PSL 303 Advanced Human Physiology Energy Physiology Overview

Greg D. Wells, Ph.D.

The University of Toronto www.per4m.ca

All Slides © Greg D. Wells, Ph.D. (2009), All Rights Reserved Web: www.per4m.ca Email: greg.wells@utoronto.ca Tel: 416-710-4618

2

Class Agenda

•  Neuromuscular Review •  Energy Systems Overview •  Aerobic Metabolism and Training •  Anaerobic Metabolism and Training •  High Energy Phosphate Metabolism and Training

3

Neuro-Muscular Review

4

Neuro-Muscular Review

5

Neuro-Muscular Review

6

ATP: The Muscle’s Energy Source

7

ATP: Sources via nutrition

•  ATP is provided via: –  Initial intra-muscular stores of ATP & PCr – Anaerobic breakdown of glycogen & glucose (CHO’s) – Aerobic oxidation of fats & carbohydrates

8

Energy Systems Overview

•  3 Energy Systems – Aerobic – Anaerobic – High Energy Phosphate

•  Purpose: To supply sufficient ATP at the rate that is required to perform the event.

9

Energy Systems Overview

•  3 Energy Systems – Aerobic Slow – Anaerobic Medium – High Energy Phosphate Fast

•  Purpose: To supply sufficient ATP at the rate that is required to perform the event.

10

Energy Systems Overview

•  3 Energy Systems – Aerobic Slow Long

– Anaerobic Medium Medium – High Energy Phosphate Fast Short

•  Purpose: To supply sufficient ATP at the rate that is required to perform the event.

12

Ener

gy/P

ower

Out

put

Time 10 s 30 s 60 s 3 min 15 min+

Low power Very high capacity Time to peak power (~180s) Peak power (~3 – 5min) Power capacity (extensive / hours)

© S. Esau, University of Calgary

Energy Systems: Aerobic Oxidative

Krebs Cycle

32 ATP

Mitochondria

Aerobic Oxidation

Blood (capillaries)

Blood Glucose

Glycogenolysis / Gluconeogenesis

4 ATP

Anaerobic Glycolysis

Pyruvate

Lactic Acid Acetyl-CoA

ATPase

Creatine Kinase

Muscle (myofibres)

Fat Metabolism &

ß-Oxidation Protein Metabolism

© Greg D. Wells, Ph.D. (2008)

Ener

gy/P

ower

Out

put

Time 10 s 30 s 60 s 3 min 15 min+

High Power Limited Capacity Time to peak power (~8s) Peak power (~40 – 70s) Power capacity (~90 – 120s)

© S. Esau, University of Calgary

Energy Systems: Anaerobic Glycolytic

Krebs Cycle

32 ATP

Mitochondria

Aerobic Oxidation

Blood (capillaries)

Blood Glucose

Glycogenolysis / Gluconeogenesis

4 ATP

Anaerobic Glycolysis

Pyruvate

Lactic Acid Acetyl-CoA

ATPase

Creatine Kinase

Muscle (myofibres)

Fat Metabolism &

ß-Oxidation Protein Metabolism

Anaerobic Glycolysis

Fibre Utilisation as a Function of Intensity

© Greg D. Wells, Ph.D. (2008)

© Greg D. Wells, Ph.D. (2008) Web: www.per4m.ca Email: greg@per4m.ca Tel: 416-710-4618

Lactate vs. Ventilation

Ener

gy/P

ower

Out

put

Time

ATP-CP

10 s 30 s 60 s 3 min 15 min+

Very high power Very low capacity Time to peak power (ms) Peak power & capacity (~7 – 10s?)

© S. Esau, University of Calgary

Energy Systems: High Energy Phosphate

Krebs Cycle

32 ATP

Mitochondria

Aerobic Oxidation

Blood (capillaries)

Blood Glucose

Glycogenolysis / Gluconeogenesis

4 ATP

Anaerobic Glycolysis

Pyruvate

Lactic Acid Acetyl-CoA

ATPase

Creatine Kinase

Muscle (myofibres)

Fat Metabolism &

ß-Oxidation Protein Metabolism

Sport Science Application

•  Monitoring of ATP / PCr depletion by cycle rate (strokes or cycles or strides / min)

Canada 4 x 100 m Relay 1996

© Greg D. Wells, Ph.D. (2008)

© Greg D. Wells, Ph.D. (2008)

© Greg D. Wells, Ph.D. (2008)

Pi

pH

PCr ATPy ATPa ATPb

MRI & MRS Results at Rest

At Rest After Exercise

4.3*105 2.9*105

1.2*105

0.4*105

pH: 7.15 pH: 6.75

© Greg D. Wells, Ph.D. (2008)

CP Metabolism

16-32 mmol /kg stored PCr (CP)

ATP Metabolism

7-10 kcal / mol ATP

4-8 mmol /kg of stored ATP

© Greg D. Wells, Ph.D. (2008) Web: www.per4m.ca Email: greg@per4m.ca Tel: 416-710-4618

ATP &Pcr Recovery Time

During chemiosmosis in eukaryotes, H+ ions are pumped across an organelle membrane into a confined space (bounded by membranes) that contains numerous hydrogen ions. The energy for the pumping comes from the coupled oxidation-reduction reactions in the electron transport chain. Electrons are passed from one membrane-bound enzyme to another, losing some energy with each transfer (as per the second law of thermodynamics). This "lost" energy allows for the pumping of hydrogen ions against the concentration gradient (there are fewer hydrogen ions outside the confined space than there are inside the confined space). The confined hydrogen cannot pass back through the membrane. Their only exit is through the ATP synthesizing enzyme that is located in the confining membrane. As the hydrogen passes through the ATP synthesizing enzyme, energy from the enzyme is used to attach a third phosphate to ADP, converting it to ATP.

30

Characteristic High energy phosphate Anaerobic glycolytic Aerobic oxidative Fuel source(s) stored ATP,

phosphocreatine (PCr) stored glycogen, blood

glucose glycogen, glucose, fats,

proteins Enzyme sytem used in breakdown

ATPase HK, PFK, LDH, PDH, others

CS, MDH, SDH, others

Muscle fibre type(s) recruited

Type I, Type IIa, Type IIb

Type I, Type IIa, Type IIb

Type I, Type IIa

Power output requirement

high moderate - high low - moderate

Metbolic byproducts ADP, P, Cr lactic acid CO2, H2O maximum rate of ATP production (mmol/min)

3.6 1.6 1

Time to maximal ATP production

1 sec 5-10 sec 2-3 min

Maintenance time of maximal ATP production

6-10 sec 20-30 sec 3 min

Time to exhaustion of system

12-15 sec 45-90 sec theoretically unlimited

Ultimate limiting factor(s)

Depletion of ATP / PCr stores

Lactic acid accumulation

Depletion of carbohydrate stores, insufficient oxygen, heat accumulation

Time for total recovery (sec)

3 min 1-2 hr 30-60 min

Time for one half recovery (sec)

20-30 sec 15-20 min 5-10 min

Relative % ATP contribution to efforts of 10 sec

50 35 15

Relative % ATP contribution to efforts of 30 sec

15 65 20

Relative % ATP contribution to efforts of 2 min

4 46 50

Relative % ATP contribution to efforts of 10 min

1 9 90