No changes during pregnancy in the net cost of cycling exercise.
OBJECTIVE
To investigate whether work efficiency improves during pregnancy.


METHODS
Longitudinal; energy expenditure measurements (ventilated hood system) before the onset of pregnancy and in weeks 13, 24 and 35 of gestation.


METHODS
Healthy Dutch women (n = 26), recruited with advertisements in local newspapers and posters displayed in public buildings.


METHODS
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.
Department of Human Nutrition, Wageningen Agricultural University, The Netherlands.
C J
CJ
Spaaij
J M
JM
van Raaij
L C
LC
de Groot
L J
LJ
van der Heijden
H A
HA
Boekholt
J G
JG
Hautvast
D000328:Adult; D004734:Energy Metabolism; D005080:Exercise Test; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D005082:Physical Exertion / Q000502:physiology*; D011247:Pregnancy / Q000378:metabolism*; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D012146:Rest