# The Effects of Tai Chi Chuan Exercise Training on the Lower Extremities of Middle-Aged and Elderly
###### Abstract  
Background: It is known that lower-limb muscle strength is easily maintained in elderly people who practice Tai Chi, although it is necessary to maintain lower-limb muscle strength even as age increases in order to prevent falls. However, the effect of long-term Tai Chi practice and age on lower-limb ability is unclear in middle-aged and elderly people. This research was designed to compare lower-extremity parameters during a countermovement jump between middle-aged and elderly individuals who frequently practice Tai Chi Chuan and individuals in the general population who constituted the healthy group. Methods: There were four groups, and each group included 12 participants. Ten Vicon motion system infrared cameras and two Kistler force plates were used. The data were standardized and analysed using independent-measure two-way ANOVA. Results: The statistical results showed that there was no interaction between the age factor and exercise type factor. The statistics of age factor also showed that age may decrease the jump height (36.36%), peak knee power (24.74%) and peak ankle power (21%) during the take-off phase. In the exercise type factor, long-term Tai Chi training significantly increased the jump height (60%), peak knee moment (19.80%), peak ankle moment (8.06%), peak hip power (29.80%), peak knee power (31.23%) and peak ankle power (16.88%) during the take-off phase. Conclusion: This study shows that long-term Tai Chi training can slow ageing-related functional decline. According to the results of this study, middle-aged and elderly people are encouraged to regularly perform Tai Chi exercises to increase the strength of various muscle groups in the lower limbs and slow the lower-limb muscle changes caused by ageing. a 2022 20  
stairs, maintain balance, or stand up from a chair. Regular exercise in elderly individuals can effectively delay muscle degeneration, and improved lower-limb muscle strength can lead to an improved quality of life in elderly individuals [7] and slow functional decline in ADLs. Tai Chi can improve the body's ability to absorb antioxidants, coordination, proprioception, blood pressure, flexibility and balance [8; 9; 10]. Tai Chi may reduce the risk of falls in older adults [11]. Tai Chi is not only very popular among the elderly, but also the exercise intensity can be adjusted according to their abilities. Studies have shown that Tai Chi can significantly improve the lower-limb muscle strength and gait performance of elderly individuals [12]. A previous study also pointed out that the fall risk of the group who regularly engages in Tai Chi exercise is one-third of the group who only engage in low-intensity exercise such as walking and hiking in the elderly over 70 years old [13]. Compared with the normal gait group, the elderly Tai Chi group adopted a gait strategy with longer steps and a faster step frequency [14]. In addition, the knee and ankle joints showed large flexion angles, indicating that the stiffness of the lower-limb joints was slightly smaller than that of the general elderly population [15]. Relevant experiments showed that elderly people practicing Tai Chi have better flexion and extension ranges of motion in the knee joint when jumping [16]. Another study also pointed out that joint stability can be increased by increasing joint torque and the larger knee torque exhibited by the Tai Chi group may lead to higher joint stability [17]. Because of the rapid availability of test results, countermovement jumps are often used to assess lower-limb power [18; 19; 20]. Previous studies have shown that lower-limb power is highly correlated with the risk of falls in older adults [21]. Therefore, this jump has also been used in elderly individuals to assess the degree of lower-limb function [6; 22]. A previous study used the countermovement jump to examine the effects of Tai Chi in older adults.