Lecture 7 - Stimulant supplements

Question 1

State 4 effects of a stimulant

Answer 1

• Mental function and behaviour
• Produces excitement and euphoria
• Reduced sensation of fatigue
• Increase in motor activity

Question 2

What does a stimulant have to stimulate (in definition)

Answer 2

Central Nervous System

Question 3

State a problem with Ma Huang/ephedra

Answer 3

Can often be contaminated

Question 4

Chemical name of caffeine

Answer 4

1, 3, 7 trymethylxanthine

Question 5

What is the half life of caffeine?

Answer 5

5 hours

Question 6

How long should a capsule be taken before effect?

Answer 6

1 hour

Question 7

State the quickest method of caffeine ingestion

Answer 7

Caffeine chewing gun (15-30 mins)

Question 8

State the general caffeine dose

Answer 8

6mg.kg.BW

Question 9

Explain the central effects of caffeine

Answer 9

Caffeine is an ‘adenosine receptor antagonist’, therefore stops adenosine from binding to receptors, making us less sleepy and more alert. Reducing the rate of perceived exertion
Evidence of cognitive effects, better alertness, decision making and reaction time

Question 10

What sports are advised to use caffeine supplementation?

Answer 10

Sports where central fatigue is a big performance indicator: exercise in the heat/altitude

• Has great benefit on endurance exercise
• Has great benefit of repeated sprint performance
• Not single sprint performance

Question 11

Explain the peripheral effects of caffeine

Answer 11

• Altered extracellular potassium level due to improved activity in sodium potassium pump, pumping potassium back to the muscle, meaning there is less extracellular accumulation, therefore resting membrane potential is better preserved so muscle can remain more excitable
• Increased release of calcium of sarcoplasmic reticulum resulting in more forceful muscle contractions and faster rate of force development

Question 12

Side effects of caffeine

Answer 12

Insomnia
Palpations
Agitation
- Importantly not a diuretic and therefore not a cause of dehydration

Question 13

How would regular coffee consumption influence caffeine effectiveness?

Answer 13

Regular caffeine intake allows your body to adapt to the effects, therefore making it less effective

Question 14

What is the improvement in performance seen when taken before exercise?

Answer 14

2.2±3.2%

Question 15

What is the improvement in performance seen when taken before and during exercise?

Answer 15

4.3±5.3%

Question 16

What type of contraction is caffeine most effective with in resistance exercise?

Answer 16

Dynamic > isometric > concentric