Athletes often use caloric restriction (CR) to manage body weight. However, the effects of post-CR weight maintenance on skeletal muscle and fat mass remain unclear. This study investigated the effects of 60% CR for either 8 (8CR) or 2 (2CR) weeks on skeletal muscle and adipose tissue in mice. In the 8CR group, weight loss slowed after 2 weeks. However, body weight and wet skeletal muscle weight were significantly higher and inguinal white adipose tissue weight was significantly lower in the 2CR group compared to the 8CR group. These findings suggest that 8 weeks of CR, including a weight maintenance phase after initial weight loss, may result in a greater loss of skeletal muscle mass and an increase in fat mass compared to 2 weeks of CR. As this study was performed in 8-week-old male mice, the differences between the 2CR and 8CR groups are likely to reflect not only the length of CR but rather the influence of conducting CR at different stages of growth.

Concussions are a growing concern in youth soccer; yet, detailed information on their mechanisms and grade-specific characteristics remains limited. This study aimed to describe the epidemiological features and mechanisms of soccer-related concussions among middle-school and high-school students in Japan. A retrospective observational analysis was conducted using nationwide insurance data for sports injuries from 2012 to 2022. Concussion cases sustained during soccer were extracted, and their mechanisms were categorized. Sex- and grade-related differences were examined, and incidence rates per 1,000 club members were calculated to account for variations in player population size. Among 696,600 soccer-related injury claims, 3,343 concussion cases met the inclusion criteria. Boys accounted for 3,217 cases (96.2%) and girls for 126 cases (3.8%), with incidence proportion of 0.85 and 0.78 per 1,000 club members, respectively. The most frequent injury mechanism was playing surface-contact with player (40.2%), followed by collisions with other players. Most concussions occurred during competitions rather than practice sessions. As school grade level increased, concussions more often resulted from player-to-player contact during games (middle school: 1st year, 49%; 2nd year, 54%; 3rd year, 63%; high school: 1st year, 57%; 2nd year, 60%; 3rd year, 69%). These findings indicate that most soccer-related concussions among middle- and high-school students occurred after contact and subsequent falls. Even when not directly caused by a collision, loss of balance leading to a fall frequently resulted in concussion. The grade-dependent variation in injury mechanisms highlights the need for tailored prevention strategies focusing on fall dynamics and safe contact techniques.

In this study, we aimed to investigate the effect of differences in hip flexion angle (HFA) at the start of Nordic hamstring exercise (NHE) on hamstring electromyographic (EMG) activity. Fifteen male volunteers performed three NHE variations implemented at three different HFA starting positions (0° was considered the neutral position): -10° HFA (NHE-10), 10° HFA (NHE10), and 30° HFA (NHE30). The primary outcomes were effects on biceps femoris (BF) and semitendinosus (ST) EMG activities in NHE-10, NHE10, and NHE30. The HFA at the break-point angle (HFA-BPA) was significantly higher in the following order: NHE30, NHE10, and NHE-10 (p < .05). BF and ST EMG activities were significantly higher in the NHE-10 group than in the NHE30 group (p < .05). Performing NHE with the upper body in an upright position could enhance BF and ST EMG activities.

Since the influence of hypoxia on mitochondrial adaptations in different muscle fiber types remains unclear, this study examined the impacts of hypoxic repeated sprint training (RST) on lactate metabolism and mitochondrial-related protein content, with a special focus on potential differences between different fiber type composition. Eight-week-old Institute of Cancer Research (ICR) mice were randomly divided into five groups: normoxic sedentary control (CON), normoxic 2set-RST (2set-NT), normoxic 4set-RST (4set-NT), hypoxic 2set-RST (2set-HT), and hypoxic 4set-RST (4set-HT). Two or four sets of 5×40-s sprints (recovery: 20-s, inter-set = 5-min) were performed for four weeks (three times/week) under either normoxia (FiO₂ = 20.9%) or hypoxia (FiO₂ = 13%). Skeletal muscle samples were analyzed for mitochondrial and metabolism-related protein content. In the fast-twitch (FT)-dominant plantaris muscle (PM), peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) and monocarboxylate transporter 4 (MCT4) were significantly higher in the 4set-NT and 4set-HT compared to the CON (p < 0.01). Notably, PGC-1α and MCT4 remained unchanged in the 2set-NT, but were significantly elevated in the 2set-HT (p < 0.05). Pyruvate dehydrogenase (PDH) E1α subunit was higher in the 2set-HT (p < 0.05) and 4set-HT (p < 0.01) compared to the CON. Additionally, mitochondrial oxidative phosphorylation (OXPHOS) subunit complex I increased significantly only in the 4set-HT (p < 0.05). In contrast, no significant changes were observed in the slow-twitch dominant soleus (SOL) muscle. These findings suggest that hypoxic RST selectively increases proteins involved in lactate metabolism and mitochondria, especially in the FT-dominant plantaris. Notably, several proteins (PGC-1α, PDH E1α, and MCT4) were elevated under hypoxia even with lower training loads (2 sets).

