Does T'ai Chi Gait Reduce External Knee Adduction Moment?

Neuromuscular control strategies of the lower limb during a typical Tai Chi brush knee and twist step in practitioners with and without knee pain: a pilot study

As a complex movement, Tai Chi (TC) could be challenging for knee control, and the compensatory changes in TC biomechanics of knee pain patients are unknown. The Brush Knee and Twist Step (BKTS) is a typical TC movement that involves basic leg motion repeated in the whole TC. This pilot study examined electromyography and retro-reflective marker trajectory data to investigate neuromuscular control strategies of the lower extremity during BKTS in TC practitioners with and without knee pain. Twelve experienced TC practitioners with (n = 6) and without knee pain (n = 6) participated. Our results revealed that knee pain practitioners presented muscle imbalance in the vastus medialis-vastus lateralis and vastus lateralis-biceps femoris, and poor alignment of the knee with the toes in TC lunge. Additionally, they adaptively developed rigid coordination strategies, showing higher levels of lower limb muscle co-contraction and activity compared to controls. Training programs for TC practitioners with knee pain should be designed to modify both abnormal muscle synergy patterns and incorrect lunge during TC, which may improve exercise safety.

Research on Knee Joint Load and Influencing Factors of Typical Tai Chi Movements

Background

Tai chi is recognized worldwide for its rehabilitation abilities and healthcare benefits. However, in recent years, some movements associated with tai chi have been shown to damage the lower limb joints. The purpose of this study was to investigate and compare the effects of different movements, postures, center of mass (COM) movements, and range of knee movement of tai chi exercises on knee joint load.

Methods

Fourteen professional tai chi practitioners in two postures (high and low) were enrolled to perform the following four typical tai chi movements: wild horse's mane (WHM), repulse monkey (RM), wave-hand in cloud (WHIC), and grasp the bird's tail (GBT). Kinematic and kinetics data were synchronously collected using the Vicon infrared high-speed motion capture system and a three-dimensional (3D) force measurement platform. Variance analysis and partial correlation analysis were performed to investigate factors influencing peak knee joint moment and vertical ground reaction force (VGRF).

Results

The results showed that the peak knee extension and abduction moment were larger in WHM and RM than those in WHIC and GBT (p < 0.05). WHM was associated with greater rotation moment than the other typical movements (p < 0.05). VGRF and joint moment among different poses were significantly different. Low-pose tai chi typical movements were associated with greater VGRF, knee joint extension and abduction, and rotation moments than high-pose movements (p < 0.05). The anteroposterior and mediolateral COM displacements were strongly and positively associated with VGRF (p < 0.001), while the mediolateral COM displacement was negatively associated with knee extension moment (p < 0.001). The knee internal-external rotation ROM and anteroposterior and mediolateral COM displacements were positively associated with knee abduction moment (p < 0.01).

Conclusion

For long-term tai chi exercises, choosing a suitable posture based on an individual exercise level and reasonable control of knee ROM and COM displacement can reduce the risk of knee injury during exercise.

Dynamic stability based identification of optimal Tai Chi forms for preventing falls among older adults with knee osteoarthritis

Objective

Knee osteoarthritis increases the risk of falls among older adults. Tai Chi (TC) has been increasingly utilized to prevent falls in older adults. However, findings from previous studies are inconclusive, possibly due to a lack of scientifically sound methodologies to identify targeted TC forms, which likely maximize the training effects in preventing falls. It has been recently indicated that individual TC forms challenge body balance to varying degrees, providing us a foundation to select optimal TC forms. The objective of this preliminary study was to examine whether the challenge to body balance quantified by the range of dynamic stability is different between identified optimal TC forms (OTC) and commonly used TC (CTC) forms among older adults with knee osteoarthritis.

Methods

Eight older adults with knee osteoarthritis learned how to perform 24 ​TC forms correctly. Their full-body kinematics during the performance of 24 ​TC forms was collected. The range of composite dynamic stability was used as the selection criteria to identify eight OTC forms. The range of composite dynamic stability was then compared between the OTC forms and eight CTC forms.

Results

Overall, OTC forms showed a significantly larger range of composite dynamic stability than CTC forms (p ​= ​0.021).

