Background: Wrist-worn consumer activity trackers are widely used to promote physical activity (PA) and reduce sedentary behavior (SB). However, evidence regarding their validity for measuring PA and SB in free-living school-aged children remains limited. This study evaluated the concurrent validity and wear compliance of a wrist-worn consumer activity tracker in school-aged children under free-living conditions with protocol-defined wear requirements. Methods: A total of 102 children (mean age: 10.2 years; 44.1% girls) wore a wrist-worn device (Fitbit Ace) and a waist-worn accelerometer (Omron Active Style Pro HJA-750c, ASP-750c). Of the 1122 person-days collected over 11 days, 135 person-days meeting inclusion criteria for both devices were included (≥10 h/day wear time and an inter-device wear time difference of ≤60 min). Step count and time in SB, light (LPA), moderate (MPA), vigorous (VPA), and moderate-to-vigorous PA (MVPA) were assessed. Correlations, mean absolute percentage error (MAPE), agreement, and wear compliance between the two devices were examined. Results: Correlations were strong for step count (r = 0.86), SB (r = 0.72), and LPA (r = 0.71); however, agreement was poor, with systematic overestimation of step count, SB, VPA, and MVPA and underestimation of LPA and MPA by the Fitbit Ace, and MAPE exceeding 20% for all PA variables. Wear compliance (≥10 h/day on ≥4 days) was higher for the Fitbit Ace (97.0%) than for the ASP-750c (62.2%). Conclusions: Although the Fitbit Ace may be useful for characterizing general patterns of LPA and SB in school-aged children, caution is warranted for accurate individual-level PA assessment.

Background: Listening to fast-tempo or motivational music before exercise may improve maximal pedaling performance, but the role of lyric comprehension remains unclear. This study tested whether self-selected music with familiar language lyrics perceived as motivational improves sprint performance and psychophysiological responses. Methods: Fourteen healthy young men (age: 19.7 ± 1.7 years; height: 171.2 ± 3.1 cm; weight: 65.8 ± 7.1 kg; body mass index: 22.4 ± 2.1 kg/m2) who exercised regularly (≥3 sessions/week) participated in a within-subject crossover design, completing a 20 s maximal pedaling test across 3 randomized conditions: control (Con; no music), music with unfamiliar language lyrics (UM), and self-selected music with familiar language lyrics (FM). All participants completed all three experimental conditions in a randomized order. Data were analyzed using repeated-measures ANOVA and paired t-tests (α = 0.05). Relative peak and mean power outputs were recorded. Motivation, arousal, and pleasant emotion were assessed at rest, after listening to music, after warm-up, and after exercise. Prefrontal hemodynamics and autonomic nervous system activity were recorded continuously. Results: Relative peak power was higher in FM (8.42 ± 0.61 W/kg) than Con (8.23 ± 0.58 W/kg; p < 0.01; d = 1.05); mean power did not differ across conditions. FM showed higher motivation and arousal after music compared with Con and UM, and higher pleasant emotion throughout. No significant differences across conditions were observed in prefrontal hemodynamics or autonomic nervous system activity. Conclusions: Listening to self-selected music with familiar language lyrics perceived as motivational during subsequent maximal pedaling enhanced peak power and psychological responses. Lyric comprehension and language familiarity likely play an important role in the ergogenic effects of music before high-intensity exercise.

