Japanese Journal of Physical Fitness and Sports Medicine
Online ISSN : 1881-4751
Print ISSN : 0039-906X
ISSN-L : 0039-906X
Current issue
Displaying 1-9 of 9 articles from this issue
Original
  • Yasutsugu Kurokawa, Manami Iwahashi, Takuma Yanaoka, Erika Wada, Hiros ...
    Article type: Original
    2022 Volume 71 Issue 5 Pages 389-399
    Published: October 01, 2022
    Released on J-STAGE: September 13, 2022
    JOURNAL OPEN ACCESS

    The increase in core temperature during exercise in a hot environment causes hyperventilation (hyperthermia-induced hyperventilation), which decreases the partial pressure of arterial blood carbon dioxide. However, the effects on the body of wearing a surgical mask during exercise that would cause hyperthermia-induced hyperventilation have not been clarified. Therefore, we investigated such effects. Ten healthy men participated in the study. A 44-minute steady-state load cycling exercise (55% of peak oxygen uptake) was performed under hot environmental conditions (30℃, 70% relative humidity). Two experimental conditions were set: exercising with surgical face mask (MASK) and without a surgical face mask (CON). The experiment was conducted as a randomized crossover design. Body temperatures, respiratory gas exchange, and subjective indices were measured during exercise. In terms of physiological indices, respiratory rate only revealed a main effect and was significantly lower in the MASK than in CON at 44 min of exercise (CON 41.0±19.2 breaths/min, MASK 35.6±11.2 breaths/min p=0.029). No significant differences were observed between conditions in other physiological parameters. As for the subjective indices, dyspnea showed a condition × time interaction (p=0.016), which was significantly higher in the MASK starting at 5 minutes through the end (CON 4.5±3.5 and MASK 8.5±2.1 at the end of exercise p=0.016). No significant differences were observed in other subjective measures. In conclusion, wearing a surgical face mask during moderate-intensity prolonged exercise under hot environmental conditions significantly worsened dyspnea, but no significant differences were observed in other physiological indices or subjective indices.

    Download PDF (1439K)
  • Aya Itoi, Yosuke Yamada, Misaka Kimura
    Article type: Original
    2022 Volume 71 Issue 5 Pages 401-415
    Published: October 01, 2022
    Released on J-STAGE: September 13, 2022
    JOURNAL OPEN ACCESS

    The purpose of this study was to examine time trend changes in the amount and type of physical activities obtained by an accelerometer and an activity record over a 20-year period in urban elementary schoolchildren. A total of 388 sixth-grade children (11–12 years old) in an elementary school in Kyoto participated in the study (n = 125 in 1999, 108 in 2009, and 155 in 2017/2018). The size and shape of the school district did not change. The school schedule was nearly the same in 1999, 2009, and 2017/2018. The children were instructed to wear an accelerometer for 5 consecutive weekdays and to keep minute-by-minute activity records with the assistance of their parents. The percentage of overweight/obese children increased with time, but the increases were not significant. The step count per day, activity energy expenditure, and physical activity level were significantly lower than they were 20 years ago, and they were significantly higher than they were 10 years ago. The time spent playing outdoors was significantly shorter than it was 20 years ago, and while it was significantly longer than it was 10 years ago. Independently from year, the time spent playing outdoors was strongly correlated with accelerometer-derived physical activity. The time spent walking to school, sleeping, studying in girls was correlated with accelerometer-derived physical activity. The factor of activity pattern related to secular changes of accelerometer-derived physical activity over the 20-year period is the time spent walking to school, sleeping in boys and the time spent club activity in girls.

    Download PDF (1157K)
  • Kazuhiro Harada, Shuhei Izawa, Nanako Nakamura-Taira, Toru Yoshikawa, ...
    Article type: Original
    2022 Volume 71 Issue 5 Pages 417-429
    Published: October 01, 2022
    Released on J-STAGE: September 13, 2022
    JOURNAL OPEN ACCESS

    Previous studies among middle-aged and older adults have shown that engagement in exercise with others is more strongly associated with better mental health than engagement in exercise alone. However, the applicability of such findings to workers remains unclear. This study aimed to examine whether 1) engagement in exercise with others and time spent exercising with others were associated with lower stress response and mental distress among workers, and 2) self-determined motivation toward exercise mediated these associations among workers. This was a cross-sectional study. A web-based questionnaire survey was conducted among 810 workers aged 20 to 59 years. The survey measured respondents’ engagement and time spent exercising alone and with others, self-determined motivation toward exercise, psychological and physical stress responses, mental distress, and basic factors. Basic factors were treated as covariates. The analyses of covariance showed that engagement in exercise with others was significantly associated with lower psychological and physical stress responses and mental distress, while engagement in exercise alone was not. Multiple regression analyses revealed that longer time spent exercising with others was not associated with lower psychological and physical stress responses or mental distress. Path analyses showed that mediation effect of self-determined motivation on these associations was not significant. Although dose-response associations and the mediating role of self-determined motivation were not confirmed, this study found that engagement in exercise with others was associated with lower stress responses and mental distress among workers.

