Tracking handgrip strength in Kendo athletes from university to middle and older adulthood.

OBJECTIVE: This study aimed to compare the current handgrip strength (HGS) of Kendo athletes with their HGS when they were in university (up to 50 years). METHODS: Eighty male graduates who were Kendo club members during their university days performed anthropometric and HGS measurements, and these HGS were compared with those measured during their university days (mean age of 19.5 years old). RESULTS: There was no evidence of a statistical difference in HGS between the current measurement and the measurement taken during university [-0.64 (-1.9, 0.67) kg, p = .336]. There was, however, evidence that the difference in HGS depended upon the current age of the individual (t = -6.43, p < .001). When probing the interaction, there were statistical differences between the ages of 24.6 and 38.2 years and between the ages of 47.4 and 69.9 years. Strength increased across time in the younger participants and decreased for those who were older. Between the ages of 38.9 and 46.1 years, there was no evidence of a statistical difference indicating a maintenance of strength. CONCLUSION: The HGS of Kendo club graduates, which they acquired during their formative years, continued to increase even after they graduated from university and entered their 30s. However, their HGS decreased from age 50, even though they practiced Kendo.

Athletes in sporting events with upper-body gripping movements have greater handgrip strength than those in sporting events that prioritize the lower body.

OBJECTIVE: Evidence suggests that acquiring a high level of handgrip strength early in life and maintaining that strength throughout life may be important for health. In addition, it is thought that sports activities performed during the developmental period are effective in improving handgrip strength, but it is unknown what types of sports are more effective. As a first step, we conducted a cross-sectional study to compare handgrip strength across different sports (upper-body gripping sports vs. lower body) in early adulthood. METHODS: We used the Juntendo Fitness Plus Study data from 1973 to 2018 and selected two types of sporting events with matching physiques (soccer, baseball, and kendo) but different degrees of gripping. Data on 7344 male first-year sports university students included 1127 soccer, 297 Kendo, and 698 baseball players. RESULTS: Those in the lower body-only (soccer) sports had -3.78 (95% CI: -4.27, -3.29) kg lower handgrip strength than those in the lower + upper (kendo and baseball). Comparing each individual sport found that each sport was different from each other with Kendo > Baseball > Soccer (between each sport, p < .001). In addition, the difference between sports has become greater across time. CONCLUSIONS: In early adulthood, handgrip strength is greatest in those participating in sports with upper-body movements compared to those participating in sports that mainly involved lower-body movements. The three sports we selected are natural activities that do not directly train handgrip strength. Therefore, sport may be one potential method to improve low handgrip strength in children/adolescents during the developmental period.

Prevalence of dry eye syndrome and risk factors in physical education and sports science graduates.

PURPOSE: There are only a few epidemiological studies of dry eye syndrome (DES) in populations with a common academic background. in this study, the prevalence of DES and associated factors were evaluated separately in men and women physical education and sports science graduates. STUDY DESIGN: Cross-sectional survey. METHODS: A questionnaire about the diagnosis of DES and associated factors was mailed to 9507 graduates of the Faculty of Health and Sports Science, Juntendo University. The questions covered subjective DES using Schaumberg et al.'s questionnaire and the prevalence of diagnosed DES. Associated factors, age, sex, smoking, alcohol consumption, body mass index, daily screen viewing time, and contact lens (CL) use were analyzed. RESULTS: A total of 2048 valid responses were received. The prevalence of diagnosed DES was 2.9% in men and 9.3% in women. For subjective DES, the prevalence was 14.8% in men and 39.8% in women. The odds ratio for DES was high in men and women who used CLs and women whose daily screen viewing time was ≥ 4 h. CONCLUSION: Both diagnosed and subjective DES were highly prevalent in men and women of all ages, particularly among those in their 20 and 30s. CL use was associated with DES in both men and women. Measures to deal with the factors that can be corrected might have a positive effect on the ocular health and quality of life of physical education and sports science graduates.