Introduction: Wearable activity trackers are widely available for promoting physical activity (PA) and reducing sedentary behavior (SB). However, studies assessing their validity for PA and SB measurement in free-living conditions in school-age children remain limited. Objective: This study aimed to evaluate the criterion validity and wear compliance of the Fitbit Ace, a wrist-worn wearable activity tracker designed for children, in measuring PA and SB under free-living conditions. Methods: A total of 102 children (mean age: 10.2 years; 44.1% girls) simultaneously wore a waist-worn accelerometer (Omron Active Style Pro HJA-750c; ASP HJA-750c) and a Fitbit Ace for 11 consecutive days. Step count and time spent in SB, light PA (LPA), moderate PA (MPA), and vigorous PA (VPA) were collected from both devices. Pearson’s and Spearman’s correlations assessed criterion validity, while Bland–Altman plots, mean absolute percentage error (MAPE), and intraclass correlation coefficients were used to evaluate agreement. Wear compliance was compared between the two devices. Results: The Fitbit Ace showed a very strong correlation with step count and strong correlations with SB, LPA, and moderate-to-vigorous PA (MVPA). However, significant differences were observed for all PA variables. The Fitbit Ace overestimated step count, SB, VPA, and MVPA, whereas it underestimated LPA and MPA. Agreement between devices was low, with proportional errors in step count, LPA, VPA, and MVPA. MAPE exceeded 20% for all variables, including step count (21.7%), SB (31.2%), LPA (30.3%), and MVPA (120.7%). The proportion of children meeting the criterion of ≥10 h/day wear criterion was higher for the Fitbit Ace (83.2%) than for the ASP HJA-750c (57.8%), as was adherence to ≥4 days (97.0% vs. 62.2%). Conclusion: While caution is needed when using the Fitbit Ace for precise measurement of individual PA, it is a useful tool for assessing overall patterns of step count, SB, and LPA in school-aged children. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement Yes ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This study was approved by the ethics committee of the Faculty of Medicine, University of Yamanashi (approval no. 1929) and was conducted with the cooperation of the Health Promotion Division and the Board of Education of the Koshu City Administration Office. The principals of the participating schools provided ethical approval. All participants provided informed assent to participate, and written informed consent was obtained from their guardians. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All relevant data are within the manuscript.

Exercise performance may be improved by listening to high-tempo and motivational music prior to exercise. However, the effects of the combination of “tempo” and “motivational factors other than tempo” of music on exercise performance have not been examined in detail. We examined whether listening to music before exercise affects repetitive sprint performance and psychological responses in healthy young men. Twenty-one healthy men performed two consecutive sets of 20-second sprint cycling with a 120-second rest period between sets. Five types of music were used during the warm-up and rest periods: no music (Con), high-tempo music that subjects judged to be motivating (MH, 130~140 bpm), high-tempo music that subjects judged to be unmotivating (UMH, 130~140 bpm), low-tempo music that subjects judged to be motivating (ML, 70~80 bpm), and low-tempo music that judged to be unmotivating (UML, 70~80 bpm). Motivation, pleasure-displeasure and arousal-sleepiness, and rate of perceived exertion were investigated using a questionnaire. The maximum power per body weight during sprint cycling was significantly higher in ML than in Con, and MH tended to be higher than in Con. Motivation increased significantly from “After Warm-up” to “After Recovery” for MH and ML, but did not change significantly for Con, UMH, and UML. These results suggest that listening to motivational music, regardless of tempo, improves the maximum power of sprint cycling.

School-based programmes need to be effective, easy for all, easy to perform within a short duration, and inexpensive. However, no studies have reported whether voluntarily and very short-time active play programmes contribute to improved health outcomes. This study aims to describe the GRoup activity, Active Play and Exercise (GRAPE) cluster randomised controlled trial that examined whether active play interventions of very short durations contribute to increasing physical activity (PA) and bone mass among school-aged children. The trial was conducted in 2018 from January to June, and the activity comprised ≥2 children jumping together for approximately 10 s per session, at least five times a day (approximately 1 min/day). School clusters, pair-matched as per school size (total number of children) and region, were randomly allocated to either intervention or wait-list control groups. The primary outcomes comprised objectively measured changes in PA levels (moderate-to-vigorous PA) evaluated using wrist-worn activity trackers from baseline to the one-year follow-up (six-month post-intervention follow-up) and changes in bone mass evaluated using calcaneus quantitative ultrasound parameters. This study could describe the problems and challenges in school-based PA intervention studies and present findings that could make a potentially important contribution to health education and PA promotion.

