Physical fitness including muscle strength and endurance capacity varies substantially among individuals. Physical activity level and exercise behavior also vary among individuals. Many family studies and studies on twins have reported that genetic factors are responsible for heterogeneity in fitness-related traits. However, there is much dispersion in heritability, as previously reported. A systematic review was performed to determine the extent of heritability in physical fitness. A literature search was conducted through PubMed using the following keywords: (heredity or heritability) and (“muscle strength” or “muscle contraction” or endurance or athlete* or fitness or exercise) and (twin* or family). Finally, 43 articles that included 137 phenotypes met the criteria. Only one article focused on the heritability of athletic status. With respect to muscle strength, 23 articles and 54 phenotypes were collected, and showed a range of heritability of 0%-98% (mean: 55±22%). This heterogeneity was partly explained by the ages of subjects. With respect to endurance capacity, 13 articles and 28 phenotypes showed heritability of 0%-93% (mean: 54±25%). The considerable degree of variability in heritability of fitness-related traits may depend on age, sex, race, and environmental factors. Therefore it is necessary to investigate the interaction between genetic factor and factors other than genetic factor. On the other hand, with respect to exercise behavior or physical activity level which is important for improving the physical fitness or health status, the heritability of 0%-85% has also been reported. That is, the genetic factor plays a role in not only physiological phenotypes but also behavioral phenotypes. Understanding of these genetic factors and their mechanisms will lead to improvement in physical fitness or encouragement of physical activity/exercise behavior.

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Overweight or obesity becomes a worldwide public health issue; the global obesity pandemic. Strategies to effectively prevent overweight and obesity are needed. Slow eating, which involves chewing food slowly and thoroughly, can be an effective strategy to prevent overweight and obesity. Previous studies reported a relationship between rapid eating and overweight. Candidate factors inducing the relationship have been thought to be related to increases in appetite and energy intake through rapid eating, allowing the ingestion of a greater-than-optimal volume of food. While the counter effect of slow eating has been widely known, effects of eating speed on digestion, absorption, and metabolism has yet to be elucidated. If eating speed affects digestion, absorption, and metabolism, eating speed can be a factor explaining the relationship between eating speed and body composition. The present review is to summarize the effects of eating speed on digestion, absorption, and metabolism, consequently suggesting preferable effects of slowly eating on increasing energy expenditure after eating.

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Several studies have reported that molecular hydrogen (H₂) acts as a therapeutic medical gas owing to scavenging reactive oxygen species (ROS). However, little is known about effects of H₂ on exercise-induced oxidative stress. The purpose of this study was to investigate the effects of weekly hydrogen bathing on exercise-induced oxidative stress and delayed-onset muscle soreness (DOMS). Nine healthy and active young men participated in this study, and each subject performed hydrogen bathing trial and placebo bathing trial in a crossover design. The subjects performed downhill running (8 % decline) at 75 % peak oxygen uptake (VO₂peak) for 30 min, and each subjects conducted hydrogen or placebo bathing for 20 min, respectively, 1-6 days after downhill running. Before and after exercise, we measured visual analogue scale (VAS) and collected blood samples (Pre- and 5 min, 60 min after the end of bathing, 1day, 2days, 3days, 7days after downhill running). Blood sample analyses include creatine kinase (CK), myoglobin (Mb), malondialdehyde (MDA), reactive oxygen metabolites (d-ROMs), biological antioxidant potential (BAP), myeloperoxidase (MPO), interleukin-6 (IL-6), interleukin-17a (IL-17a) and lactate concentrations. Weekly hydrogen bathing had no effects of exercise-induced oxidative stress and muscle damage. On the other hand, hydrogen bathing significantly reduced DOMS (VAS) 1 and 2days after downhill running (p=0.033). These findings suggest that hydrogen bath after downhill exercise can be effective for reduction of DOMS.

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The purpose of this study was to examine the relationships between running performance and the cross–sectional area of the psoas major, peak oxygen uptake, and running economy in male junior long–distance runners. The subjects were 37 male junior athletes who achieved good records in interscholastic athletic competition during 5 years (2011–2015). Their seasonal best times in a 5,000 m race (5,000m–SB) were 14:04.11 ± 0:07.25 (13:53.64–14:16.15). In a multiple regression analysis, 5,000m–SB was statistical significantly correlated with the cross–sectional area of psoas major (16.0 ± 1.7 cm²) measured on magnetic resonance imaging and peak oxygen uptake (4.25 ± 0.36 l min^-1 [76.9 ± 5.8 ml min^-1 kg^-1]) during a lactate curve test comprising five stages. However, 5,000m–SB was not related to oxygen uptake at the work–load which was less than the load at the lactate threshold estimated by using the lactate curve test results. These results suggest that a high volume of the psoas major, the largest hip–flexor muscle, and peak oxygen uptake are among the important factors for junior long–distance runner performance.

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The purpose of the present study was to investigate the baseline characteristics related to the participation status in a longitudinal epidemiological study for the elderly. Nine hundred twenty-six self-supporting older adults lived in a local city located southwest in Japan were classified into the following 3 groups; non-participants (NP, n=170), participants for the baseline measurements (PB, n=278), and participants for both the baseline and follow-up measurements after two-years (PBF, n=478). The basic attributes including socioeconomic status, depressive symptoms, cognitive function, sleep quality, fitness, objectively- measured physical activity, habitual behavior, psychosocial characteristics and functional problems in daily life were assessed. Regarding the NP group, data were collected by questionnaire or home visits. According to the results of a multinomial logistic regression analysis adjusted for age, sex and years of education, significant odds ratios which indicate a poor status in most of the assessment items were observed in both the NP and PB groups in comparison to the PBF group. We concluded that sex (female), a higher age, fewer years of education, a cognitive function decline, depressive symptoms, a low fitness level, physical activity and daily living function, and poor psychosocial backgrounds were related to the non-participation and dropouts. These results should be considered in a longitudinal data analysis of the present study, as well as in the design setting of epidemiological studies dealing with physical activity indexes and care risk factors. Furthermore, these findings are also considered to be useful as basic data for such care prevention activities in the community.

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The 30-seconds all-out sprint test on the cycle ergometer was performed by 10 high school and 13 college men’s cyclists. In addition, this study investigated their best time for 200 m (200mTT) and 1000 m (1000mTT) time trials in the velodrome. This study clarifies the relationship between muscle thickness of thigh, shank, and trunk and 1) the average speed for the 200mTT and 2) the 1000mTT in the field, and 3) the mean power of the 30-seconds all-out sprint cycling test. 1) The average speed for the 200mTT significantly correlated with the muscle thickness of posterior shank and front and lateral abdomen. 2) The average speed for the 1000mTT significantly correlated with the muscle thickness of posterior thigh and shank and front and lateral abdomen. 3) The mean power of the 30-seconds all-out sprint cycling test significantly correlated with the muscle thickness of anterior and posterior thigh, posterior shank, and front and lateral abdomen. Except for the average speed for the 200mTT and 1000mTT, the mean power of the 30-seconds all-out sprint cycling test was significantly related to the muscle thickness of anterior thigh. These results suggest that increasing muscle thickness of posterior thigh and shank and front and lateral abdomen is important for enhancing performance in sprint cycling.

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