Transcript Bioenergetics

Bioenergetics of
Exercise
Reading: Essentials of S&C 73-91
Christopher T. Ray, Ph.D., ATC, CSCS
Extra Credit Opportunity
#1
Housekeeping
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Schedule
– Assessments with partners
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Next Wed & Fri
– Sign in 9:00-9:05; Assessments 9:00–9:35 Plan accordingly
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Equipment = Calipers, S&R Box, VERTEC, Tape
Measurer, cones, masking tape, courts, indoor track &
weight room.
Questions?
What?
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What does Exercise Rx mean to you?
What do mean when I say “Be
Evidence Based”
Why Did Usain Bolt not
Run the 400 meters?
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WR 100 meters = 9.69
WR 200 meters = 19.30
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WR 400 meters = 43.18; 43.75 = Gold
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*45.29
Table 5.3 Effect of Event Duration
on Primary Energy System Used
Duration
of event
Intensity
of event
Primary energy
system(s)
0-6 s
Very intense
Phosphagen
6-30 s
Intense
Phosphagen and fast
glycolysis
30 s-2 min
Heavy
Fast glycolysis
2-3 min
Moderate
Fast glycolysis and
oxidative system
> 3 min
Light
Oxidative system
Practice
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Sport
Assessment
Training Regime (Int., Duration, Rest)
Calculations
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200 meter PR = 20; Training 75% 90%; Recovery = 1:3-1:5
– 20 X 1.10 = 22 X 5 = 110 sec.
– 20 X 1.25 = 25 X 3 = 75 sec.
“Wolff’s Law”
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The body adapts to the stress placed
upon it.
law according to which biologic
systems such as hard and soft tissues
become distorted in direct correlation
to the amount of stress imposed upon
them.
Bio-energetics is dynamic
Basic Training Principles
1.
2.
3.
4.
5.
6.
The Principle of Individuality
The Principle of Specificity
The Principle of Progressive Overload
The Principle of Hard / Easy
The Principle of Periodization
The Principle of Disuse
Basic Training Principles
1. The Principle of Individuality
Different people respond to the same training in different
ways. Heredity plays a major role in determining how
quickly and to what degree the athlete adapts to a training
program.
For these reasons any training program “must take into
account the specific needs and abilities of the individuals
for whom it is designed.”
Basic Training Principles
2. The Principle of Specificity
To maximize the benefits, training must be specifically
matched to the type of activity the athlete use to be
engaged in. (endurance vs strength and power training).
By this principle the training program must stress the
physiological systems that are critical for optimal athlete’s
performance, in order to achieve specific adaptations for
specific sports.
Basic Training Principles
3. The Principle of Progressive Overload
Overload and Progressive Training are the foundation of
all training programs.
A well-designed Training Program must involve working
the muscles, respiratory and cardiovascular systems
harder than normal (overload); as the body adapts,
Training progresses to a higher work level (progressive
training)
Basic Training Principles
4. The Principle of Hard / Soft
Bill Bowerman (former U.S. Olympic track coach and
founder of NIKE) developed a training strategy for his
distance running that became known as ‘ The principle of
hard / soft’.
According to this principle, one or two days of hard
training should be followed by one day of soft training,
allowing the fully recover of body and mind and prevent
the athlete’s overtraining.
Basic Training Principles
5. The Principle of Periodization
Periodization is the gradual cycling of
specificity, intensity and volume of training to
achieve peak levels of fitness for competition.
Basic Training Principles
6. The Principle of Disuse
“ Use it or loose it”
According to this principle, training benefits are lost if
training is either discontinued or reduced too abruptly.
To avoid this, all training programs must include a
maintenance program.
Opportunity to get back
on my good side #1
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Pick a sport
– What are the components
– Where does it fit on the bioenergetics
spectrum?
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How would you train athletes in this
sport?
How would you Assess them?
Introduction
- Energy
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Ability to do work
– Bioenergetics
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Flow of energy in a biological system
– Catabolism
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Breakdown of larger molecules into smaller
molecules (glucose to pyruvate)
– Anabolism
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Synthesis of larger molecules from smaller
molecules (polypeptide from AA residuals)
Introduction
– Exergonic reactions
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Energy-releasing reaction; generally catabolic reaction
Ex. Blood glucose during catabolism = release of
energy
– Endergonic reactions
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Energy-consuming reaction; generally anabolic
reaction
Ex. Protein synthesis
– Metabolism
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Total of all the catabolic/exergonic and
anabolic/endergonic reactions in a system
Introduction
– ATP

