Sex-specific associations of moderate and vigorous physical activity with physical fitness in adolescents.

The present study examined the sex-specific associations of moderate and vigorous physical activity (VPA) with physical fitness in 300 Japanese adolescents aged 12-14 years. Participants were asked to wear an accelerometer to evaluate physical activity (PA) levels of various intensities (i.e. moderate PA (MPA), 3-5.9 metabolic equivalents (METs); VPA, ≥6 METs; moderate to vigorous PA (MVPA), ≥3 METs). Eight fitness items were assessed (grip strength, bent-leg sit-up, sit-and-reach, side step, 50 m sprint, standing long jump, handball throw, and distance running) as part of the Japanese standardised fitness test. A fitness composite score was calculated using Japanese fitness norms, and participants were categorised according to their score from category A (most fit) to category E (least fit), with participants in categories D and E defined as having low fitness. It was found that for boys, accumulating more than 80.7 min/day of MVPA may reduce the probability of low fitness (odds ratio (ORs) [95% confidence interval (CI)] = 0.17 [0.06-0.47], p = .001). For girls, accumulating only 8.4 min of VPA could reduce the likelihood of exhibiting low fitness (ORs [95% CI] = 0.23 [0.05-0.89], p = .032). These results reveal that there are sex-specific differences in the relationship between PA and physical fitness in adolescents, suggesting that sex-specific PA recommendation may be needed to improve physical fitness in adolescents.

Interrupting Sitting Time with Regular Walks Attenuates Postprandial Triglycerides.

We compared the effects of prolonged sitting with the effects of sitting interrupted by regular walking and the effects of prolonged sitting after continuous walking on postprandial triglyceride in postmenopausal women. 15 participants completed 3 trials in random order: 1) prolonged sitting, 2) regular walking, and 3) prolonged sitting preceded by continuous walking. During the sitting trial, participants rested for 8 h. For the walking trials, participants walked briskly in either twenty 90-sec bouts over 8 h or one 30-min bout in the morning (09:00-09:30). Except for walking, both exercise trials mimicked the sitting trial. In each trial, participants consumed a breakfast (08:00) and lunch (11:00). Blood samples were collected in the fasted state and at 2, 4, 6 and 8 h after breakfast. The serum triglyceride incremental area under the curve was 15 and 14% lower after regular walking compared with prolonged sitting and prolonged sitting after continuous walking (4.73±2.50 vs. 5.52±2.95 vs. 5.50±2.59 mmol/L∙8 h respectively, main effect of trial: P=0.023). Regularly interrupting sitting time with brief bouts of physical activity can reduce postprandial triglyceride in postmenopausal women.

Studies on responsiveness of hepatoma cells to catecholamines. IV. Lack of adrenergic activation of phosphorylase in rat ascites hepatoma cells.

Glycogen phosphorylase a activity in 7 rat ascites hepatoma cell lines treated with adrenergic agents, phenylephrine, epinephrine and isoproterenol, was investigated as compared with that in freshly isolated rat hepatocytes. Basal phosphorylase activities in hepatoma cells except AH7974 cells were lower than that in hepatocytes. Phosphorylase in hepatoma cells was not activated by any of the agents, while the enzyme activity in hepatocytes was clearly increased in a dose- and time-dependent manner. Phosphorylase in hepatocytes was sensitive to glucagon, but it was found to be insensitive to glucagon in all hepatoma cells. The present results suggest that rat ascites hepatoma cells may escape the glycogenolytic regulation by catecholamines and glucagon.