A review of caffeine's effects on cognitive, physical and occupational performance.
Caffeine is consumed by over 80% of U.S. adults. This review examines the effects caffeine has on cognitive and physical function, since most real-world activities require complex decision making, motor processing and movement. Caffeine exerts its effects by blocking adenosine receptors. Following low (∼40mg or ∼0.5mgkg-1) to moderate (∼300mg or 4mgkg-1) caffeine doses, alertness, vigilance, attention, reaction time and attention improve, but less consistent effects are observed on memory and higher-order executive function, such as judgment and decision making. Effects on physical performance on a vast array of physical performance metrics such as time-to-exhaustion, time-trial, muscle strength and endurance, and high-intensity sprints typical of team sports are evident following doses that exceed about 200mg (∼3mgkg-1). Many occupations, including military, first responders, transport workers and factory shift workers, require optimal physical and cognitive function to ensure success, workplace safety and productivity. In these circumstances, that may include restricted sleep, repeated administration of caffeine is an effective strategy to maintain physical and cognitive capabilities.
TM McLellan Research Inc., Stouffville, ON L4A 8A7, CANADA, Canada. Electronic address: DrTom.McLellan@gmail.com.
Tom M
TM
McLellan
Oak Ridge Institute for Science and Education, Belcamp, MD 21017, USA. Electronic address: drjohncaldwell@gmail.com.
John A
JA
Caldwell
Military Nutrition Division, US Army Research Institute of Environmental Medicine (USARIEM), Natick, MA 01760-5007, USA. Electronic address: harris.r.lieberman.civ@mail.mil.
Harris R
HR
Lieberman
D002110:Caffeine; D000697:Central Nervous System Stimulants; D003071:Cognition; D006801:Humans; D011930:Reaction Time; D012890:Sleep; D014851:Wakefulness
D000697:Central Nervous System Stimulants; D002110:Caffeine
Adenosine receptors; Attention; Energy drinks; High-intensity sprints; Muscle strength and power; Reaction time; Restricted sleep; Sustained wakefulness; Time-to-exhaustion; Time-trial; Vigilance