Athletic Performance and Muscle Biochemistry

'Shirvo' versus 'Deek'

  • AGRC2001 is the course code.

Human Running Performance

  • Links to YouTube videos are provided:
    • https://www.youtube.com/watch?v=3nbjhpcZ9g
    • https://www.youtube.com/watch?v=NMJRDVOys-c

'Run for Form' - Pat Clohessy

  • Patrick Andrew "Pat" Clohessy AM (born 16 May 1933) is an Australian runner and distance running coach.
  • He grew up in Muswellbrook and Tamworth, New South Wales.
  • His father worked as a postmaster.
  • Clohessy started running in 1953 with the Muswellbrook Athletics Club.
  • In 1954, he won the New South Wales Country Championships in the 880 yards and one-mile events.
  • He moved to Sydney to run for Randwick Botany Athletics Club.
  • He studied and lectured at the University of Houston.
  • He encouraged Allan Lawrence to study at the University of Houston, who later won the 5000m at the 1960 NCAA Championship.
  • Notable performances as an athlete:
    • Won the 3 Miles NCAA Championship in 1961 (Philadelphia in 13:47.7) and 1962 (Eugene in 13:51.6).
    • Won the Amateur Athletic Union 3 miles in 1963.
    • 7th in the 3 Miles at the 1962 British Empire and Commonwealth Games.
    • 3rd World Games in Helsinki in 1963.
  • Coaching career:
    • After returning to Australia, he became a teacher and athletics coach at Xavier College in Melbourne.
    • He coached Robert de Castella, who won the marathon at the 1982 and 1986 Commonwealth Games and the 1983 World Championships in Athletics.
    • In 1983, he became the distance running coach at the Australian Institute of Sport (AIS) until 1994.
    • He then took up an Athletics Australia coaching position in Brisbane, Queensland.

Nature and Nurture

  • The quote "Sprinters are born, but endurance runners are made" is discussed.
  • The discussion includes whether this statement is true and how it might be stated more formally or scientifically.

Wildlife Athletes

  • The lecture discusses wildlife species that represent sprint and endurance adaptations.
  • Examples from mammals, birds, fish, insects, reptiles, and amphibians are considered.

Questions

  • How does athletic performance relate to the biochemistry of the sarcomere?
  • What anatomical, physiological, and biochemical features distinguish sprinters from endurance athletes?

ATP Supply to Support Muscle Contraction

  • Comparing a 100m sprint (~10 seconds) and a marathon (~2 hours).
  • What is the total ATP requirement for each?
  • What is the rate at which that ATP requirement must be met?
  • How does the difference in demand inform the metabolic support required?
  • In all cases, the metabolic support is driving ADP + P \rightarrow ATP

ATP Production Rate and Athletic Gears

  • Immediate/very rapid/rapid ATP supply (ANAEROBIC).
  • Slow ATP supply (AEROBIC).

Metabolic Map

  • The pathway transforming glucose to pyruvate is glycolysis.
  • Glycolysis occurs constitutively, irrespective of whether the system is aerobic or anaerobic.
  • Under most circumstances, the system is aerobic, and pyruvate is channeled into the mitochondrion.
  • If the system is anaerobic (e.g., skeletal muscle max. power output, such as sprinting), the pyruvate is subject to reduction in the cytosol, forming lactic acid.

Muscle Fiber Types

  • Why are some fibers redder than others?
  • Why are some fibers larger than others?
  • What other features are associated with red fibers?

Muscle Hierarchical Structure

  • The structure is bone \rightarrow tendon \rightarrow connective tissue \rightarrow muscle.
  • Muscle: sarcolemma (muscle fiber membrane) containing muscle fiber bundles.
  • Muscle fiber: Contains myofibrils.
  • Myofibrils: Contain myofilaments.
  • Components include muscle nerve fiber, blood vessels, and nucleus.
  • Sarcoplasmic reticulum is also present.

The Sarcomere

  • The sarcomere is the basic unit of muscle contraction.
  • Z line defines the boundaries of a sarcomere.
  • H zone is the region in the center of the A band that contains only thick filaments.
  • M line is in the middle of the H zone, holding thick filaments in place.
  • I band contains only thin filaments.
  • Thick filaments: Primarily myosin.
  • Thin filaments: Primarily actin.

Myosin and Actin Isoforms

  • Fast Fiber:
    • Myosin, actin, and related contractile subunits/ATP handling: MYL1, TPM1, TNNT1 high.
    • Calcium cycling machinery/release of contraction: ATP2A1 highly expressed.
    • Mitochondrial content/Electron transport chain proteins: low (e.g., NADH subunits).
    • Myoglobin: Mb expression low.
    • Glycolytic proteins: GAPDH high.
    • Capillarity: TEK low.
    • Fuel use and fuel storage: Creatine kinase, Glycogen phosphorylase high.
  • Slow Fiber:
    • Myosin, actin, and related contractile subunits/ATP handling: MYL2, MYL3, TPM3, TNNT2 high.
    • Calcium cycling machinery/release of contraction: ATP2A2 highly expressed.
    • Mitochondrial content/Electron transport chain proteins: high (e.g., NADH subunits).
    • Myoglobin: Mb expression high.
    • Glycolytic proteins: GAPDH low.
    • Capillarity: TEK high.
    • Fuel use and fuel storage: Creatine kinase, Glycogen phosphorylase low.

Tissue-Specific Expression Patterns

  • Using the BioGPS webtool, search for ‘MYL3’.
  • Characterize the expression pattern across tissues.
  • Given the very high expression in cardiac muscle, what implication does this have for the type of muscle fiber using this contractile isoform?

Production Species and Muscle Phenotype

  • Comparison of muscle phenotypes in different production species.
  • Examples include middle distance running, sprint, and long-distance running phenotypes.

Production Species Cont.

  • Broiler strains at 55 days of age are compared across different years (1957, 1977, Modern Broiler).

Why are Modern Production Species Transitioning to Type IIB Muscle Fibres

  • Type IIB fibers are large and have a low mitochondrial content.
  • Possible implications for:
    • Muscle mass
    • Feed efficiency
    • Meat quality (postmortem metabolism)