Methods
The study is conducted in TWO separate: Part I, on (Earth) and Part II, on Earth and in Space on the International Space Station (ISS). PART I is completed TWO months prior the launch (February 2002), in Star City, while PART II is started 1 week prior to the launch, and continues for the 10 days of space flight, on-board the Soyuz capsule and ISS.
EXPERIMENTAL PROTOCOL FOR PART 2, ENERGY EXPENDITURE IN MICROGRAVITY.
Part 1 will be completed two months prior to the launch, in February 2002. Mark will be tested over a period of 10 days. During this time, he will perform an energy expenditure calibration test to determine his individual heart rate energy expenditure relationship, using a portable K4B2 Cosmed gas analyser and telemetric heart rate monitor, conducted in laboratory in Star City. This relationship is determined by measuring heart rate, VO2 (amount of oxygen he consumes in one minute) and VCO2 (amount of carbon dioxide he produces in one minute) simultaneously for 7 to 8 workloads of increasing intensity. Energy expenditure (measured in kilojoules (kJ) or kilocalories (kcal)) is determined for each workload, using the equations of Weir. In the first 3 stages of the protocol, Mark will be tested in the supine (lying down) resting position, followed by quiet sitting and subsequently standing. Following these resting measurements, he will perform 5 progressive exercises, where he will walk on a treadmill at 3 different speeds, and then finally run at 2 different speeds, each workload increasing his heart rate on average by about 10 beats per minute.
During this initial 10 day period of testing, Mark will have his body composition measured with a mechanical scale and skin calipers, to determine his body fat percentage. He will also have his resting metabolic rate measured for a 30 minute period, very early in the morning, with the portable K4B2 Cosmed gas analyzer.
Mark will consume a pre-weighted dose of Doubly labeled water (DLW). DLW is a stable isotope. A stable isotope of water is essentially water as we know it, but with extra ions, attached to the hydrogen and oxygen atoms, forming the molecule of water. Just prior to the consumption of the water, Mark will give his first saliva sample, and this will constitute his baseline saliva measurement. The saliva sample is collected using a dried dental cotton wool swab. Mark will place the swab in his mouth for at least 2 minutes, during which time he should “chew” on it, to ensure that it is filled with saliva. Mark will then consume the DLW dose, in the evening. 12 Hours after Mark consumed the DLW dose, he will collect his second saliva sample. During the next 10 days, saliva will be collected on Days 1, 3, 7 and 10. Initially the first sample is collected 12 hours after the dosing, to allow for the stable isotope to equilibrate with the body’s own water. Mark will collect the saliva samples in the early morning, immediately after his daily sleep period and immediately prior to any consumption of food or fluid.
During the 10 day period, accurate time recordings of all samples will be made in a logbook. In addition, Mark will need to keep accurate food, fluid and physical activity records.
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