This study aimed to investigate the relationship between cross-sectional area (CSA) of lower limb muscles and underwater undulatory swimming (UUS) velocity in swimmers. Eighteen male swimmers at the regional to national level participated in this study. Kinematic data during maximum-effort UUS were collected using an underwater motion capture system to determine the mean UUS velocity. T1-weighted cross-sectional magnetic resonance (MR) images of the lower limb muscles were acquired using a 3T MR imaging system to determine the CSA of 17 muscles on the swimmers’ right side. Relationships between UUS velocity and the CSA of lower limb muscles were examined using correlation coefficients. A positive significant correlation was found between CSA of rectus femoris and UUS velocity (absolute value: r = 0.475 p = 0.046; relative value: r = 0.548 p = 0.019). However, UUS velocity was not significantly correlated to the CSA of other lower limb muscles (r = - 0.445 ~ 0.469). These results suggest that the CSA of the rectus femoris has a moderate relationship with UUS velocity among the lower limb muscles, regardless of body size. Revealing the relationships between muscle size and UUS velocity can provide important insights for swimmers, coaches and researchers into which lower limb muscles should be strengthened to enhance UUS performance.

Many high school teachers in Japan supervise school sports club activities, which leads to long working hours and elevated stress. However, the relationship between club factors and the health status of coaches remains unclear. Accordingly, this study examined associations between club factors and the health status of Japanese high school sports club activity coaches. We conducted a nationwide cross-sectional survey of school sports club activity coaches in all Japanese high schools. Two health outcomes were assessed: self-rated health (SRH: good or poor) and psychological distress using the Kessler 6 scale (K6: high distress or not). Data on seven club factors were collected: sport type, weekday and weekend activity duration and frequency, number of student managers, and club aim. Odds ratios for a favorable health outcome of each factor were calculated. Among 6,045 respondents, weekday activity time ≥ 3 hours was associated with poor SRH (OR = 0.70; 95% confidence interval: 0.58–0.85) and high psychological distress (0.67; 0.52–0.86). Coaching ≥ 5 days per week (0.80; 0.68–0.95) and weekend activity ≥ 4 hours (0.83; 0.70–0.98) were also linked to poor SRH. Aiming for national competitions (1.28; 1.06–1.56) and having ≥ 2 student managers (1.29; 1.07–1.55) were associated with favorable health. Multiple student managers and an emphasis on national competitions were linked to good coach health, whereas extended weekday and weekend activities were associated with poor outcomes.

Many women are aware of feeling cold in their daily lives. To elucidate the interrelationships among having a cold constitution, exercise habits, and sleep, we conducted an Internet survey that included 600 women and 600 men aged 15 to 69 years. The items in the survey included sex, age, coldness, practice of exercise, and sleep condition. The participants answered all questions with a “yes” or “no” answer. In all age groups, women reported a significantly higher number of coldness-related items than men; however, no differences were found among the age groups. Men who exercised regularly reported a higher number of applicable coldness-related items than those who did not (p = 0.027), but this was not found in women (p = 0.208). In both men and women, regular exercise was positively associated with falling asleep (p < 0.05) and getting enough rest through sleep (p < 0.01). These findings suggest that regular exercise is beneficial for sleep in men and women of all ages; however, in men, it is also associated with increased cold-related symptoms.