Handgrip Strength and Healthspan: Impact of Sports During the Developmental Period on Handgrip Strength (Juntendo Fitness Plus Study).

Handgrip strength as a biomarker is being studied as a factor in predicting disease onset. However, the effect of improving handgrip strength through physical exercises, such as sports during the developmental period, on disease prevention has yet to be fully elucidated. The Juntendo Fitness Plus (J-Fit Plus) Study is a unique database of anthropometric and physical fitness measurements with over 50 years of accumulated data. It has the potential to explore the effects of sports on the association between handgrip strength and morbidity/mortality. We first outline previous studies on the impact of physical exercise interventions on handgrip strength, separated into adulthood and developmental period. We then introduced a unique effort to investigate the effects of sports using the J-Fit Plus Study database and describe the challenges of finally elucidating the impact of exercise on the association between handgrip strength and health status.

Sports activities at a young age decrease hypertension risk-The J-Fit+ study.

This study aimed to assess (1) blood pressure between young, current athletes, and non-athletes early in life; (2) hypertension prevalence between former athletes and the general population later in life; and (3) understand the mechanisms between exercise training and hypertension risks in the form of DNA methylation. Study 1: A total of 354 young male participants, including current athletes, underwent blood pressure assessment. Study 2: The prevalence of hypertension in 1269 male former athletes was compared with that in the Japanese general population. Current and former athletes were divided into three groups: endurance-, mixed-, and sprint/power-group. Study 3: We analyzed the effect of aerobic- or resistance-training on DNA methylation patterns using publicly available datasets to explore the possible underlying mechanisms. In young, current athletes, the mixed- and sprint/power-group exhibited higher systolic blood pressure, and all groups exhibited higher pulse pressure than non-athletes. In contrast, the prevalence of hypertension in former athletes was significantly lower in all groups than in the general population. Compared to endurance-group (reference), adjusted-hazard ratios for the incidence of hypertension among mixed- and sprint/power-group were 1.24 (0.87-1.84) and 1.50 (1.04-2.23), respectively. Moreover, aerobic- and resistance-training commonly modified over 3000 DNA methylation sites in skeletal muscle, and these were suggested to be associated with cardiovascular function-related pathways. These findings suggest that the high blood pressure induced by exercise training at a young age does not influence the development of future hypertension. Furthermore, previous exercise training experiences at a young age could decrease the risk of future hypertension.

Sports and Kinetic Visual Acuity.

Kinetic vision acuity (KVA) is an index developed in Japan that refers to the capacity to recognize a moving object that moves back and forth against the observer. This review outlines the history of KVA and studies on KVA conducted at the Faculty of Health and Sports Science of Juntendo University, i.e. characteristics of KVA in athletes, factors associated with KVA, sports and age-dependent decline of KVA, and effects of docosahexaenoic acid (DHA) and astaxanthin on KVA. KVA was defined in the early 1960s, and the measurement device was invented in 1968. Studies at the Faculty of Health and Sports Science began in the 1990s. In track-and-field athletics and skeleton, a winter downhill event, higher-ranked athletes had higher KVA than lower-ranked athletes. Although KVA cannot be predicted from static visual acuity or reaction time, a significant correlation was found between KVA and the peak latency of visual-evoked potentials. KVA could not be improved by training and did not change between age of 8 and 17 years. In contrast, habitual practice in kendo may inhibit the age-dependent decline in KVA. DHA may also improve KVA in subjects with low KVA; however, astaxanthin did not improve KVA.

Engagement in different sport disciplines during university years and risk of locomotive syndrome in older age: J-Fit+ Study.