In the workplace, sit-stand workstations are being installed to reduce excessive sitting time and the consequent risk factors for cardiovascular ailments (e.g., postprandial hyperglycemia). However, a prolonged standing posture also has detrimental effects in terms of musculoskeletal symptoms and work efficiency. We thus investigated whether alternating between a sitting and standing work posture improves postprandial glucose response and computer task performance. Nine healthy young males completed 4 x 20-min computer tasks in the early afternoon (i.e., 30 min after eating lunch) under three different work conditions, had no change in posture (only sitting-the control trial, CON), and engaged in two styles of alternating between sitting and standing every 20 min (sitting -> standing -> sitting -> standing, SIT-STAND; standing -> sitting -> standing -> sitting, STAND-SIT). For the computer tasks, all participants had to subtract a two-digit number from a four-digit number and to input the answer in the answer column on the computer. Task performance was evaluated as the number of achievements and accuracy rate every 20 min. Blood glucose concentration was assessed before, immediately after, 30 min, 52 min, 74 min, 96 min, and 118 min after eating lunch. The number of achievements and accuracy rate did not differ among the three trials. The total area under the curve (AUC) for blood glucose concentration was significantly lower in the SIT-STAND and STAND-SIT trials compared with CON, whereas no significant difference was observed between the SIT-STAND and STAND-SIT trials. In conclusion, alternating between a sitting and standing work posture attenuated postprandial blood glucose accumulation without reducing task performance, irrespective of the order of changes in work posture.

Listening to music during active recovery between exercise bouts has been found to help maintain high levels of exercise performance; however, the effect of listening to music alone with no exercise while resting passively has not been elucidated. We examined whether listening to music during static (passive) recovery affects subsequent repeated sprint performances and/or psychological and physiological responses in healthy young males. Twelve healthy young male athletes completed two consecutive sets of 7 × 7 second maximal cycling sprints with a 30-second rest interval between the sprints. During a 15-minute interval between the sets, the participants rested passively while listening to fast-tempo (Fast, 130 bpm), slow-tempo (Slow, 70 bpm) music, or no music (Con). We assessed affective valence and arousal using the Affect Grid. The valence and arousal scores immediately after listening to fast-tempo music were significantly higher than those in the no music condition. Mean and peak power outputs during the second set after listening to fast-tempo music were significantly higher compared to those after the Slow and Con conditions (both adjusted p < .05). Moreover, the changes in exercise performances between the first and second set were significantly associated with changes in the arousal score induced by the music conditions, but not with changes in the valence score. These results suggested that listening to fast-tempo songs during passive recovery between the exercises improved subsequent repeated sprint cycling performance in physically active males. This type of rapid exercise recovery might be useful for competitive athletes, such as judo, track and fields, and swimming races.

This study examined the relationship between meeting the World Health Organiza-tion’s (WHO) 24-Hour Movement Guidelines for the Early Years and motor skills and cognitive function in preschool children. Participants were 4-year-old boys and girls in urban and rural areas (n=69). Physical activity was measured using a triaxial accelerometer (ActiGraph GT3X). Screen time and sleep duration were assessed via self-report by guardians. Meeting the 24-h movement guidelines was defined as: 10 to 13 h/night and nap of sleep, ≤1 h/day of sedentary screen time, and at least 180 min/day more than 1.5 METs. Motor skills were evaluated by the Ages & Stages Questionnaires, Third Edition (ASQ-3). Executive functions (shifting, visual-spatial working memory and inhibition) were evaluated by the Early Years Toolbox (Japanese translation). The prevalence of children meeting all three recommendations was 7.2% and 7.2% met none of the three recommendations. Children meeting physical activity recommendation had a better inhibition score compared to children meeting none of the recommendation (p=0.005). While, children not meeting the sleep recommendation had a better inhibition score compared to children meeting of the recommendation (p=0.042). In conclusion, meeting the physical activity or sleep recommendations were positively or negatively associated with the inhibition score. On the other hand, meeting none of the sedentary behaviour and the 3 recommendations was not associated with motor skills or cognitive function.

Circumference measurements have been used to estimate muscle cross-sectional area (CSA) in clinical settings. Measurements of thigh circumference are affected by muscle and subcutaneous fat (SF). In fact, SF could increase over a short period. Therefore, clarifying the relationship between thigh circumference and muscle and SF following ACL reconstruction is important. This study's primary purpose was to examine pre- and post-operative changes in thigh circumference, thigh muscles and SF CSAs in both legs. Secondary, the relationship between thigh circumference and muscle and SF CSAs was examined to demonstrate that circumference measurements could be used to detect atrophy. Quadriceps, hamstrings, and SF CSAs at 15, 10, and 5 cm proximal to the patella were measured by MRI pre- and 4 weeks postoperatively to examine how reconstruction affected those tissues in the thighs. The results showed increases in SF CSA (r=0.72 at 10 cm, r=0.67 at 15 cm) greatly affected thigh circumference in females on the surgical side. In males, increases in SF CSA (r=0.83) at 15- and 5-cm and decreases in quadriceps muscle CSA (r=0.73) at 5 cm affected thigh circumference on the surgical side. Thigh circumference measurements might not reflect actual muscle CSA in ACL patients.

