Published papers

Ice slurry ingestion enhances exercise performance by lowering the core body temperature. However, an operational issue related to this ingestion is the requirement for a high intake of 7.5 g·kg-1 to produce the desired effects. We investigated the effects of the intake of low amounts of ice slurry at -2°C on the tympanic temperature and exercise performance during repeated high-intensity intermittent exercises in a hot environment. This study was a randomized, crossover study, with a 6-day washout period. Twelve university rugby union players performed two 30-min sessions of high-intensity intermittent exercises separated by a 15-min half-time break on a cycle ergometer in a hot environment (28.8°C ± 0.1°C, 49.5% ± 0.6% relative humidity). The participants ingested 450 g of -2°C-ice slurry (ICE), or a 30°C-beverage (CON) having the same composition as ICE, or 30°C-water (WAT) during the half-time break. The tympanic temperature and skin temperature were measured as the physiological data, and the peak power and mean power as the exercise performance data. The tympanic temperature at the half-time break and beginning of the 2nd session was significantly lower in the ICE group as compared with the CON and WAT groups. The skin temperature at the half-time break was significantly lower in the ICE group as compared with the WAT group. While the peak power and mean power during the 2nd session were significantly greater in the ICE group as compared with the CON and WAT groups. Our findings suggest that even the intake of lower amounts, as compared with those used in previous studies, of low-temperature ice slurry can reduce the body temperature and improve the peak power. These results suggest that intake of low-temperature ice slurry as a strategy for internal body cooling is useful for improving endurance exercise performance in hot environments.

It is mandatory to manage musculoskeletal disorders in the elderly to prevent their becoming bed-ridden or requiring long-term care. However, the prevalence of musculoskeletal disorders such as osteoporosis and sarcopenia in otherwise healthy people over 85 years old is not completely known. Here we enrolled 1026 healthy subjects between 85 and 89 years old and evaluated them for the presence of osteoporosis, sarcopenia and fragility fracture(s), and how those conditions were related. We also evaluated biomarkers such as serum levels of insulin-like growth factor 1 (IGF1) and vitamin D status. The prevalence of osteoporosis, sarcopenia or fragility fracture(s) in these subjects was 22.4, 10.2 or 15.0 %, respectively. Serum IGF1 and 25(OH)D were significantly and negatively correlated with osteoporosis or sarcopenia. Osteoporosis and either sarcopenia or fragility fracture(s) were significantly related and shown to be risk factors for each other, even after adjustment for gender and BMI, while sarcopenia and fragility fracture(s) were not associated. Our data may provide a health platform for the very elderly and suggest strategies to prevent musculoskeletal disorders in this population.

Aim: While the proportion of people of ≥85 years of age is expected to increase, there is limited research on the dietary patterns and physical performance of this population in Japan. The purpose of this study was to identify the dietary patterns of people of ≥85 years of age who live in Tokyo and to examine the relationship with their physical performance. Methods: Using data from the baseline survey (conducted in 2008-2009) of The Tokyo Oldest Old survey on Total Health study, the estimated 58 food intake items were aggregated into 33 items after energy adjustment, and a principal component analysis was performed. For physical performance, the results of grip strength, chair standing test, and 3 m timed up and go test conducted at normal walking speed were used. A multiple regression analysis was used to adjust for confounders and to examine the relationship between each dietary pattern and physical performance. Results: The subjects of the analysis were 87.3 (86.2-88.8) years of age (median [25-75th percentile] ). From the principal component analysis, three dietary patterns were identified: “various vegetable foods”, “fish and mushrooms”, and “cooked rice and miso soup”. A higher propensity for the “fish and mushrooms” dietary pattern was significantly associated with grip strength (partial regression coefficient, B (95% confidence interval): 0.48 (0.13-0.83) ). Conclusions: In a population of people of ≥85 years of age in Tokyo, a positive association was observed between hand grip strength and a dietary pattern characterized by fish and mushroom intake.