Adenosine triphosphate; intermediate
molecule that allows the transfer of energy
from exergonic to endergonic reactions
– Smallest usable form of energy
Biological Energy Systems
– Three energy systems used to replenish
ATP
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Phosphagen
– Occurs in the sarcoplasm
– An anaerobic energy system
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Glycolytic
– Occurs in the sarcoplasm
– An anaerobic energy system
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Oxidative
– Occurs in the mitochondria
– An aerobic energy system
Biological Energy Systems
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Phosphagen system (anaerobic), occurs
without oxygen.
Glycolysis (Fast & Slow) is the breakdown of
carbohydrates, either glycogen stored in the
muscle or delivered in the blood to produce
ATP.
Oxidative system is the primary source of ATP
at rest and low-intensity, it uses primarily
carbohydrates and fats as substrates.
All three energy systems are active at a given time; the extent to
which each is used depends on the intensity of the activity and its
duration.
Biological Energy Systems
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All energy systems are active at any
given time
– The extent of their contribution:

Primary
– Intensity, power output, work rate
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Secondary
– Duration
Phosphagen System
– Primary functions
Provide ATP for high intensity activities
(e.g., sprinting, weight training)
 For 0-6 seconds up to 20-30 seconds of
activity
 Active at the start of all exercise

– Regardless of intensity!
Summary of Phosphagen
System
– Summary:
Rapid ATP resynthesis rate
 Efficient system (due to the few number of
involved reactions)
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– Creatine kinase reaction
– Myokinase reaction
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BUT a low capacity of total ATP produced
Glycolytic System
– Primary functions
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Carbohydrate (CHO) (i.e., blood glucose and
muscle glycogen) break down to produce ATP
in the sarcoplasm of a muscle cell
– Provides energy primarily for moderate to high
intensity activities
– For 30 seconds up to 2-3 minutes of activity
– Hypoxic (anaerobic) cellular environment
Glycolytic System
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Fate of pyruvate
–
–
–
–
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High rate of energy demand
Insufficient O2 present
Fast glycolysis (pyruvate to lactate)
Example: 1200 meter sprint run
Low rate of energy demand
– Sufficient O2 present
– Slow glycolysis (pyruvate [with NADH] is sent to
the Krebs Cycle in the mitochondria)
– Example: 30 minute stair climbing workout
Summary of Fast Glycolysis
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Fast glycolysis occurs during reduced oxygen availability
and the end product is lactic acid.
Lactic acid accumulation in tissue is the result of an
imbalance of production & utilization.
As lactic acid accumulates, there is an increase in the
concentration of H++ ions.
H++ ions inhibit glycolytic reactions.
H++ ions interfere with E-C coupling by inhibiting Ca from
binding with troponin.
The decrease in pH also inhibits enzymatic
activity.
Lactic Acid and Lactate
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Lactic acid is converted to its salt, lactate, by buffering
systems in the muscle and blood.
Lactate is not fatigue producing, it is often used as an
energy system in Type I and cardiac muscle.
Lactate is used in gluconeogensis, the formation of
glucose from lactate and non-carbohydrate sources
during extended exercise and recovery.
Concentrations of lactate in blood and muscle:
– At rest, 0.5 – 2.2 mmol/L
– At high intensity exercise 20 – 25 mmol/L
Peak blood lactate concentrations occur approximately 5
minutes after the cessation of exercise.
Blood lactate accumulation is greater following highintensity intermittent exercise, than lower intensity
continuous exercise.
Oxidative System
- Primary function
– Provide ATP for low intensity activities (e.g.,
long distance running, cycling, swimming)
– For longer than 3 minutes of activity
– Substrates
CHO
 Fats
 Proteins
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– Reactions occur in the mitochondria
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“Power house” of the muscle cell
Oxidative (Aerobic) System
Requires molecular oxygen
Provides ATP at rest and during low-intensity
activities
Uses primarily carbohydrates and fats as substrates
At rest, 70% of ATP is from fats & 30% carbs.
As exercise intensity increases there is a shift from
fats to carbohydrates as substrates.
At high intensity, almost 100% of ATP is from carbs.
During prolonged, submaximal steady state work,
there is a gradual from carbs back to fats & proteins.
Summary of Oxidative
System
– Adaptations to training
Increased muscle mitochondrial content
 More effective sparing of CHO for use by the
central nervous system
 Blunted drop in intracellular pH during a longterm aerobic endurance event
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Substrate Depletion and
Repletion
– Energy substrates used to produce ATP
– Phosphagen
– Glycogen
– Glucose
– Lactate
– Free fatty acids
– Amino acids
Substrate Depletion and
Repletion
– Phosphagen and ATP
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Depletion
– Creatine phosphate (CP) stores can decrease 5070% in the first 5-30 seconds
– CP stores are virtually eliminated as a result of
high intensity exercise
– ATP stores do not decrease more than 60% even
with very intense exercise
Substrate Depletion and
Repletion
– Phosphagen and ATP
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Repletion
– Post-exercise resynthesis of ATP can occur within
3-5 minutes
– Post-exercise resynthesis of CP may require up to
8 minutes
– Most post-exercise CP resynthesis is accomplished
through oxidative energy pathways
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Oxidative
system yields
38 ATP from 1
glucose
molecule.
Energy Production and
Capacity
– Rate and capacity of the three energy
systems to supply ATP
Inverse relationship
 Rate (how fast ATP can be created)
 Capacity (how much ATP can be created)
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Table 5.4 Rankings of Rate and Capacity
of ATP Production
System
Rate of ATP
production
Capacity of ATP
production
Phosphagen
1
5
Fast glycolysis
2
4
Slow glycolysis
3
3
Oxidation of carbs
4
2
Oxidation of fats
and proteins
5
1
1 = fastest/greatest; 5 = slowest/least
Energy Production and
Capacity