We aimed to develop regression models for estimating oxygen consumption (VO₂, ml·kg^-1·min^-1) during treadmill walking based on accelerations of the upper and lower limbs and walking velocity, quantitatively assess the contribution of each sensor location, and validate the accuracy and practicality of a simplified model. Eighteen healthy adults with regular exercise habits (nine men, nine women) participated in treadmill walking trials at varying speeds (3–6 km·h^-1; up to 5.5 km·h^-1 for women). Vector magnitude (VM) from triaxial accelerometers attached to both wrists and both ankles was recorded simultaneously with VO₂ measurements from a portable breath-by-breath gas analyzer. Multiple regression models were constructed using FootVM (ankle VM), HandVM (wrist VM), and walking velocity as predictors. FootVM alone showed a moderate correlation with VO₂ (R² = 0.464), but adding walking velocity substantially improved the model’s accuracy (Model 2: R² = 0.810, standard error of estimate = 1.25 ml·kg^-1·min^-1). Incorporating HandVM yielded only a minimal, non-significant model fit improvement (R² = 0.815, ΔAIC = +18.4, βstd = −0.06), with no meaningful statistical contribution. Bland–Altman analysis indicated 95% limits of agreement for estimation error within ±2.46 ml·kg^-1·min^-1, corresponding to < 1 MET (3.5 ml·kg^-1·min^-1). These findings support the rational selection of a simplified model using only FootVM and walking velocity, which achieved a balance between high accuracy and practicality. The ability to estimate VO₂ precisely using only ankle-mounted accelerometers highlights its potential for use in clinical and home-based physical activity assessment.

For busy individuals seeking to establish an exercise habit, weight-bearing exercise-based high-intensity interval training (HIIT) is a time-efficient option. Although single sessions have been shown to improve postprandial blood glucose, whether unsupervised HIIT supports long-term adherence remains unclear. Therefore, this study compared the effects of eight weeks of supervised HIIT and moderate-intensity continuous training (MICT) on adherence and blood glucose indicators. We recruited 46 healthy young adults with no exercise habits, and low to moderate physical activity. After a two-week pre-measurement period, participants were randomly assigned to a HIIT group that performed weight-bearing exercise-based HIIT three times a week for eight weeks without supervision, an MICT group that performed running three times a week for eight weeks without supervision, or a control group that did not change their lifestyle. The intervention period was followed by a two-week post-measurement period for between-group and pre- and post-intervention comparisons. The primary outcome was exercise adherence, assessed based on a self-report and supplemented with a tri-axial accelerometer and glycemic index. Adherence was significantly higher in the HIIT group (60.6 ± 25.7%) than in the MICT group (27.9 ± 22.3%). No significant differences in glycemic index were observed either pre- to post-intervention or between groups. Overall, unsupervised HIIT produced greater adherence than comparable running, but did not alter blood glucose levels in healthy young adults.

In Japan, research on how specific types of sedentary behavior are associated with academic performance among school-aged children remains limited. This cross-sectional study investigated the relationship between various sedentary behaviors and academic performance among Japanese children and adolescents. Data were collected in 2023 from 342 primary and 456 junior high school students in Unnan City, Shimane Prefecture. Academic performance was categorized as high or low based on median scores in Japanese and mathematics. Sedentary behaviors were assessed using a questionnaire—including time spent on reading books and newspapers and total recreational screen time, which was calculated from the time spent playing TV games, watching videos or using social networking services (SNS), and using educational tablets at home. Multiple linear regression analyses were conducted, adjusting for factors such as gender, grade, breakfast habits, sleep duration, sports club participation and cram school attendance. Spending <2 hours on TV games, watching videos, or SNS use was significantly associated with higher academic performance across school levels. Conversely, spending <2 hours on total recreational screen time and using educational tablets at home was linked to higher scores among primary students. Reading books was positively associated with Japanese language scores in both groups. Thus, the type of sedentary activity plays a crucial role in the academic outcomes. A shorter duration of recreational screen time and longer duration of educational and literacy-related behaviors were associated with higher academic performance. This study highlights the need for further longitudinal research considering household socioeconomic factors to better understand these associations.

This study aimed to develop and conduct a preliminary validation of the hitoe system, a novel smartphone application and wearable device designed to tailor exercise loads to individual exercise tolerance, with the goal of supporting personalized cardiac rehabilitation. A preliminary validation study was conducted involving 28 healthy adults (26 males, mean age 42.3 ± 11.2 years). Participants used the hitoe system to perform 13 activities, including sedentary tasks, household chores, walking, and cycle ergometer. Exercise intensity was measured in metabolic equivalents (METs) and compared with values obtained using a standard gas analyzer. Statistical analyses, including intraclass correlation coefficients (ICCs) and Bland-Altman analyses, were applied to assess the accuracy and reliability of the device. The hitoe system demonstrated satisfactory agreement with gas analyzer measurements across most activities. Bland-Altman analyses revealed that the majority of data points fell within ± 2.0 METs, indicating limits of agreement. High ICCs were observed for activities such as cycle ergometer (ICC = 0.797), vacuuming the floor (ICC = 0.693), and lifting a 5 kg weight (ICC = 0.614), reflecting strong reliability. In contrast, sedentary activities such as sitting (ICC = 0.033) and desk work (ICC = 0.144) showed lower ICCs, although the absolute differences between the two methods remained within approximately 1 MET. The preliminary findings suggest that the hitoe system may be useful for assessing physical activity intensity, particularly during higher-intensity activities. The system may offer a promising tool for real-time feedback and tailored exercise prescription in cardiac rehabilitation. Further studies involving patients with cardiovascular diseases are warranted to validate these preliminary results and enhance the system’s precision in clinical settings.

