Lecture 6- Caffeine Flashcards
What is the background of Caffeine?
-Sources incl coffee, tea, chocolate. 80/90% of people consume regularly.
-Av daily intake is 200-400mg w/ one cup coffee=100mg
What is the pharmacology of Caffeine?
-Caffeine absorbed through gastrointestinal tract in 30-60mins.
-Caffeine converted to metabolites by the liver as 95% excreted in urine, 2-5% in faeces and rest through saliva. -Caffeine acts primarily by blocking adenosine receptors in the brain.
What is the half life of Caffeine?
-Plasma half-life of 4hours but is often topped up. People have rising concentration in blood plasma throughout day.
What are the behavioural effects of Caffeine?
-Caffeine has biphasic effects in rats/mice Low dose - Stimulant, ↑ locomotor activity High dose - Reversed, ↓ locomotor activity
-Low-to-intermediate doses result in variety of pos subjective effects eg increased alertness, reduced tension, reduced reaction time.
How can caffeine effect sports performance?
Enhances- Modest but signif benefits to muscle strength, power, endurance (Grgic et al., 2018, 2019,2020).
May not be actual effects as alertness and muscle tensions could be through a placebo effect (Elhaj, 2021)
What is the Tolerance of caffeine?
Tolerance to subjective effects of caffeine (Griffiths & Mumford,1995) found heavy drinkers can consume coffee before bed due to increased tolerance.
What happens with Abstinence from caffeine?
Leads to withdrawal symptoms (Griffiths et al., 1990) found in those with less than 100mg a day drinker. Leads to headaches, drowsiness, impaired concentration.
Withdrawal effects last a few days but will eventually dissipate.
