MACRONUTRIENTS

•These are out direct sources of energy for daily life, physical exercise and work

• consumed in large amounts• There are 3 types:

1. Protein 2. Carbohydrate 3. Fat

PROTEIN• directly involved in fundamental chemical processes of life

• when ingested:

-broken down into 20 amino acids

PROTEIN• directly involved in fundamental chemical processes of life

• when ingested:

-broken down into 20 amino acids

- 9 essential amino acids attained through food (body produces 11 others)

• Complete protein – food that contains all 9 amino acids

- meat, eggs, cheese and milk

• Incomplete protein –foods containing one but not all essential amino acids

- vegetables and fruits

• each gram of protein contains 4 Calories of energy

• for every kilogram of body weight, an adult needs 0.8 grams of protein

• necessary for growth and repair of all tissues, and a critical component of hormones, enzymes and the immune system

FAT• insulate and protect vital organs

• highest energy yield = 9 calories of energy per gram

Saturated

-animal sources

-LDL (low-density lipoproteins)

-high levels LDL increased cholesterol plaque on artery walls heart disease

Unsaturated

-plant sources

- high concentrations of high-density lipoproteins (HDL)

- flushed out of body

CARBOHYDRATE• most accessible energy source for the body is the most abundant organic substance in nature

• GLUCOSE -produced by photosynthesis, stored as GLYCOGEN in human

• each gram yields 4 Calories of energy

If not utilized, becomes fat

• Complex (starch)

-takes body longer to absorb

-80 % of total carb intake

-cereals, fruits, vegetables, legumes and pasta

• Simple (sugars)

-absorb MUCH faster

- refined white sugar, pop, candy, etc

. . .but why is it important that we ingest carbohydrates?

ATP (Adenosine Triphosphate)

- 3 phosphates attached to adenosine

Fritz Albert Lipmann and Herman Kalckar, 1941

ATP ADP + P +ENERGY

The question we will be answering is not how the body uses ATP, but rather how the body goes about resynthesizing ATP.

2 methods for resynthesizing ATP

1. Anaerobic System

-without oxygen

-muscle fibre

-quick; powerful short activities

2. Aerobic System

-with oxygen

-mitochondria

-several complex reactions

-endurance activities

-These systems work together

-coexist and overlap

-all physical activity relies on some combination of these systems

What we are going to examine are the three metabolic pathways that make up these two systems.

• ATP-PC pathway

•Glycolysis

• Cellular Respiration

METABOLISM

ATP-PC System Anaerobic alactic

-first and simplest of the 2 anaerobic pathways

-Short, powerful energy bursts 10-15 seconds

Without O2 No lactic acid

PC + ADP ATP + Creatine

Phosphocreatine

-high energy molecule

-phosphate used to convert ADP to ATP

-small stores

-highest rate of ATP synthesis

-sprinting, high jump, powerlifting

-the replenishment of PC for this system needs ATP

-once levels of PC are depleted, a new system must take over for the body to continue and also for the body to replenish its PC levels

Takes 2-5 minutes

Glycolysis Anaerobic lactic

Produces lactic acid-partial breakdown of glucose in cytoplasm

-plentiful in the human body

-holds useable energy (ATP)

Although ATP production is rapid, glycolysis is a much more complex process

-11 separate biochemical reactions

-yields twice as much ATP as the ATP-PC system

-lasts 1-3 minutes

C6H12O6 + 2ADP + 2Pi 2C3H6O3 + 2ATP + 2H2O

Glucose Lactate

-basically glycolysis transfers energy from glucose to rejoin phosphate to ADP

Total ATP count = 2

-if O2 present, pyruvate (pyruvic acid)

-if insufficient O2, pyruvate lactic acid

- hi Lacid low Glucose breakdown

-decrease muscle contraction

-burning sensation

When sufficient O2 is present, the pyruvate left over from Glycolysis will move into a new, even more complex pathway. . .

Cellular Respiration Aerobic

-complete breakdown of glucose in the mitochondria of cells

-kicks roughly 90 sec into activity and lasts for endurance activities

-fats and proteins also used as energy sources in this pathway

Exercise longer than 20 minutes

As a last resort

-involves 3 separate pathways:

• Glycolysis -same as before, but pyruvate Acetyl CoA (2 ATP)

• Kreb’s Cycle (citric acid cycle)

-Acetyl CoA enters the more complicated pathway

-series of 8 reactions; also site of fat and protein metabolism

The Kreb’s Cycle

When sufficient O2 is present, the pyruvate left over from Glycolysis will move into a new, even more complex pathway. . .