BACKGROUND: Among former Olympic-level athletes, engagement in different sport disciplines has been associated with mortality risk in subsequent years. However, limited evidence is available on whether engagement in different sport disciplines at a young age is associated with locomotive syndrome (LS) risk later in life. This study examined the relationship between engagement in different sport disciplines during university years and LS risk in older age among former university athletes. METHODS: Participants were 274 middle-aged and 294 older men alumni who graduated from a school of physical education in Japan. LS risk was defined as answering "yes" to any of the Loco-check questions. Data on university sports club membership were collected using questionnaires. University clubs were classified into three groups of cardiovascular intensity (low, moderate, high), following the classification system of sport disciplines by the American College of Cardiology. This classification considers the static and dynamic components of an activity, which correspond to the estimated percent of maximal voluntary contraction reached and maximal oxygen uptake achieved, respectively. University clubs were grouped based on the risk of bodily collision (no, yes) and extent of physical contact (low, moderate, high). Relationships between engagement in different sport disciplines and LS risk were analyzed using Cox proportional hazards models, and adjusted for age, height, weight, joint disease, habitual exercise, and smoking and drinking status. RESULTS: Adjusted hazard ratios and 95% confidence intervals associated with the low, moderate, and high cardiovascular intensity sports were 1.00 (reference), 0.48 (0.22-1.06, P = 0.070), and 0.44 (0.20-0.97, P = 0.042) in older men, respectively; however, there was no significant association between these parameters among middle-aged men. Engagement in sports associated with physical contact and collision did not affect LS risk in either group. CONCLUSIONS: Engagement in sports associated with high cardiovascular intensity during university years may reduce the risk of LS in later life. Encouraging young people to participate in such activities might help reduce LS prevalence among older populations.

Female Athletes Genetically Susceptible to Fatigue Fracture Are Resistant to Muscle Injury: Potential Role of COL1A1 Variant.

PURPOSE: We aimed to investigate the hypothesis that type I collagen plays a role in increasing bone mineral density (BMD) and muscle stiffness, leading to low and high risks of fatigue fracture and muscle injury, respectively, in athletes. As a potential mechanism, we focused on the effect of the type I collagen alpha 1 chain gene (COL1A1) variant associated with transcriptional activity on bone and skeletal muscle properties. METHODS: The association between COL1A1 rs1107946 and fatigue fracture/muscle injury was evaluated in Japanese athletes. Effects of the polymorphism on tissue properties (BMD and muscle stiffness) and type I collagen α1/α2 chain ratios in muscles were examined in Japanese nonathletes. RESULTS: The C-allele carrier frequency was greater in female athletes with fatigue fracture than in those without (odds ratio = 2.44, 95% confidence interval [CI] = 1.17-5.77) and lower in female athletes with muscle injury than in those without (odds ratio = 0.46, 95% CI = 0.24-0.91). Prospective validation analysis confirmed that in female athletes, muscle injury was less frequent in C-allele carriers than in AA genotype carriers (multivariable-adjusted hazard ratio = 0.27, 95% CI = 0.08-0.96). Among female nonathletes, the C-allele of rs1107946 was associated with lower BMD and lower muscle stiffness. Muscle biopsy revealed that C-allele carriers tended to have a larger type I collagen α1/α2 chain ratio than AA genotype carriers (2.24 vs 2.05, P = 0.056), suggesting a higher proportion of type I collagen α1 homotrimers. CONCLUSION: The COL1A1 rs1107946 polymorphism exerts antagonistic effects on fatigue fracture and muscle injury among female athletes by altering the properties of these tissues, potentially owing to increased levels of type I collagen α1 chain homotrimers.

Association of physical fitness and motor ability at young age with locomotive syndrome risk in middle-aged and older men: J-Fit+ Study.

