Objective: Physical education (PE) has been attributed an important role in providing young people with physical activity. If sufficiently active, PE lessons could contribute to physical activity levels in youth. Therefore, the purpose of this study was to determine the overall intensity of Dutch primary and secondary school physical education (PE) lessons and the influence of various lesson characteristics on these intensity levels. Methods: Between September 2008 and June 2009 heart rates were measured using the Polar Team System in a nationally distributed sample of 913 students in 40 schools in the Netherlands. Results: Overall percentages lesson time in moderate-to-vigorous physical activity (MVPA) were 46.7% and 40.1% during primary school and secondary school PE respectively. Results indicated a sharp decline in girls' PE intensity levels at the beginning of secondary school. Furthermore, secondary school boys were more active than girls. The high prevalence of teamgames in the Dutch PE curricula might prevent secondary school girls from attaining similar physical activity levels during PE.

The beta-adrenergic system is involved in the control of energy metabolism and expenditure. The beta2-adrenergic receptor (beta2-AR) gene shows polymorphisms that have been associated with obesity in several studies. In vitro and in vivo studies suggest differences in beta2-AR-mediated function between these polymorphisms. The aim of this study was to investigate the influence of genetic variation in codon 16 of the beta2-AR gene on energy metabolism in humans. Thirty-four subjects were recruited [Gly16Gly (n = 13), Gly16Arg (n = 16), or Arg16Arg (n = 5)]. The beta2-AR was stimulated with two doses of salbutamol (50 and 100 ng/kg fat-free mass per minute) after blockade of the beta1-adrenergic receptors with atenolol. Energy expenditure and plasma substrate and hormone concentrations were measured. The increase in energy expenditure (DeltaEE) was significantly different among groups in which the Arg16Arg group showed the lowest increase (P < 0.05 vs. Gly carriers). In a multiple regression model, variations in the increase in nonesterified fatty acid concentration during salbutamol infusion (partial r = 0.51) and the polymorphism contributed significantly to the variation in DeltaEE. Thirty-five percent of the variation in DeltaEE was explained by these two factors. We conclude that subjects with the Arg16Arg polymorphism of the beta2-AR gene have a reduced thermogenic response to beta2-adrenergic stimulation. Although this relatively small study needs confirmation, the findings support a role for this polymorphism in the development and maintenance of overweight and obesity.

The aim of this study is to investigate potential differences in fine motor control between strength trained (ST) and non-strength trained (NT) individuals. By use of an isometric force production task, two groups, 20 ST (mean age 25.6, SD 4.9) and 19 NT (mean age 24.1, SD 2.9) male individuals, were measured on the ability to control forces with the muscles of their index finger. The maximum voluntary contraction (MVC) was higher in ST than in NT group. Error and SD of the signal increased with increasing force levels in both groups. Despite higher absolute force levels of the ST group, SD and Error were the same in both groups for a given MVC percentage. Signal to noise ratio values showed inverted U-shapes for both groups, with no significant differences between groups on various force levels. The power spectral density analysis disclosed significant differences between groups, with more power in the lowest frequency band (1 - 6 Hz) for the ST group. It is concluded that strength training of arm muscles has no negative effect on the stability of sustained contractions of finger muscles. No evidence was found to support the notion of a loss in accuracy as a result of strength training.

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Gross ME in COPD was largely predicted by the absolute work rate (r = .87; P < .001) while indices of the severity of the disease did not predict ME in COPD.

The sympathetic nervous system is involved in the control of energy metabolism and expenditure. Diet-induced thermogenesis is mediated partly by the ß-adrenergic component of this system. The aim of the present study was to investigate the role of genetic variation in the ß 2 -adrenoceptor in diet-induced thermogenesis. Data from twenty-four subjects (fourteen men and ten women; BMI 26·7(SEM 0·8) kg/m 2 ; age 45·2(SEM1·4) years) with different polymorphisms of the ß 2 -adrenoceptor at codon 16 (Gly16Gly, Gly16Arg or Arg16Arg) were recruited for this study. Subjects were given a high-carbohydrate liquid meal, and the energy expenditure, respiratory exchange ratio, and plasma concentrations of NEFA, glycerol, glucose, insulin and catecholamines were measured before and over 4 h after the meal. The AUC of energy expenditure (diet-induced thermogenesis) was not significantly different between polymorphism groups, nor was the response of any of the other measured variables to the meal. In a multiple regression model, the only variable that explained a significant proportion (32 %) of the variation in diet-induced thermogenesis was the increase in plasma adrenaline in response to the meal (P,0·05). The ß 2 -adrenoceptor codon16 polymorphisms did not contribute significantly. In conclusion, an independent contribution of the codon 16 polymorphism of the ß 2 -adrenoceptor gene to the variation in thermogenic response to a high-carbohydrate meal could not be demonstrated. The interindividual variation in thermogenic response to the meal was correlated with variations in the plasma adrenaline response to the meal. Energy expenditure (EE) is an important factor in body-weight regulation. Diet-induced thermogenesis (DIT) is the EE associated with ingestion, absorption and storage of food and accounts for 10 -15 % to the total daily EE. DIT shows considerable interindividual variation (Donahoo et al. 2004), and it can be hypothesised that a low DIT contributes to weight gain. Many studies have investigated DIT in obese and lean subjects, but these studies show equivocal results (de Jonge & Bray, 1997Granata & Brandon, 2002). Nevertheless, when multiple interfering factors are taken into account simultaneously, the evidence for a reduction in DIT in obesity becomes stronger (de Jonge & Bray, 2002). In addition, several studies show no change in DIT after weight reduction, suggesting that a reduced DIT in obesity is not the consequence of the obese state per se (Bessard et al. 1983;Schutz et al. 1984). In response to feeding, especially to carbohydrate intake, sympathetic nervous system activity increases (Schwartz et al. 1999;Tappy, 2004). The sympathetic nervous system-mediated thermogenic response is also referred to as facultative thermogenesis (Tappy, 2004). The sympathetic nervous system response is biphasic, with an initial increase in noradrenaline and a delayed adrenaline response (Astrup et al. 1986(Astrup et al. , 1989. The sympathetic nervous system-mediated component of DIT can be blocked by ß-adrenoceptor antagon...

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