The use of appropriate exercise intensities and rest
intervals allows for the “selection” of specific energy
systems during training and results in more efficient and
productive regimens for specific athletic events with
various metabolic demands.
Substrate Depletion and
Repletion
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ATP and creatine phosphate, glucose,
glycogen, lactate, FFA and amino acids
can be selectively depleted.
Phosphagen Depletion &
Repletion
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Phosphagens are more rapidly depleted with high intensity
exercise than aerobic exercise.
Creatine Phosphate decreases 50-70% during high intensity
exercise and can be almost eliminated by exercise to exhaustion
Muscle ATP concentrations do not decrease by more than 60%
of initial value even during intense exercise.
Intramuscular ATP is spared by the depletion of creatine
phosphate from the myosine kinase reaction.
Post exercise repletion of phosphagen with:
– Resynthesis of ATP in 3 – 5 min
– Complete creatine phosphate resynthesis in 8 min
Resistance training can result in an increase in the resting
concentration of phosphagens.
Glycogen Depletion &
Repletion
Limited stores of glycogen are available for exercise, approx. 300
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400 g in total body muscle and 70-100 g in the liver.
Anaerobic training can increase glycogen stores.
Muscle glycogen is more important than liver during moderate –
intense exercise.
Liver glycogen is more important in low intensity exercise and its
contribution increases with duration.
Repletion of muscle glycogen during recovery is related to post
exercise carbohydrate consumption.
Repletion is optimal if 0.7 – 3.0 g of carbs/kg is ingested every 2
hrs.
Muscle glycogen may be completely replenished within 24 hrs
with sufficient carbs in diet.
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Glycogen depletion can be a limiting factor both for:
– Long duration, low intensity exercise
– Repeated very high – intensity exercise
Lactic acid and tissue H++ ion concentration can be limiting
factors for resistance training, sprinting and other
anaerobic activities.
Low-Intensity, Steady-State Exercise Metabolism
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EPOC = Excess postexercise oxygen uptake
At the start of
exercise, some of the
energy is provided by
anaerobic metabolism.
The anaerobic
contribution to the
total energy cost is
termed Oxygen
Deficit.
Post-exercise oxygen
uptake remains
elevated according to
intensity and duration
and is termed Oxygen
Debt.
High-Intensity, Non-Steady-State
Exercise Metabolism