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Neural Activation of Skeletal Muscle

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					Exercise metabolism – wrap up
  1. Validity of VO2 as measure of exercise metabolism
  2. EPOC – caused by lactate clearance?
Exercise metabolism – wrap up
  Validity of VO2 as measure of exercise metabolism

    Assumptions:
    1. All ATP resynthesis must be from respiration
    2. ATP and CP stores are maintained
    3. Protein metabolism is nonexistent
 Exercise
 metabolism
Validity of VO2 as measure of exercise
metabolism

  Assumptions:
         1. All ATP resynthesis must
  be from respiration

  Measurement must be made during
  steady-state submaximal exercise




                                         Brooks et al.
OXYGEN DEFICIT




     Powers and Howley, Exercise Physiology, 2004
Exercise metabolism
      All ATP resynthesis must be from respiration




                          Brooks et al.
Exercise metabolism
Blood lactate
during exercise




                  Seeherman et al., Resp Physiol 44: 11, 1981
O2 Uptake vs Time and Power Output




 Wilmore and Costill, Physiology of Sport and Exercise,Human Kinetics, 2004
Exercise metabolism
                     [LA]
                     mg%
        Error



                Leg LA
                release




           Leg net LA
           exchange




                            Brooks et al.
Exercise metabolism




                      Brooks et al.
Exercise
metabolism




             Brooks et al.
OXYGEN DEFICIT AND EPOC (excess post-
exercise oxygen consumption)




Wilmore and Costill, Physiology of Sport and Exercise,Human Kinetics, 2004
OXYGEN DEFICIT AND EPOC (excess post-
exercise oxygen consumption)


   Is the EPOC caused by need to clear lactate?
Exercise metabolism


                               “alactacid” debt
                               (fast component)

                               “lactacid” debt
                               (slow component)




               Brooks et al.
Exercise     However, the Margaria et al. conclusions
metabolism   resulted from using a relatively high
             intensity exercise




              Brooks et al.
Exercise
metabolism
     Metabolic fate of lactate after exercise
Exercise
metabolism




             Brooks et al.
Exercise
metabolism




             Brooks et al.
Exercise metabolism
       What then is the explanation for the EPOC?
              1. Hyperthermia
                     a. Q10 effect
                     b. Some uncoupling(?)
              2. FFA causing uncoupling (?)
              3. Catecholamines and thyroid hormone
increasing Na+-K+ pump activity
              4. Elevated mitochondrial Ca2+ pumping
              5. Elevated catecholamine stimulation of
metabolism

				
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posted:9/1/2012
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