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ID: 227013 • Letter: P
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point until time has expired. The timer wil oontinue to run if you leave Completion Enter your password tor Remaining Time: 3 hours,24 minutes, o9 seconds. Question Completion Status: A Moving to another question will save this response. Question 20 of 62 Question 20 1.5 points save A Reducing the number of motor units required to perform an exercise task may reduce the heart rate and ventilation required to perform the task. O True O False A Moving to another question will save this response. Question 20 of 62
Explanation / Answer
20.A motor unit is defined as a motor neuron and all of the skeletal muscle fibers (cells) that it innervates. A great number of motor units are engaged, when the body is in need of movement such as during sprinting. As a result of this, there is a greater number of skeletal muscle fibers activated to contract. This phenomenon is referred to as motor unit recruitment. In response to exercise, heart rate will rise in a predictable manner. The speed of the heart rate will increase in proportion to the increasing workload.
The correct answer choice for this question is therefore, True i.e. reducing the number of motor units required to perform an exercise task will reduce the heart rate and ventilation required to perform the task.
22. Detraining refers to the loss of physiological adaptations that occurs with complete cessation of training or reduction in the volume and intensity of training. This is comonly observed post endurance or resistance training. After periods of detraining as long as 30 weeks, results in significant reduction in strength from trained values, although it will still be significantly greater than it was before training. 30 weeks of detraining would result in 31% loss of strength. However, it is easier to regain strength and muscle mass once it’s lost because of muscle memory (myonuclei and neural adaptations). Therefore, one can regain most of the strength after 6 weeks of training. Therefore, the correct answer choice is option (D).
23. Intensive exercise like strength training increases blood lactate concentration. During submaximal exercise, oxygen availability is one of the several factors that cause an increase in muscle and blood lactate. In some circumstances, the body requires energy production faster than our bodies can adequately deliver oxygen. The energy required comes from the breakdown of glucose to pyruvate, which is then broken down further aerobically due to plenty supply of oxygen to provide the required energy. However, when oxygen is limited, the body temporarily converts pyruvate into a substance called lactate, which allows glucose breakdown—and thus energy production—to continue. Increased mitochondrial pyruvate oxidation results in lower lactate accumulation. Also, decreased production of pyruvate also results in lower lactate production.
LDH is involved in the reversible reaction of oxidation of lactate to pyruvate and reduction of pyruvate to lactate. LDH-M isoform is more prone to a reduction of pyruvate to lactatewhile LDH-H isoform is more prone to oxidation of lactate to pyruvate. Endurance training results in decrease in LDH-M, so less lactate production will result and LDH-H increases.
Therefore, correct answer is option (A) as utilization of glycogen or glycogenolysis results in increase in lactate production, during exercise.
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