Physical activity (PA) is a key factor of bone mass acquisition in peripubertal children. Sedentary behavior (SB) has been shown to influence bone outcomes. This study aimed to examine the association between objectively measured PA and SB and bone stiffness in Japanese children. Participants were fifth-grade children aged 10–11 years from Project Koshu. The stiffness index (SI) of the calcaneus was measured by quantitative ultrasound; PA and SB were evaluated by an accelerometer. Each PA parameter was divided into sex-specific tertile or stratified by recommended PA guideline [≥ 60 min/day of moderate-to-vigorous PA (MVPA)]. The SI was compared among PA and SB through analysis of covariance with Bonferroni correction. Of 174 children, complete data were obtained from 134 (60 boys and 74 girls). The SI in boys was higher in the highest tertile of MVPA than that in the other groups. A similar association was found in girls but was not significant. Children who met the PA guideline had higher SI than those who did not, but there was no significant difference. A negative relation was observed in girls, with the SI gradually decreasing along with increasing SB (p for trend = 0.038). This association was not observed among boys. This study suggests that MVPA is positively associated with bone stiffness in Japanese schoolchildren in boys and SB is negatively associated with that in girls. Reducing SB might be a brief modifiable factor for preventing lower peak bone mass in girls, in addition to increasing MVPA.

PURPOSE: Recently, it is going noteworthy that an exercise-induced novel myokine, secreted protein acidic and rich in cysteine (SPARC) has the potential to prevent colon cancer. Moreover, regular resistance exercise (RE) has been known to reduce the mortality risk of cancer. From these points of view, RE might prevent colon tumorigenesis via increasing SPARC, while it is unclear whether resistance exercise can promote SPARC secretion in human. Thus, the purpose of this study was to investigate the both effects of exercise intensity and duration of rest interval between exercise sets on acute response of RE-induced SPARC secretion. METHODS: We designed two experiments in this study. In study 1, 7 subjects completed three experiments in a random order. They performed two RE at both 70% (High) and 35% (Low) of the individual’s one repetition maximum (1-RM), and stayed rest condition without RE (Rest). The RE consisted of 8 kinds of exercise (double arm curl, shoulder press, double knee extension, chest press, lat-pull down, triceps press down, parallel squat, and seated rowing), for 3 sets of 7 repetitions. We recruited different 7 subjects in study 2, and let them conduct three experiments in a random order: RE (the same 8 kinds of exercise as described in study 1, 16 repetitions × 3 sets at 50% 1-RM) with long inter-set rest interval (LIE, 150 s), RE with short inter-set rest interval (SIE, 50 s), and rest with no-exercise (NE). Blood samples were obtained before, immediate after, and 1h after RE in both study. RESULTS: In study 1, serum SPARC concentration immediately after RE was significantly increased from baseline in High trial (P < 0.05), and that level was significantly higher than those in Rest and Low trials (P < 0.05, in both). In study 2, serum SPARC level immediately after RE in SIE trial significantly elevated compared with baseline (P < 0.05), and the increase was also significantly higher than NE trial (P < 0.05). However, the elevated SPARC concentrations in both High and SIE trials were swiftly returned to baseline within 1 h after RE. CONCLUSIONS: Our findings indicate that RE can induce temporally SPARC secretion. It is also conceivable that increasing exercise load and/or shortening rest intervals between exercise sets during RE might enhance SPARC production.

