China’s population exceeds 1.4 billion, accounting for one-fifth of the world’s population. Of this, the elderly population aged 65 and over is 216.76 million, accounting for 15.4% of the total population [1] . Meanwhile, Japan’s population is 123.8 million, and the elderly population aged 65 and over is 36.24 million, accounting for 29.3% of the total population [2] . Maintaining and improving motor function in old age is an important factor in preventing physical deterioration associated with aging and maintaining an active social life. In recent years, the importance of preventing the need for nursing care has increased, and comprehensive geriatric training [3] and the practical methods and effects of preventive exercise [4] aimed at promoting health and preventing falls have become widely known. Furthermore, cross-sectional and longitudinal studies [5] [6] have reported that regular physical activity can maintain and improve the physical fitness of older people. However, there are few studies directly comparing the physical function of Japanese senior citizens’ club members and Chinese tai chi club members. Therefore, in this study, we report a comparison of the motor function of older women who belong to senior citizens’ clubs in Japan and those who belong to Tai Chi clubs in China.

The age and grip strength of the Chinese elderly group was significantly greater than those of the Japanese elderly group (p = 0.01) ( Table 2 ).

Notes: *p < 0.05 by unpaired student’s t -tests.

A comparison of the motor function of a group of elderly Japanese and Chinese people revealed that grip strength was 19.3 kg for the Japanese elderly group and 22.3 kg for the Chinese elderly group. Walking time was 5.3 seconds for the Japanese elderly group and 5.4 seconds for the Chinese elderly group. Ishizaki et al. [7] reported that because weak grip strength is a risk factor for decreased independence in basic and instrumental ADLs, measuring grip strength is useful as an indicator of health status, and Shinkai et al. [8] proposed a target level of physical fitness for elderly people to prevent a decline in basic ADLs. They pointed out that a grip strength of 15 kg or more and a maximum time of 6.5 seconds or less for women are sufficient to lead an independent life.

Participants in this study included Japanese elderly individuals who belonged to senior clubs and engaged in exercises and community cleanup activities at community centers. Meanwhile, Chinese elderly participants belonged to Tai Chi clubs and practiced Tai Chi in parks. Basic Tai Chi movements include pushing hands, pulling hands, turning, and footwork. These movements involve pairs of people maintaining contact with one or both hands, rotating the point of contact in a circular motion or pushing against each other. Therefore, it is effective as training for strengthening the forearm muscles located between the wrist and elbow [9] . Rather than the Japanese elderly group being significantly 2 years older than the Chinese elderly group, the difference in the nature of these group activities likely explains why the Chinese elderly group had significantly greater grip strength than the Japanese elderly group. Liu et al. [10] reported significant improvements in grip strength and forward bend flexibility after three months of tai chi instruction for healthy elderly individuals. Lan et al. [11] reported that after 12 months of Tai Chi exercise for 20 elderly individuals, significant differences were observed between the Tai Chi group and the control group (18 individuals) in knee flexor muscle strength and thoracolumbar flexion flexibility. These prior studies also support the finding that the Chinese elderly group in this study had significantly greater grip strength.

Health promotion programs for the elderly are actively being implemented to understand, maintain, and improve physical function. In these programs, muscle strength, flexibility, and balance function are used to evaluate physical function. Among these, balance function is an indicator that reflects important elements of daily living functions such as standing and walking. Balance function has also been reported to be associated with falls in the elderly.

In this study, the balance function of standing on one leg with eyes closed was measured in both the Japanese and Chinese elderly groups and was lower than the national average (10 seconds for 68-year-old women) [12] . In general, elderly people experience a decline in postural adjustment function due to degeneration of the musculoskeletal system, nervous system, and sensory receptors, and balance function is a physical ability achieved through appropriate postural adjustment [13] . Normal balance function involves many elements related to physical movement, such as perception of the external world via sensory receptors and the sensory nervous system, integration of sensation and movement by the central nervous system, and expression of movement via the motor nervous system and musculoskeletal system [14] . Tanida et al. [15] conducted a 12-week exercise program in 22 community-dwelling elderly people and compared LNG with eyes open and closed before and after exercise. Results showed a significant decrease in LNG with eyes open, but no significant change in LNG with eyes closed.

Tai Chi is inherently considered effective for improving balance function [16] . The Chinese elderly group in this study did not demonstrate superior results in the one-legged stance with eyes closed. The one-legged stance in this study was performed with eyes closed, not open. It has been reported that the vestibular system plays a major role in postural adjustment function in the elderly and affects balance functions requiring attention [17] [18] . Furthermore, decreased plantar sensitivity affects standing maintenance and balance function. Women, in particular, tend to have lower body temperatures than men, resulting in higher sensory receptor thresholds [19] . These factors may explain why the Chinese elderly group in this study performed poorly in the closed-eye single-leg stance test.

In the future, we plan to conduct follow-up surveys to explore the relationship between the degree of independence and medical expenses in old age.

The differences in the nature of activities between the senior citizens’ club and the tai chi group suggest that the grip strength of the Chinese elderly group was significantly greater than that of the Japanese elderly group.

The authors express sincere thanks to the members of the research and volunteers who participated as subjects.