenti nella propriocezione della flessione ed estensione del ginocchio, questi non risultano statisticamente significativi.

Parole chiave. Taichi, malattia di Parkinson lieve, anziani, forza muscolare, propriocezione.

Introduction

Parkinson’s disease (PD) is a prevalent neurodegenerative disorder characterized by symptoms such as resting tremors, bradykinesia, rigidity, and postural instability1. Among these, the decline in postural control ability, which encompasses the capacity to maintain stable body posture, including balance, joint muscle strength, proprioception, and neuromuscular response, is one of the most common motor impairments in older individuals with PD, increasing the risk of falls2,3. Therefore, identifying effective rehabilitation interventions to enhance postural control and prevent falls in older PD patients is of significant importance.

Taichi, a traditional Chinese exercise, is characterized by slow, gentle movements combined with deep breathing4,5. Previous studies have demonstrated that Taichi exercise offers various benefits for the physical postural control of older adults, including improved balance6,7, enhanced proprioception8,9, increased joint muscle strength10,11, and reduced neuromuscular response times12,13. Meta-analyses have confirmed the effectiveness of Taichi in improving balance14,15, lower limb function16, and motor abilities in older PD patients17,18. Although existing research indicates that Taichi has positive effects on both motor and non-motor symptoms in older PD patients, whether Taichi can further enhance postural control ability in mild PD patients when added to rehabilitation remains to be verified. Additionally, as PD is a progressive neurodegenerative disease with no known cure, exploring non-pharmacological treatment methods that can slow disease progression and improve patients’ quality of life is of great significance.

In light of this, the present study introduces a 12-week regular Taichi intervention for older individuals with mild PD, in addition to conventional rehabilitation, to investigate its effects on balance, lower limb joint muscle strength, and proprioception. It aims to promote traditional Chinese medical therapies such as Taichi exercise to enhance postural control and prevent falls in more older individuals with mild PD. This study seeks to provide scientific evidence for the long-term management of PD and explore the potential value of Taichi as an adjunctive therapeutic approach in PD treatment. The hypothesis of this study is that a 12-week Taichi exercise, when added to conventional rehabilitation, will further improve balance, lower limb joint muscle strength, and proprioception in older individuals with mild PD.

Materials and methods

Participants

This study was approved by the Ethics Committee of the First People’s Hospital of Zunyi (No. 2023-1-212). Participants were recruited from the Phoenix and Taoxi campuses of the First People’s Hospital of Zunyi, consisting of older individuals with mild PD who met the inclusion criteria. Inclusion criteria included: being aged 60 years or older; meeting the UK Brain Bank criteria for PD diagnosis; having a Modified Hoehn-Yahr staging score of 1-2.5, indicating an early stage of PD19; being able to walk independently and possessing a certain level of self-care ability in daily life; and providing informed consent in accordance with the Declaration of Helsinki. Exclusion criteria included: severe cognitive impairment; severe visual or auditory impairment; other neurological diseases or serious internal medical conditions affecting balance; and participation in other regular exercise programs.

Referring to studies on Taichi exercise for older PD patients14,15, this study employed a 2 (groups) × 2 (measurement times) experimental design, accounting for approximately 15% sample loss. Using G-power software with an Effect Size of 0.3, Power of 0.8, and α of 0.05, the minimum sample size was calculated to be 40. Initially, 50 participants were recruited and randomly assigned to groups using a computer-generated random number sequence, ensuring an equal probability of allocation to either group. The Taichi Group (TG, n = 25) and Control Group (CG, n = 25) were formed. At the beginning of the study, three participants from TG and four from CG withdrew due to personal reasons, resulting in a sample loss rate of 14.0%. Ultimately, 43 participants completed the entire process. There were no statistically significant differences in age, height, and weight between the groups (p >0.05) (table 1).

Conventional Rehabilitation and Taichi Exercise

Firstly, all participants underwent the same conventional rehabilitation therapy. This lasted for 12 weeks, with 5 sessions per week, each approximately 45 minutes long. Each session included the following exercises: Range of Motion Training: Involving joints such as the neck, shoulders, elbows, wrists, fingers, hips, knees, and ankles, with exercises including flexion, extension, and rotation of each joint (10-12 repetitions per set, 3 sets, with a 20-second rest between sets); Balance Training: Including anterior-posterior, lateral, and side-to-side weight shifts while seated, kneeling, and standing (10-12 repetitions per set, 3 sets, with a 20-second rest between sets); Gait Training: Starting with heel strike, followed by the foot sole, and finally the toes, with steps taken as slowly as possible and arms swinging as much as possible during walking (10-12 repetitions per set, 3 sets, with a 20-second rest between sets). Secondly, the Taichi group received regular 24-form Taichi exercises. This lasted for 12 weeks (with the first 4 weeks as the learning period and weeks 5-12 as the consolidation and reinforcement period), with 3 sessions per week, each approximately 60 minutes long (including a 5-minute warm-up; 50 minutes of Taichi practice, completing one full set of Taichi movements in about 5 minutes, with a total of 6 sets and a 1-2 minute rest between each set; and a 5-minute cool-down activity).

