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Metabolism Semester 2 > Lecture 11 - sports nutrition > Flashcards

Lecture 11 - sports nutrition Flashcards

1
Q

What are the three systems to produce energy for muscle contraction?

A
  1. ) Phosphagen system
  2. ) glycolytic system
  3. ) mitochondrial system
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2
Q

What happens in the phosphates system?

A
  • Phosphocreatine becomes creatine and PO3

- ADP + ADP – AMP

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3
Q

What happens in the glycolytic system?

A

Glycogen or glucose becomes lactic acid (fast) or private slow

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4
Q

What happens in the mitochondrial system?

A

Pyruvate, amino acids, and fatty acids are mixed with O2 and become CO2 and water and urea

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5
Q

How is energy used in the in the muscle during exercise?

A

1.) ATP and creatine phosphate stored in the muscles provide ATP for muscle contraction
2.) As creatine phosphate stores are depleted, anaerobic metabolism,
which breaks down glucose from the blood or from muscle glycogen, becomes the
predominant source of ATP
3.) After about 3 minutes, aerobic metabolism, which uses fatty
acids and glucose to produce ATP, takes over as the predominate source.

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6
Q

What happens to the proportion of energy supplied from carbs as exercise intensity increases?

A

Proportion of energy from carbs also increases. During exercise, the total amount of energy expended is far greater than at rest.

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7
Q

Each metabolic pathway exhibits characteristic and capacity.

A

ATP

generating power

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8
Q

No single exercise relies solely on …..

A

one energy system

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9
Q

What dictates the metabolic pathway used?

A

The demand for ATP

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10
Q

phosphagen is predominant for activities that are?

A

less than 15 seconds

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11
Q

Glycolytic is predominant for activities that are?

A

predominant for activities that last less than 2 mins.

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12
Q

Mitochondrial respiration is predominant for activities that are?

A

more than 5 mins

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13
Q

What do the energy sources of the physical activity depend on?

A
  • intensity of the physical activity
  • Duration of the physical activity
  • personal characteristics like genetic features and fitness of an athlete
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14
Q

What fuels does muscle use?

A
  • Plasma glucose
  • its own reserve of glycogen
  • TAG from plasma lipoproteins
  • Plasma non-esterfied FAs
  • Plasma ketone bodies
  • TAG from adipose tissue reserves within the muscle
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15
Q

Selection of the kind of fuel depends on?

A

-The intensity of work being performed
• The duration of the exercise
• Whether the individual is in the fed or fasting
state

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16
Q

What is anaerobic glycolysis?

A

• It uses glycogen to form glucose, to fuel anaerobic glycolysis.
• ATP and lactic acid is produced.
• Modest power output: fast-twitch fibres mainly (Type 11 (white muscle fibres))
• It can support muscle contraction up to 10 minutes only
• After that time it is exhausted
• White muscle fibres used mainly in high-intensity work of short duration -
sprinting

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17
Q

What is aerobic metabolism?

A

-It is a combination of all aerobic processes, all involve the
mitochondria (aerobic glycolysis, beta-oxidation)
• Very low power output: slow-twitch muscle fibres mainly
• It can support muscle contraction up to hours or even days in
ultra marathon
• After that time it is exhausted
• Typical sports are long-distance running

18
Q

In aerobic physical activity the metabolic fuels
(carbohydrates and lipids) are ……. in
the …..

A

are completely oxidised in the citric acid cycle and electron transport system.

19
Q

Energy expenditure in aerobic is …. and as a result ……. is not accumulated in high concentrations

A

not very high and as a result lactate is not accumulated in high concentrations.

20
Q

A large percentage of the energy required for aerobic physical activity comes from?

A

oxidation of lipids

21
Q

Aerobic energy production depends on the availability of?

A

oxygen

22
Q

Why can’t anaerobic performance be increased substantially by exercise?

A

.because there is a physiological limit: the accumulation of
lactic acid in the muscle cell. It cannot exceed about 25
mM;

23
Q

Why can aerobic performance be increased by exercise?

A

because the capacity of the circulatory system
can be enormously increased by training.

Thus, more oxygen can be carried to the muscle
resulting in a higher rate of oxidation,
consequently higher rate of ATP synthesis,
without increasing the steady state concentration
of lactate.

24
Q

Sources of muscle glucose for glycolytic metabolism?

A
  • blood glucose from exogenous source
  • glycogen from muscle which is converted to glucose
  • blood glucose from liver glycogen
25
Q

Differences between glucose and glycogen?

A 
-Both require initial ATP “investment”
to phosphorylate glucose to glucose6-phosphate.
-Because glycogen is already
phosphorylated, glycogenolysis has a
greater yield of ATP during
exercise.
26
Q

effects of doping agents?

