Effects of a mobile health intervention on health-related outcomes in Japanese office workers: a pilot study.

OBJECTIVES: The purpose of the current study was to explore the effects of a mobile health (mHealth) intervention based on the Persuasive System Design (PSD) model on health-related outcomes among office workers. MATERIAL AND METHODS: The authors conducted a trial that consisted of a 4-week baseline and an 8-week intervention period by reference to 23 office workers in a private research company. The mHealth application was developed to improve these workers' daily step count, decrease their sedentary time, and increase their sleep duration in accordance with the PSD model. The app features included at least 1 principal factor from each of the 4 main categories of the PSD model (primary task support, dialogue support, system credibility support, and social support). The objective health-related variables were measured using a smartwatch (Fitbit Luxe) that was synchronized with the application using the Fitbit Web Application Programming Interface. Subjects used the app, which included self-monitoring, personalized messages, education, and a competition system for users, during the intervention period. RESULTS: Sedentary time exhibited a significant decrease (a median reduction of 14 min/day, p < 0.05) during the intervention period. No significant differences in daily step count and sleep duration were observed between the baseline and intervention periods. CONCLUSIONS: This study suggests that the mHealth intervention based on the PSD model was useful for reducing sedentary time among office workers. Given that many previous studies on this topic have not been based on any theories, future studies should investigate the impact of structured selection behavior change theories on health-related outcomes among office workers. Int J Occup Med Environ Health. 2024;37(2):153-64.

The Relationship between 24 h Ultramarathon Performance and the "Big Three" Strategies of Training, Nutrition, and Pacing.

BACKGROUND: The present case study examined the relationship between 24 h ultramarathon performance and the "big three" strategies of training, nutrition, and pacing. METHODS: A 32-year-old male ultramarathon runner (body mass: 68.5 kg, height: 179 cm) participated in a 24 h ultramarathon race. Training status was quantified based on from a GPS sports watch. The nutritional status was evaluated during the week leading up to the race, and blood glucose level and heart rate were measured during the race. RESULTS: His aim of the distance was 200 km, but the actual performance was 171.760 km. The blood glucose level was stable because of adequate CHO intake before (7.2 ± 0.8 g/kg/day) and during the race (48 g/h). The running speed decreased in the middle and later stages of the race despite adequate CHO intake and a lack of high intensity running in the early stage of the race. The longest training session before the race (80 km) had to be significantly shorter compared to the aim. CONCLUSIONS: For optimal 24 h ultramarathon performance, the "big three" strategies of training, nutrition, and pacing are all important. However, the performance level estimated based on previous studies may be achievable even with insufficient training, as long as the nutritional and pacing strategies are appropriate.

Relationship between oxygen cost and C-reactive protein response to marathon running in college recreational runners.

PURPOSE: Individual variations in response of C-reactive protein (CRP) to acute strenuous exercise are less well known. The purpose of this study was to investigate the relationship between running economy and systemic inflammation following a marathon. MATERIALS AND METHODS: Sixteen college recreational runners participated in this study. To measure maximal oxygen uptake and running economy, the treadmill running test was performed 1-2 weeks before the marathon race. Running economy was defined as oxygen cost (mL/kg/km) at submaximal running. CRP and muscle damage markers (creatine kinase and lactate dehydrogenase) were measured before and 1, 2, and 3 days after the race. RESULTS: All subjects completed the race in 4 hours 7 minutes 43 seconds±44 minute 29 seconds [mean±SD]. The marathon running significantly increased CRP and muscle damage markers. The levels of inflammation and muscle damage peaked after 1 day and remained high throughout the 3-day recovery period compared to that before the race. Spearman correlation analysis showed that the change in CRP level was significantly positively correlated with oxygen cost (r=0.619, P=0.011) but not maximal oxygen uptake. There was no significant relationship in responses between muscle damage markers and CRP. CONCLUSION: These findings suggest that running economy is related to postmarathon race CRP response. Further study to clarify the cause of the relationship and clinical significance of transient increase in CRP is necessary.

Effects of Marathon Running on Aerobic Fitness and Performance in Recreational Runners One Week after a Race.

It is not clear whether or not recreational runners can recover aerobic fitness and performance within one week after marathon running. This study aimed to investigate the effects of running a marathon race on aerobic fitness and performance one week later. Eleven recreational runners (six men, five women) completed the race in 3 h 36 min 20 s ± 41 min 34 s (mean ± standard deviation). Before and 7 days after the race, they performed a treadmill running test. Perceived muscle soreness was assessed before the race and for the following 7 days. The magnitude of changes in the treadmill running test was considered possibly trivial for maximal oxygen uptake ([Formula: see text]O2max) (mean difference -1.2 ml/kg/min; ±90% confidence limits 2 ml/kg/min), unclear for %[Formula: see text]O2max at anaerobic threshold (AT) (-0.5; ±4.1%) and RE (0.2; ±3.5 ml/kg/km), and likely trivial for both velocity at AT and peak (-0.2; ±0.49 km/h and -0.3; ±0.28 km/h). Perceived muscle soreness increased until 3 days after the race, but there were no clear differences between the values before the race and 4-7 days after it. These results show that physiological capacity associated with marathon running performance is recovered within 7 days after a marathon run.