SUMMARY1. The effects of moderate degrees of hypercapnia in hypoxia and in hyperoxia on the baroreceptor-cardiodepressor reflex have been studied in nine normal men.2. The beat-by-beat relation between pulse interval (I) and systolic pressure (P) during transient elevations of arterial pressure induced by intravenous injections of angiotensin II and phenylephrine was used to assess the sensitivity (XI/AP) and setting (I at a single reference arterial pressure) of the reflex..3. There was no consistent change in reflex sensitivity in any of the conditions studied.4. In hyperoxia (PA, 02 200 torr) hypercapnia was associated with significant re-setting of the reflex in the direction of tachycardia. The extent of the re-setting was correlated with the degree of hypercapnia and with the accompanying increase in breathing.5. When hyperoxia with hypercapnia was replaced by hypoxia (PA 02 55 torr) with hypercapnia (which causes substantial arterial chemoreceptor activity), pulse interval at constant arterial pressure was further decreased.6. The tachycardia of hypoxia could not be accounted for by change of arterial pressure, PA, co. or pulmonary ventilation, since it was most clearly demonstrable at constant values of pressure andeitherPA cOorventilation.

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Background: The effect of exercise on subjective appetite and short-term food intake has received little investigation in children. Despite a lack of reported evaluation of short-duration activity programs, they are currently being implemented in schools as a means to benefit energy balance. The purpose of this study was to determine the effect of duration of exercise at the ventilation threshold (VeT) on subjective appetite and short-term food intake in normal weight boys and girls aged 9 to 14 years.

The objective of these studies was to assess the reproducibility of (i) short-term food intake (FI) and subjective appetite following a glucose preload, (ii) ventilation threshold (VT) and subjective appetite after short-duration exercise, and (iii) body composition assessed by bioelectrical impedance (BIA). On two separate weekend mornings, boys (n = 11; aged 9-14 years) received drinks containing 50 g glucose made up to 250 mL with water 2 h after a standardized breakfast. FI from a pizza meal was measured 30 min later. Subjective appetite was measured before and after the glucose loads and the VT measures. VTs were measured on 2 weekday evenings, 1 week apart. BIA was measured during the FI assessment sessions. Short-term FI after the glucose preload was highly reproducible. Mean energy intake was 925 +/- 139 kcal on the first day and 988 +/- 147 kcal on the second day (coefficient of repeatability (CR) = 259 kcal; intra-class correlation coefficient (ICC) = 0.96). Moderate reproducibility of the average appetite score was found at 30 min (CR = 24 mm; ICC = 0.82). Subjective appetite was increased similarly by short-duration exercise on both days (CR = 19 mm). Absolute VT was more highly reproducible (CR = 359 mL O2.min(-1), ICC = 0.85) than VT expressed on the basis of body weight (CR = 8.0 mL O2.kg(-1).min(-1), ICC = 0.59). Fat mass (FM) estimated from BIA was highly reproducible (CR = 2.7 kg, ICC = 0.95), but underestimated FM compared with skinfolds. In conclusion, FI and subjective appetite scores in response to glucose preloads, VT, subjective appetite after short-duration exercise, and estimates of FM from BIA are reproducible in boys.

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