It reflects that aerobic metabolism needs to be supplemented

It reflects that aerobic metabolism needs to be supplemented with anaerobic metabolism to meet increasing energy demands It reflects the point at which lactic acid production exceeds the body\'s ability to recycle lactate during exercise It will be higher in PCr trained persons It reflects the point at which the fuel being burned switched from predominantly carbohydrates to predominantly lipids If no O2 is present, an NAD that picked up hydrogens from glycolysis will yield how many ATP from the electron transport chain? 1.5 ATP 2 ATP 2.5 ATP none Major causes of fatigue are: inadequate energy delivery/metabolism Accumulation of metabolic by-products Failure of muscle contractile mechanism Altered neural control of muscle contraction All of the above True or False. The RER measured from gases expired from the lungs will reflect the RQ measured at the muscle level at exercise intensities above the L.T True or False. The volume of inspired gas = the volume of expired gas. During muscle contraction, the binding of ATP to the myosin head causes which one of the following to happen: Recocking of the head to a higher energy position The power stroke Breaking of the actin-myosin crossbridge Breaking of the actin-troponin bond Neural factors associated with strength gains do NOT include: uparrow synchronization of motor units uparrow motor unit recruitment uparrow coactivation of agonist and antagonist muscles downarrow inhibition by golgi tendon organs Aerobic training is NOT associated with which of the following: uparrow cross-sectional area of Type I fibers capillary to fiber ratio uparrow myoglobin in type 1 fibers downarrow in lactate threshold workload downarrow RER for a given submaximal workload

Solution

Following are the answers with explanations to the given multiple choice questions:

24. d) None

NAD⁺ is an electron carrier molecule and accepts two electrons and a hydrogen ion when any metabolite of the glucose metabolism process is oxidized.

NAD⁺ ------> NADH + H⁺

The electrons received by NAD⁺ are high energy electrons which are carried to the electron transport chain for the production of ATP. But in the absence of oxygen, the electron transport chain is not carried out and the cell utilizes anaerobic pathway to generate energy.

25. e) All of the above

Muscle fatigue is caused when the muscles are unable to generate the desired force to carry out work. It may be neural fatigue when the nerves are unable to generate a sustained signal. It may be also be a metabolic fatigue when the muscles fibers are not able to contract. This is due to lack of oxygen supply and hence anaerobic respiration, leading to accumulation of metabolic by-products and lack of energy.

26. False

The respiratory exchange ratio (RER) is only correlated to the respiratory quotient (RQ) at steady state or during moderate exercise within the lactate threshold (LT).

27. False

The volume of inspired gas is not equal to the volume of expired gas as other respiratory parameters are involved.

28. c) Breaking of the actin-myosin cross-bridge

ATP binds to myosin twice. Firstly ATP binding moves the myosin to a higher energy state. Upon hydrolysis of ATP, the myosin head attains a cocked position. Then after the formation of actin-myosin cross bridge, the ATP bind and breaks the cross-bridge.

29. c) (Increase) Coactivation of agonist and antagonist muscle

Such increase in coactivation leads to reduction in strength gain.

30. a) increase in cross-sectional area of type 1 fibers

Aerobic training exercises results in increase in cross-sectional area of type II muscle fibers.