BACKGROUND: Physical fitness and motor ability are associated with the incidence of locomotive syndrome (LS) in older adults. The relationships between physical fitness and motor ability at a young age to LS risk in later life remain unclear. This study examined the association between physical fitness and motor ability among university students and their risk of LS in middle and old age. METHODS: The participants were 231 male alumni aged 48-65 years from the Department of Physical Education of a university in Japan. Physical fitness and motor ability test results during their fourth year at the university were used. Physical fitness tests included the side-step test, vertical jump test, back muscle, grip strength, trunk lift, standing trunk flexion, and step-test. Motor ability was tested using the 50-m and 1500-m run, running long jump, hand-ball throw, and pull-up test. LS risk was assessed using a seven-question standardized self-administered Loco-check questionnaire. Participants were divided into three groups (low, medium, and high) based on physical fitness and motor ability test results at young age, and LS risk was assessed at an older age across the three groups using Cox proportional hazards models. RESULTS: From the 2017 follow-up survey, the median follow-up period was 37 years (interquartile range, 33-41), and LS risk was suspected for 31 (13.4%) participants. Better performance on the side-step test was associated with the reduced risk of LS (hazard ratio 0.32; 95% confidence interval, 0.101-0.983, P = 0.047). CONCLUSIONS: Good agility (side-step test) at a young age may reduce the future risk of LS among middle-aged and older men.

Secular trends in the grip strength and body mass index of sport university students between 1973 and 2016: J-Fit＋study.

Sport university students are a unique population because they usually have a strong sport background since early childhood. In this study, we aimed to examine secular trends in grip strength of male, first-year sport university students in comparison with the general population between 1973 and 2016. Existing data on the grip strength of 6,308 sport university students aged 18 years were examined. The data were obtained from the Juntendo Fitness Plus Study, a study of the Department of Physical Education/Health and Sports Science of Juntendo University. For reference, age- and sex-matched data (18 years old, male) on the grip strength were obtained from a national database. Compared with the general population, the sport university students had greater body mass index and stronger grip strength at all times. The grip strength of sport university students significantly declined between the 1980s and 1990s, and it has plateaued since 2000, albeit at low levels. Compared with the peak performance of sport university students in 1984, the grip strength of students in 2016 was significantly lower by 8.1 kg. The downward trends were also confirmed in the general population during the same periods. In conclusion, the grip strength of sport university students has significantly declined over the last few decades.

A body mass index over 22 kg/m2 at college age is a risk factor for future diabetes in Japanese men.

BACKGROUND: There is a high incidence of type 2 diabetes in Asian adults, even those with a normal body mass index (BMI) (<25.0 kg/m2). For example, it has been shown that a slightly increased BMI (>23 kg/m2) at middle age is a risk factor for type 2 diabetes in Asians. In this historical cohort study, we investigated whether a slightly increased BMI at college age was also a risk factor for future diabetes in Japanese men. METHODS: Six hundred and sixty-one male alumni who graduated from a physical education school between 1971 and 1991 and who responded to follow-up investigation between 2007 and 2017 were included in this study. Participants were categorized into four categories: college BMI of <21.0 kg/m2, 21.0-22.0 kg/m2, 22.0-23.0 kg/m2, and ≥23.0 kg/m2, and the incidence and risk ratio of diabetes were compared between groups. RESULTS: The median follow-up period was 32 years (interquartile range, IQR: 27-36), which included 20,983 person-years of observation. Subjects were 22 (22-22) years old at college graduation, and 55 (50-59) years old at the final follow-up investigation. During the study period, 56 men developed diabetes; the prevalence rates for the lowest to highest BMI categories were 4.4%, 7.6%, 10.5%, and 11.3%, respectively, and their adjusted hazard ratios were 1.00 (reference), 1.77 (95% CI: 0.68-4.30), 2.42 (1.00-5.84), and 2.53 (1.06-6.07), respectively (p = 0.03 for trend). CONCLUSION: Our data suggest that a BMI over 22.0 kg/m2 at college age is a risk factor for diabetes later in life in Japanese men.

Effects of Batting Practice and Visual Training Focused on Pitch Type and Speed on Batting Ability and Visual Function.

