Neighborhood-level socioeconomic factors moderate the association between physical activity and relative age effect: a cross-sectional survey study with Japanese adolescents.

BACKGROUND: Relative age effect is defined as a phenomenon where children born early generally perform better than children born later in the same cohort. Physical activity is an important factor that might be influenced by the relative age effect. Socioeconomic factors (e.g., parent's income, education level) are also associated with the adolescent's physical activity. However, no existing study has examined whether socioeconomic factors moderate the relative age effect on the adolescent's physical activity. This study aims to clarify whether and how birth month and socioeconomic factors relate to organized sports and physical activity among adolescents in Japan. METHODS: We conducted a questionnaire survey targeting 21,491 adolescents who live in a widespread neighborhood. We included 8102 adolescents (4087 males and 4015 females: mean age 13.1 ± 1.4) in the analysis. Based on the participants' birth months, we divided them into four groups (April to June, July to September, October to December, January to March). We asked participants to report their organized sports participation. Using the International Physical Activity Questionnaire for Japanese Early Adolescents, we identified their moderate to vigorous physical activity (MVPA). Neighborhood-level socioeconomic factors (areal deprivation, average annual income, education level) were analyzed based on national surveys, such as the population census. We performed multilevel logistic and linear regression analysis for organized sports participation and MVPA, respectively. Moreover, a simple slope analysis was implemented if the interaction between birth month and socioeconomic factor was significant in the multilevel linear regression analysis. RESULTS: Among males, relatively younger adolescents (adolescents who were born later in the same grade) were less likely to participate in organized sports activites (OR=0.90, 95% CI 0.82-0.97, p<0.05), while both males and females engaged in less MVPA (b=-0.54, b=-0.25, p< 0.01, respectively). We observed an interaction between birth month and socioeconomic factors. Among males in low-income neighborhoods, and females in more deprived neighborhoods, relatively younger adolescents engaged in less MVPA. CONCLUSIONS: Socioeconomic factors moderate the relative age effect on adolescents' physical activity. The relative age effect on adolescents' physical activity might be more likely to appear among adolescents from socioeconomically disadvantaged neighborhoods.

Esports for Seniors: Acute Effects of Esports Gaming in the Community on the Emotional State and Heart Rate among Japanese Older Adults.

In the last few years, esports have become popular among older individuals. Although participation in esports can become a novel activity for older adults, evidence on their effects is limited to young individuals. This study investigated the effects of esports participation on the emotional and physiological states of older adults. Twenty-five older men and women participating in health promotion activities in community centers (75 ± 8 years old) played a two-player racing game (Gran Turismo Sport, Sony) for 8-10 min. Their heart rates (HRs) were measured while the subjects played the games. The blood pressure (BP) and Profile of Mood States (POMS) were measured before and after gaming. The average HR during games (98 ± 17 bpm) was significantly higher than at pre-gaming (76 ± 11 bpm, p < 0.001). The BP before and after the games did not significantly change. Interestingly, the vigor scores (positive mood affect) in POMS increased after the games (p < 0.05) in females, but not in males. In summary, among older individuals, playing esports games showed a moderate increase in HR, no spike/drop of BP, and positive mood elevation. Our preliminary data suggest the feasibility of participating in esports in a community for older adults and that it could affect mood positively, especially among older women.

Association of Neighborhood Food Environment and Physical Activity Environment With Obesity: A Large-Scale Cross-Sectional Study of Fifth- to Ninth-Grade Children in Japan.

