Taiji training improves knee extensor strength and force control in older adults

Christou EA, Yang Y, Rosengren KS.

University of Illinois at Urbana-Champaign, USA. evangelos.christou@colorado.edu

The purpose of this study was to examine the effects of Taiji training on knee extensor strength and force control in older individuals. Twenty-six healthy older adults (71.9 +/- 1.8 years) participated in the study. Sixteen of the older adults (70.2 +/- 1.8 years) underwent Taiji training for 20 weeks (experimental group), whereas the other 10 (74.6 +/- 1.2 years) served as the control group. For both groups, strength and force control of the knee extensors was assessed twice with an isokinetic dynamometer. Strength was assessed with a maximum voluntary isometric contraction (MVC). Force control was measured as the standard deviation (SD) and coefficient of variation (CV) of force during a constant isometric knee extension task at 2%, 30%, 60%, and 90% MVC. For the experimental group, MVC significantly increased (19.5 +/- 4.9%) and the CV of force decreased (18.9 +/- 3.3%) following Taiji training. Improvements in the CV of force were primarily due to decreases in the SD of force (R(2) =.86) rather than increases in strength (R(2) =.12). Furthermore, decreases in SD of force were independent of improvements in strength. For the control group, strength, SD, and CV of force were not different for the 2 tests. The overall findings suggest that Taiji training improves knee extensor strength and force control in older adults.

 

Elderly patients practicing Taiji (Tai Chi) for 20 weeks experienced significant improvements in knee extensor strength and force control, according to a recent American study. Older individuals have an increased risk of slipping, tripping and falling, which can cause serious injury or death. The ancient Chinese martial art Taiji, more commonly known as Tai Chi in the United States, has been shown to improve balance, coordination, and aerobic capacity, particularly in the elderly. Furthermore, studies have determined that Taiji can decrease the frequency of falls in the elderly and reduce their fear of falling. Given its slow, gentle, non-aerobic movements, this form of exercise may be an ideal therapeutic option for older persons. Karl S. Rosengren, PhD, and colleagues at the University of Illinois at Urbana-Champaign, United States, analysed the effects of Taiji training on knee extensor strength and force control in healthy elderly patients. The study included 26 healthy individuals (average age 72 years old), 16 of which received Taiji training for 20 weeks and 10 that did not receive Taiji training and served as a control group. Knee extensor strength was measured with an isokinetic dynamometer from the maximum voluntary isometric contraction (MVC). Force control was determined from the variation of force during constant isometric knee extension at 2%, 30%, 60%, and 90% MVC. Overall, participants undergoing Taiji training showed increased improvement in knee extensor strength and force control after 20 weeks. More specifically, a 20% higher MVC and a 19% lower variation of force were observed in this group after training. Further analysis revealed that the improvement in force control was primarily due to decreases in the standard deviation of force and not due to increases in strength. This result indicates that the improvement in force control was independent of improvements in strength. Measurements of strength and force control did not differ between tests in the control group, demonstrating a direct effect of Taiji training on knee extensor strength and force control. Dr. Rosengren concludes from this study that "older individuals can become stronger and have a better force control with the knee extensors following [Taiji] training." He further suggests that "intervention programs that use [Taiji] should be at least four months long for individuals to achieve a moderate level of [Taiji] skill."