This longitudinal study aimed to determine the performance-related knee injury risk factors in male university rugby union players. Baseline performance measurements were taken in the pre-season and included: (1) strength tests–maximal isometric voluntary contraction (MVC) and single-limb hop test; (2) balance tests–Balance Error Scoring System and Y Balance Test–Lower Quarter; and (3) movement quality–Landing Error Scoring System. The Limb Symmetry Index (LSI) was calculated using strength tests. Knee injury surveillance data, including incidence, severity, and burden, were tracked and analyzed over 1 year. Of the 79 candidate players, 64 completed the test set, and 58 were included in the analysis. We observed 15 knee injuries in 13 players. The injury incidence was 0.4 injuries/1000 player-hours (1000 h) (95% confidence interval [CI], 0.2–0.5); severity was 51 days (95% CI, 0–104); and the burden was 19 days/1000 h (95% CI, 11–31). High LSI of hip internal rotation (odds ratio [OR], 1.09; 95% CI, 1.02–1.16) and MVC of hip extension (OR, 1.10; 95% CI, 1.00–1.20) were identified as significant factors associated with the occurrence of knee injury. In conclusion, the present study suggests that knee injuries are associated with the LSI of hip internal rotation and MVC of hip extension. Players with high performance levels are more exposed to higher injury risks during matches. Given that performance test results may predict knee injury incidence, regular monitoring of such tests may help prevent knee injuries.

Lateral ankle sprains (LAS) account for a substantial proportion of ankle injuries in rugby union and are associated with a high recurrence rate. A history of LAS is known to increase future injury risk, yet few studies have quantitatively examined this relationship. This study aimed to investigate the epidemiological characteristics of LAS among male collegiate rugby players based on the presence or absence of prior injury history. A total of 146 players were prospectively followed over seven seasons and divided into two groups according to their LAS history. Group-specific exposure time was used to calculate injury incidence, severity, and mechanism-specific burden. A total of 131 LAS cases were recorded. The History group showed a significantly higher incidence rate (1.22/1,000 player-hours) than the No History group (0.72/1,000 player-hours), while no significant difference in severity was observed. Contact-related mechanisms, including other player collisions and lineout landings, were more frequent and burdensome in the History group. These findings suggest that injury history is not merely a contextual factor, but a key determinant of future injury risk and characteristics. Prevention and rehabilitation strategies should be tailored accordingly. Mechanism-specific training and history-informed return-to-play protocols are essential to reduce the burden of LAS in athletes with prior injuries.

Knee injuries in rugby union have higher incidence and severity than other injury types. However, the underlying mechanisms and trauma remain unclear. This study aimed to identify knee injury trends and clarify the associated mechanisms in male university rugby players using longitudinal injury surveillance and video analysis. An observational study with longitudinal injury surveillance included 198 university male rugby players who played at least one season over a six-season period (2017–2022). The mean incidence, severity, and burden of injuries were calculated by position and injury type. Video data of knee injuries in matches were analyzed by three analysts, who independently assessed variables, including mechanism/play, movement/posture, and external factors. Injury mechanisms were classified as direct, indirect, and non-contact. The incidence of knee injuries was 8.3/1000 h, with 29 videos analyzed. Indirect contact injury was the most frequent, with an incidence of 3.7/1000 h and a burden of 380 days/1000 h. A significant association was found between injury severity and movement direction, with being tackled from downwards and sideways directions showing a significant difference compared to other directions (Cramer’s V = 0.44). Most knee injuries were caused by being tackled, a heel strike, and an upright body position. Indirect injuries, the most frequent knee injury mechanism, imposed the highest burden. Movement direction may further affect injury severity. Despite their lower incidences, these injuries cause greater burden and severity than those observed in professional rugby, emphasizing the need for specialized prevention programs.