In this study, each exercise session was supervised and guided by a coach with at least 5 years of Taichi teaching experience and research personnel to ensure the standardization and safety of the movements. The exercise intensity was referenced from Chang’s experimental design: 50% to 65% of maximum heart rate (maximum heart rate = 220 - age, with heart rate monitored using Huawei Smart Sports Bracelets)5. Participant adherence to the exercises was recorded through attendance records, exercise duration records, movement quality assessments, and self-reported questionnaires, documenting their compliance in both Taichi exercises and conventional rehabilitation therapy. The impact of adherence on the study results was assessed, and our findings indicated that participants demonstrated high levels of engagement and compliance in both Taichi exercises and conventional rehabilitation therapy.

Balance assessment

The Berg Balance Scale (BBS) and Modified Falls Efficacy Scale (MFES) were used to assess participants’ balance abilities. The BBS is a scale for evaluating individual balance abilities, consisting of 14 items, each scored from 0 to 4, with a total score ranging from 0 to 56, where higher scores indicate better balance abilities20. The MFES is a scale for assessing the self-efficacy of older individuals in performing daily activities without fear of falling. It is a 14-item questionnaire, with each item scored from 0 to 10, where lower scores indicate greater concern about falling, i.e., higher perceived risk of falling21.

Isokinetic muscle strength testing

Participants’ lower limb muscle strength was tested using the IsoMed 2000 isokinetic muscle strength testing system from Germany. The dominant side knee and ankle joints of the subjects were tested at 60°/s (5 times) and 180°/s (5 times). Each participant performed approximately 10 minutes of lower limb stretching as a warm-up before the test. The knee joint muscle strength test was conducted in a seated position with a joint range of motion of 80°, and the ankle joint test was conducted in a supine position with a joint range of motion of 45°. The “concentric and eccentric” mode was selected, and participants were first familiarized with the testing procedure and the isokinetic movement of the tested joint. Before the formal test, participants were required to complete two submaximal intensity exercises, and then they entered the testing state. The experimenters verbally encouraged the participants to exert as much force as possible during the joint movement. The measurement index was peak torque, which refers to the maximum torque value produced by the tested joint during the isokinetic muscle strength test, reflecting the muscle strength level of the subjects at different angular velocities22.

Proprioception testing

The isokinetic device’s movement angular velocity was adjusted to 1°/s to measure the proprioception of knee and ankle joint flexion and extension movements on the dominant side of the subjects. Subjects were tested in a seated position, and to prevent external interference, their eyes were covered with a black cloth, and they wore headphones playing music. The initial angle of the lower limb joint was adjusted by the isokinetic device, with the knee joint flexed at 90° and the ankle joint perpendicular to the ground. The “gravity compensation” was used to eliminate the gravity of the device and the subject’s lower limb joint. When testing knee joint proprioception, the isokinetic dynamometer head randomly moved the knee joint in flexion or extension. When testing the ankle joint, it randomly moved the ankle joint in flexion (dorsiflexion) or extension (plantar flexion). Once the subject perceived the joint movement and its direction, they immediately pressed a handheld button, and the isokinetic dynamometer head would stop moving. The experimenters recorded the difference between the actual angle and the corresponding test angle, called the proprioceptive threshold (in degrees). Each proprioceptive angle was measured three times, and the average value was taken, with a 30-second rest in between. A smaller angle indicates a lower proprioceptive threshold for the corresponding joint, indicating better proprioception8,23. The IsoMed 2000 isokinetic muscle strength testing system has been proven by previous researchers23 to have good reliability and validity for measuring knee and ankle joint proprioception in humans.

