New research shows that caffeine intake positively affects dynamic visual acuity and resolves fine details where a relative motion exists between the target and the observer.
At a glance:
- Caffeine has long been known to boost performance during physical exercise.
- New research suggests that caffeine intake has an ergogenic effect on dynamic visual acuity (DVA).
- The placebo-controlled, double-blind, and balanced crossover study recruited 21 low caffeine consumers.
- Researchers found a greater accuracy for both the horizontal and random motion paths of DVA after caffeine ingestion.
What is caffeine?
Caffeine is a naturally occurring psychoactive compound commonly found in fruits, leaves, and beans of coffee, tea, cacao, and guarana plants. The compound is known for its modulatory effect on cognitive and physical performances. By inhibiting the action of adenosine on its receptor, caffeine prevents adenosine-induced drowsiness—the known mechanism of action to explain the biological effects of the compound.
The compound also stimulates thermogenesis and fat oxidation through inhibition of phosphodiesterase, an enzyme that degrades intracellular cyclic AMP, and through antagonism of the negative modulatory effect of adenosine on increased noradrenaline release (Dulloo et al., 1992).
New research (Redondo et al., 2021) now shows that caffeine consumption may influence the ability to detect moving objects. The skill, also known as dynamic visual acuity (DVA), is critical in sports where an athlete needs to react quickly to track moving objects, hitting or catching a moving ball in sports like cricket or baseball.
The researchers used a single letter “Tumbling E” chart in black on a white background at four orientations (right, left, up, and down) in the study. The participants had to indicate the correct orientation of the branches of the letter E with the keyboard’s arrow keys.
“A lot of what happens in our environment is moving — like trying to cross a busy intersection as a pedestrian or finding something on a shelf as you’re walking through the aisles of a grocery store,” said Dr. Kristine Dalton, a researcher in the School of Optometry & Vision Science at the University of Waterloo.
“Testing visual acuity under dynamic conditions can provide more information about our functional performance in these scenarios than traditional static visual acuity measurements alone.”
“While we already know that caffeine increases the velocity of rapid-eye movements, we wanted to further investigate how exactly caffeine enhances visual processing and facilitates the detection of moving visual stimuli by testing dynamic visual acuity,” said Dr. Beatríz Redondo, a researcher in the Department of Optics at the University of Granada.
Trial and results
The researchers recruited twenty-one low caffeine consumers (22.5 ± 1.6 years) in the randomized controlled trial. Following a random order on two different days, participants consumed either caffeine (4 mg/kg) or placebo. After 60 min of caffeine ingestion, the researchers assessed DVA using a recently validated software (moV& test, V&mp Vision Suite, Waterloo, Canada).
The researchers observed that participants who had consumed the caffeine capsules exhibited greater accuracy and faster speed when identifying more minor moving stimuli than those who had not consumed the tablets, and the difference was significant. The results show that caffeine consumption positively influences stimulus processing and decision-making skills.
Caffeine consumption also influenced eye movement velocity and contrast sensitivity, essential in dynamic visual acuity performance.
“Our findings show that caffeine consumption can actually be helpful for a person’s visual function by enhancing alertness and feelings of wakefulness,” Dr. Dalton said.
“This is especially true for those critical, everyday tasks, like driving, riding a bike or playing sports, that require us to attend to detailed information in moving objects when making decisions.”
Dulloo, A. G., J. Seydoux, et al. (1992). “Potentiation of the thermogenic antiobesity effects of ephedrine by dietary methylxanthines: adenosine antagonism or phosphodiesterase inhibition?” Metabolism 41(11): 1233-1241. 10.1016/0026-0495(92)90015-3. https://www.ncbi.nlm.nih.gov/pubmed/1435297
Redondo, B., R. Jiménez, et al. (2021). “Effects of caffeine ingestion on dynamic visual acuity: a placebo-controlled, double-blind, balanced-crossover study in low caffeine consumers.” Psychopharmacology (Berl) 238(12): 3391-3398. 10.1007/s00213-021-05953-1.