Caffeine and Creatine Lecture

what is the most widely consumed legal psychoactive agent

caffeine

where does caffeine occur naturally

dozens of plants, can also be synthetically made

typical caffeine dose in foods/drinks

~30-300 mg depending on the product

at what dose can caffeine become toxic

around 15 mg/kg body weight

what receptor does caffeine compete with

adenosine

blocking adenosine has what effect

reduces adenosine action -> increases alertness

how quickly does caffeine appear in the bloodstream

5-15 minutes

when does caffeine peak in the bloodsteam

40-80 minutes

what dose of caffeine shows ergogenic effects

~2-6 mg/kg body weight

what is considered a high dose of caffeine

~10-13 mg/kg

side effects of high caffeine intake

elevated HR, increased catecholamines/lactate/FFAs, GI distress, jitteriness, anxiety, and mental confusion

does caffeine >9 mg/kg improve performance further

no evidence of additional benefit

why is caffeine dosing difficult to control

energy drinks contain other stimulants; coffee varies by preparation and bean type

what percentage of the body's creatine is in skeletal muscle

about 95%

in what form is most creatine stored in muscle

phosphocreatine (PCr)

what is PCr's main function

rapidly rephosphorylate ADP -> ATP

where can creatine come from

diet and endogenous production in liver and kidneys

what is the typical creatine loading protocol

20 g/day for 5-7 days -> then 3-5 g/day maintenance

what happens when creatine stores are full

excess converts to creatinine and is excreted

why might creatine loading increase lean body mass

water retension -> increased total body water

what effect does creatine have on time to fatigue

increases time to fatigue in short bouts

what types of performance improve with creatine

power/strength in single or repeated bouts <2.5 minutes

why do long-term improvements occur

enhanced ability to resist fatigue -> better training adaptations

does creatine benefit long-duration endurance exercise

no noted benefit

is creatine safe

yes, generally safe when taken in recommended amounts

how long have studies followed creatine users without negative effects

up to 4 years

who may be at risk with long-term high doses of creatine

individuals with kidney disease

how may creatine help patients with muscular dystrophy

combined with resistance training -> improved function

how may creatine help with mental health and sleep deprivation

supports brain energetics

what injury type is creatine being tested to reduce damage in

concussion and traumatic brain injury (TBI)

when was creatine removed from the WADA banned list

2004

what caffeine limit does the NCAA allow in urine samples

15 ug/ml

is creatine banned by the NCAA or WADA

no

can NCAA institutions provide creatine supplements to athletes

no, they are not allowed to supply it