2:45-3:15 PM on the Thursday (28 th November). Meet with quality assurance external reviewers

2:45-3:15 PM on the Thursday (28th November).

Meet with quality assurance external reviewersfor the school of professional studies.

Nutrition student volunteers please email me and Marcy MacKinnon:

[email protected]

indicating whether you are year 1 or 2 and with you willingness to do so- your help is verymuch required and essential. Thank you!!!

Lecture 11- 21 November 2013

This lecture is based largely on CHAPTER 23 IN KRAUSE'S FOOD NUTRITION AND DIET THERAPY (ON RESERVE IN LIBRARY) AND CHAPTERS 7,8,9 IN ROLFES ET AL.

Final exam-120 multiple choice-120 marksfrom vitamins to end of course

-4 short answer questions-15 points each for a total of 60 points

covers whole course

-3 hours- 180 marks

Lecture 11

OutlineMetabolic aspects of Nutrition and fitness/Sports Nutrition

Energy production ATP Anaerobic pathway Aerobic pathway Energy continuum Sources of fuel

Outline of lecture 11

Energy production

Substrate choice

Intensity Duration Effect of training Diet


Nutritional Requirements Fluid Fluid Balance Fluid Absorption

Factors affecting fluid absorption Requirements Short duration Endurance


Nutritional Requirements Carbohydrate Types of carbohydrate

Pre-event

During event Post-event


Nutritional Requirements Protein Endurance

Resistance Exercise

Amino acid supplementation

Outline of lecture 11Nutritional Requirements Lipid

Minerals Iron Calcium Vitamins Anti-oxidant vitamins and B-

carotene C E B vitamins


Regulation of metabolism

More Detailed Comments

Energy production

Aerobic and anaerobic both provide ATP but which system predominates depends on oxygen supply to the tissues

Energy productionATP Energy currency of the cell ATP to ADP plus Pi -done by ATPase Creatine phosphate is split to creatine and

phosphate -this provides the energy to

resynthesise ATP via creatine kinase

Energy production

ATP

limited amount of creatine phosphate in the body so this is a very limited way to replace ATP- creatine phosphate process is anaerobic if all-out exercise -this process can only go

on for 5-8 seconds- eg power lifting

Energy production Anaerobic pathway No oxygen

Glycolysis is the quickest way to make ATP Lactic acid is endproduct (enzyme

implications)

Two hydrogens transferred to pyruvate thus making lactate- This results in the freeing of NAD to participate further in making ATP-but relatively small amount of ATP synthesis

Energy production Anaerobic pathway Lactic acid is rapidly removed from the muscle

and transported in the blood and is eventually converted to energy in the muscle, liver or brain OR it is converted to glycogen

Conversion to glycogen occurs largely in the

liver and to some extent in the muscle Lactic acid buildup in the blood leads to drop

in pH resulting in enzymatic activity drops which in turn results in fatigue

Energy production Anaerobic pathway

Oxygen debt-recovery oxygen consumption- the difference between oxygen consumption in the post-exercise recovery phase and the

oxygen consumption at rest

Fuel source is limited to glucose and produces a relatively small amount of ATP relative to aerobic metabolism

All out effort for 60-120 seconds

Energy productionAerobic pathway

If going for continued muscle activity of more than 90-120 seconds one needs oxygen

Energy is stored in high-energy phosphate bonds in ATP through a complex series of enzymatically guided reactions involving separation of hydrogen atoms from the parent compounds

Energy production

Aerobic pathway

Vital to this process is the presence of coenzymes which act as hydrogen acceptors until the process of oxidative phosphorylation results in the formation of ATP

Ultimately hydrogen combines with O2 to form water and the coenzymes are freed to accept more hydrogen so as to continue the process

Energy productionAerobic pathway

Glucose is broken down much more efficiently than is the case with anaerobic glycolysis

In the presence of oxygen, pyruvate is

converted to Acetyl CoA Acetyl CoA enters the mitochondria and is

then introduced into the Kreb’s cycle

Energy production Aerobic pathway

Proteins and lipids can also be metabolized to produce ATP

Lipids- the beta oxidation of lipids produces a large amount of ATP

Proteins can be catabolised to Acetyl CoA or

to Kreb’s cycle intermediates and in this way produce ATP

Break

Energy production

Energy continuum

All pathways can produce ATP

At the beginning of any exercise whatsoever anaerobic metabolism is in place to produce ATP

If the person continues to exercise at a

moderate level for a prolonged period then the aerobic pathway will become the predominant pathway for energy production (eg marathon run)

Energy production Energy continuum

If the person continues to exercise for a short period of high power and high intensity then the anaerobic pathway will become the

predominant pathway for ATP energy production(eg 100 metre sprint)

Production of ATP is therefore a continuum that depends on the:

-availability of oxygen -the capacity for intensity of the exercise -the capacity for the duration of the exercise

Energy production Energy continuum

There is an inverse relation between the capacity for intensity and the capacity for the duration of the exercise

-one cannot perform high intensity exercise over a long period of time

-the duration increases as the intensity

drops and as the intensity of the exercise increases the duration of that exercise drops

