Gas exchange response to exercise in children.

We measured the gas exchange response to exercise in 109 normal children (51 girls and 58 boys, ranging in age from 6 to 17 yr old) using noninvasive breath-by-breath techniques. The protocol consisted of cycle ergometry in which the work rate increased in a linear manner (ramp forcing function) until the limit of the subject's tolerance was reached. We measured the maximal oxygen uptake (VO2max) and the VO2 at the anaerobic threshold (AT). We found that both of these parameters were highly correlated with increasing height, and that for both the AT and VO2max, the values for boys were significantly higher than girls. We compared our results of VO2max to those obtained by Astrand over 30 years ago using different techniques. When boys and girls were considered together, there were no significant differences between our study and Astrand's; however, girls in our study had significantly lower values for VO2max than did girls in Astrand's study. These data provide normal values for both VO2max and AT and can be used to evaluate the exercise impairment resulting from disease in children

Gas exchange response to exercise in children.

We measured the gas exchange response to exercise in 109 normal children (51 girls and 58 boys, ranging in age from 6 to 17 yr old) using noninvasive breath-by-breath techniques. The protocol consisted of cycle ergometry in which the work rate increased in a linear manner (ramp forcing function) until the limit of the subject's tolerance was reached. We measured the maximal oxygen uptake (VO2max) and the VO2 at the anaerobic threshold (AT). We found that both of these parameters were highly correlated with increasing height, and that for both the AT and VO2max, the values for boys were significantly higher than girls. We compared our results of VO2max to those obtained by Astrand over 30 years ago using different techniques. When boys and girls were considered together, there were no significant differences between our study and Astrand's; however, girls in our study had significantly lower values for VO2max than did girls in Astrand's study. These data provide normal values for both VO2max and AT and can be used to evaluate the exercise impairment resulting from disease in children

Compulsory detention of recalcitrant tuberculosis patients in the context of a new tuberculosis control programme in Israel.

OBJECTIVE: To analyse the use of compulsory detention in the context of a new national tuberculosis (TB) control programme launched in 1997. METHODS: A retrospective review was made of the use of compulsory detention in the management of infectious TB before and after the initiation of a new TB control programme, using data from the central TB registry in the Ministry of Health and the charts of each patient. RESULTS: Between 1994 and 2001, 13 recalcitrant patients out of 3056 (0.43%) cases of pulmonary TB were brought to trial. Eleven patients were detained. All were either hospitalized under a court order and, when failing to comply with the order, hospitalized in prison, or referred directly to a prison hospital. Twelve of 13 (92%) patients were new immigrants. After the new programme was launched, proportionately fewer patients were brought to trial [6/943 (0.64%) in 1994-1996 compared with 7/2113 (0.33%) in 1997-2001]. CONCLUSION: The reduction in the number of individuals detained could be viewed as an improvement in TB control due to the new TB control programme. It remains to be shown whether these individuals, most of whom had drug-resistant strains of TB, posed a sufficient threat to public health to justify detention

Growth-related changes in oxygen uptake and heart rate during progressive exercise in children.

Although body size and muscle mass increase considerably during growth in children, certain aerobic responses to exercise appear to be regulated so that the delivery of oxygen to muscle is maintained at optimized levels. We proposed that the relationship between oxygen uptake, (VO2) and heart rate (HR) was one of the regulated responses. We further hypothesized that the increase in VO2 per increase in HR during progressive exercise would differ in subjects of different size, but when normalized to body weight would be constant since changes in muscle mass are highly correlated to changes in body mass. To test this, we performed a cross-sectional study of 107 normal children, 50 girls and 57 boys ranging in age from 6 to 17 years. The protocol consisted of a continuously increasing work rate on a cycle ergometer, to the limit of the child's tolerance (ramp forcing function). Gas exchange was measured breath-by-breath for the determination of VO2, and heart rate was measured beat-by-beat. We used linear regression techniques to determine M, the slope, and B, the y intercept of the equation: VO2 = M X HR - B. In both boys and girls, M increased significantly with body weight, but when normalized for body weight (M/kg), there was no systematic change with increasing weight or age, the mean value being 0.33 +/- 0.10 ml/min/kg (SD). The mean value for the boys was 0.37 +/- 0.10 which was significantly greater than that of the girls (0.29 +/- 0.08, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS

Aerobic parameters of exercise as a function of body size during growth in children.

To examine the relationship between body weight in children and aerobic parameters of exercise, we determined the anaerobic threshold (AT), maximum O2 uptake (VO2max), work efficiency, and response time for O2 uptake (RT-VO2) in 109 healthy children (51 girls and 58 boys, range 6-17 yr old) using a cross-sectional study design. Gas exchange during exercise was measured breath by breath. The protocol consisted of cycle ergometry and a linearly increasing work rate (ramp) to the limit of the subject's tolerance. Both AT and VO2max increased systematically with body weight, whereas work efficiency and RT-VO2 were virtually independent of body size. The ratio of AT to VO2max decreased slightly with age, and its mean value was 60%. AT scaled to body weight to the power of 0.92, not significantly different from the power of 1.01 for VO2max. Thus both the AT and the VO2max increase in a highly ordered manner with increasing size, and as judged by AT/VO2max, the onset of anaerobic metabolism during exercise occurred at a relatively constant proportion of the overall limit of the gas transport system. We conclude that in children cardiorespiratory responses to exercise are regulated at optimized values despite overall change in body size during growth