Objective: This study examined the relationship between neighborhood food and physical activity environment, and obesity among elementary and junior high school students in Japan. Methods: The participants were fifth- to ninth-grade children (n=7277), who were attending municipal schools in Japan. Percent overweight (POW) was calculated using their age, gender, height, and weight, which were collected through a questionnaire. A POW of < 20% was considered non-obese, while ≥ 20% was considered obese. Furthermore, using a geographic information system, we investigated the density of convenience stores, fast-food stores, casual restaurants, supermarkets and department stores, parks, sports facilities, stations, and intersections in the school district. Additionally, from the census, we obtained information regarding the population density of the municipality where the participants' schools were located. Multiple logistic regression analysis was used to examine the relationship between obesity and food environment (the food environment model), between obesity and physical activity environment (the physical activity environment model), and among obesity, food, and physical activity environment (the food and physical activity environment model). Results: In the food environment model and the food and physical activity environment model, the density of convenience stores showed a significant positive association. In the physical activity environment model, the density of stations showed a significant negative association. Conclusion: This study's findings can contribute to the development of appropriate community interventions for improving children's health in Japan and similar areas.

The relationship between sleep habits, lifestyle factors, and achieving guideline-recommended physical activity levels in ten-to-fourteen-year-old Japanese children: A cross-sectional study.

The current focus of meeting the physical activity guidelines for children and young people include preventing conditions such as high blood cholesterol, high blood pressure, metabolic syndrome, obesity, low bone density, depression, and injuries. However, the relationship between sleep habits and meeting physical activity guidelines is still unclear. This study aimed to assess this relationship among fifth- to eighth-grade (ages 10-14) Japanese children. This cross-sectional study included 3,123 children (boys: 1,558, girls: 1,565, mean age: 12.5 ± 1.2 years). Questionnaires were used to assess parameters such as moderate-to-vigorous physical activity per day, school and weekend night sleep durations, social jetlag, daytime sleepiness, napping, screen time, and breakfast intake. Participants were divided into an achievement and a non-achievement group depending on their physical activity guideline achievement status (i.e., whether they met the children's physical activity guideline of 60 min or more of moderate-to-vigorous physical activity per day). Then, to determine the sleep habits in relation to the children's achievement of guideline-recommended physical activity levels, multivariate logistic regression analyses were conducted. In fifth- and sixth-grade (ages 10-12) boys, an inverse association was observed between physical activity guideline achievement and daytime sleepiness. In seventh- and eighth-grade (ages 12-14) boys, physical activity guideline achievement was inversely associated with social jetlag and skipping breakfast. Additionally, in seventh- and eighth-grade girls, physical activity guideline achievement was inversely associated with inappropriate sleep duration on weekends and screen time. These results suggest that meeting the physical activity guideline is related to favorable sleep habits in Japanese children. However, their relevance may differ by school type and gender.

Comparison between eccentric and concentric resistance exercise training without equipment for changes in muscle strength and functional fitness of older adults.

PURPOSE: The present study tested the hypothesis that resistance exercise training focusing on eccentric muscle contractions would improve muscle strength and functional physical fitness more than concentric contraction-focused resistance training in older adults. METHODS: Healthy older adults (65-84 years) were placed into eccentric (ECC; n = 9) or concentric training group (CON; n = 8). They performed 4-6 basic manual resistance exercises focusing on either eccentric or concentric muscle contractions once at a community centre and at least twice at home a week for 8 weeks. Muscle thickness of the quadriceps femoris (MT), knee extensor maximal voluntary isometric contraction strength (MVC), 30-second chair stand (CS), 3-metre timed up and go (TUG), 2-minute step (2MS), sit and reach (SR), and static balance with eyes open and closed (Bal-EC) were assessed before and 7 days after the last community centre session. RESULTS: Changes in MT (ECC: 21.6 ± 9.2% vs CON: 6.7 ± 7.1%), MVC (38.3 ± 22.6% vs 8.2 ± 8.4%), CS (51.0 ± 21.7% vs 34.6 ± 28.3%), TUG (16.7 ± 9.9% vs 6.3 ± 7.7%), 2MS (9.9 ± 6.0% vs 6.0 ± 7.3%) and Bal-EC (35.1 ± 6.7% vs 8.8 ± 16.2%) from baseline were greater (P < 0.05) for the ECC than the CON group. CONCLUSION: These results show that the eccentric manual resistance exercise training was more effective for improving lower limb strength, mobility, and postural stability of older adults when compared with the concentric training. This suggests the significance of emphasising eccentric muscle contractions in movements to maintain and improve physical function.

