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No changes during pregnancy in the net cost of cycling exercise
C J Spaaij1, J M van Raaij, L C de Groot
1Department of Human Nutrition, Wageningen Agricultural University, The Netherlands.
Objective:
To investigate whether work efficiency improves during pregnancy.
Design:
Longitudinal; energy expenditure measurements (ventilated hood system) before the onset of pregnancy and in weeks 13, 24 and 35 of gestation.
Subjects:
Healthy Dutch women (n = 26), recruited with advertisements in local newspapers and posters displayed in public buildings.
Main Outcome Measures:
Resting metabolic rate (RMR); metabolic rate during cycling at workloads of 30, 45, 60 and 75 W (CMRgross); post-cycling metabolic rate (PCMRgross); net energy costs of cycling (CMRnet = CMRgross - RMR); net recovery costs after cycling exercise (PCMRnet = PCMRgross - RMR).
Results:
RMR, CMRgross and PCMRgross increased during pregnancy; under all conditions, metabolic rates were 0.9 kJ/min higher at 35 weeks gestation than before pregnancy (P < 0.05). CMRnet and PCMRnet showed no significant change during gestation.
Conclusions:
Changes in metabolic rate during cycling exercise suggest that pregnancy does not induce an improvement of work efficiency.