Recently, a standing desk is being installed as a behavior change strategy to reduce sitting time in the workplace. However, the standing posture has been suggested to decrease forehead oxygenated hemoglobin (oxy-Hb), which might impair task performances. Therefore, we examined whether prolonged standing impairs speed and accuracy of computer subtraction task associated with a decrease in forehead oxy-Hb. Nine healthy young males completed 4 × 15-min computer tasks under two conditions, i.e., sitting and standing. In the computer tasks, all subjects were required to subtract a two-digit number from a four digit number written on the paper and to input the answer to the answer colomn on the computer. Task performances were evaluated as the number of achievements and accuracy rate every 15 minutes. Moreover, oxy-Hb and deoxygenated-hemoglobin (deoxy-Hb) in the site of left forehead area and lower limb were monitored throughout the experimental period by near-infrared spectroscopy. Forehead oxy-Hb was significantly associated with the number of achievements during computer tasks (p < 0.001). In addition, forehead oxy-Hb and task performances did not differ between sitting and standing. The number of achievements of subtraction task under standing condition was significantly decreased as time proceeds. Our results demonstrate that prolonged standing might impair computer subtraction task performances irrespective of the change in forehead oxy-Hb.

The purpose of this study was to investigate the impact of acute exercise and hypoxic exposure on the level of circulating selenoprotein P (SeP), which is known to cause insulin and exercise resistance, and expression of the muscle peroxisome proliferator-activated receptor-γ co-activator-1α (PGC-1α) gene in pre-diabetes rat models. Fifteen week old male Wistar rats (n = 20) were fed with a high-fat diet and water ad libitum for 3 weeks. After the acclimation period, they were assigned to sedentary or exercise groups under normoxic (20.9% O2) and hypoxic (14.5% O2) conditions. Each of the exercise groups (NE and HE) was administered two 30-min no-load swimming exercises with an interval of 5-min rest. The serum, the liver, and the triceps muscle were obtained 3 h after the exercises. Hypoxic exposure did not affect hepatic SeP mRNA, serum SeP protein, and muscle PGC-1α mRNA expression. In contrast, acute swimming exercise reduced circulating SeP concentration and increased PGC-1α mRNA expression in triceps muscle. In conclusion, acute swimming exercise rather than moderate hypoxic exposure might improve insulin and exercise resistance in pre-diabetes conditions for type 2 diabetes.

We investigated the effects of resistance exercise under hypoxia on postexercise hemodynamics in eight healthy young males. The subjects belonged to a track & field club (sprinters, hurdlers, and long jumpers) and engage in regular physical training (1-2 h per day, 3-5 days per week). Each participant performed eight sets of bilateral leg squats with a one-minute interval under normoxia (room air) and hypoxia (13 % FiO2). During a 60-minute recovery, we set normoxic condition either after normoxic or hypoxic exercise. These two experimental protocols (normoxia and hypoxia) were performed in a random order with a one-week washout period. The leg squat exercise consists of 50 % 1-RM (14 repetitions) × 5 sets and 50% 1-RM (repetitions max; 7 repetitions) × 3 sets. The resting period between each set was 1 min, and a total of 91 repetitions were performed. Blood pressure, heart rate (HR), and several biomarkers were measured pre- and postexercise. The mean arterial pressure (MAP) significantly decreased after exercise compared to the pre-exercise values under both conditions (P < 0.05). The MAP at 20 and 30 min of recovery in hypoxia was significantly lower than in normoxia (P < 0.05, respectively). The antidiuretic hormone significantly increased after 60 min of recovery in both conditions; moreover, the values in hypoxia were significantly higher than those in normoxia (P < 0.05). The delta changes in MAP from baseline (pre-exercise) were significantly related to changes in HR from baseline in normoxia (r = 0.560, P < 0.001) but not in hypoxia. These results suggest that the hypoxic condition elicits greater hypotension after resistance exercise in comparison to normoxia. Moreover, the underlying mechanisms for the attenuation of hypotension after resistance exercise may differ between normoxia and hypoxia.