Thresholds of physical activities necessary for living a self-supporting life in elderly women.

BACKGROUND: To decide the minimal levels (thresholds) of physical activities necessary for a self-supporting life using discriminate analysis between community-dwelling elderly individuals and daycare-service-receiving elderly individuals in Japan. METHOD: A total of twenty-six elderly women, including twelve living a self-supporting life and fourteen using a daycare service, were recruited in this study. The parameters examined were physical performance, activities of daily living, exercise capacity. Discriminate analysis was used to determine the thresholds of physical activities needed to live a self-supporting life. RESULTS: Muscle masses, grip strength, lower-extremity muscle force, gait ability and balance function in elderly individuals living a self-supporting life were significant higher than those in elderly individuals using a daycare service. A threshold of physical ability over 75% classifies accurately using the methods of discriminate analysis indicate total body muscle mass, thigh muscle mass, knee extension force, 6 min walking distance (6MD), 10 m obstacle walking time, Activity of daily living (ADL) index and daily steps. CONCLUSIONS: The present study indicates that thresholds of physical activities including gait abilities, muscle force, and muscle mass are very important factors in maintaining a self-supporting life for elderly individuals. Thresholds of physical activities were more effective than standard values of physical activity for elderly individuals using a care service in meeting the goals of rehabilitation.

Which common NIRS variable reflects muscle estimated lactate threshold most closely?

Various near-infrared spectroscopy (NIRS) variables have been used to estimate muscle lactate threshold (LT), but no study has determined which common NIRS variable best reflects muscle estimated LT. Establishing the inflection point of 2 regression lines for deoxyhaemoglobin (DeltaHHb(i.p).), oxyhaemoglobin (DeltaO2Hb(i.p.)), and tissue oxygenation index (TOIi.p.), as well as for blood lactate concentration, we then investigated the relationships between NIRS variables and ventilatory threshold (VT), LT, or maximal tissue hemoglobin index (nTHImax) during incremental cycling exercise. DeltaHHb(i.p.) and TOI(i.p.) could be determined for all 15 subjects, but DeltaO2Hb(i.p.) was determined for only 11 subjects. The mean absolute values for the 2 measurable slopes of the 2 continuous linear regression lines exhibited increased changes in 3 NIRS variables. The workload and VO2 at DeltaO2Hb(i.p.) and nTHImax were greater than those at VT, LT, DeltaHHb(i.p.), and TOI(i.p.). For workload and VO2, DeltaHHb(i.p.) was correlated with VT and LT, whereas DeltaO2Hb(i.p.) was correlated with nTHImax, and TOI(i.p.) with VT and nTHImax. These findings indicate that DeltaO2Hb strongly corresponds with local perfusion, and TOI corresponds with both local perfusion and deoxygenation, but that DeltaHHb can exactly determine deoxygenation changes and reflect O2 metabolic dynamics. The finding of strongest correlations between DeltaHHb and VT or LT indicates that DeltaHHb is the best variable for muscle LT estimation.

Effects of electrical stimulation and voluntary exercise on muscle oxygenation assessed by NIRS.

