EXERCISE PHYSIOLOGY FOR THE PRACTICING CLINICIAN Ray F. Moss, Ph.D. Professor Health Sciences Furman University Director of Molnar Human Performance Laboratory

Years of Training %Performance Capacity VO 2MAX 100% Lactate Threshold Running Economy Components Of Running Performance

Cash Currency for Performance ATP used CP reforming ATP Eventually all paid for aerobically

PCr Shuttle PCr + ADP ATP + Cr ATP ADP CPK mitochondria sarcoplasm PCr Cr CPK ADP ATP ATPase Sarcomere Major Regulators of Cell Metabolism

MAXIMUM OXYGEN UPTAKE (VO 2Max )

Maximal Oxygen Uptake Maximal amount of oxygen that can be consumed during physical activity at sea level VO 2 = Cardiac Output x arterial – venous O 2 Endurance athletes have VO 2Max levels as high as 94 mlO 2 /kg/min for 76 kg athlete 212 b/min x 200 ml/beat x 20 Vol% - 3 Vol% = 7.2 L/min Average 25 year old male has VO 2Max of 42 mlO 2 /kg/min

Contributing Factors Very large stroke volumes Over 200 ml/beat (42 L/min) Increased blood volume Increased capillarization of skeletal muscle Increase myoglobin All of these permit greater delivery of O 2 to skeletal muscle to generate ATP

Maximal Oxygen Consumption VO 2MAX Increasing Workload Oxygen Uptake in ml/min VO 2Max Heart Rate beats/min

Generating ATP

Mitochondria and Training Increases in Number/size of mitochondria May actually be a reticulum Density of mitochondria More protein per volume This reduces the “strain” on mitochondria during heavy exercise Mitochondria greater capacity to produce ATP

Adaptability / Trainability Fat(%) CHO(%) Aerobic Power (%) 0 ( Rest ) (Max) Untrained “Cross-Over” FAT CH O 1-mile Pace (min/mile) (Max) Trained “Cross-over”

LACTATE THRESHOLD

Lactate Threshold (LT) When the body’s requirements of O 2, surpass the body’s ability to deliver that O 2, there begins a rapid rise in blood lactate Considered to be best predictor of endurance performance LT in untrained occurs about 50% of VO 2Max LT in trained occurs as high as 90% of VO 2Max

Determination Of Lactate Threshold Lactate Running Velocity Lactate Threshold Lactate Increase by 1 mM from previous stage Sample blood after every 4 minute stage of work

% VO 2MAX Lactate Untrained Trained Lactate Threshold in Trained and Untrained Runners LT

Lactate Appearance (mg/kg min -1 VO 2 (L/min) Lactate Appearance During Exercise Pre-Training Post-Training Brooks et al 2000

Lactate Clearance (mg/kgmin -1 ) Lactate (mM) Pre-Training Post-Training Lactate Clearance During Exercise Brooks et al 2000

Lactate Shuttle Systems

Lactate Mono Carboxylate Transport Protein Lactate Oxidized Inside Mitochondrion

PERFORMANCE ECONOMY

Running Economy And Performance Defined as the Cost of Running a Particular Pace Improving Economy Decreases the Cost of Running There are Many Areas in which to Improve Running Economy a. Biomechanically b. Metabolically c. Psychologically

Why Does It Take 10 + Years To Improve Economy? 1.Sarcoplasmic Reticulum and Associated Pumps 2.Sarcolemmal Transport Protein Carriers a. Sodium Pump b. Monocarboxilic Transport Protein 3. Glucose Receptor Density a. Glut 4 Receptors 4. Mitochondrial Matrix/Membrane Proteins 5. Biomechanics of Stride Rate/Length a. Stretch-Shortening Cycle of Connective Tissue 6. Heat Shock Prevention of Glycolytic and Oxidative Metabolic Enzymes

Increase in Glut 4 Receptors; Skeletal and Adipose Tissue

Questions? Ha, Ha, Ha