Both exercise training and chronic caloric restriction contribute to brain health through enhanced expression of brain-derived neurotrophic factor (BDNF). This study investigated the synergistic effects between 12-week low-intensity exercise training and caloric restriction on hippocampal BDNF expression with redox status in rats. Twenty-six, 7-week-old male Wistar rats were randomly divided into the following 4 groups: (1) sedentary control (Con, n = 7), (2) exercise (Ex, n = 6), (3) caloric restriction (CR, n = 7), and (4) caloric restriction and exercise training (ExCR, n = 6). Although Con and Ex rats were fed ad libitum over time, CR and ExCR rats consumed 40% less food compared to Con rats. Ex and ExCR rats underwent low-intensity treadmill running (30 min/day, 5 days/week). Forty-eight hours after the termination of the 12-week intervention, rats were sacrificed and the hippocampus was quickly dissected for measuring BDNF expression and markers of oxidative stress, including 4-hydroxy-2-nonenal (4-HNE). Hippocampal BDNF expression was significantly increased in Ex compared to Con rats (p = 0.007), whereas the exercise-induced increase in BDNF was completely suppressed by a combination with caloric restriction. Furthermore, we observed a significant relationship between hippocampal BDNF and 4-HNE expression (r = 0.725, p < 0.001). Our findings indicate that exercise training combined with caloric restriction might not have a synergistic effect on hippocampal BDNF expression in young rats. Moreover, exercise-induced oxidative stress can trigger BDNF expression in the hippocampus.

Background: Lower birth weight (BW) is associated with increased chronic disease risk later in life. Previous studies suggest that this may be mediated principally via physical activity (PA). However, the association between BW and PA in children has not been clarified. The purpose of this study was to examine the association between BW and PA in school-aged children in Japan. Methods: Participants were children from a prospective birth cohort study (Project Koshu) who were born from 1996 through 2002 in rural Japan. BWs were obtained from the Maternal and Child Health Handbook. Data on PA during childhood were collected using a self-reported questionnaire when participants were 9-15 years of age in July 2011. Analysis of covariance was used to evaluate exercise duration; Poisson regression analysis was used to evaluate if the recommended PA amount was met. Results: Data from 657 children (boys: 54.8%, follow-up rate: 77.6%) were analyzed. Compared with the normal BW group, only girls in the low-BW group had significantly lower PA level (normal BW, 11.4 [standard error, 1.0] hours/week; low BW, 5.8 [standard error, 3.6] hours/week, P = 0.010), and were more likely to not meet the recommended PA level (prevalence ratio 1.57; 95% CI, 1.14-2.16). Conclusion: Low BW was associated with a lower PA level in school-aged girls but not boys. Earlier consideration of BW may be an important public health strategy to prevent physical inactivity in school-aged girls.

Aims: Active transport to/from school is important for increasing children's physical activity.This study aimed to assess the association of active school transport with obesity of Japanese elementary school children.Methods: In total, 541 elementary school children (aged 9-12 years, with 243 girls) at 10 out of 13 schools in Koshu, Yamanashi Prefecture were included.Active school transport was assessed by a questionnaire and classified into two groups: those walking to school (to and from school) and those transported by vehicles (at least one way).Height and weight were measured at regular health checkups.Obesity was defined as weight >=20% of the standard weight calculated by age, sex, and height.Poisson regression analysis was used to assess the association of active school transport with obesity after adjusting for age in months, time spent performing physical activity per week, eating habits, and socioeconomic status evaluated by a family affluence scale.Results: Among 283 boys and 235 girls, obesity prevalence was 10.6% and 8.2%, respectively; 8.8% of boys and 11.2% of girls were transported by vehicles.In boys, the prevalence ratio (PR) of obesity was higher in the transported by vehicles group than in the walking to school group (PR: 3.60, 95% confidence interval [CI]: 1.66-7.83).No significant association was found in girls (PR: 1.52, 95% CI: 0.49-4.69). Conclusion:Transportation to/from school by vehicles may be a risk factor for obesity.Future longitudinal studies in other communities with more children are needed.

