Carbohydrates Lab Report

Introduction: When the body exercises, it uses two types of fuel, carbohydrates, and fatty acids. At the beginning of exercise the main source of fuel is carbohydrates, however the duration of the exercise progresses the carbohydrates deplete and fatty acids are needed to maintain the exercise. The type of fuel being used can be seen in the ratio called, respiratory exchange rate, or RER. An RER of 0.7 means that carbohydrates are being used for fuel, and a ratio of 1.0 means that only fatty acids are being used for fuel; of course, values can fall between. Methods: To observe the effects of prolonged exercise on the metabolic system the lab subject needed to walk on the treadmill at a rate that kept his heart rate at 60% of his maximum. The
The subjects respiratory and metabolic data was collected through the respiratory mask and heart rate monitor. Results: See figure 1, and table 1. Discussion: The human body breaks carbohydrates down into monosaccharides which are mainly absorbed into the blood as glucose. As stated previously, carbohydrates are an essential fuel source for skeletal tissue, as well as the brain. The brain solely functions of the use of glucose, making it an essential fuel. In addition to breaking carbohydrates down to attain glucose, the liver can also create it through a process called gluconeogenesis. Despite having multiple was to get glucose the body still needs to produce an alternative form of energy for when glucose gets depleted, that alternate form is triglycerides, or fatty acids. These are key because unlike glycogen, there is no limit to how much fatty acids can be stored in the body. Eventually over a period of time the glycogen will be depleted and no longer be a sufficient fuel, so the fatty acids take over. Fatty acids cannot travel through the blood alone because they are hydrophobic, thus in order to travel through the blood and be circulated to the muscles in need they must bind to a hydrophilic protein, called
This phenomena can be seen in figure 1, as the subject began to exercise the RER level rose to nearly one but dramatically dropped to 0.75 soon thereafter. After this drop, the RER then rose to 0.90-0.95, where it then fluctuated around 0.85-0.95 constantly. This rise and constant maintaining of a RER close to 1.0 depicts the body switching to fatty acids as fuel. A ratio of 0.83 represents the equal use of both carbohydrates and fatty acids, the minima of the graph are closer to equal use, while the maxima represent a fatty acid reliant body. As time progressed the subjects body followed a constant pattern of carbohydrate/ fatty acid fluctuation; which can be seen in figure 1. In table two it is less evident the subject ever used carbohydrates as fuel because of the time ranges of the table. However, it does accurately depict the RER of the later time frames, in which the subject was using mostly fatty acids as fuel. Conclusion: Prior to the experiment the hypothesis formulated was that over a period of prolonged exercise the RER of the subject would