Physical inactivity is a major risk factor for death from noncommunicable diseases and injuries.¹⁾ In middle-aged and older adults, decreased physical activity levels are associated with greater health risks, such as dementia, cardiovascular disease, and cancer.²⁾ Therefore, guidelines recommend physically active lifestyles, defined as 150–300 minutes of moderate-intensity or 75–150  minutes of vigorous-intensity physical activity per week and muscle-strengthening activities at moderate or greater intensity ≥2 days per week, for all adults.³⁾

Physical inactivity is also a risk factor for the increased incidence of functional limitations in middle-aged and older adults.⁴⁾ During the coronavirus disease 2019 (COVID-19) pandemic, many people experienced negative lifestyle changes, including an approximately 30% decrease in physical activity among middle-aged and older adults.⁵⁾ Physical inactivity due to the pandemic might have increased the risk of frailty and locomotive syndrome.^6,7) However, some people positively changed their lifestyle by exercising indoors and walking in their neighborhoods.⁸⁾ Higher physical activity levels during the pandemic may also be associated with healthy lifestyle habits, such as the use of physical activity monitors.

During the COVID-19 pandemic, physical activity monitoring may have played an important role in the maintenance of a physically active lifestyle. Increased sedentary behavior and weight gain during the COVID-19 pandemic occurred among middle-aged individuals regardless of physical activity monitoring.⁹⁾ However, the proportion of older adults using such monitors during the COVID-19 pandemic have not been reported. Among older adults, activity monitoring was linked with meeting aerobic physical activity requirements and walking.¹⁰⁾ In addition, although continuity and goal setting are important for adopting healthy behavioral changes,¹¹⁾ the association between the period of physical activity monitoring, step goal setting, and health status remain undetermined.

In 2007, the Japanese Orthopaedic Association defined locomotive syndrome as a condition that requires nursing care due to a decline in mobility resulting from disorders of the locomotive system, including the bones, joints, muscles, and nerves.¹²⁾ Understanding the relationship between physical activity monitoring and its relevance in the maintenance of physical activity levels and locomotion status among individuals, including older adults, will provide clinical information for the adoption of healthy habits in normal daily life.

This study investigated whether users of physical activity monitors in Japan were more physically active, and whether the duration of use of monitors and having personal step goals were associated with a lower risk of locomotive syndrome in middle-aged and older adults. Clarification of these associations may provide information to promote the use of physical activity monitors and to develop guidance strategies.

We analyzed data from 742 Japanese adults aged 60–79 years (mean age, 64.9 years; 31.4% women) (Fig. 1). Table 1 shows the characteristics of physical activity monitor users and non-users. Almost two-thirds (66.2%) of the users had been using the monitors for >2 years. Subsequently, we classified the users based on whether they had used the device for >2 or <2 years. Among all monitor users, 55.2% had personal step goals. There were no significant differences in age, sex, and BMI between the physical activity monitor users and non-users. The monitor users had a higher educational level than non-users (p=0.001). Table 2 shows the results of the comparison of physical activity duration and locomotive syndrome status between users and non-users, in which users demonstrated significantly higher total physical activity time, moderate-to-vigorous physical activity time, and walking time per week than non-users but no differences in sedentary time, compared with non-users (p=0.635).

The results of both crude and adjusted logistic regression models demonstrated the association between physical activity monitoring and locomotive syndrome status (Table 3). In the adjusted model, which included age, sex, education, BMI, and medical history (i.e., hypertension, diabetes mellitus, spinal canal stenosis, lumbar vertebrae herniated disk, rheumatoid arthritis, osteoporosis, and osteoarthritis) as covariates, physical activity monitor use was significantly associated with a decreased risk of locomotive syndrome (OR=0.48; 95% CI, 0.30–0.79). Additionally, participants who used a physical activity monitor for >2 years were less likely to experience locomotive syndromes (OR=0.42; 95% CI, 0.23–0.75) than those that did not. However, <2 years of use showed no such associations (OR=0.63; 95% CI, 0.33–1.22). Similarly, users with a personal step goal were observed to have significantly lower odds of having locomotor syndrome (OR=0.32; 95% CI, 0.16–0.64), whereas no such association was observed for users without a personal step goal (OR=0.65; 95% CI, 0.36–1.16).

The results of the analysis of the web-based survey of 742 Japanese adults aged 60–79 years in this study demonstrated that users of physical activity monitors were more physically active and less likely to develop locomotive syndromes. In particular, long-term (≥2 years) use and having a personal step goal were associated with lower odds of locomotive syndrome. Our results highlight the benefits of long-term monitoring of physical activity, and underscore the importance of setting personal goals for physical activity.