This study aimed to examine the effects of batting practice and visual training focused on the pitch type and speed on batting ability and visual function. A total of 46 participants took part in 12 training sessions for 4 weeks. The participants were divided into six groups according to the training type as follows: Group 1, batting practice with a fastball at 100 km/h; Group 2, tracking (watching) a fastball at 100 km/h; Group 3, batting practice with a fastball at 115 km/h; Group 4, tracking a fastball at 115 km/h; Group 5, batting practice with a curve ball at 100 km/h; and Group 6, tracking a curve ball at 100 km/h. Dynamic visual acuity, depth perception, hand-eye coordination, and batting ability were measured before and after training. Group 1 showed significant improvement in batting ability in the tests with 100 km/h fastballs and curve balls, while Groups 3 and 5 showed significant improvement in batting ability with 100 km/h fastballs and curve balls, respectively. Group 6 also showed significant improvement in batting ability with 100 km/h fastballs. Moreover, Groups 2 and 4 showed significant improvement in Dynamic visual acuity and hand-eye coordination, respectively. The results of the present study suggest that batting practice and visual training improve batting ability for the same pitch types and speeds as those encountered in practice. Therefore, visual training may be an effective method for improving batting ability and visual function in coaching settings.

Slightly increased BMI at young age is a risk factor for future hypertension in Japanese men.

BACKGROUND: Hypertension is developed easily in Asian adults with normal body mass index (BMI) (~23 kg/m2), compared with other ethnicities with similar BMI. This study tested the hypothesis that slightly increased BMI at young age is a risk factor for future hypertension in Japanese men by historical cohort study. METHODS: The study participants were 636 male alumni of the physical education school. They had available data on their physical examination at college age and follow-up investigation between 2007 and 2011. The participants were categorized into six categories: BMI at college age of <20.0 kg/m2, 20.0-21.0kg/m2, 21.0-22.0kg/m2, 22.0-23.0kg/m2, 23.0-24.0kg/m2, and ≥24.0kg/m2, and the incidence of hypertension was compared. RESULTS: This study covered 27-year follow-up period (interquartile range: IQR: 23-31) which included 17,059 person-years of observation. Subjects were 22 (22-22) years old at graduated college, and 49 (45-53) years old at first follow-up investigation. During the period, 120 men developed hypertension. The prevalence rates of hypertension for lowest to highest BMI categories were 9.4%, 14.6%, 16.1%, 17.5%, 30.3%, and 29.3%, respectively (p<0.001 for trend), and their hazard ratios were 1.00 (reference), 1.80 (95%CI: 0.65-4.94), 2.17 (0.83-5.64), 2.29 (0.89-5.92), 3.60 (1.37-9.47) and 4.72 (1.78-12.48), respectively (p<0.001 for trend). This trend was similar after adjustment for age, year of graduation, smoking, current exercise status and current dietary intake. CONCLUSION: Slightly increased BMI at young age is a risk factor for future hypertension in Japanese men.

Cardiorespiratory fitness and the incidence of type 2 diabetes: a cohort study of Japanese male athletes.

BACKGROUND: In Japan, although the incidence of overweight (BMI ≥ 25) is still low compared with that in Europe and the United States, the prevalence of type 2 diabetes has increased over the last 15 years,. In both Japanese and Caucasian populations it has been reported that a high level of cardiorespiratory fitness protects against the development of type 2 diabetes. However, there are no reports focused specifically on athletes that investigate whether high cardiorespiratory fitness at a young age can prevent disease later in life. We examined the relationship between cardiorespiratory fitness at a young age and the development of type 2 diabetes in Japanese athletes using a cohort study. METHODS: The cardiorespiratory fitness of male alumni of the physical education department of Juntendo University, as measured by stored data of a 1,500-m endurance run in college (1971-1991) was compared with their incidence of type 2 diabetes as determined by follow-up questionnaires (2007-2009). This study used Cox's proportional hazards models and adjusted for age, year of graduation, BMI, smoking, and sports club participation at college age. RESULTS: We collected data on cardiorespiratory fitness at college age and medical history survey data during 2007-2009 from 570 male alumni. The median follow-up period was 26 years (IQR: 23-29 years), and 22 men had developed type 2 diabetes. An inverse relationship was observed between incidence of type 2 diabetes and level of cardiorespiratory fitness at time of college after adjustment for age, year of graduation, BMI, smoking, and sports participation. The adjusted hazards ratio and 95% CI by category (low, medium, and high) were 1.00 (reference), 0.40 (0.14-1.13) and 0.26 (0.07-1.00) (p = 0.03 for trend). CONCLUSIONS: A high level of cardiorespiratory fitness at a young age can help prevent type 2 diabetes later in life.

