New research suggests that caffeine intake (i.e., a capsule containing 4 mg/kg) has an ergogenic effect on dynamic visual acuity (DVA) — the ability to resolve fine details when there is relative motion between the target and the observer — which may be of special relevance in real-word contexts that require to accurately and rapidly detect moving targets (e.g., sports, driving, or piloting).
“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.
The study involved 21 low caffeine consumers (11 women and 10 men; mean age – 22.5 years; mean weight – 68.4 kg).
On two separate days, half of the study’s participants ingested a caffeine capsule (4mg/kg) while the other half ingested a placebo capsule.
Using a computer-based test, each participant’s dynamic visual acuity skills were measured before and 60 min after caffeine ingestion.
The researchers found that participants who had ingested the caffeine capsules showed significantly greater accuracy and faster speed when identifying smaller moving stimuli, inferring caffeine positively influences participants’ stimulus processing and decision-making.
Eye movement velocity and contrast sensitivity, which are implicated in dynamic visual acuity performance, were also sensitive to caffeine intake.
“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.”
The results were published in the journal Psychopharmacology.
B. Redondo et al. 2021. Effects of caffeine ingestion on dynamic visual acuity: a placebo-controlled, double-blind, balanced-crossover study in low caffeine consumers. Psychopharmacology 238, 3391-3398; doi: 10.1007/s00213-021-05953-1
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