In present-day society with its proliferation of various work styles, many companies and workplaces are faced with the important and complicated tasks of maintaining and promoting workers’ health. Amid this climate, the Ministry of Health, Labour and Welfare of Japan on March 31, 2020, announced its revised “Guidelines for Total Health Promotion Plan for Workers in Workplaces.” This is a major revision of the original Total Health Promotion Plan (THP) that had been implemented up to that point. In the field of industrial/occupational health, physical activity and exercise are key topics addressed within the THP. This necessitates further study of physical fitness and sports medicine. In this study, based on societal trends and previous studies, we have reviewed the role of physical fitness and sports medicine research within the field of industrial/occupational health. We conclude it is important to clarify issues and objectives in each workplace and ways of concretizing plans to resolve and achieve them. Specific methods for doing so are diverse and indefinite, and creativity is required. Numerous options and types of tools should be created for applying outcomes on physical activity and exercise in accordance with the THP. Not only the viewpoint of avoiding risk, but also the viewpoints of accruing assets and taking a behavioral science approach toward continuing physical activity and exercise need to be considered. Research on these matters has not progressed sufficiently and we must advance a high volume of studies through various academic societies.

Health issues with workers include many aspects that scientific research in physical fitness and sports medicine can contribute to. Nevertheless, in Japan, there are few studies on the health problems in workers reported in the field of physical fitness and sports medicine. One reason could be the difficulty of obtaining cooperation in research from companies. This paper introduces results of epidemiological studies on health problems in workers by the Physical Fitness Research Institute. Our research serves as an example of physical fitness and sports medicine studies, including methods for securing fields for research. For the last decade, various epidemiological studies on worker’s mental health, sleep, non-alcoholic fatty liver disease, and labor related issues have been conducted in our research institute. Most of these studies indicated that lack of physical activity is associated with these indicators in Japanese workers. In recent years, we have also been conducting observational and interventional studies focusing on sedentary behavior in workers. Physical activity is deeply linked to worker’s health, therefore, the important approach to start a research in occupational health is to plan research that solves the company’s health challenges. In occupational health, the needs to promote physical activity and to reduce sitting time are growing under the movement of “Health and Productivity Management” and burden of the COVID-19 pandemic. We believe that current challenges provide an opportunity to advance physical fitness and sports medicine research in occupational health.

Although research on physical fitness science in Japan has developed along with occupational health issues, the role of researchers in this area has been reduced by technological advancements. Nowadays, the automation and mechanization of manual tasks have created new occupational problems. These new problems affecting workers, such as prolonged occupational sitting and a decline in cardiorespiratory fitness (CRF), have been shown to increase the risk of several diseases (i.e., diabetes, obesity, heart diseases, and mortality), and further studies are needed to clarify this issue. Furthermore, in response to changes in the social structure due to the “low birthrate, aging society, and shrinking population”, a workforce with a different form than that from the postwar period is required. Therefore, the need to consider how we can avert this national crisis with the new role of researchers in the field of physical fitness science is once again drawing attention. In this article, we introduce the research being conducted by the National Institute of Occupational Safety and Health in Japan to meet the needs of “healthy and long working” and discuss this research in the context of future issues. Specifically, we introduce the development of a tool (the Worker’s Living Activity-time Questionnaire) to assess workers’ sitting time and epidemiological research using it. Finally, we describe the efforts to develop a new index for evaluating workers’ CRF and social implementation experiments to make the workplace a base for health promotion.

Evidence is growing on adverse health outcomes associated with less physical activity (PA) and more sedentary behavior (SB). As most workers generally spend approximately one-third of the day at work, measuring the amount of occupational PA/SB time would contribute to understanding the health risks of physical inactivity and SB among workers. In this review article, we describe the amount of time spent in different intensities of activity (moderate-to-vigorous PA [MVPA]; light PA [LPA]; and SB), on work and non-work days, while at work and outside working hours among workers. The review used objective measurements made by an accelerometer and showed the proportion of MVPA that office workers engaged in on work and non-work days accounted for 3-5% and 2-4% of accelerometer wear time, respectively. Moreover, office workers spent more time in SB and less time in LPA on work days than non-work days (SB, 66-76% vs. 60-69%; LPA, 20-28% vs. 23-36%). Especially on work days, office workers spent the greatest proportion of the day in SB during working hours (71-82%), compared with that outside working hours (63-67%). The proportion of MVPA accounted for 2-5% during working hours and 3-7% outside working hours. In addition, there were considerable differences in the proportions of LPA and SB between white-collar and blue-collar workers during working hours (SB, 73 vs. 55%; LPA; 22 vs. 40%), whereas the MVPA time was similar (5 vs. 5%). Some occupational exposure to unfavorable PA/SB at work might be unavoidable; however, inadequate PA/SB during working hours should be corrected.

