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Sports Nutrition > W7 - Stimulant Supplements incl. Caffeine (NEW) > Flashcards

W7 - Stimulant Supplements incl. Caffeine (NEW) Flashcards

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Sports Trivia flashcards
1
Q

Stimulants stimulate the CNS with a marked effect on what?

A

Mental function + behaviour

Produces excitement + euphoria

⬇️ sensation of fatigue

⬆️ motor activity

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2
Q

Roughly how long does it take for caffeine to reach peak plasma concentration after consumption?

What does this mean?

A

~1hr

Means people tend to take caffeine an hour prior to our req to get ergogenic effects.

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3
Q

What is caffeines half life

A

~5hrs

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4
Q

What is the half life of caffeine informed by to some extent?

A

Liver function

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5
Q

What happens in regards to caffeine half life with someone who has hepatic dysfunction?

A

Tend to have a longer half life due to 1 of livers key roles being to detoxify substances like caffeine.

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6
Q

As well as liver function, what else has a role in influencing the metabolism of caffeine?

A

Habituation

  • Those who are caffeine naive will respond differently.
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7
Q

What % of athletes have been reported to consuming caffeine before or during competitive events?

A

75-90%

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8
Q

What is the habitual consumption of caffeine among athletes?

A

~300mg/day from just normal dietary sources.

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9
Q

What are the 3 mechanisms by which caffeine operates?

A

⬆️ central drive from brain to muscle

⬆️ FA levels in blood

Influencing kinetics of Ca2+ in muscle

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10
Q

MECHANISMS BY WHICH CAFFEINE OPERATES

Central effects (⬆️ central drive from brain to muscle)

What is meant by this?

A

Adenosine has a calming effect.

Caffeine is suggested to bind to adenosine receptors in the brain.

This displaces adenosine from the receptors to give a stimulant effect.

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11
Q

MECHANISMS BY WHICH CAFFEINE OPERATES

⬆️ FA levels in blood

How?

A

Due to activating the sympathetic NS to ⬆️ rate of lipolysis.

⬆️ release of noradrenaline through activation of sympathetic NS.

⬆️ noradrenaline activates LPL enzymes responsible for lipolysis.

⬆️ Lipolysis = ⬆️ glycerol + FA into blood.

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12
Q

MECHANISMS BY WHICH CAFFEINE OPERATES

Influence of Ca2+ kinetics in muscle

Explain

A

Could be promoting the reuptake of Ca2+ into the sarcoplasmic reticulum.

= Might ⬆️ contractility of muscles = more powerful contraction.

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13
Q

Some evidence to suggest that caffeine might result in lower extracellular K+

Why is this beneficial?

A

High intensity exercise ⬆️ extracellular K+ (which actually contributes to the development of fatigue).

So… caffeine can help preserve the excitability of the muscle = improve perf.

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14
Q

Overall effects of caffeine

A

⬆️ max + submax perf

Delays fatigue

May ⬆️ contractility

⬆️ voluntary activation

== Particularly helpful where central fatigue is a key cause of poor performance?

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15
Q

What impact does caffeine have on lipolysis?

A

Stimulates it at REST

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16
Q

Does caffeine have any metabolic effects?

A

No

17
Q

What impact does caffeine have in plasma K+?

A

Lowers it

18
Q

According to Shen et al, 2019, what effect does caffeine have on TT performance?

A

Enhances it by ~3% compared to placebo.

19
Q

Are the magnitude of the effects of caffeine influenced by the characteristics of the participants?

A

no

20
Q

What is caffeine supplementation not effective for?

A

800m perf

21
Q

Effect of caffeine on team sports perf

A

Improves it

22
Q

Performance effects summary of caffeine supplementation

A

Improved endurance perf.

Improved team sport performance

Improvement in movement velocity + resistance exercise performance.

23
Q

What is the effective dose of caffeine?

A

3-6 mg per kg of body weight

24
Q

What does the exact dose of caffeine supplementation depend on?

A

Sex, mode, timing + habituation

25
Q

What are the modes for caffeine supplementation

A

Ingestion (pill or drink)

Chewing gum

Patch

26
Q

Diuretic effects from caffeine supplementation

A

Moderate diuretic effects at rest but NOT in exercise trials.

Females are more susceptible

27
Q

Alternative stimulants to caffeine

A

Guarana

Yerba Mate

Ginseng

Sports Nutrition (14 decks)

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