Term
| At low intensity exercise (25% of VO2Max) from where does energy predominanty come? |
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Definition
| FFAs from adipose tissue. (85%) |
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Term
| At low intensity exercise, (25% VO2Max) what hormone has prodominating control? |
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Definition
| Insulin. It spares CBHY use and forces lipid use. |
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Term
| At low intensity exercise (25%VO2Max) There is a low level increase in epinephrine, that has some effects. What are they? (2) |
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Definition
| Stimulates lipolysis, stimulates uptake of FFA in working muscle, but it has no effect of vasomotor tone. |
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Term
| What effect does type one muscle use have on lipid breakdown? Why? |
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Definition
| Type 1 has a high oxidative capacity, which helps w/ fat breakdown. |
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Term
| At low intensity exercise (25%VO2Max) how does circulation distribution impact lipid use? |
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Definition
| Circulation goes through adipose tissue at low intensity exercise, which helps transport FFAs from adipose to working muscle. |
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Term
| What happens to the distribution of circulation as exercise intensity increases from low to high? |
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Definition
| Circulation gets drawn away from non-essential areas of the body, which decreases circulation to adipose tissue which makes it harder to mobilize the FFAs from adipose to muscle. |
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Term
| What is the “Feed-Forward” Mechanism to control glycemia? |
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Definition
| increased epinephrine --> increased hepatic glucose production --> increased glucose release from the liver àIncreased plasma glucose. Also, decreased insulin release --> increased effect of glucagon. |
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Term
| Why does plasma glucose increase at the beginning of moderate intensity (60% VO2 Max)? |
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Definition
| Because the increased sympathetic output led to increased epinephrine, which led to an increase in hepatic glucose production and a decreased insulin release. |
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Term
| What substrate do we use primarily during high intensity (80% VO2Max)? |
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Definition
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Term
| Why is there an increased use in intramuscular stores during high intensity exercise? |
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Definition
| Because it’s faster – they’re more readily available. |
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Term
| What is the ratio of fat to carbohydrate use in high intensity exercise? |
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Definition
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Term
| How is the use of FFAs limited in high intensity (80%VO2 Max) exercise? (2 major ways) |
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Definition
| Vasoconstriction mediated by catacholamines (diverts blood flow from non-essential to essential areas) and Lactic acidosis also inhibits FFA use. |
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Term
| What type of muscles are preferentially recruited at more than 85% VO2 Max? |
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Definition
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Term
| What are some of the major properties of type 2b muscle fibers? (6) |
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Definition
| 1.They’re preferentially recruited at >85% VO2 Max, 2. They have a lot of glycolytic enzymes, 3. They have high glycogen and low lipid stores, 4. They are insensitive to insulin and catecholamines, 5. They have low capillary density (so they have low blood slupply and are laregely anaerobic., 6. They fatigue rapidly. |
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Term
| How do catacholamine levels compare from rest to the levels at high intensity exercise? |
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Definition
| They increase exponentially, and are 20xs higher at H.I. exercise than at rest. |
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Term
| Do catecholamines stimulate muscle glycogenolysis? |
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Definition
| No. They lead to liver glycogenolysis. |
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Term
| What role do catecholamines play in high intensity exercise? |
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Definition
| They increase vasodilation to type 2 fibers secondary to lactic acidosis. |
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Term
| What is the relationship between epinephrine, insulin and blood glucose as exercise duration increases? |
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Definition
| Epi increases, insulin decreases, blood glucose increases. |
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Term
| What happens to plasma lactate levels as exercise intensity increases? |
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Definition
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Term
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Definition
| The point at which exercise intensity and blood lactate levels no longer have a linear relationship due to an exponential increase in blood lactate levels. |
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Term
| What is the difference in lactate threshold in the untrained vs. the trained individual? |
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Definition
| The untrained individual will reach lactate threshold at about 50-60% VO2Max. The trained individual doesn’t reach their lactate threshold until 65-85% VO2Max. |
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Term
| Why is a later lactate threshold preferable in the edurance athlete? |
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Definition
| Because an increased L.T. delays carb use, which is better for the endurance athlete b/c energy stores will last longer. |
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Term
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Definition
| Onset of blood lactate accumulation |
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Term
| Does increased production of lactate mean that there is not enough O2 present in the system? |
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Definition
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Term
| In what ways can lactate levels increase that are not related to O2? (3 major) |
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Definition
1.
If more NADH is made than can be used, it combines w/ pyruvate to make lactic acid. 2. At high intensity exercise we use more type 2b fibers, which are largely anaerobic and depend on glycolysis for energy which leads to increased lacate production. 3. During exercise, circulation doesn’t support the removal of lactate, so removal is slower which leads to increased lactate levels because it’s not being cleared away effectively. |
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Term
| What are the effects of training on the neuroendocrine system? (3major) Why do these happen? |
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Definition
| 1.1. decreased hormone release at a given workload (because exercise has become less stressful, so lower leevels or hormones are triggered). 2. Plasma glucose is more stable (due to increased lactate threshold, decreased O2 deficit). 3. Increased epi release at extreme exercise which leads to increased hepatic glucose production. |
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