This study aimed to evaluate a musculoskeletal screening method for elementary school students using ultrasound and lower limb flexibility assessments, with the goal of early detection of Osgood-Schlatter disease during the growth period. A total of 143 boys in the fourth to sixth grades of elementary school from a single prefecture underwent musculoskeletal screening between November 2021 and February 2023. Using a diagnostic ultrasound device, the tibial tuberosity was observed, and its developmental stage was classified based on Ehrenborg’s four-stage classification (Ehrenborg G and Lagergren C. 1961. Acta Chir Scand 121: 315–327). The presence of Osgood-Schlatter disease was determined based on the presence of irregularities in the ultrasound image. Lower limb flexibility was assessed quantitatively using finger-floor distance (FFD) and heel-hip distance (HHD). The cartilaginous stage (C stage) was the most common developmental stage observed. Osgood-Schlatter disease was identified in eight children (5.6%) and was found only in the epiphyseal (E) and bony (B) stages (p = 0.004, φ = 0.308). HHD was significantly greater in the Osgood-Schlatter group (p = 0.040, r = 0.680). In some children without knee pain or tenderness, irregularities in the tibial tuberosity were detected on ultrasound imaging, suggesting that ultrasound imaging may be useful for the early detection of asymptomatic lesions. This screening approach, which combines ultrasound examination and flexibility assessment, is expected to serve as a novel method for the early detection and prevention of musculoskeletal disorders in children during their growth period. Further large-scale studies and continued investigation into methods for assessing flexibility in growing children are warranted.

While mortality due to spinal cord injuries (SCI) and urinary tract infections has markedly decreased, the incidence of malignant tumors and lifestyle-related diseases is increasing among people with physical disabilities. However, regular assessment of body weight and composition remains challenging in this population. This cross-sectional study aimed to clarify the relationship between waist circumference, trunk fat percentage, and visceral fat level, with a particular focus on waist circumference as an easily measurable indicator. A total of 151 individuals participated, including 42 with SCI, 42 with cerebrovascular disease (CVD), and 67 without disabilities. Waist circumference, trunk fat percentage, and visceral fat level were measured in sitting and supine positions for all participants, and in the standing position for those without disabilities. Position-related differences were analyzed, with statistical significance set at 5%. Waist circumference varied by measurement position, with the highest values observed in the sitting position. For participants with SCI, the average waist circumference was 90.9 ± 13.1 cm in the sitting position and 81.6 ± 10.9 cm in the supine position. In participants with CVD, the respective values were 93.4 ± 9.8 cm and 86.5 ± 8.5 cm. Waist circumference showed significant positive correlations with both trunk fat percentage and visceral fat level. Standard screening values may underestimate adiposity in people with physical disabilities. These findings suggest the necessity of adopting specific reference values and support the utility of waist circumference measurements taken in the sitting and supine positions in this population.

More research is needed to understand how exercise time and physical fitness relate to body size. In particular, there are no studies that have examined the relationship between physical activity and physical fitness, taking into account both overweight/obesity and thinness, using national samples. This study aimed to analyze exercise time by body size and physical fitness using a Japanese national sample of Japanese children and adolescents. The survey included 19,471 primary and 10,596 secondary schools in Japan. After excluding participants with missing data, the analysis included 878,348 Year 5 primary school students and 757,358 Year 8 secondary school students. Body mass index (BMI) was calculated based on participants’ height and weight, and they were subsequently categorized into four BMI groups: underweight, normal weight, overweight, and obese. Physical fitness was classified as high or low based on the total score from eight physical fitness tests. Exercise time was assessed via a questionnaire and compared between the high- and low-fitness groups within each BMI category. Among the boys and girls in primary and secondary schools, exercise time was greater in the high-fitness group compared to the low-fitness group across all four BMI categories (underweight, normal weight, overweight and obesity). In conclusion, this study suggested that exercise time is positively associated with higher physical fitness regardless of whether an individual is obese, overweight, normal weight or underweight. These results may indicate the importance of promoting exercise time among all children, and further longitudinal studies are needed.

