Supplements for Endurance

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Supplements for Endurance Lecture 15
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• body fat
• ? ?
• free fatty acids
• ? ?
• mitochondria
• ?
• beta-oxidation
• ?
• acetyl-CoA
• ?
• NADH, FADH
• ?
• electron transport system
• ? ?
• ATP

As we discussed, any intervention that can shift
energy production toward a greater use of fat
can enhance endurance exercise performance. There
are 3 potential places where a substance could
be effective.
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In response to the action of epinephrine and
norepinephrine (secreted in large quantities
during exercise) hormone-sensitive lipase, an
enzyme located in adipose tissue (body fat) and
muscle, breaks down triglycerides to free fatty
acids (FFA).
Body fat
Increased levels of FFA in the blood allows
greater uptake of FFA by muscle cells.
action of hormone- sensitive lipase
TG
FFA
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• Fatty acids are converted to Acetyl-CoA. Before
  this
• can take place, the fatty acid must get into the
• mitochondria. An enzyme called carnitine
• acyltransferase (CAT 1), located on the
• mitochondrial membrane, is the door that allows
  the
• fatty acids to enter the mitochondria. This
  process is
• the rate-limiting step in fatty acid oxidation.

outside mitochondria
inside mitochondria
? -oxidation
Acetyl-CoA
TCA Cycle
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• The NADH and FADH2 produced in the TCA cycle
• are sent to the Electron Transport System and
  used
• to create a proton gradient across the membrane
  of
• the mitochondria this potential energy provides
  the
• energy to convert ADP to ATP. 90 of ATP
• synthesis happens during electron transport.

The mobile part of the ETS is a
lipid-soluble compound called Coenzyme Q10
Q10
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• body fat
• ? ? CAFFEINE
• free fatty acids
• ? ? CARNITINE
• mitochondria
• ?
• beta-oxidation
• ?
• acetyl-CoA
• ?
• NADH, FADH
• ?
• electron transport system
• ? ? CoQ10
• ATP

As we discussed, any intervention that can shift
energy production toward a greater use of fat
can enhance endurance exercise performance. There
are 3 potential places where a substance could
be effective.
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Caffeine

• Caffeine is found in many
• common products. It is in
• highest concentration in
• coffee at about 175 mg
• per 5 oz. Since modern
• coffee places sell coffee in
• 12-20 oz. servings, you
• get 420-700 mg/cup at a
• place like Raos or
• Starbucks.
• Caffeine is also a listed
• (and unlisted) component
• of MANY supplements

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• Caffeine increases the breakdown of TG
• to FFA

Increase in blood FFA allows muscle more access
and can increase the uptake of FFA into
muscle. Increased fat oxidation less CHO
oxidation.
Thong et al (2002)
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Less CHO oxidation can spare muscle and/or liver
glycogen exercise longer at same intensity or
at a higher intensity for the same distance.
Fat use DOES increase when subjects are treated
with caffeine BUT effect is much smaller in
frequent users. Desensitization reduces
lipolytic effect. In many studies, caffeine (gt
300 mg) does enhance endurance performance.
Effect greater in caffeine- naive individuals.
Surprisingly, several studies show no rise in
fat use but performance is enhanced. Other
studies show higher fat use but performance not
enhanced.
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Side effects of caffeine include 1. blood
levels consistent with ingesting 4-5 small cups
of coffee can result in a positive drug test
(urine levels greater than 12 ug/ml). 2.
caffeine is a diuretic increased water loss
greater likelihood of dehydration. 3. in large
quantities can cause cardiac arrhythmia,
tachycardia. Also may result in mental confusion.
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Caffeine also enhances performance of short
exercise tasks requiring power/speed. Improves
mental performance (recall, reflexes, etc.). Can
improvements on these types of tasks be
explained by increased availability of
FFA? Probably not, time frame too short for
physiologically relevant contribution of fat to
energy production. More likely related to
action of caffeine as general CNS stimulant.
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Caffeine Doping Extra Info

• The International Olympic Committee took caffeine
  off the banned list in January 2004. Urinary
  levels up to a concentration of 12 mg/liter were
  acceptable, representing casual use. Levels above
  this are viewed as achieved through a deliberate
  attempt at doping by the athlete. Approximately
  1000mg of caffeine (about 8 cups of coffee) would
  be required to exceed the current IOC limit, but
  it is very important to note that people can
  metabolize caffeine at very different rates.
  Differences in metabolism, medications, and
  certain diseases may significantly alter the rate
  in which caffeine is cleared from the body. Some
  athletes came close to flunking the drug test
  after ingesting only 350mg.

