If reflects that aerobic metabolism needs to be supplemented with anaerobic metabolism to meet increasing energy demands  If reflects the point at which tactic 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 O_2 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 LT.  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:  Recording 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  synchronization of motor units  motor unit recruitment  coactivation of agonist and antagonist muscles  inhibition by golgi tendon organs  Aerobic training is NOT associated with which of the following:  cross-sectional area of Type I fibers  capillary to fiber ratio  myoglobin in type I fibers  in lactate threshold  RER for a given submaximal workload
24. C. 2.5
 25. B. Accumulation of metabolic by products.
 Accumulation of metabolic by product (lactic acid) produced during anaerobic respiration in muscle cells cause fatigue.
 26. TRUE.
 The respiratory exchange ratio (RER) is the ratio between the amount of carbon dioxide (CO2) produced in metabolism and oxygen (O2) used. The ratio is determined by comparing exhaled gases to room air. Measuring this ratio can be used for estimating the respiratory quotient (RQ). Calculation of RER is commonly done in conjunction with exercise tests.
 27. True
 Volume of inspired or expired air in a normal effortless breath is called as tidal volume. It accounts for about 500 mL.
 28. C. Breaking the actin myosin cross bridge.
 The binding of ATP to a myosin head detaches myosin from actin, thereby allowing myosin to bind to another actin molecule.