Objectives: As the world's population is ageing, improving the physical performance of the older population is becoming important. Although diets are fundamental to maintaining and improving physical performance, few studies have addressed the role of these factors in adults aged ≥85 years, and none have been conducted in Asia. This study aimed to determine the dietary patterns and examine their relationship with physical performance in this population. Design: This cross-sectional study (Kawasaki Aging and Wellbeing Project) estimated food consumption using a brief-type self-administered diet history questionnaire. The results were adjusted for energy after aggregating into 33 groups, excluding possible over- or underestimation. Principal component analysis was used to identify dietary patterns, and outcomes included hand grip strength, timed up-and-go test, and usual walking speed. Setting: This study was set throughout several hospitals in Kawasaki city. Participants: In total, 1,026 community-dwelling older adults (85-89 years) were enrolled. Results: Data of 1,000 participants (median age: 86.9 years, men: 49.9 %) were included in the analysis. Three major dietary patterns (DP1: various foods, DP2: red meats and coffee, DP3: bread and processed meats) were identified. The results of multiple regression analysis showed that the score of DP2 was negatively associated with hand grip strength (B, 95% confidence interval: -0.35, -0.64 to -0.06). Conclusions: This study suggests a negative association between hand grip strength and dietary patterns characterised by red meats and coffee in older adults aged ≥85 years in Japan.

Sarcopenia is one of the primary risk factors for various adverse health events in later life. However, its pathophysiology in the very old population remains unclear. Hence, this study aimed to examine whether plasma free amino acids (PFAAs) correlate with major sarcopenic phenotypes (i.e., muscle mass, muscle strength, and physical performance) in community-dwelling adults aged 85–89 years living in Japan. Cross-sectional data from the Kawasaki Aging Well-being Project were used. We included 133 adults aged 85–89 years. In this study, fasting blood was collected to measure 20 plasma PFAAs. Measures for the three major sarcopenic phenotypes included appendicular lean mass assessed by multifrequency bioimpedance, isometric handgrip strength, and gait speed from a 5 m walk at a usual pace. Furthermore, we used phenotype–specific elastic net regression models adjusted for age centered at 85 years, sex, body mass index, education level, smoking status, and drinking habit to identify significant PFAAs for each sarcopenic phenotype. Higher histidine and lower alanine levels were associated with poor gait speed, but no PFAAs correlated with muscle strength or mass. In conclusion, PFAAs such as plasma histidine and alanine are novel blood biomarkers associated with physical performance in community-dwelling adults aged 85 years or older.

Background: Regular and appropriate physical activity has health benefits; however, to ensure safety, a pre-exercise medical check based on health information is important. In this study, we aimed to clarify the relationship between risk classification by physicians at a health promotion facility in Japan and the occurrence of adverse events during facility use. Methods: We evaluated 3,571 individuals, excluding those with an unknown sex, age, medical assessment of exercise limitations, and facility usage status. Based on the results of the medical checkups conducted by a physician, the participants were divided into an exercise-prohibited group and an exercise-permitted group (exercise-permitted group, subdivided into non-restricted, orthopedic-restricted, internal medical-restricted, and combined-restricted groups). The risk of adverse events was examined. Results: The group in which exercise was prohibited comprised 72 participants, and that in which exercise was permitted comprised 1935, 612, 456, and 496 participants in the non-restricted, orthopedic-restricted, internal medical-restricted, and combined-restricted groups, respectively. Logistic regression analysis was performed on the four subgroups of the exercise-permitted group, and the odds ratios for adverse events adjusted for individual attributes were 1.04 [95% confidence interval (CI), 0.59–1.84; p = 0.89], 0.97 (95% CI, 0.53–1.78; p = 0.93), and 0.80 (95% CI, 0.42–1.54; p = 0.51) for the orthopedic-restricted, internal medical-restricted, and combined-restricted groups, respectively. A power analysis revealed that the study had a high level of power (0.99), based on a Cox–Snell R2 of 0.05 and a sample size of 3,499, indicating sufficient sensitivity to detect differences between groups. Conclusion: No significant difference in the odds of adverse events was found regardless of the presence or absence of exercise restrictions. Therefore, despite exercise-related risks, pre-exercise screening can help ensure that exercise is performed as safely as it is by individuals without such risks. However, further discussion is required regarding the necessity of screening for all exercise participants.