Effect of yellow-tinted lenses on visual attributes related to sports activities.

The purpose of this study was to clarify the effect of colored lenses on visual attributes related to sports activities. The subjects were 24 students (11 females, 13 males; average age 21.0 ±1.2 years) attending a sports university. Lenses of 5 colors were used: colorless, light yellow, dark yellow, light gray, and dark gray. For each lens, measurements were performed in a fixed order: contrast sensitivity, dynamic visual acuity, depth perception, hand-eye coordination and visual acuity and low-contrast visual acuity. The conditions for the measurements of visual acuity and low-contrast visual acuity were in the order of Evening, Evening+Glare, Day, and Day+Glare. There were no significant differences among lenses in dynamic visual acuity and depth perception. For hand-eye coordination, time was significantly shorter with colorless than dark gray lenses. Contrast sensitivity was significantly higher with colorless, light yellow, and light gray lenses than with dark yellow and dark gray lenses. The low-contrast visual acuity test in the Day+Glare condition showed no significant difference among the lenses. In the Evening condition, low-contrast visual acuity was significantly higher with colorless and light yellow lenses than with dark gray lenses, and in the Evening+Glare condition, low-contrast visual acuity was significantly higher with colorless lenses than with the other colors except light yellow. Under early evening conditions and during sports activities, light yellow lenses do not appear to have an adverse effect on visual attributes.

Post-training consumption of wheat gluten hydrolysate suppresses the delayed onset of muscle injury in soccer players.

Wheat gluten hydrolysate (WGH) is reported to suppress the muscle injuries associated with exercise in long distance running and weight training. In the present study, we investigated the effects of WGH consumption on suppression of muscle injury after soccer training in a double-blind crossover study. Immediately after a mini soccer game, six soccer players consumed 18.0 g of WGH, and muscle injury was investigated using serum creatine kinase (CK) as an indicator. The results showed a significant increase in serum CK from immediately after exercise to 12 h after exercise stress (p<0.05) in the placebo group, while serum CK decreased during this same time period in the WGH group, and the difference between the two groups was significant. This suggests that WGH consumption suppresses delayed-onset muscle injury after exercise in soccer.

Development of a baseball-specific battery of tests and a testing protocol for college baseball players.

In this study, the relationship between the physical fitness of college baseball players found from 6 field tests and a performance evaluation by coaches was investigated. The purpose was to ascertain whether the results would be similar to those obtained in a previous study. The subjects of the study were 43 college baseball players (mean age, 20.7 +/- 1.4 years; mean athletic career, 10.9 +/- 2.6 years). Referring to the previous study, the field tests of physical fitness were composed of 6 items: throwing distance, back strength, medicine ball throwing, standing long jump, T-test, and base running. For capabilities in batting, fielding, and running, the coach's evaluation was expressed by T scores. The results of the analysis indicated that those players with high evaluation scores had significantly better test results in comparison with those players who were rated low in the evaluation. Although the multiple regression models of the previous study were associated with a middle goodness of fit, a significant correlation was found between physical fitness found in the field tests and performance. The results from a partial correlation analysis indicated a significant correlation between the following: batting evaluation with back strength (p < 0.01) and medicine ball throwing (p <0.01); fielding evaluation with throwing distance (p < 0.05); and running evaluation with medicine ball throwing (p < 0.01), standing long jump (p < 0.05), T-test (p < 0.01), and base running (p < 0.01). It is certain that the performance of college baseball players is related to their physical fitness.