The physiological functions of expiratory isoprene, which is abundantly contained in human breath, are not well known. Recently, breath isoprene has been proposed to be related to oxidative stress, although no direct evidence has been reported. Therefore, the purpose of this study was to investigate the relationship between breath isoprene and oxidative stress status. Ten healthy male subjects performed a 20-min submaximal step-load cycling exercise, the intensity of which corresponded to a 60% peak oxygen uptake after a 10-min rest. Breath isoprene excretion during the exercise was calculated from the product of minute ventilation and isoprene expiratory concentration. To evaluate the oxidative stress, we collected blood samples from the subject’s fingertips before and immediately after the end of the exercise, and then diacron reactive oxygen metabolites (d-ROMs), which is an index of oxidative stress level, and biological antioxidant potential (BAP), which is an index of antioxidant potential, were measured. The breath isoprene concentration at the rest was significantly positively correlated with the ratio from BAP to d-ROMs (BAP/d-ROMs), which is an index of latent antioxidant potential (r = 0.63, P < 0.05). Furthermore, the change in breath isoprene excretion from before to after the exercise was significantly negatively correlated with the change in d-ROMs (r = -0.73, P < 0.05) and positively correlated with the change in BAP/d-ROMs (r = 0.88, P < 0.01). These results suggest that isoprene might play a role in the control of oxidative stress.

In this study, we performed echo intensity obtained from ultrasonographic images was used as a reference for intramuscular fat mass to determine whether intramuscular fat can be estimated non-invasively using the bioelectrical impedance method. The subjects were 45 healthy male university students (mean age 20.2±1.4 years) of the athletic club. An ultrasound images were taken from vastus lateralis, and the echo intensity was calculated from the obtained image using image analysis software. The impedance corresponding to each of the 17 points from 4to 700 kHz were collected using a multi-frequency impedance measuring device. In addition, intracellular resistance and extracellular resistance were calculated using Cole-Cole distribution model. Pearson’s correlation coefficient was used for the relationship between echo intensity and impedance. As a result, when using a frequency of 50 kHz or more, we observed a moderate correlation (r=0.529 ~ 0.597, p<0.001) between an impedance of 2cm at the distance between the sensing (V) and current (I) electrodes and echo intensity at 2cm from the skin surface. A moderate correlation (r=0.551, p<0.001) was observed between the intracellular resistance at the V-I electrode spacing of 2cm and echo intensity at 2cm form the skin surface. However, there was only a weak correlation between extracellular resistance and echo intensity. This suggests that the impedance and intracellular resistance measured at a frequency of 50 kHz or higher and with a V-I electrode spacing of 2cm reflect intramuscular fat.

Heat-not-burn (HNB) tobacco smoking has spread throughout the market. While it is suggested that HNB tobacco smoking reduces the vascular endothelial function and is associated with a high risk of developing cardiovascular disease. The antioxidant of vitamin C may attenuate the unfavorable effects of HNB tobacco smoking. In the present study, we examined the effect of oral vitamin C ingestion on the flow-mediated dilation (FMD) at the brachial artery and oxidative stress markers in patients before and after transient HNB tobacco smoking. Twelve healthy adult males underwent high-resolution ultrasonography of the brachial artery and evaluations of reactive oxygen metabolites (d-ROMs) and the biological antioxidant potential (BAP) before and after a single session of HNB smoking. FMD was used to examine the endothelial function and the oxidative stress and antioxidant status were determined by using a FRES4 analyzer. In this randomized, crossover, controlled trial, measurements were performed on 2 different days 20 min after the oral administration of 1000 mg of ascorbic acid (VC trial) or a placebo (P trial). Although the FMD values decreased after a single HNB smoking session in both trials, the VC trial showed significantly higher values than the P trial at 60 and 120 min after smoking. Whereas the FMD values 120 min after smoking in the P trial were lower compared to the Pre values, there was no difference in the VC trial. These results suggested that the ingestion of vitamin C might suppress the decrease in the endothelial function caused by a single HNB smoking.