    Download PDF (1223K)
  • Yuta Nemoto, Nobumasa Kikuga, Susumu Sawada, Munehiro Matsushita, Yuko ...
    Article type: Original
    2022 Volume 71 Issue 5 Pages 431-441
    Published: October 01, 2022
    Released on J-STAGE: September 13, 2022
    JOURNAL OPEN ACCESS

    Approximately 40%–65% of new fitness club (FC) members cancel their membership within 6 months. To prevent such cancellations, it is essential to identify members at high risk of doing so. This study developed a model to predict the probability of discontinuing FC membership among new members. We conducted a cohort study and enrolled participants from 17 FCs in Japan. We asked 5,421 individuals who became members from March 29, 2015 to April 5, 2016 to participate in the study; 2,934 completed the baseline survey, which was conducted when the participants became FC members. We followed up the participants until September 30, 2016. We excluded 883 participants with missing values and 69 participants under aged 18 years; thus, our analysis covered 1,982 individuals. We conducted the random survival forest to develop the prediction model. The mean follow-up period was 296.3 (standard deviation, 127.3) days; 488 participants (24.6%) cancelled their membership during the follow-up. The prediction model comprised 8 predictors: age; month of joining FC; years of education; being under medical follow-up; reasons for joining FC (health improvement, relaxation); and perceived benefits from exercise (maintaining good body weight, recognition of one’s ability by other). The discrimination and calibration were acceptable (C statistic: 0.692, continuous ranked probability score: 0.134). Our findings suggest that the prediction model could assess the valid probability for early FC cancellation among new members; however, a validation study will be needed.

    Download PDF (1519K)
  • Koji Koyama, Kozo Furushima, Yoshinori Sugano, Azusa Niitsu, Yuka Koda ...
    Article type: Original
    2022 Volume 71 Issue 5 Pages 443-453
    Published: October 01, 2022
    Released on J-STAGE: September 13, 2022
    JOURNAL OPEN ACCESS

    Previous studies have reported that poor posture can induce various musculoskeletal disorders. Recently, poor posture in children has become a problem. This study aimed to determine the characteristics of sagittal spinal alignment in standing and sitting positions in elementary school students and how spinal alignment changes from standing to sitting position. Moreover, it clarifies how poor posture (hyperkyphosis) in the standing position affects sitting posture. This study was conducted among 83 elementary school students. The Spinal-Mouse® System was used to measure the thoracic kyphosis angle (TKA), upper thoracic angle (UTA), lower thoracic angle (LTA), lumbar lordosis angle (LLA), and sacral anteversion angle (SAA) in the standing and sitting positions. Hyperkyphosis was defined as a thoracic kyphosis angle of >40°. Participants were assigned to two groups: hyperkyphosis and non-hyperkyphosis. Significant differences were noted in all spinal alignment characteristics in both the positions. When spinal alignment was changed from standing to sitting, ΔUTA and ΔLTA correlated with ΔLLA and ΔSAA, respectively. A strong negative correlation was noted between ΔLLA and ΔSAA. In the sitting position, TKA, UTA, and LLA were significantly higher in the hyperkyphosis group than in the non-hyperkyphosis group. ΔUTA was significantly higher in the hyperkyphosis group than in the non-hyperkyphosis group when spinal alignment was changed from standing to sitting. The characteristics of sagittal spinal alignment in the sitting position were significantly different from those in the standing position. The study findings suggest that poor posture (hyperkyphosis) in the standing position affects the sitting posture.

    Download PDF (1639K)
  • Mioko Nagashima, Koji Hamada, Misato Sakanaka, Isao Matsumura, Katsuyu ...
    Article type: Original
    2022 Volume 71 Issue 5 Pages 455-461
    Published: October 01, 2022
    Released on J-STAGE: September 13, 2022
    JOURNAL OPEN ACCESS

    Iron deficiency in athletes induces negative effects on their athletic performances. The present study aimed to examine a possibility of non-invasive screening with urine ferritin value for iron deficiency by examining its association with serum ferritin value. A group of 30 male college soccer players,13 male endurance runners, 22 female volleyball players, and 9 female long distance runners voluntarily participated in this study. Blood samples were collected before breakfast. The urinary samples were collected to the special tube in the morning and analyzed by ELISA in accordance with the manufacture’s specification. The urinary ferritin value was significantly correlated with serum ferritin value (r=0.32, p<0.05). In addition, the corresponding association was improved in athletes whose urinary ferritin values were less than 2314 ng/gCre (n=52) (r=0.49, p<0.05). In each of male and female athletes, the results on the event-related differences in urinary ferritin had a similar trend as those on serum ferritin. In future studies, further testing should be accomplished using larger numbers of athletes for use the urine ferritin as non-invasive screening iron deficiency in athletes.

    Download PDF (1283K)
Abstracts
feedback
Top