Conclusion

The selected OTC forms could impose a greater challenge on balance control among older adults than CTC forms. The finding in this study is significant as it could furnish a scientific basis for identifying the best TC forms to optimize the effectiveness of TC-based fall prevention interventions.

Individual analysis of dynamic stability for twenty-four Tai Chi forms among persons with knee osteoarthritis: A pilot study

BACKGROUND

Tai Chi (TC) training has been increasingly used to prevent falls. However, the underlying biomechanical mechanisms of TC training which influence fall risk remain unknown. As a result, the selection of TC forms differs among studies, leading to inconsistent results.

RESEARCH QUESTION

Is dynamic stability different between the simplified 24 Yang-style TC forms among adults with knee osteoarthritis?

METHODS

Ten participants with mild to moderate knee osteoarthritis were recruited. Under one-on-one instruction by an experienced TC master, each participant learned how to correctly perform the 24-form TC movements. Participants' full-body kinematic and kinetic data was collected during walking trials and performance of the respective TC forms. Their dynamic stability was calculated in both sagittal and frontal planes and compared between each TC form and regular walking.

RESULTS

The results indicate that dynamic stability in both planes significantly varies among forms. Moreover, some forms pose a greater challenge to dynamic stability in comparison to others. The most challenging TC forms are Form 8 for stability in the sagittal plane and Form 10 in the frontal plane. Among all forms, Form 1 appears to be the least challenging.

SIGNIFICANCE

Our findings could provide foundational information to identify the best TC forms for optimizing the effectiveness of TC-based fall prevention interventions.

Knee joint biomechanics of simplified 24 Tai Chi forms and association with pain in individuals with knee osteoarthritis: A pilot study

Objectives

Tai Chi (TC) is a multi-beneficial exercise for improving health and function in knee osteoarthritis (OA). Biomechanical insights of 24 TC forms at the knee joint are not well understood. We aimed to examine knee joint biomechanics of TC actions form by form and their interactions with pain in individuals with knee OA.

Methods

Ten knee OA participants were recruited. Their full body motion during performance of 24 TC forms was collected. The knee joint biomechanics were determined by using an inverse dynamic approach based on collected full body kinematics and kinetics. In addition, the knee joint pain level was scored during each TC form. The joint moments were compared between walking trials and each TC form. The relationship between knee joint biomechanics and pain scale was assessed.

Results

The knee adduction moment for five TC forms was different from the walking trial. The knee extension moment for 21 TC forms differed from the walking trial. For TC trials, the knee extension moment, but not the adduction moment, was positively correlated with pain level. Similarly, the knee extension moment was moderately proportional to pain level during the walking trials, but not the adduction moment.

Conclusions

Our pilot results explored the knee joint biomechanics profiles of individual TC forms and examined their associations with knee joint pain. The findings in this study could provide scientific basis to select the best TC forms for the purpose of reducing knee joint pain among individuals with knee OA.

Biomechanical mechanism of Tai-Chi gait for preventing falls: A pilot study

Tai-Chi (TC) practice has been increasingly used to prevent falls in older adults. However, the biomechanical mechanisms underlying the effects of TC practice on fall risk among older adults remain unanswered. The objective of this pilot study was to examine how TC gait biomechanically impacts the human body in terms of dynamic gait stability and lower limb muscle strength in comparison with regular walking gait. Ten healthy adults performed five trials of TC gait following three to seven trials of regular walking. Full body kinematics and kinetics were collected, and then dynamic gait stability and lower limb joint moments were determined. During TC gait, individuals were less stable, moved more slowly and experienced a larger mediolateral movement in comparison with regular walking gait. The peak moment at the ankle joint on the sagittal and transverse planes, at the knee joint on all three planes, and at the hip joint on the frontal plane was significantly different when performing TC gait than during regular gait. The results indicate that TC gait challenges body balance and requires more muscle strength of the lower limb joints compared to regular walking gait. To cope with these challenges, the body could develop neuromuscular control strategies to maintain body balance and thus reduce the risk of falls. The findings and methodology in this study could provide preliminary guidance for identifying optimal TC forms in order to maximize the effects of TC-based fall prevention interventions among various populations with elevated risk of falls.