PURPOSE: Recent studies have suggested that exercise training and caloric restriction have beneficial effects on brain function, including the improvements of cognitive function by the promotion of brain-derived neurotrophic factor (BDNF) expression in the hippocampus. In addition, the level of oxidative stress might be involved in the mechanism to explain these effects. The purpose of this study was to investigate the synergy effects between 12-week low-intensity exercise training and caloric restriction on BDNF expression and the level of oxidative stress in rat hippocampus. METHODS: Twenty-six, 7 week-old male Wistar rats were randomly divided into the following 4 groups: 1) sedentary control (Con, n=7); 2) exercise (Ex, n=6); 3) caloric restriction (CR, n=7); and 4) exercise training and caloric restriction (ExCR, n=6). Ex and ExCR underwent treadmill running at 10 m/min, 5° slope, 30 min/day, 5 days/week. Although Con and Ex were fed ad libitum over time, CR and ExCR consumed 40 % less food compared with Con. Forty-eight hours after the termination of the 12-week intervention, rats were sacrificed and the hippocampus was quickly dissected for measurement of BDNF and 4-hydroxy-2-nonenal (4-HNE) contents, and serum total antioxidant capacity (TAC) were also assessed. RESULTS: 4-HNE contents in Ex and CR were significantly increased compared with Con (p<0.05, respectively). However, these elevation was not observed in ExCR. On the other hand, no changes were observed in the alteration of serum TAC among 4 groups. Hippocampal BDNF contents was significantly increased in Ex compared with Con (p<0.05), whereas the exercise-induced elevation in BDNF was completely suppressed by a combination with caloric restriction. Furthermore, we found a significant relationship between hippocampal BDNF and 4-HNE contents (p<0.05), suggesting the hypothesis that oxidative stress is essential for the expression of BDNF in the hippocampus. CONCLUSION: Our findings indicate that optimal stimulus of oxidative stress induced by low-intensity exercise training contributes to BDNF expression in hippocampus. However, it is conceivable that exercise training combined with caloric restriction might not have a synergy effect on hippocampal BDNF expression.

The effects of physical activity (PA) on bone mass gained during growth in Japanese are not well understood. The purpose of this study was to examine whether changes in PA affected bone mass gained by Japanese schoolchildren, as measured by calcaneus quantitative ultrasound (QUS). Three hundred and seven children aged 9–13 years participated in the study and were followed for a 2-year period. The stiffness index (Stiffness) of the calcaneus was measured by QUS, and PA evaluated by a questionnaire. Participants were divided into two groups according to PA: high (≥ 7 hours/week, H) or low (< 7 hours/week, L). Participants were also divided into four groups according to their 2-year change in PA: consistently high (HH), consistently low (LL), changed from high to low (HL), and changed from low to high (LH). Analysis of covariance was used to compare adjusted Stiffness across all four groups. The adjusted 2-year changes in Stiffness ranked in decreasing order among girls: HH (20.8 %), HL (17.6 %), LH (14.3 %), and LL (12.2 %), respectively (trend test, P = 0.027). This trend was not observed among boys. These results suggest that changes in PA significantly affected bone mass gain among peripubertal girls, and that a continuing PA of more than 7 hours a week (approximately ≥ 60 min/day) from a young age is effective in increasing peak bone mass. However, given the limitations of this study, further robust studies which recruit representative samples and consistently employ validated measurement instruments are needed.

Objective. We determined detailed time-course changes in the irisin response to acute exercise using different exercise modes.Methods. In experiment 1, seven healthy males rested for 12 h (8:00-20:00) to determine the diurnal variation in plasma irisin concentration. In experiment 2, 10 healthy males conducted three exercises to clarify time-course changes in plasma irisin concentration over 6 h, using a randomized crossover design. The resistance exercise (R) trial consisted of eight exercises of 12 repetitions with 3-4 sets at 65% of one repetition maximum (1RM). The endurance exercise (E) trial consisted of 60 mm of pedaling at 65% of maximal oxygen uptake (VO2max). In the combined mode (R + E) trial, 30 min of endurance exercise was preceded by 30 min of resistance exercise.Results. In experiment 1, no significant changes in plasma irisin concentration were observed over 12 h. In experiment 2, the R trial showed a marked increase in plasma irisin concentration 1 h after exercise (P < 0.05), but not in the E or R + E trials. The area under the curve (AUC) for irisin concentrations for 6 h after exercise was significantly higher in the R trial than in the R + E trial (P < 0.05). The AUC for irisin concentrations was significantly correlated with AUC values for blood glucose, lactate, and serum glycerol (r = 0.37, 0.45, 0.45, respectively. P < 0.05).Conclusions. Resistance exercise resulted in significantly greater irisin responses compared with endurance exercise alone, and resistance and endurance exercises combined. (C) 2015 Elsevier Inc. All rights reserved.