Background: Goal setting is an important step in planning physical activity promotion strategies. Based on the dose–response relationships between physical activity and health and the goal-setting theory, setting higher goals without exceeding people’s acceptance is desirable. Understanding maximum acceptance of physical activity increases is helpful for enabling such goal setting. Nonetheless, the level of maximum acceptance of physical activity increase and its sociodemographic differences remain unclear. This study examined the level and sociodemographic correlates of maximum acceptable physical activity increase among Japanese adults. Methods: A web-based cross-sectional questionnaire survey was conducted with 2259 Japanese adults aged 20–64 years. Based on the Capability, Opportunity, Motivation, and Behavior model, the acceptable time for increasing physical activity in a day was examined from three perspectives: capabilities, opportunities and motivations. For motivation, two definitions were employed: definition I regarded unchanged motivation as acceptable, and definition II regarded it as unacceptable. The maximum acceptable physical activity increase was identified by combining the responses of these subcomponents. This study measured sociodemographic factors such as gender, age, current marital status, current working status, educational background, annual household income and current physical activity duration. Results: The means (95% confidence intervals) and standard deviations of maximum acceptable physical activity increase were 17.0 (16.3–17.7) and 16.9 min per day in definition I and 9.0 (8.4–9.6) and 13.9 min per day in definition II. Across both definitions, multiple regression analyses showed that younger age, greater levels of annual household income and longer current physical activity duration were significantly associated with longer maximum acceptable physical activity increases. Conclusions: From the findings, an increase in physical activity of approximately 10–15 min per day might be an important option in goal setting, and setting higher goals would be feasible for younger adults, adults with higher household incomes, and physically active adults.

The scattering of Rb atoms on an anti-relaxation coating was studied. No significant change in the spin relaxation probability of Rb atoms by single scattering from a tetracontane surface was observed by cooling the film from 305 to 123 K. The mean surface dwell time was estimated using a time-resolved method.Delay-time spectra, from which mean surface dwell times can be estimated, were measured at 305, 153, and 123 K, with a time window of $9.3\times 10^{-5}$ s. The increase in mean surface dwell time with cooling from 305 to 123 K was smaller than $4.4\times 10^{-6}$ s, which is significantly smaller than the value expected from the mean dwell time at room temperature measured using the Larmor frequency shift. These results can be explained by assuming a small number of scattering components, with a mean surface dwell time at least three orders of magnitude longer than the majority component.

A healthy diet and regular physical activity (PA) are delineated as healthy behaviours. Their implementation is associated with better health outcomes and improved quality of life. There is less evidence of a relationship between dietary patterns (DP) and PA, especially in adults aged ≥ 85. Hence, this cross-sectional study investigates the association between DP and PA in people of this age group, using the data from The Kawasaki Aging and Well-Being Project. Brief-type self-administered diet history questionnaire was used to estimate the intake of fifty-eight types of food. After energy adjustment, principal component analysis was performed to identify DP. PA was measured objectively using an accelerometer and subjectively using a questionnaire validated for this age group. Thousand participants (median age: 86·9 years, men: 49·9 %) were included in the analysis. Three major DP (DP1 'various foods', DP2 'red meats and coffee', DP3 'bread and processed meats') were identified. DP1 'various foods' was similar to DP previously named 'healthy' or 'prudent' and showed a positive association with PA time (PAT) as measured by accelerometer (B, 6·25; 95 % CI 0·13, 12·37) and relatively shorter sedentary behaviour (SB) time. DP2 'red meats and coffee' and DP3 'bread and processed meats' were negatively associated with PAT and positively associated with SB time. This study observed the relationship between diet and PA behaviours in adults aged ≥ 85, with healthier and more food-diverse DP associated with longer PAT and relatively unhealthy DP with shorter PAT.

Background: Awareness, knowledge, beliefs, and behavioral intentions of physical activity (PA) guidelines may be important mediating factors for promoting PA. However, these pathways of the psychological process to PA behavior have not been examined. These pathways may differ depending on health literacy levels. This study investigated the pathways to PA, from guideline awareness to behavior, and further examined whether they differed by health literacy. Methods: A cross-sectional study was conducted with 7,000 Japanese participants aged 20–69 years. The participants were registered with an Internet survey company. Participants’ awareness, knowledge, beliefs, and behavioral intentions regarding the PA guidelines of Japan, the volume of moderate-to-vigorous intensity PA, activity level, and health literacy were examined through a questionnaire. The PA pathways, from guideline awareness to behavior, were examined by structural equation modeling (SEM), with PA behavior as the dependent variable. Multi-group SEM was conducted to examine the moderating effect of health literacy on PA pathways. Health literacy scores were dichotomized into high and low groups in multi-group modeling by the median split. Results: SEM revealed that PA guideline awareness directly affects PA behavior and has certain indirect effects through the mediation of knowledge, beliefs, and behavioral intentions. Furthermore, the multi-group SEM showed that the proportion of indirect effects (path coefficient [PC]: 0.11, 95% confidence interval [CI]: 0.10–0.13) was higher than direct effects (PC: 0.07, 95%CI: 0.03–0.11) in the high-health literacy group. In contrast, the proportion of direct effects (PC: 0.22, 95%CI: 0.15–0.30) was higher than indirect effects (PC: 0.06, 95%CI: 0.05–0.07) in the low-health literacy group. Conclusions: PA guideline awareness is both directly and indirectly associated with PA behavior, mediated by psychological pathways of knowledge, beliefs, and behavioral intentions, and influenced by health literacy. These results suggest that health literacy should be considered when implementing PA guideline-based interventions.

