Age was the clearest pattern
Reaction times rose by about six milliseconds for each year of age among healthy Greenlander adults. The pattern appeared across all four limbs tested: estimated increases were 5.5 milliseconds per year in the dominant upper limb, 6.3 in the non-dominant upper limb, 6.4 in the dominant lower limb and 5.6 in the non-dominant lower limb.
The finding is an association, not evidence that ageing caused slower responses. The research was cross-sectional, meaning it measured participants at one point rather than following them over time, so it cannot establish cause and effect.
How the reaction-time test worked
The study included 114 healthy adults, 72 women and 42 men, recruited in Nuuk and Sisimiut during autumn 2023. Participants had to be at least 20 years old and have at least one parent born in Greenland. The group included 56 people from Nuuk and 58 from Sisimiut. Recruitment was feasibility-based across healthcare and community settings, using mail and social-media or flyer outreach.
Researchers used a portable Wii Balance Board with Fysiometer software. The system recorded reaction time in milliseconds from visual-stimulus onset to board contact for all four limbs, with the stimulus side presented in random order. Participants provided written informed consent, and the study received ethics approval in Greenland.
Dominance did not change the result
The dominant side did not produce a measurable speed advantage. Reaction times did not differ between dominant and non-dominant upper limbs, or between the corresponding lower limbs. The p-value was 0.7 for the upper-limb comparison and 0.5 for the lower-limb comparison.
After adjustment, age and height were the only characteristics described as important. Height was associated with reaction time in both upper and lower limbs, while sex did not influence the result after adjustment.
The researchers had expected Greenlanders to have faster reaction times than a Scandinavian population. Instead, reaction times were numerically higher, meaning slower, across all reported age groups and extremities than in an external historical Scandinavian dataset. Because this was not a concurrent control comparison, it should not be treated as a direct head-to-head test between the populations.
What the results do not establish
Several features narrow what can be concluded. The volunteers came from two towns and were recruited through community and healthcare channels, so the results may not extend to villages and settlements. The test used visual stimulation only, and the study did not directly measure balance adaptation, gait, postural responses, sensory integration or falls. It also did not directly measure environmental exposure, so the findings do not show that Arctic terrain made reactions faster or slower.
The analysis was exploratory. The authors did not perform an a priori sample-size calculation because prior Greenlandic reaction-time data were unavailable, and they used paired-sample t-tests, Pearson correlations, and univariate and multivariable linear regression. Two observations more than two standard deviations above the age-specific average were excluded after review; follow-up identified cerebral tuberculosis in one participant and inability to follow instructions in the other.
The authors interpret the age pattern as similar to patterns observed in Scandinavians, while noting that the study found no faster Greenlandic reaction times despite the physically demanding terrain described in its interpretation. They speculate that other motor adaptations or sensory responses might compensate, but say the mechanisms remain uncertain. The findings provide descriptive reaction-time data, not evidence that Arctic living improves or worsens balance or falls.
Further work would need harmonized Greenlandic and Scandinavian datasets, tests involving tactile or auditory stimuli, and direct measures of balance, gait, postural responses and sensory integration. Studies in villages and settlements, along with prospective follow-up of falls, could show whether these reaction-time patterns have broader relevance.
The authors state that raw data supporting the conclusions will be made available without undue reservation. The study was funded by the Karen Elise Jensens Fond, which reported no influence on design, data collection, analysis or interpretation, writing, or the publication decision. One author was a Fysiometer shareholder and had no role in recruitment, data collection or statistical analysis; the other authors reported no relevant commercial or financial relationships.
Paper data and sources
Original title: Quantification of reaction time in an Arctic population
Authors: Bjerg J, Rønberg M, Jørgensen M, Andersen S
Journal/Repository: Frontiers in sports and active living
Status: Peer-reviewed
First online: 2026-10-09
DOI: Not available
Original paper · Full text