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Relative contribution of physical activity to neonatal oxygen consumption
C Billeaud1, B Piedboeuf, J C Jéquier
1Perinatal Service and Research Center, Hospital Sainte-Justine, Montreal, Canada.
Insights
This study examined oxygen consumption in newborn infants during rest and exercise. For smaller infants, body weight predicted energy expenditure during activity, while gestational age was key for larger infants.
Area of Science:
- Neonatal physiology
- Energy metabolism in infants
Background:
- Accurate assessment of energy expenditure is crucial for optimizing nutritional support in newborn infants.
- Distinguishing between resting and activity-related energy expenditure is important for understanding neonatal metabolic demands.
Purpose of the Study:
- To investigate the relationship between oxygen consumption, body weight, and gestational age in newborn infants during rest and physical activity.
- To determine the predictors of exercise-induced oxygen consumption in neonates of varying sizes and developmental stages.
Main Methods:
- Oxygen consumption (VO2) was measured in 17 parenterally fed newborn infants (1.0-3.4 kg; 28-41 weeks gestational age) under resting and intense physical activity (exercise) conditions.
- Each infant served as their own control to compare VO2 during different activity levels.
- Nutrient intake was kept constant throughout the study.
Main Results:
- Resting oxygen consumption (VO2) strongly correlated with body weight (r = 0.96).
- During intense activity, body weight predicted exercise-induced VO2 in infants < 2.0 kg, whereas gestational age predicted it in infants > 35 weeks.
- The oxygen cost of exercise decreased with increasing body weight.
Conclusions:
- The predictors of exercise-induced oxygen consumption differ based on infant size and gestational age.
- Physical activity contributes minimally to the overall energy balance of low-birth-weight infants, suggesting focused nutritional strategies.
- Understanding these metabolic differences is vital for clinical management and nutritional support in neonates.
Abstract:
To explore the relevance of distinguishing between resting and global energy expenditure in newborn infants, oxygen consumption (VO2) was measured during extremes of physical activity in 17 parenterally fed newborn infants with a large range of body weights (1.0-3.4 kg) and gestational ages (28-41 weeks). Under constant nutrient intakes, each infant served as his/her own control when comparing VO2 during resting conditions and spontaneous intense physical activity, called exercise. VO2 was significantly correlated with body weight at rest (r = 0.96). But during intense activity, the better predictor of exercise-induced VO2 was body weight in the smaller infants (< 2.0 kg) and gestational age in the larger infants (> 35 weeks). The difference in VO2 between both levels of activity represented the oxygen cost of exercise, which decreased (P < 0.01) with body weight. For clinical purposes, the physical activity of low-birth-weight infants does not contribute substantially to their energy balance.