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$$$ \rightarrow $$ 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$$$ \rightarrow $$ tendon $\rightarrow$$$ \rightarrow $$ connective tissue $\rightarrow$$$ \rightarrow $$ 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)