Statistical analysis

All measured data were processed using SPSS 20.0 to obtain mean values ± standard deviations. This was a 2 (group) × 2 (measurement times) experimental design. The Shapiro-Wilk test was used to assess the normality of the measured data, and the homogeneity of variance was tested. Two-way analysis of variance was used to analyze the main effects of group and time, as well as their interaction. If there was an interaction, the main effects of time or group were analyzed separately; if there was no interaction, the main effects of group or time were analyzed24. The significance level was set at α = 0.05.

Results

Initially, the Shapiro-Wilk test confirmed that the data followed a normal distribution, and the homogeneity of variance was also established. Two-way analysis of variance revealed significant interaction effects between group and time for the BBS scores (p = 0.024, η² = 0.061) and MFES scores (p = 0.001, η² = 0.124), indicating that both group and time had individual effects. However, no interaction effects were observed for lower limb muscle strength and proprioception test indicators (p >0.05). Further analysis of the main effects of group and time is presented in table 2 and 3.

Between-group comparisons: At baseline, there were no statistically significant differences between the Taichi group and the control group in all tested indicators (p >0.05). By the 12th week, the Taichi group exhibited significantly higher BBS and MFES scores compared to the control group (p = 0.001, η² = 0.235; p <0.001, η² = 0.278). Additionally, the knee extension peak torque at 60°/s was significantly greater in the Taichi group than in the control group (p = 0.015, η² = 0.136). Notably, while the Taichi group showed greater knee flexion peak torque (at 60°/s and 180°/s), extension peak torque (at 180°/s), and ankle dorsiflexion and plantar flexion peak torque (at 60°/s and 180°/s) compared to the control group, these differences were not statistically significant (p>0.05). Similarly, the Taichi group had lower proprioceptive thresholds for knee flexion and extension, as well as ankle dorsiflexion and plantar flexion, compared to the control group, but these differences were not statistically significant (p >0.05).

Within-group comparisons: For the control group, compared to baseline, the BBS and MFES scores increased by 7.5% (p = 0.026, η² = 0.118) and 24.4% (p = 0.002, η² = 0.208) by the 12th week, respectively. However, there were no statistically significant differences in muscle strength and proprioception test indicators (p >0.05). In contrast, the Taichi group showed a significant increase in BBS and MFES scores by 17.2% (p <0.001, η² = 0.460) and 59.3% (p <0.001, η² = 0.656), respectively. The knee extension peak torque at 60°/s increased by 16.1% (p = 0.007, η² = 0.159), and the ankle plantar flexion peak torque at 60°/s increased by 35.0% (p = 0.001, η² = 0.226). Notably, the knee extension peak torque at 180°/s increased by 12.7% (p = 0.061, η² = 0.081). The proprioceptive threshold for knee flexion decreased by 13.2% (p = 0.136, η² = 0.052), and the extension proprioceptive threshold decreased by 7.7% (p = 0.384, η² = 0.018).

Discussion

This study investigated the effects of 12 weeks of Taichi exercise, in addition to conventional rehabilitation, on balance, lower limb muscle strength, and proprioception in older individuals with mild PD. Our findings partially confirmed the study hypothesis: adding Taichi exercise can further enhance balance and fall efficacy in older individuals with mild PD, as well as increase knee extensor and ankle plantar flexor peak torque. While there were improvements in knee flexion and extension proprioception, these changes were not statistically significant.

The study observed that by the 12th week, the Taichi group showed a 17.2% and 59.3% increase in BBS and MFES scores, respectively, compared to baseline, which were significantly higher than the 7.5% and 24.4% increases observed in the control group. Two meta-analyses support our conclusions. One meta-analysis, including 17 randomized controlled trials of Taichi intervention in PD patients (951 participants, aged 53-74 years, exercise duration 8-24 weeks, single exercise time 40-60 minutes), found that Taichi significantly improved BBS scores in PD patients14. Another meta-analysis, including 5 randomized controlled trials of Taichi intervention in PD patients (355 participants, aged 40-85 years, exercise duration 4-24 weeks, single exercise time 30-60 minutes), also found that Taichi significantly improved BBS scores in PD patients15. This study, with a 12-week Taichi intervention, extends previous research14,15 by demonstrating significant improvements in BBS scores among older individuals with mild PD. Compared to previous studies14,15, we found that Taichi intervention could reduce participants’ concerns about falling (increased MFES scores). This result may be closely related to the characteristics of Taichi movements. Taichi emphasizes dynamic shifts and continuous adjustments of the body’s center of gravity, such as “alternate half-squats with both knees,” requiring practitioners to constantly adjust their body’s center of gravity during practice to maintain stability and balance6.7. This fine control and adjustment of the body’s center of gravity help improve proprioception and neuromuscular coordination, thereby significantly enhancing balance abilities.

