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

Study on Two Typical Progressive Motions in Tai Chi (Bafa Wubu) Promoting Lower Extremity Exercise

BACKGROUND

By comparatively investigating the joints, muscles and bones of the lower extremity during two progressive motions in Bafa Wubu and normal walking, this paper aims to enrich the diversity of walking exercise and scientifically provide theoretical guidance for primary practitioners. The scientific training methods and technical characteristics of Bafa Wubu, as well as its contribution to comprehensive exercise of the lower extremities, are further explored.

METHODS

A total of eight professional athletes of Tai Chi at the national level were recruited. The kinetic parameters of the lower extremity were calculated using AnyBody 7.2 musculoskeletal modeling. Stress analysis of the iliac bone was performed using an ANSYS 19.2 workbench.

RESULTS

In Bafa Wubu, the ground reaction force during two progressive motions was significantly smaller than that noted during normal walking. During warding off with steps forward and laying with steps forward, the load at the three joints of the lower extremity was significantly smaller than that during normal walking in the frontal plane, but significantly greater than that noted during normal walking in the vertical axis. In addition, the lower limb joint torque was higher than that of normal walking in both progressive movements, and lower limb muscle activation was higher. The iliac bone loads during the two progressive motions were larger than those during normal walking, and the maximum loading point differed.

CONCLUSIONS

This is the first study to demonstrate the biomechanical performance of Bafa Wubu in professional athletes of Tai Chi. Two progressive motions of Bafa Wubu require the lower extremity to be slowly controlled, thereby resulting in a smaller ground reaction force. In addition, the loads of the three joints at the lower extremity all increase in the vertical direction and decrease in the lateral direction, reducing the possibility of lateral injury to the joints. In addition, the two progressive motions significantly enhance the muscle strength of the plantar flexion muscles, dorsiflexor, and muscles around the thigh, and effectively stimulate the bones of the lower extremity. Therefore, progressive motion training contributes to improving the controlling and supporting capabilities of the lower extremities during normal walking.

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.