We investigated the effects of feeding a large meal to female rats (n = 66) just before or just after voluntary wheel running on energy metabolism during a final endurance exercise test. The rats were divided into three groups ; one fed a large meal just before exercise (BE), one fed a large meal just after exercise (AE), and one fed ad libitum (AD) . The rats were allowed to run voluntarily from 20 : 00 to 07 : 00 h. The BE group were given a large meal (more than 12 g) between 19 : 00 and 20: 00 h and a small meal (3 g) between 07 : 00 and 08 : 00 h. The AE group were given a large meal (more than 12 g) between 07 : 00 and 08 : 00 h and a small meal (3 g) between 19 : 00 and 20 : 00 h. After 4 weeks, 6 rats in each group were sacrificed at 22 : 00 h, and 12 rats in each group were sacrificed after 30 min starting from 22 : 00 h at 15 m/min (n=6) or 35 m/min (n=6) on a rodent treadmill (0° grade) . Four rats in each group were sacrificed after 30 min starting from 22 : 00 h at rest on the treadmill as a control. The plasma free fatty acid (FFA) and glycerol concentrations increased significantly during low-speed exercise in the AD group, and during higher-speed exercise in all groups. The liver glycogen concentration was significantly greater in the AE group than in the other groups at rest, and decreased significantly during exercise at both speeds in the AD group, but not in the BE and AE groups. The gastrocnemius muscle glycogen concentration was decreased significantly during exercise at both speeds in the AD group, and at high speed in the BE and AE groups.
These results indicate that intake of a large meal just after exercise can store a high level of liver glycogen at the beginning of exercise than ad libitum feeding or large meal intake just before exercise, and expend plasma FFA in muscle during exercise compared with ad libitum feeding. This suggests that large meal intake just after exercise contributes to improvement of metabolic capacity in endurance exercise with enhanced liver glycogen sparing.

A study was conducted to examine the effects of exhaustive enduring exercise training on the skeletal muscle of rats. Twenty-six male Wistar rats were divided into 3 groups : an exhaustive training group (EE), a free-eating control group (Co), and a pair weight group in which body weight was matched to EE (PW) . The rats in EE were forced to run on a treadmill with an inclination of 0-3°, 6 days/week for 4 weeks. At first the rats ran at a constant speed for 60 min. Then we gradually added 2 m/min to the basic speed every minute until they were exhausted. The treadmill speed was 20 m/min during the first, 30 m/min during the second, 35 m/min during the third, and 40 m/min during the final week. The muscle wet weight, the quantity of the muscle protein and the isometric tetanic force were measured with the soleus and extensor digitorum longus (EDL) . Food restriction induced significant decreases in EDL weight. Exhaustive enduring exercise training induced noteworthy decreases in soleus weight, but remarkable gains in EDL weight. It also induced significant changes of the quantity of the muscle protein in the two muscles, which corresponded to the changes in muscle weight. The isometric tetanic force of both muscles was not affected by food restriction. The isometric tetanic force showed a significant decreases in EDL in EE comparison Co. The isometric tetanic force of the soleus did not show a significant decreases. However, its degree of decrease corresponded to that of the muscle protein. These findings illustrate that exhaustive endurance exercise training induces degradation of the soleus and hypertrophy of the EDL. However, it also decrease the muscle force which generats the capacity of the two muscles. We think that this phenomenon depends on the skeletal muscle characteristics, such as fiber type, and eccentric or concentric contraction.

Several studies have shown that low cardiorespiratory fitness (CRF) or heavy alcohol consumption is risks of total or certain types of cancer death. However, the combined influence of CRF and drinking habits on total cancer mortality is not clear. The purpose of this study was to investigate the joint effect of CRF and drinking habits on total cancer mortality among Japanese men. We evaluated the CRF and drinking habits on risk of total cancer mortality in 8,760 Japanese men (age: 19-59 yr) who were given a submaximal exercise test, a medical examination test, and questionnaires on their health habits. CRF was measured using a cycle ergometer test, and the men were classified into two categories by CRF levels based on the reference value of CRF (R-CRF) in “Physical Activity Reference for Health Promotion 2013” (Under R-CRF and Over R-CRF). Also, the men were assigned to Non Drinking, Moderate Drinking, and Heavy Drinking categories. There were 178 cancer deaths during the 20-yr follow-up period. Relative risk and 95% confidence intervals for total cancer mortality were obtained using the Cox proportional hazards model while adjusting for age, body mass index, systolic blood pressure, and smoking habits. Using the Under R-CRF & Heavy Drinking group as reference, the relative risk and 95% confidence intervals were 0.37 (0.16–0.85) for the Over R-CRF & Non Drinking group. This result suggests that Japanese male with a high CRF and a low drinking habit have a lower risk of total cancer mortality.

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.