Metabolic Adaptations

Metabolic Adaptations


Metabolic Adaptations to Training

RER decreases at submax - ↑ use of fats, spares CHO

Lactate threshold

– ↑ to a higher % of VO2max

– ↑ clearance and/or ↓ production of lactate

– Higher intensity without accumulation of lactate → good!

Oxygen consumption (VO2)

– Unchanged (or slightly reduced) at submax ex – VO2max increases

– Limited by ability of CV system to deliver O2

• RestingandsubmaximalV•O2

– Resting V• O2 unchanged with training

– Submaximal V• O2 unchanged or  slightly with training

• MaximalV•O2(V•O2max)

– Best indicator of cardiorespiratory fitness –substantially with training (15%-20%) –due to cardiac output and capillary density

Changes in VO2 Max with training

• Long-term •

– Highest possible VO2max achieved after 12 -18 months

– Performance still after V• O2max plateaus • Due to lactate threshold

• Individual Responses Affected By – Training status & pre training V• O2max – Heredity

  • Level of conditioning: Less fit will have larger increase than more fit

  • Heredity: Accounts for 25-50% of the variation inVO2max

  • Sex: Generally lower in women than men

  • Individual responsiveness: High responders and low responders, determined by genetics


  • Training status and pretraining V• O2max
    – Relative improvement dependent on fitness – More sedentary individual: greater
    – More fit individual: smaller 

  • Heredity •
    – Finite VO2max range determined by genetics
    • • V• O2max altered within that range by training
    – VO2max more similar for identical than fraternal twins – 25%-50% of V• O2max variance due to heredity

Key Points

  • VO2max has upper limit but performance still ↑

  • Genetics predetermines VO2max & accounts for 25-50% • Heredity largely explains response to training of the variance

  • Highly conditioned females have VO2max values about 10% lower than male counterparts

Adaptations to Anaerobic Training

• Muscle:

  • Increased fiber recruitment

  • Increased cross-sectional area of type IIa and type IIx fibers (FT fibers)

• Energy Systems:

  • • ATP-PCr

    • Little change in enzyme activity (Creatine Kinase (CK))

    • • Specific training increases strength, which enhances performance

  • • Glycolysis

    • • Increased activity of key glycolytic enzymes (phosphorylase, phosphofructokinase (PFK), lactate dehydrogenase (LDH))

    • • Performance gains mostly from strength gains

Key Points

  • Anaerobic training bouts improve both anaerobic power and anaerobic capacity (i.e., performance on Wingate test)

  • Increased performance with anaerobic training is attributed to strength gains