Transcript 2106lecture 11b powerpoint

Lecture 11b-21 March 2016
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 marks
from 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
Outline
Metabolic 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
Outline of lecture 11
Nutritional Requirements
Fluid
Fluid Balance
Fluid Absorption
Factors affecting fluid absorption
Requirements
Short duration
Endurance
Outline of lecture 11
Nutritional Requirements
Carbohydrate
Types of carbohydrate
Pre-event
During event
Post-event
Outline of lecture 11
Nutritional Requirements
Protein
Endurance
Resistance Exercise
Amino acid supplementation
Outline of lecture 11
Nutritional Requirements
Lipid
Minerals
Iron
Calcium
Vitamins
Anti-oxidant vitamins and Bcarotene
C
E
B vitamins
Outline of lecture 11
Regulation of metabolism
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
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)
Energy production
Sources of fuel
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
Energy production
Sources of fuel
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 activity18-19 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)/(glucoselipid) 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
relative to low intensity exercise
However, once the glycogen stores are depleted then
that is the end of the high intensity exercise as
carbohydrate utilisation is critical to lipid utilisation
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 aerobic training-increase number of
mitochondria and activity of ATP
producing enzymes-this impacts
efficiency of both carbohydrate and
lipid utilisation which ever is
chosen
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 dietcrowd 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
Nutritional Requirements
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
Nutritional Requirements
Carbohydrate
Pre-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
Nutritional Requirements
Protein
Endurance
Less required than for resistance events
Resistance Exercise
More required than for endurance events
-muscle mass issue
Nutritional Requirements
Protein
Amino acid supplementation
A 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
Nutritional Requirements
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 exercise
b) Anaerobic exercise
Break
Nutritional Requirements
Minerals
Iron
-oxygen carrying-hemoglobin and
myoglobin
-part of electron transport chain-ATP
Calcium
-bone mass
Nutritional Requirements
Vitamins
Anti-oxidant vitamins and b-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 supply
As 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 ?