The present study aimed to investigate whether daily steps in male college students have actually decreased in the last decade. If the decline in steps is found, we additionally aimed to examine whether the decline in steps is attributed to a reduction of exercise or, rather, to a reduction of non-exercise activity. A serial cross-sectional study was performed from 2003 to 2012 at the Osaka Institute of Technology. A total of 1,215 male college freshmen were analyzed. Every year, scores of the physical activity levels were evaluated by a questionnaire, and we measured daily steps of participants using a pedometer during usual 1 week. Daily behavior record was also analyzed (n = 69). There were no significant trends or differences in characteristics of participants and the scores of physical activity levels throughout the 10 years. However, interestingly, significant decreasing trends were observed in the steps of average and weekend. In addition, daily behavior record analyses indicate that a cell-phone or a PC usage increased significantly in both weekday and weekend and that playing video games increased significantly in weekday. Therefore, these data support the view that daily steps have actually reduced in the last decade. Our findings also raise the possibility that the decline in steps may be related to the decline in non-exercise activity associated with the increase in a cell-phone or a PC usage and playing the video games.

The present study aimed to examine the effects of Internet addiction on daily steps. A cross-sectional study was performed at the Osaka Institute of Technology. A total of 334 male college freshmen were analyzed. The participants were assigned to five groups according to Internet addiction levels. Internet addiction levels were assessed by Diagnostic Questionnaire, which has been reported by Young (1998), and we measured daily steps of the participants using a pedometer during usual 1 week. There were no significant trends or differences among five groups in physical characteristics of the participants, sleep duration, frequency of eating breakfast, and walking during commute time. However, with the level of Internet addiction increasing, daily steps showed a statistically significant decreasing trend. Therefore, Internet addiction levels might be related to reductions in steps in a dose-response manner. To clarify this point, further investigations will be required after considering confounding factors.

The effects of running exercise on bone histomorphometric parameters were examined in sham-treated (Sham) and ovariectomized (OVX) rats. The rats were either kept sedentary (C) or trained (T) on a rodent treadmill at 25 m/min, 30 min/day, 5 days/week for 10 weeks. Fat-free dry bone weight, bone mineral content (BMC), and histomorphometric parameters were assessed after excision of the tibiae at sacrifice. The results are summarized as follows
1) There were no significant differences in fat-free dry bone weight and BMC between OVX-C and Sham-C rats. However, BMC/body weight in OVX-C rats was significantly lower than in Sham-C animals. OVX-C rats had significantly lower trabecular bone volume at the proximal tibial metaphysis than Sham-C animals. Values of bone formation parameters were significantly higher in OVX-C rats than in Sham-C animals.
2) BMC/body weight in OVX-T rats was significantly higher than in OVX-C animals. OVX-T rats had a significantly higher trabecular bone volume at the proximal tibial metaphysis than OVX-C animals. There were no significant differences in bone formation parameters between OVX-T and OVX-C rats.
3) No significant differences were found in any parameters between sham-C and Sham-T rats.
These results suggest that (1) running exercise has a suppressive effect on bone loss after OVX, and (2) training-induced reduction of bone loss by OVX does not seam to be associated with facilitation of bone formation but with suppression of bone resorption.