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• Carnitine is an amino acid-like molecule that is
• found in meat products (muscle). It can
• also be synthesized. Vegetarians usually have
• normal levels of muscle carnitine.
• Carnitine functions as part of the carnitine acyl
  
• transferase enzymes (CAT-I and CPT-II) that
• regulate entry of long chain fatty acids from the
  
• cytosol to the mitochondria.

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• IF transport through CAT-1 is the rate-limiting
  step in
• the ability to oxidize FFA for energy, increasing
  the
• quantity of carnitine may benefit performance.
• More carnitine greater transport of fatty acids
  into
• mitochondria more fat oxidation less
• carbohydrate oxidation spare glycogen use
• and enhance endurance performance.
• glycogen triglyceride
• ? ?
• glucose free fatty acid
• ? ?
• pyruvate fatty acyl CoA
• ? ?
• acetyl-CoA

TCA cycle
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• Studies about 20 different studies
• done looking at the impact of
• carnitine supplementation on some
• aspect of human performance.
• Some show benefits, some show no effect
• Common theme in studies they were
• generally done in Italy and funded by Sigma-
• Tau, an Italian pharmaceutical company that
• produces/sells carnitine.

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• Studies about 20 different studies
• done looking at the impact of
• carnitine supplementation on some
• aspect of human performance.
• Some show benefits, some show no effect
• Most well-controlled, double-blind studies
• show no positive effects of carnitine on
• performance.

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Research

• Long-term oral treatment of healthy adults with
  L-carnitine is not associated with a significant
  increase in the muscle carnitine content,
  mitochondrial proliferation, or physical
  performance. (Wachter 02)

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If it were possible, increasing levels of CAT-1
would be more effective. Despite lack of evidence
showing efficacy, carnitine remains very popular
as both a supplement for athletic performance and
for weight maintenance, overall health and
longevity.
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• Coenzyme Q10 (CoQ10) is found in many animal
• products and synthesized by the body. Consists of
  a
• polar head and a very long hydrocarbon tail.
• Carries electrons among enzyme
• complexes in the ETS

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• As a part of the system that is mobile, some
• scientists believe that CoQ10 levels limit the
  rate at
• which energy can be produced in the ETS.
• If true, raising levels of CoQ10 could increase
  ability
• to produce energy oxidatively
• Does not translate directly into more fat use but
  
• greater ability to oxidize the NADH and FADH
• produced in the TCA cycle means less need to
• produce energy by glycolysis less glycogen use

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• Blood levels of CoQ10 tend to be lower in very
• active individuals. Used as evidence that
• athletes are relatively CoQ10-deficient.
• Many studies on CoQ10 and performance all show
• increase in blood levels of CoQ10 but very few
• show a positive effect.
• Likely that blood levels of CoQ10 do not reflect
  what
• is happening inside muscle mitochondria.

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• It was speculated that the non-significant
  effects of supplementation in healthy, non
  CoQ(10)-deficient men could be due to either that
  the mitochondrial membrane is normally saturated
  with CoQ(10) (Zhou 05)

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In addition to its use by athletes, Coenzyme Q10
is an extremely popular supplement for
everything from impotence to longevity. It is
widely used during open heart surgery to prevent
free radical damage to the heart when blood flow
is restarted.
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• Of the 3 Cs (caffeine, carnitine, CoQ10),
• only caffeine has been reliably shown to
• benefit athletic performance.
• Side-effects and de-sensitization with repeated
  use.
• Still remains very popular among athletes (and
  non-
• athletes) of all types.
• Military scientists very active in research on
  caffeine,
• especially the development of novel delivery
• systems (e.g. transdermal patch).