Cellular Respiration Aerobic

-complete breakdown of glucose in the mitochondria of cells

-kicks roughly 90 sec into activity and lasts for endurance activities

-fats and proteins also used as energy sources in this pathway

Exercise longer than 20 minutes

As a last resort

-involves 3 separate pathways:

• Glycolysis -same as before, but pyruvate Acetyl CoA (2 ATP)

• Kreb’s Cycle (citric acid cycle)

-Acetyl CoA enters the more complicated pathway

-series of 8 reactions; also sight of fat and protein metabolism

-2 ATP produced along with 6NADH and 2FADH

The third and most “profitable” sub-pathway is the final stage of cellular respiration

• Electron Transport Chain

-occuring in the mitochondria, the ETC takes high energy electrons, found within FADH and NADH molecules, through a chainlike process

-this process creates VAST amounts of ATP with only CO2 and water as by products

-video

The electron transport chain contributes a whopping 32 ATP to the cellular respiration process

C6H12O6 + 6O2 + 36ADP + 36Pi 6 CO2 + 36ATP + 6H2O

• Glycolysis = 2 ATP/glucose

• Kreb’s Cycle = 2 ATP/glucose

• ETC = 32 ATP/glucose

36 ATP/glucose

Interplay of Energy Systems

-video

Copy 5.1: Three Energy pathways compared (p.86) into your notes

Lactic Acid-we know that lactic acid is a painful by product of glycolysis when insufficient oxygen is present

-one of the main causes of stopping activity

Anaerobic threshold

(Blood lactate threshold)

Point at which a large increase in blood lactate occurs (compared to resting levels)

Onset of blood lactate accumulation (OBLA)

Rapid accumulation of blood lactate; always occurs after the lactate threshold

• The longer it takes a person to reach their threshold, the more “endurance” they have

•Elite endurance athletes will have a high lactate threshold

•Untrained individuals will have a low lactate threshold

Therefore, the lower your LT, the less efficient your energy systems are working, or the poorer your energy systems are

The Cori CycleWe can’t just think of lactic acid as a bad thing

Remember that blood lactate levels don’t ALWAYS increase

Therefore the body MUST have a way of ridding itself of lactic acid

• takes lactic acid (lactate) and converts it to pyruvate in the liver

• the pyruvate is then converted to glucose/glycogen and re-enters the energy pathways, allowing further production of ATP

Better endurance athletes will have a greater ability to convert their lactic acid

So what is the difference between these two athletes?

What allows one athlete to excel at running for 5 hours and another to excel at running for 10 seconds?

Muscle Fibre TypesIn general there are 2 types:

• Slow-twitch muscle fibres: -dark in in colour

-low levels of ATPase (instant energy) and glycolytic enzymes (promote glycogen release)

-high levels of oxidative enzymes

-lower tension/contraction over longer periods of time

-most active during endurance activities

• Fast-twitch muscle fibres: -paler colour

-high levels ATPase and glycolytic enzymes

-large amounts of tension with relatively low endurance levels

-activate 2X’s faster than slow twitch fibres

-most active for fast, powerful activities

(Oxygen storage)

There are two main muscle fibres, but researchers are starting to lean towards three different types:

• Type I –Slow Oxidative (SO)

•Type IIa –Fast Oxidative Glycolytic (FOG)

•Type IIb –Fast Glycolytic (FG)

Strong research evidence, that with consistent aerobic training, the body can convert type IIb fibres into type Iia

-that is, fast twitch muscles fibres can become an intermediary fibre that acts as both fast twitch and slow twitch

-no evidence for Type II Type I

Tonic versus Phasic musclesThe function of a muscle is a pretty good indicator of its fibre make up.

-muscles that maintain posture and stability

-mainly type I slow twitch fibres

-little explosiveness, considerable endurance

-soleus

-muscles that create power and speed

-mainly type II fast twitch fibres

-biceps brachii

Read page 91, “Kenya’s Famous Long-Distance Runners –The greatest concentration of achievement in the annals of sport.”

From the reading, find and write down the FIVE most important points, that could help you write a research paper on the topic of ENERGY SYSTEMS.