Tai Chi exercise and muscle strength and endurance in older people.

The purpose of the study was to investigate the influence of regular Tai Chi (TC) practice on muscle strength and endurance of the lower extremities in older people. Twenty-one long-term older TC practitioners were compared with 18 regular older joggers and 22 sedentary counterparts. Maximum concentric strength of knee flexors and extensors was tested at angular velocities of 30 degrees and 120 degrees /s. Ankle dorsiflexors and plantar flexors were tested at 30 degrees /s. Moreover the dynamic endurance of the knee flexors and extensors was assessed at the speed of 180 degrees /s. The strength of knee extensors and flexors in the sedentary group was significantly lower than that in the jogging group and marginally lower than that in the TC group at the higher velocity. For ankle joint, the subjects in both the TC group and the jogging group generated more torque in their ankle dorsiflexors. In addition, the muscle endurance of knee extensors was more pronounced in TC practitioners than the controls. Regular older TC practitioners and joggers showed better scores than the sedentary controls on most of the muscle strength and endurance measures. However, the magnitude of the exercise effects on muscles might depend on the characteristics of different types of exercise.