Substrate Utilization and Hormonal Status in Women
Women sexual hormones (i.e. estrogen) are involved in the regulation of substrate utilization and storage. Being under oral contraception (OC) may conduct to metabolic and hormonal modifications, but results are confused regarding the impact on substrate utilization. In the present study, the aim is then to explore the effect of hormonal status on substrate utilization during sous-maximal exercise, comparing women with and without OC.
We hypothesised that women under OC have a lower Respiratory Exchange Ratio (RER) at exercise than women without contraception underlying a greater reliance on fat oxidation.
|Official Title:||Impact of Women Hormonal Status (Oral Contraception vs no Contraception) on Substrate Utilization During Exercise|
- Substrate utilization will be the main outcome under study.For each volunteer, it will be assessed during exercise (between 12h and 12h45) for the 2 experimental conditions with exercise [ Time Frame: during exercise (between 12h and 12h45) ] [ Designated as safety issue: Yes ]
The Respiratory Exchange Ratio (RER) that corresponds to carbon dioxide production divided by oxygen consumption (VCO2/VO2) will be used to determine the energetic substrate used during exercise. This RER will be obtained, in continuous, thanks to an indirect calorimetric system composed of a breath by breath gas analyzer. A RER closed to 0.7 illustrates lipid utilization while carbohydrate use will correspond to a RER that reached 1.
- The hormonal regulation involved in substrate utilization. It will be assessed during the 3 experimental conditions during all the experimental day: - Breakfast + exercise - Exercise alone - Breakfast alone [ Time Frame: before (8h, 8h45), during (12h, 12h20, 12h30, 12h45) and after exercise (13h15, 13h45; 14h45) ] [ Designated as safety issue: Yes ]
The hormonal regulations involved in the substrate utilization will be assessed thanks to blood samples collected before, during and after exercise.
At each blood collection, the nurses will collect a EDTA tube (5ml) used to assess free fatty acid and glycerol; and 2 heparin ones (2*5ml) to assess 17β-œstradiol, progesterone, triglycerides, cholesterol, HDL-C, LDL-C, glucose, insulin, growth hormone, IGF-I, IGFBP-1, IGFBP-3, adrenaline, noradrenaline, Atrial Natriuretic Peptide, and C-Reactive Protein.
|Study Start Date:||February 2010|
|Study Completion Date:||November 2010|
|Primary Completion Date:||November 2010 (Final data collection date for primary outcome measure)|
|12 women with oral contraception|
|12 women without any contraception|
24 healthy young women (12 with OC and 12 without any contraception) will complete a maximal test on an ergometer cycle to obtain their maximal oxygen consumption (VO2max).Their body composition will be assessed by DXA. They will be asked to complete 3 experimental sessions.
During a first session the volunteers will remain inactive, and only a breakfast will be offered. During the second session, a breakfast will be offered and they will have to complete a sub-maximal exercise set at 60% of their VO2max 3 hours after breakfast. And the third session will consist in the realisation of exercise on fast state. Those three sessions will be realized in a randomized order. Several blood (catheter) and salivary samples will be collected during the three sessions, throughout the experimental day.
|Clermont-Ferrand, France, 63003|
|Principal Investigator:||Martine DUCLOS, Pr||University Hospital, Clermont-Ferrand|