Term
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Definition
| The process of quantifying energy production by measuring the body's heat production first described by Zuntz and Hagemann in the late 1800s. This process involves keeping a person in a chamber on a treadmill where their changes in body temperature will alter the temperature of the air in the chamber, as well as the water running through a series of tubes within. They are slow to generate results and cannot follow rapid changes in energy expenditure, but they measure heat directly and accurately measure total body energy. The heat from the treadmill, stored heat that the body retains, and sweat cooling the body all lead to inaccuracies. Best for studying resting metabolism. |
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Term
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Definition
| The method of estimating total body energy expenditure by measuring the respiratory exchange of O2 (taken in) and CO2 (expelled) in the body. Relies on oxidative expenditure, so subjects must be in a steady state of aerobic activity to gain an accurate reading, which closely simulates daily activities and exercise. Uses the difference between O2 and CO2 concentration to determine oxygen capacity and CO2 production. Using a Douglas bag to collect expired air and chemically analyzing gas samples is the most accurate version of the test, but is slow and can only provide a few measurements per session. Modern electronic methods make rapid and repeated measurements. Are only accurate in a resting state or during steady-state exercise. |
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Term
| Respiratory Exchange Ratio (RER) |
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Definition
| The ratio between the rate of CO2 released (VCO2) and oxygen consumed (VO2). The value can vary depending on the type of fuel being used. For example, FFA's have more carbon and hydrogen than glucose, but with less oxygen. It ultimately determines the amount of fuel being used by how high or low the RER is. |
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Term
| Basal metabolic rate (BMR) |
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Definition
| A standardized measure of energy expenditure at rest. Measured in a supine position in a thermoneutral environment immediately after 8 hours of sleep and 12 hours of fasting. The value determined is the minimum amount of energy to carry out essential physiological functions and is generally higher if the body surface area and fat-free mass are high. |
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Term
| Resting metabolic rate (RMR) |
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Definition
| An alternate measurement of metabolism that does not require the standardized conditions of a true BMR. While not as accurate, the RMR typically falls within 5% to 10% of the BMR with the BMR slightly lower. |
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Term
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Definition
| The maximal limit of a person's ability to increase their VO2. It is considered the single best measurement of cardiorespiratory endurance or aerobic fitness. Will increase after about 8-12 weeks of training before plateauing, but some continue to improve by developing the ability to perform at a higher percentage of their VO2MAX. |
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Term
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Definition
| The highest oxygen uptake achieved for when subjects get fatigued before reaching their VO2max. |
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Term
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Definition
| A deficit accrued at the start of exercise. When a workout begins, the body takes time to channel enough oxygen to meet its new requirements. During this period where the body isn't receiving enough oxygen for its state during exercise, this is where the oxygen deficit builds up. |
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Term
| EPOC (Excess Postexercise Oxygen Consumption) |
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Definition
| The excess postexercise oxygen consumption. This is the state immediately after exercise where the body continues to generate an increased amount of O2 intake and CO2 expulsion despite it returning to a resting or low activity state. It was initially believed to be responsible for rebuilding ATP and phosphocreatine used up during the initial stages of exercise, but more recent theories believe that it's also responsible for replenishing oxygen stores in hemoglobin and myoglobin, clearing accumulated CO2 in the tissues and bringing in more oxygen to keep up with elevated body temperature. |
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Term
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Definition
| The point at which blood lactate begins to substantially accumulate above resting concentrations during exercise of increasing intensity. It is measured by taking a blood sample at various points of exercise to measure blood lactate to find the relationship between exercise and blood lactate. Perhaps best defined as the point in time during exercise of increasing intensity where the rate of lactate production exceeds the rate of lactate clearance. |
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