Exercise may limit usefulness of visual tasks in sports-related concussion assessments
Key takeaways:
- A single bout of maximal aerobic exercise affected performance in all visual tasks except visual memory.
- Therefore, these tasks may need to be used with caution in sideline sports-related concussion assessments.
A single bout of maximal aerobic exercise affected performance across multiple visual tasks in women, bringing into question their usefulness in sideline concussion assessments, according to a study published in Journal of Optometry.
“Based on the existing literature, it is essential to acknowledge that conducting visual function tests during sporting events could yield different results due to the physical demands of sports, impacting the visual system,” Brandon S. Shaw, PhD, of the School of Sport, Rehabilitation and Exercise Sciences at University of Essex in the U.K., and colleagues wrote. “This is because during exercise or sport, the human body undergoes a plethora of changes, such as modifications in blood pressure, blood glucose, blood oxygenation, intraocular pressure and ocular perfusion pressure, all of which can impact the visual system.
“Acute exercise can either enhance or deteriorate visual performance, further complicating assessments conducted immediately post-head trauma,” they added.
To determine the effect of a single bout of maximal aerobic exercise on acute visual performance, Shaw and colleagues randomly assigned 79 sedentary women with a minimum visual acuity of 20/20 to an experimental group (n = 39; mean age, 24.5 ± 2.7 years) or control group (n = 40; mean age, 24.5 ± 2.8 years), all of whom had no previous experience with sport vision testing and used no medication that could affect the physical or visual assessments.
All participants underwent an identical visual task test battery that assessed accommodation facility, saccadic eye movement, speed of recognition, hand-eye coordination, peripheral awareness and visual memory.
Following a 2-week washout period, both the experimental and control groups were reassessed for inclusionary and exclusionary criteria and underwent a second visual task test battery. Prior to doing so, the experimental group engaged in a single bout of incremental maximal treadmill exercise.
After the experimental group exercised, the researchers observed significant improvements in accommodation facility, saccadic eye movement, speed of recognition, peripheral awareness and hand-eye coordination (all P < .001), but not in visual memory.
“Given the relative acute ‘stability’ of visual memory following exercise, it may be that this visual task should be considered for inclusion in sports-related concussion assessments as it is unlikely to be affected by previous exercise,” the researchers wrote. “However, further research is needed to confirm this.”
In the control group, they observed significant differences for accommodation facility (P = .005; small effect size), speed of recognition (P < .001; medium effect size) and hand-eye coordination (P = .038; small effect size), but not for saccadic eye movement, peripheral awareness or visual memory.
Results of repeated measures analysis of variance to measure the acute effects of exercise of visual performance revealed a significant main effect on all factors as a universal visual task performance (P < .001).
Lastly, a single-factor model based on all visual tasks except visual memory approximated the root mean square error of approximation threshold value at 0.112, according to the researchers.
Shaw and colleagues acknowledged several study limitations, including an initial lack of binocular testing at the pretest optometric assessment and the use of a women-only sample, limiting applicability to men.
“Clinically, these results provide caution for the use or inclusion of multiple visual tests within comprehensive and more complex sideline sports-related concussion assessments for return to play decisions,” they wrote. “This is especially relevant given the subtle changes in ocular motor function that occur with concussion.”
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