American football (AF) has a high incidence of sports-related concussions (SRC), raising concerns about the long-term effects on neuromuscular function. This study aimed to compare the cortical silent period (cSP) and the strength of the cervical muscles to investigate neuromuscular function in patients with SRC. All 38 participants were males, including 12 AF players with a history of SRC, 9 AF players without a history of SRC, and 17 normal healthy males with no experience in contact sports. Cervical muscle strength was measured with a hand-held dynamometer. cSP was measured using transcranial magnetic stimulation. Electromyography was obtained from the upper trapezius muscle. AF players demonstrated stronger cervical muscle strength than the control group. No significant differences were observed in corticospinal excitability among the groups. AF players with a history of SRC demonstrated a significantly longer cSP than the control group (80.5 ± 27.8 ms vs. 113.1 ± 35.1 ms) (F (2, 32) = 3.66, p < .05). These results suggest that cortical inhibition of the cervical muscle is enhanced in AF players with a history of SRC. This could lead to neuromuscular dysfunction of the cervical muscles and should be considered an important factor in preventing recurrent SRC.

We aimed to examine the relationship between marathon time and running distance during 8 months before a race for runners who live in cold, snowy regions and those who do not. A questionnaire was conducted for male runners who participated in the 2018 Hokkaido Marathon held at the end of August. The subjects were divided into runners from Hokkaido (Hokkaido runners), which is a cold and snowy region, and runners from other regions (non-Hokkaido runners). In addition, Hokkaido and non-Hokkaido runners were divided into two groups, high-volume and low-volume runners, based on their average running distance over an 8-month period. Regardless of high-volume or low-volume, Hokkaido runners’ monthly running distances significantly increased from March compared to January, but non-Hokkaido runners showed no change in their monthly running distances. For non-Hokkaido runners, a significant correlation was found between cumulative monthly running distance and marathon time starting from 8 months prior to the marathon. On the other hand, among Hokkaido runners, no correlation was found between cumulative monthly running distance and marathon time for low-volume runners from January to April, or for high-volume runners from January to February or January to March. These results suggest that marathon times for runners from cold, snowy regions are more closely linked to seasonal changes in running distance than for other runners.

This study aimed to determine the effect of running step frequency (SF) on oxygen consumption during running on spot (ROS) exercises and low-speed running in adult male and female participants. Twenty Japanese participants (22 ± 1.2 years) were included. ROS exercises and running speeds of 4 km h^-1 and 5 km h^-1 were measured at SFs of 140, 160, 180 and 200 steps min^-1. Oxygen consumption, heart rate (HR), and rate of perceived exertion (RPE) were measured during exercise, and oxygen consumption were expressed as metabolic equivalents (METs). In the participants, ROS and 4 km h^-1 running showed no significant difference in SFs (140 steps min^-1 and 160 steps min^-1, respectively) and had significantly higher SFs of 200 steps min^-1 than the other SFs. Moreover, 5 km h^-1 running showed no significant difference between SFs of 140 steps min^-1, 160 steps min^-1 and 180 steps min^-1, and was significantly higher at an SF of 200 steps min^-1 than other SFs. Individual differences in METs at an SF of 180 steps min^-1 were similar at running speeds of 4 km h^-1 and 5 km h^-1. No difference was noted in oxygen consumption between SF of 140 steps min^-1 and 160 steps min^-1 during ROS exercise and 4 km h^-1 and 5 km h^-1 running. Oxygen consumption tended to increase depending on SF above 160 steps min^-1 during ROS, 4 km h^-1, and 5 km h^-1 running exercises. These results suggest that SF should be considered for low-speed running instruction.

Walking for transportation (using your feet to travel to a destination) is influenced by multiple determinants, including psychological perceptions and environmental factors. Acceptable walking time indicates the maximum time (in minutes) a person would walk to reach a destination, and is a psychological factor whose association with walking behavior remains insufficiently examined. Therefore, this study clarified the relationship between acceptable walking time and actual walking behavior in the Japanese working-age population, hypothesizing a positive linear association. A cross-sectional online survey of 881 persons (males, n = 310; females, n = 571; age: 20–59 years) in Japan was conducted to analyze acceptable walking time. Participants indicated “What distance (in minutes) would you walk to a destination?” with responses categorized into six groups (≤2 to ≥21 min). Weekly walking time was measured using the International Physical Activity Questionnaire - Short Form (IPAQ-SF). Linear and quadratic trends were assessed using regression analysis with orthogonal polynomial contrast, adjusted for age and stratified by sex and residential location (Greater Tokyo vs rural Okinawa). Weekly walking duration showed significant positive linear associations with acceptable walking time across all four demographic groups, with some evidence of quadratic components in males after adjusting for age. These consistent positive associations were observed across both residential locations for both sexes, with predominantly linear patterns. This study confirmed a positive association between acceptable walking time and actual walking behavior in the Japanese working-age population, with consistent patterns across sex and locations. Acceptable walking time may serve as a useful psychological indicator of walking behavior.