In this study, we investigated the effect of low-frequency ES (electric stimulation) to muscle oxygenation level by NIRS (near infrared spectroscopy) from comparing with V-Ex (voluntary exercise). Ten subjects performed ES and V-Ex test in supine position on a bed with 90 degrees flexion of the right knee joint and fixation of the right ankle to the end of the bed with a strap. NIRS probe was placed on middle point of the vastus lateralis, and four electrodes were placed across the motor point of the rectus femoris and vastus lateralis. Stimulation voltage was started at 20 V (20 Hz, pulse duration: 200 micros, duty-cycle: 1s-1s), and then was increased at a rate of 3 V/30 s until maximal tolerance level. V-Ex (isometric knee extension) was performed with same posture as in ES, and exercise pattern was set at a 1-s contraction and 1-s relaxation cycle. Exercise intensity was started at 5% MVC (maximal voluntary contraction) and was increased at a rate of 5% MVC/30 sec until exhaustion. In ES and V-Ex, tissue oxygenation index was decreased with decrease in O2Hb (oxy-hemoglobin) and increase in HHb (deoxyhemoglobin), and muscle oxygenation levels at the end of test were very alike. Oxygen consumption, heart rate, systolic and diastolic blood pressure in ES and V-Ex increased significantly, however, the degree of change in ES was significantly lower than V-Ex. Blood lactate was significantly increased in both tests. Adrenaline and noradrenaline were significantly increased in V-Ex, even though they showed no change in ES. These results lead us to believe that ES is an effective technique activated muscle hypoxia and glycolytic pathway metabolism with low stress on respiratory, circulatory and sympathetic nervous systems.

Body composition is related to increase in plasma adiponectin levels rather than training in young obese men.

We assessed the major factors regulating adiponectin levels and the influence of exercise training on adiponectin levels in young obese men (19.2 +/- 1.1 yrs, BMI: 31.1 +/- 4.2, %fat: 27.2 +/- 3.9%). Subjects were separated into three groups (aerobic exercise group [AE: n=7], aerobic and resistance exercise group [AE + RE: n = 7], control group [n = 7]). AE underwent an 8-week training program (three times per week, more than 30 min endurance exercise at ventilatory threshold (VT) intensity). AE + RE went through resistance exercise two or three times per week together with the above endurance exercise for 5 months. Prior to intervention (n = 21), adiponectin levels were significantly correlated with percentage of fat. Stepwise multiple regression analysis revealed that percent body fat was an independent predictor of basal adiponectin levels (r2 = 0.370; P<0.01). After intervention, fat mass, and VT were significantly improved in AE. AE + RE exhibited significant reduction in weight, BMI, percent body fat and fat mass, and had significantly increased VT, VO2max cycling power and torque. Insulin was not changed in both groups. The control group exhibited no significant change in any variables. Although adiponectin levels were unchanged in the three groups, a significant negative correlation between delta fat mass and delta adiponectin levels was observed (n = 21, r = -0.461, P<0.05). In addition, delta percent body fat was an independent predictor of delta adiponectin levels (r2 = 0.327, P<0.05). These findings indicate that for increasing the adiponectin level, improvement of the body composition of young obese men is more important than the way training is performed.

Decreased plasma adiponectin levels in young obese males.

Plasma adiponectin levels are reduced in middle-aged obesity and in patients with type 2 diabetes and coronary artery disease. The purpose of this study was to investigate the effects of early-aged obesity on plasma adiponectin level. Twenty-six male college students (19.2 +/- 1.1 years, obese group: n = 15, [body mass index > 25, percent body fat > 25%], non-obese group: n = 11) participated in the present study. We measured anthropometric parameters and plasma adiponectin and leptin level. Plasma adiponectin levels in the obese group were significantly lower than those in the non-obese group (obese: 4.7 +/- 2.0 micro g/ml, non-obese: 6.8 +/- 2.2 micro g/ml, p < 0.05). On the other hand, plasma leptin levels in the obese group were significantly higher than those in the non-obese group (obese: 8.4 +/- 3.2 ng/ml, non-obese: 2.6 +/- 2.1 ng/ml, p < 0.001). Plasma adiponectin levels were significantly correlated with body weight (r = -0.415, p < 0.05) and percent body fat (r = -0.412, p < 0.05). Stepwise multiple regression analysis revealed that percent body fat was a significant independent predictor of plasma adiponectin level (r = 0.406, p < 0.05). These results show that obesity is associated with reduced plasma adiponectin even in young subjects.