Aim: Some studies have reported a higher incidence of falls during winter with similar proportions of indoor and outdoor falls. We investigated the relationship between indoor temperature during winter and falls at home in the past year among community-dwelling older adults.Methods: This cross-sectional study enrolled 964 individuals of ≥65 years of age in Japan. Participants answered questions about falls (including trips) at home within the past year, and the living room temperature was measured for 2 weeks during winter. Participants were divided into those living in cold (mean temperature near the floor <12°C), slightly cold (12-17.9°C), and warm (≥18°C) houses. The association between indoor temperature (cold vs. slightly cold vs. warm houses) and falls at home in the past year was examined using a logistic regression analysis adjusted for potential confounding factors.Results: Valid data were obtained from 907 participants (mean age: 72.0±6.3 years), of whom 265,553, and 89 lived in cold, slightly cold, and warm houses, respectively. In the past year, falls occurred once in 325 (35.8%) participants and multiple times in 148 (16.3%) participants. In warm houses, the odds ratio of falling once and multiple times in the past year was 0.49 (p=0.032) and 0.34 (p=0.035), respectively, in comparison to cold houses.Conclusions: Living in cold houses may be associated with an increased risk of falling at home among older adults. Maintaining an appropriate indoor thermal environment during winter may reduce the risk of falling among individuals who spend most of their time at home.

Objectives: Poor cardiorespiratory fitness (CRF) and high body mass index (BMI) increased the risk of developing metabolic Syndrome (MetS) mostly in Caucasians. However, the sex-specific combined association of CRF and BMI on MetS considering health-related behaviors has yet to be thoroughly examined in Japanese. This study aims to investigate the sex-specific independent and combined associations of CRF and BMI with MetS in middle-aged Japanese adults. Methods: 421 participants were included in this cross-sectional study. CRF was estimated using a submaximal cycle ergometer. CRF and BMI were respectively divided into three categories according to tertile distribution. MetS was diagnosed based on five risk factors: waist circumference, triglycerides, high-density lipoprotein cholesterol, blood pressure, and fasting glucose. Multivariable logistic regression models were used to estimate independent and combined association of CRF and BMI with MetS. Results: Results showed that 154 (57.5%) and 70 (45.8%) of men and women had MetS, respectively. Compared to men with lower CRF or higher BMI, men with middle and higher CRF or middle and lower BMI were less likely to have MetS. Compared with ‘unfit and higher BMI’ group, ‘unfit and lower BMI’, ‘fit and higher BMI’, and ‘fit and lower BMI’ groups in men showed statistically significant decreased prevalences of MetS. However, no significant associations were found in women. Conclusions: This study found significant independent and combined associations of CRF and BMI with MetS only in men, but not in women. However, prospective studies are warranted to confirm sex-specific associations of CRF and BMI with MetS.

Background: Sarcopenia and frailty often worsen in older adults because of declines in activities of daily living and social connections that are associated with chronic diseases and traumatic injuries such as falls and fractures. Exercise intervention for sarcopenia can take >3 months to improve muscle mass, muscle strength, and walking speed. Thus, a specialized intervention system for shorter periods of time is needed. In this study, we aimed to evaluate the short-term efficacy of an exercise program using the wearable cyborg Hybrid Assistive Limb (HAL) lumbar type in physical function in mobility-limited older adults who do not require transition to long-term care. Methods: This randomized, single-blind, parallel-group study involved 79 community-dwelling older adults with physical frailty or locomotive syndrome assigned to an intervention group (n = 40) with the HAL lumbar type exercise program or a control group (n = 39) without the exercise program. The intervention group underwent trunk training (including trunk and hip flexion, standing and sitting from a single sitting position, and squats) and gait training (treadmill and parallel bars) twice a week for 5 weeks while wearing the HAL lumbar type. The 10-m usual and maximum walking speeds, Timed Up and Go test results, 5-times chair-standing test results, 5-question Geriatric Locomotive Function Scale (GLFS-5) scores, body-fat percentage, and muscle mass were measured before and after the intervention and analyzed using the intention-to-treat method. Results: The intervention (23 % male; mean age, 74.7 ± 4.7 years) and control (21 % male; mean age, 75.1 ± 4.1 years) groups did not differ significantly in baseline characteristics. Seventy-seven participants completed the program; two withdrew for personal reasons. The mean difference (standard error) between the groups for the primary outcome (usual walking speed) was 0.35 (0.04) m/s; the time-by-group interaction was significant (p < 0.001). Secondary outcomes (maximum walking speed, Timed Up and Go test results, 5-times chair-standing test results, and GLFS-5 scores) significantly improved in the intervention group. Body composition was unchanged in both groups. Conclusions: A 5-week exercise program using the HAL lumbar type is a promising option for community-dwelling older adults with limited mobility who do not require nursing care, resulting in clinically meaningful improvements in most physical functions within a short period.

