The impact of high- and moderate-intensity exercise on near-point of convergence metrics

ABSTRACT

Background: Near point of convergence (NPC) assesses the vergence ability of the visuo-oculomotor system; however, little is known regarding: the extent and duration exercise impacts NPC and the between- and within-day reliability of NPC metrics.

Methods: An accommodative ruler with a miniature Snellen chart was placed upon the philtrum (upper lip). Participants (n=9) focused upon a ‘V’ sized 20/20, while the chart was moved at ~1–2 cm/s toward and away from the eyes (twice in each direction). Testing commenced at 8:00am with NPC measures being collected at baseline before three randomized conditions with serial follow-ups occurring at six post-condition timepoints (0–8 hours following). The conditions consisted of 25-minutes high-intensity intervals (10, one-minute intervals at ~85-90% heart-rate reserve), 45-minutes of moderate-intensity exercise (at ~50-60% heart-rate reserve), and a control condition (30-minutes quiet rest).

Results: NPC was not impacted across any of the three conditions (all p > .59). Additionally, NPC measures between baseline conditions and across the control condition displayed very high levels of within-day and between-day reliability (coefficient of variation <3.8%).

Conclusions: Future NPC measures using an accommodative ruler can be taken immediately following exercise and may be pertinent as a complementary tool in the future sideline screening of concussion.

KEYWORDS:

• Near point of convergence/divergence
• diplopia
• exercise
• acute recovery
• vision

Disclosure Statement

The authors report no conflicts of interest and have no proprietary interest in any of the materials mentioned in this article.

Additional information

Funding

The work was supported through the Canada Foundation for Innovation [30979], Mitacs [IT03862], the Natural Science and Engineering Research Council of Canada [1274829, 464009, 477210] and the Innovations in Wellness Fund [65R25912].