A
  1. ) Increasing endurance and aerobic capacity
  2. ) Increasing muscle mass and strength
  3. ) Decreasing feelings of fatigue and nervousness
  4. ) improving recovery processes
27
Q

What are agents that increase endurance and aerobic capacity called and how do they do it?

A

Blood doping and erythropoietin (EPO):

-increase the concentration of hemoglobin,
thus, they increase the aerobic performance

28
Q

How can EPO be tested for and what are its risks?

A

by determining
hematocrit;
maximum 50% is acceptable

-Extremely high hematocrit value could induce serious, deleterious
consequences, including:
-Heart attack
-Stroke
-Embolism
-(increased blood viscosity, increased platelet adhesion, arterial
hypertension, headache, muscle cramps…….)

29
Q

What are substances that increase muscle mass and strength called?

A

Anabolic androgen steroids - especially hormone testosterone

other ones - aromatase inhibitors - slows down conversion of testosterone to estradiol which increases the steady state concentration of testosterone, beta-2-agonists used for treatment of asthma and improves the aerobic performance in lung of healthy individuals. Administered orally than will have an anabolic effect.

30
Q

What is the most anabolic hormone ?

A

insulin which is more anabolic than anabolic steroids

31
Q

What are diuretics?

A
  • These substances are used in sports where
    body weight is important such as wrestling,
    boxing
    -resulting in unfavorable dehydration and
    subsequent reduced performance.
    Some of them are not considered as doping
    agents.
32
Q

What are some substances that decrease feelings of fatigue and nervousness?

A

stimulates that imitate the effects of the stress hormones epinephrine and norepinephrine

  • Amphetamine derivatives
  • Ephedrine
  • Cocaine
  • Caffeine
33
Q

Protein as a fuel source? glucogenic vs ketogenic?

A

glucogenic - may be used to form pyruvate, oxaloacetate, malate

ketogenic - used to form acetyl-CoA and acetoacetate

34
Q 
Muscle glycogen vs liver glycogen?
use?
metabolism?
Athlete?
Depletion?
A 
muscle:
use - immediate energy 
metabolism - directly B cell (no glucose phosphatase)
athlete - primary energy 
depletion - hitting the wall

Liver:
use - short term storage for muscle and brain
metabolism - labile pool - glucose phosphate remove PO4
athlete - hard used after 1 h intense exercise
depletion - crashing

35
Q

Simple vs complex carbs?

A

simple:

  • Rapid absorption
  • Rapid increase in blood glucose
  • Strong increase in insulin
  • glucose stored as glycogen and fat because TCA cycle saturated with acetyl-CoA

Complex:

  • slow absorption
  • slow increase in blood glucose
  • less insulin response
  • maximise glucose stored as glycogen
  • preferred for athletes
36
Q

Phase 1 of exercise effects ?

A
  • Physical activity causes a large increase in energy utilization
  • Glucose is a major fuel for contracting muscles
  • Glucose uptake acutely increases during exercise
37
Q

Phase 2 of exercise effects?

A

• Transient increase in muscle insulin
sensitivity for up to 48 h after exercise in
healthy volunteers and for > 15 h in
patients with T2D
• Some but not all studies show whole body
improved insulin sensitivity

38
Q

Chronic effects of exercise?

A

• Improves glucose handling machinery
• Inceased HK and GLUT4 increase capacity for
the muscle to take up glucose
• Upregulated mitochondrial proteins –TCA
and ox phos
• Increased capillarization – enhanced delivery

39
Q

How are the effects of phase 1 taking place ?

A
  1. Increased amount of glucose transporter GLUT4 at the PM and
    t-tubules (parallel molecular pathways involving the molecular
    sensor AMPK, The Rho GTPase Rac 1, ROS ….all activated in
    distinct steps in glucose transport regulation
  2. Accelerated intracellular metabolism of glucose
  3. Exercise stimulated uptake is insulin–independent
  4. Exercise also induces the secretion of circulating factors
    that can act in an autocrine or paracrine way (hence proposed
    mechanism by which exercise can benefit other tissues)
    5.Exercise rapidly modifies hundreds of bioactive peptides in
    the circulation
40
Q

bioactive peptides during exercise?

A

APELIN:
• secreted from muscle during exercise
• activated AMPK
• Prevented age-associated sarcopenia in mice
• Increased insulin action in overweight men
Suggests it might mediate some of the beneficial
effects of exercise
INTERLEUKIN-6 :
• Secreted from skeletal muscle during exercise
• Stimulates lipolysis – reduces visceral adipose
tissue
IRISIN:
• Secreted from muscle
• Recently was found to play a role in exercisemedicated benefits on Alzheimer’s disease

Metabolism Semester 2 (20 decks)

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