Objectives Numerous reports have described injuries and illnesses in competitive athletes, but studies on leisure-time physical activity and associated adverse events in the general population have not been adequately reviewed. This study aimed to summarise the previous findings on this topic. Design Scoping review. Data sources PubMed and Ichushi-Web for articles in English and Japanese, respectively (13 April 2023). Eligibility criteria for selecting studies Articles on adverse events related to sports performed by € individuals and groups active in the community' were included, whereas those on elite athletes, exercise therapy and rehabilitation, and school sports were excluded. Terms related to physical activity, exercise, sports and adverse events were used for the search strategies. Results The literature search yielded 67 eligible articles. Most articles were from the USA, Japan and Australia. Running, scuba diving, rugby and soccer were the most commonly reported sports. Adults were the most common age category in the samples. The most commonly reported adverse events were injuries; only 10 articles reported diseases. 13 longitudinal studies reported the frequency of adverse events based on the number of events/participants×exposure. Conclusion Adverse events such as sports trauma, disability and certain diseases occur sometimes during sporting activities by residents; however, the articles identified in this review showed biases related to the countries and regions where they were published and the sports disciplines and types of adverse events reported, and articles reporting the frequency of adverse events were also limited. This highlights the need for more high-quality observational studies on diverse populations in the future.

Background: This research was conducted to investigate the association between cognitive function and smartphone ownership among very old adults, a rapidly growing age group. Additionally, we conducted a longitudinal investigation as a sub-analysis to determine whether owning a smartphone affects the level of long-term care certification as a proxy outcome for cognitive decline. Method: Data from a cross-sectional and longitudinal survey of the Kawasaki Aging and Wellbeing Project (KAWP) was used. Multivariate regression analysis was performed to examine the relationship between the Mini-Mental State Examination (MMSE) score and smartphone ownership. We also examined the association between smartphone ownership and the level of nursing care 1,278 days after the baseline. Results: Among 483 participants aged 85–90 years at baseline, 165 (46.9%) were male, and 131 (27.1%) owned a smartphone. In adjusted regression, smartphone ownership was associated with an MMSE score of ≥ 27 (odds ratio [OR]: 1.76, 95% confidence interval [CI]: 1.13–2.77), after controlling for potential confounders, including hypertension (OR: 1.65, 95% CI: 1.01–2.69). The results revealed no relationship between smartphone ownership and long-term care level. Discussion: Our results suggest that minimal cognitive decline in very old adults could make the ownership of a smartphone difficult.

Aim : Robotic suit-based exercises can be safely used for older adults. However, the effects of performing and discontinuing such programs on physical function remain unknown. We examined the long-term effects of a 5-week robotic suit-based exercise program on physical function in older adults with low fitness and assess the impact of exercise discontinuation during a 5-month follow-up period. Methods : We conducted a follow-up analysis of a completed randomized controlled trial. Community-dwelling older adults ( n  = 75, mean age = 74.7 ± 4.4 years) participated in a 5-week hybrid assistive limb robotic suit-based exercise program. We measured six physical function tests (gait speed at usual pace, five times sit-to-stand test, timed up and go test, functional reach test, two-step test, and grip strength), and the five-question Geriatric Locomotive Function Scale score. Evaluations were conducted at baseline, postintervention, and after the 5-month follow-up. Participants were stratified into those who continued exercising during the follow-up at the intervention facility (facility-attending group) and those who discontinued (nonattending group). Results : Significant improvements were observed postintervention in all physical function, especially gait speed (effect size: Cohen’s d  = 1.7), which remained higher than baseline after the follow-up period (Cohen’s d  = 1.2). Most physical function declined during the follow-up period. However, participants in the facility-attending group maintained their physical function levels, with no significant decline in most measures. Conclusion : Hybrid assistive limb-based exercise improved physical function, especially gait speed. Continuous exercise postintervention is essential to maintain these improvements.