This study investigated the physical activity levels and prevalence of locomotive syndrome in users and non-users of physical activity monitors, and the potentially positive association with the duration of use and a set personal step goal. In a previous meta-analysis and systematic review, pedometer use was associated with significantly increased physical activity, corresponding to an increase of approximately 2,000 steps or roughly 1 mile of walking per day, compared with non-users.¹¹⁾ The results of the current study revealed that the median difference in walking time and total physical activity time between physical activity monitor users and non-users was 210 min/wk (30 min/day) and 300 min/wk (43 min/day), respectively. Increased physical activity can positively influence future health conditions of the bone, brain, heart, and lung, as well as cardiometabolic health.²³⁾ In addition, step goals are an important predictor of increased physical activity.¹¹⁾ The results of the present study indicated that the long-term (≥2 years) use of a physical activity monitor and having a step goal were associated with higher levels of physical activity and reduced chances of developing locomotive syndrome. Therefore, using physical activity monitors and setting personal step goals may promote a physically active lifestyle and decrease the incidence of locomotive conditions in middle-aged and older adults.

Physical inactivity is a risk factor for death from non-communicable diseases and harm due to smoking and high blood pressure.¹⁾ A current social issue associated with secondary health issues during the COVID-19 pandemic is reduced physical activity in middle-aged and older individuals.^5,24) To our knowledge, the present study is the first study conducted during the COVID-19 pandemic which examines the proportion of individuals using physical activity monitors and the relationship between their use, physical activity levels, and locomotive syndrome status. Our findings indicate that users of physical activity monitors walked more and spent more time per week on total physical activity and moderate-vigorous physical activity during the COVID-19 pandemic (June 2021), compared with non-users. Although most older adults have seen gradual improvement in their physical activity levels after the COVID-19 pandemic, socially inactive people and people living alone have not regained their level of physical activity.²⁵⁾ Middle-aged and older adults who used physical activity monitors during the COVID-19 pandemic may have exhibited more physical activity-associated behavior, compared with non-users.

Users of physical activity monitors may be health-conscious and exhibit healthy behavior in terms of physical activity, as well as with respect to other lifestyle traits, including those associated with cognitive stimulation, social networking, and nutrition.²⁶⁾ Higher health literacy may also influence behavioral changes, such as the use of physical activity monitors during the COVID-19 pandemic. Health literacy plays a role in motivating older adults to adopt healthy lifestyles (e.g., regular physical activity monitoring).²⁷⁾ Among community-dwelling older adults, high communicative health literacy was associated with exercise during the COVID-19 state of emergency in Japan.²⁸⁾ In addition, electronic health literacy, defined as the ability of older adults to apply knowledge to address or solve health problems by seeking, finding, and understanding health information from electronic sources, is essential for promoting an improved response to major public health events such as the COVID-19 pandemic.²⁹⁾ Although the cross-sectional design of the present study prevented us from directly investigating the interactional relationship between the use of a physical activity monitor and risk of locomotive syndrome, our findings indicated that older adults using a physical activity monitor were less likely to develop locomotive syndromes.

The estimated prevalence of worsened locomotive function, defined as locomotive syndrome, in Japan is >65%.¹⁶⁾ As locomotive syndrome increases the risk of disability and mortality,¹⁶⁾ early assessment and prevention strategies are required in the older adult population. Locomotion training (strengthening, muscle strength, and balancing exercises) in older adults with locomotive syndrome has positive effects on physical functions such as muscle strength and aerobic capacity.^30,31) Multidimensional intervention strategies (e.g., in-person exercise classes and self-management to maintain physical activity) are needed. Using a physical activity monitor and setting a personal step goal could be useful strategies for maintaining locomotive performance in middle-aged and older populations.

This study has some limitations. First, owing to the cross-sectional design, the causal relationship between the use of physical activity monitors and the development of locomotive syndrome remains unclear. Moreover, this study used a self-administered questionnaire to determine the locomotive syndrome status. The reference values for this risk assessment of locomotive syndrome were based on nationwide data from Japanese adults.¹⁵⁾ The two physical tests (the two-step and stand-up tests) are more sensitive to increase in age than was the self-reported test (GLFS-25 score).¹⁵⁾ Detailed assessments, including objective measures, are needed to examine their validity for the evaluation of locomotive syndrome. A selection bias was also possible as all participants routinely used the Internet. Older adults who routinely use digital health information are associated with higher educational levels and higher income.³²⁾ We did not consider factors such as economic status, health behaviors, and chronic diseases. Additionally, we excluded individuals who reported a history of dementia and other neurological disorders; however, poor cognitive performance status (e.g., mild cognitive impairment) might have influenced the responses to the questionnaires. Furthermore, recall bias or memory impairment during the self-administered survey might also have affected the results. Further studies are needed to determine the causal relationship between the use of physical activity monitors and risk of age-related functional decline.

In conclusion, approximately half of the participants aged ≥60 years used physical activity monitors during the COVID-19 pandemic. Middle-aged and older Japanese adults who used physical activity monitors during the pandemic may have engaged in more physical activity-associated behavior, compared with non-users. Such users with long-term (i.e., >2 years) usage and personal step goals were less likely to develop locomotive syndromes. Therefore, long-term physical activity monitoring and personal step goal setting could be beneficial for the physical health of middle-aged and older adults.