The global pandemic of childhood physical inactivity and the associated reduction in physical fitness have become the major health problem. Based on such background, there is growing interest in child development research to investigate the associations among physical fitness, cognitive function, and the underlying neurobiological mechanisms. In the present narrative review, we first summarize the findings from behavioral studies that examined the relations of childhood fitness to academic performance and executive function. Because these behavioral findings remain controversial due to methodological inconsistencies, we further discuss differences in independent variables (e.g., physical activity vs. fitness), confounders (e.g., socioeconomic status), study designs (e.g., cross-sectional vs. randomized controlled trial), and assessments used to measure academic performance and executive function (e.g., task difficulty). Subsequently, we introduce neuroimaging studies on brain volume, task-evoked brain activation, and white matter fiber integrity which may provide mechanistic insights into the behavioral observations. To date, several randomized controlled trials using advanced imaging techniques showed that regular physical activity may change brain activations during executive function tasks and improve white matter fiber integrity in children. Collectively, our literature review suggests that regular physical activity leading to increase in physical fitness is likely to contribute to healthy brain development. Nevertheless, the current evidence is still limited and inconclusive, thus further rigorously designed randomized controlled trails are needed to clarify the association between childhood fitness and brain development.

Green tea catechins are well known to be one of polyphenols, and its regular ingestion induces body fat reduction in obese individuals. Cocoa polyphenols of high-cocoa chocolate can also improve arterial stiffness. However, it is unclear whether green tea catechins improve body fat and arterial stiffness even in healthy young adults. Therefore, this study aimed to examine the effects of regular green tea intake on body fat and arterial stiffness in young adults. This randomized, controlled, parallel-group intervention study included 53 Japanese college students (mean age, 21.1 ± 0.1; men, n = 40; women, n = 13). They were randomly divided into three groups: control group (n = 14), intervention I group (n = 19), and intervention II group (n = 20). The participants ingested 500 ml/day of commercially available natural water (0 mg of catechin/day) or green tea (intervention I group, 200 mg of catechin/day; intervention II group, 400 mg of catechin/day) for 4 weeks. After 4 weeks of intervention period, no significant changes in body weight, body mass index, pulse wave velocity, and cardio-ankle vascular index were observed in all groups. However, body fat and carbon dioxide output significantly reduced only in the intervention II group. With the level of catechin concentrations increasing, significant decreasing trends were found in body fat changes and respiratory exchange ratio changes. Therefore, these findings suggest that four weeks of regular green tea intake would reduce body fat, but not arterial stiffness, in young adults.

Dynamic knee valgus is considered a risk factor for anterior cruciate ligament (ACL) injuries. This study identified how knee in distance (KID) and hip out distance (HOD) affect one’s lateral trunk lean (LTL). The results were also tested for reliability. Fifteen female basketball players (30 legs) from a university participated in this study. The participants performed single-leg squats by bending the knee of the supporting leg to 60°. The trials were recorded using a video camera. The KID, HOD, and LTL were measured with two-dimensional images using the Dartfish software, which measured the maximal knee valgus. The Pearson’s correlation coefficient was used to measure the correlation between dynamic knee valgus (KID and HOD) and LTL. Additionally, the Interclass Correlation Coefficient (ICC) was used to measure the reliability of the KID, HOD, and LTL data sets. The statistical significance was established at a level of p<0.05. Results showed that the KID and LTL had a significantly negative correlation, measured at r=-0.227, p<0.05. The ICC (2.1) values were: 0.83 for HOD, 0.99 for KID, and 0.96 for LTL; while the ICC (1.2) values were: 0.86 for HOD, 0.83 for KID, and 0.85 for LTL. The two-dimensional analysis technique revealed that the values were highly reliable. In sum, dynamic knee valgus had a negative correlation with LTL during single-leg squats. Therefore, it was suggested that the factors of dynamic knee valgus might be evaluated using LTL on two-dimensional screening test.