The study found that conventional rehabilitation did not significantly improve lower limb muscle strength in older individuals with mild PD, while the addition of Taichi intervention increased knee extension peak torque (60°/s) and ankle plantar flexion peak torque (60°/s). Early studies have shown that 24 weeks of Taichi exercise can improve knee flexor and extensor peak torque (60°/s) in PD patients (aged 40-85 years)25. The changes in knee extensor peak torque in this study are consistent with previous research25. However, there were no significant changes in flexor torque, which may be related to the insufficient duration of Taichi intervention. Notably, this study found that Taichi practice also had a positive effect on ankle plantar flexor strength in older individuals with mild PD, which may be related to the emphasis on ankle joint movement in Taichi actions. Taichi movements include a large number of lower limb support and movement actions, such as stepping and turning, which require knee and ankle joints to perform flexion and extension movements at different angles and speeds to support and transfer body weight8. During practice, participants’ knee and ankle joints need to repeatedly perform resistance exercises to maintain stability and complete various movements. This repeated resistance training can effectively enhance the strength of muscles around the knee and ankle joints, improve joint stability and mobility, and thereby significantly increase knee extension peak torque and ankle plantar flexion peak torque.

It is worth noting that although 12 weeks of Taichi did not significantly improve knee and ankle joint proprioception in older individuals with mild PD, we found that the proprioceptive thresholds for knee flexion and extension in the Taichi group decreased by 13.2% (p = 0.136, η² = 0.052) and 7.7% (p = 0.384, η² = 0.018), respectively. This may be related to the relatively low intensity and frequency of proprioception training in Taichi exercises. Although Taichi movements emphasize the perception and control of body movements, their primary goal is to improve balance and coordination, rather than specifically targeting proprioception for high-intensity training9. Additionally, the improvement of proprioception may require longer periods of continuous training and practice, and the intervention period of this study was only 12 weeks, which may not be sufficient to fully stimulate the potential for improvement in proprioception. Future studies could consider extending the intervention period or incorporating elements specifically targeting proprioception training in Taichi exercises to further explore the effects of Taichi on proprioception and its underlying mechanisms.

This study has limitations. First, the sample representativeness is limited. The sample was only from the First People’s Hospital of Zunyi, which may lack breadth and representativeness, limiting the general applicability of the study results. Second, the intervention period is relatively short. A 12-week intervention may not be sufficient to comprehensively assess the long-term effects of Taichi on PD patients, especially changes in lower limb proprioception. Third, there is a lack of long-term follow-up. The study did not include long-term follow-up visits, so it is not possible to assess the long-term effects of Taichi exercise on patients’ balance, muscle strength, and proprioception. Finally, the assessment of non-motor symptoms is insufficient. This study mainly focuses on motor functions and lacks sufficient evaluation of the effects of Taichi on non-motor symptoms in PD patients (such as quality of life, emotional state, etc.). Future research should expand the sample size, extend the intervention and follow-up period to comprehensively assess the long-term effects of Taichi on PD patients, and explore its mechanisms for improving non-motor symptoms.

Conclusion

Adding Taichi exercise to conventional rehabilitation can further enhance balance and fall efficacy in older individuals with mild PD, and increase knee extensor and ankle plantar flexor peak torque. Although there are improvements in knee flexion and extension proprioception, these changes are not statistically significant. As a safe and feasible exercise method, Taichi can serve as a beneficial supplement to the routine rehabilitation of older individuals with PD.

Conflicts of interest. The authors declare that there is no conflict of interest.

Funding. This work was supported by the Zunyi City Joint Science and Technology Project (Zunshi Kehe E No. 2023-27).

Author’s contributions. DGC and LL: designing this study, writing initial draft and revision, revising language and content, supervision, project administration, and funding acquisition. DGC and LL: making figure and table. DGC and LL: rechecking the manuscript and putting forward suggestions for amendment. All authors contributed to the article and approved the submitted version.

Acknowledgements. We thank the athletes who participated in the experiment.

Consent to participate. This study was approved by the Ethics Committee of the First People’s Hospital of Zunyi (No. 2023-1-212). Participants were recruited from the Phoenix and Taoxi campuses of the First People’s Hospital of Zunyi. This study complied with the Declaration of Helsinki, and informed consent was obtained from all participants.

Data availability statement. The datasets used and/or analysed during the current study available from the corresponding author on reasonable request.

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