Energy production

Energy continuum

-the aerobic pathway cannot tolerate the same level of intensity as the duration increases due to the decreased availability of oxygen and the

production of lactic acid

Energy production

Energy continuum-as the intensity increases the power output

decreases POWER = WORK/TIME

WORK = FORCE X DISTANCE

-as the intensity decreases the power output increases

POWER = WORK/TIME WORK = FORCE X DISTANCE

Energy production Sources of fuel

as the duration increases more energy is obtained from fat (fatty acids) and as the duration decreases and the intensity increases more energy is obtained from carbohydrate

carbohydrate is obtained from dietary carbohydrate, glycogen or amino acids (amino acids can be synthesized to glucose-this process is known as gluconeogenesis)


Kreb’s cycle-alanine is the main amino acid contributing to the Krebs cycle

-3 carbon units of glucose

contributing to the Krebs cycle

-2 unit carbons of fatty acids

contributing to the Kreb’s cycle


Kreb’s cycle

-all of these substrates are used most of the time however the intensity and duration of the exercise dictates the relative rates of substrate utilisation

Energy production

Substrate choice

Intensity- high intensity must rely on carbohydrate

Because oxygen is not available for high intensity exercise glycogen must be utilized

Glycogen catabolism is much higher than with aerobic activity- 18-19 times faster (2 ATP versus 36-38 ATP)

-Energy production

Substrate choice

Intensity-Hockey, basketball for eg favour higher glycogen utilization rates than marathon running while moderate intensity exercise favours 50/50 split of (glycogen)/(glucose-lipid) use

-Energy production

Substrate choice Low intensity exercise like walking is entirely

aerobic and most of the ATP comes from lipid

Fat yields 4.65 kcal / L of oxygen consumed vs for carbohydrate a yield of 5.01 kcal/L of oxygen consumed

-thus in longer term exercise carbohydrate use is favoured

Once the glycogen stores are depleted then that is the end of the high intensity exercise

Energy production

Substrate choice Duration-the longer the event the greater the

proportion of lipid used to produce ATP

-consequently the lower the amount

of lactate produced

Effect of training-increase number of mitochondria and activity of ATP producing enzymes

Energy production

Substrate choice Diet-dictated by fuel utilization for a particular

event

-high intensity requires more carbohydrate in the diet

-lower intensity requires more lipid in the diet however do not consume a high fat diet-

crowd out carbs and run the risk of heart disease

Class exercise

Explain the effects of exercise intensity, duration and training on substrate utilisation.

Break

Nutritional Requirements Fluid Fluid Balance

Important for maintaining blood flow which in turn is important for supplying blood to skin and hence temperature control

75 percent of energy goes out as heat-therefore must sweat

regulated by kidney, sweat loss, feces, respiration and fluid intake

important to consume sodium and water to replace water lost as sweat-thus blood sodium is maintained and therefore so are hormone levels which limit the rate of urine production

Nutritional Requirements

Fluid Absorption Factors affecting fluid absorption -glucose and sodium travel across

intestine on same carrier

Nutritional Requirements Fluid Requirements Short duration

-if several heats before actual race this can be problem for hydration

- plain water dilutes the blood, increases

urination and results in dehydration Endurance

-plain water lowers blood glucose concentrations thus increasing the demand on muscle glycogen


Carbohydrate Types of carbohydrate

After glycogen runs out must use gluconeogenesis to maintain blood glucose levels

Glycogen loading is important-eg pasta diet some have suggested complex carbs are better at glycogen loading in muscle than are simple carbs but this is debatable


CarbohydratePre-event

Takes care of hunger Maintains adequate blood glucose levels for

event During event Maintains blood glucose and delays fatigue Post-event Builds glycogen up in muscle after

depletion


Protein

Endurance Less required than for resistance events Resistance Exercise More required than for endurance events -muscle mass issue


Protein

Amino acid supplementationA waste of time- eat more calories in accordance with Canada’s food guide to meet increased energy demands and this will easily meet added protein/amino acid requirements

Can lead to dehydration, loss of urinary calcium, weight gain and stress on the kidney and liver


Lipid -supplies essential fatty acids

-important energy source during endurance exercise

-less important as an energy source for high intensity exercise

Class exercise

How do the 6 nutrient classes work together to allow:

a) Aerobic exerciseb) Anaerobic exercise

Break


Minerals Iron -oxygen carrying-hemoglobin and

myoglobin

-part of electron transport chain-ATP Calcium -bone mass

Nutritional RequirementsVitamins Anti-oxidant vitamins and -carotene, vitamin C

and E-exercise produces increased amount of lipid peroxides and free radicals-damage muscle

-supplements are not required-no evidence

that they improve performance B vitamins -important co-enzymes in energy production

-B12-supplement required in strict vegans

Regulation of Metabolism

Oxygen supplyAs intensity of exercise increases the oxygen supply becomes limiting-with training one can supply more oxygen

Substrate supply

Availability of co-enzymes

Hydration

Mechanisms described for each of the nutrient classes

Class exercise

What is the major direction of metabolism

during exercise?

after exercise?

Why ?

2:45-3:15 PM on the Thursday (28 th November). Meet with quality assurance external reviewers

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