Sweat can be a reliable, non-invasive marker for monitoring exercise intensity. Electrolyte concentrations in sweat rise with effort, mirroring blood lactate patterns that have traditionally been used in sports science.
Advances in microfluidic technology are making it possible for wearable sweat sensors to monitor athletes in real time, outside of the lab. Previous studies have shown that sweat thresholds align closely with conventional measures such as blood lactate and ventilatory thresholds, making it a less invasive monitoring option.
How The Study Was Conducted
Researchers used the AbsoluteSweat brush-chip smart sweat analyser to measure sodium and potassium ions in sweat during incremental cycling tests. They compared these these results with blood lactate levels, the current gold standard for anaerobic threshold determination.
Fifty-five healthy male university students took part, representing a range of fitness levels. Some had more than three years of endurance training, others had over a year, while a third group had fewer than three months’ experience.
Each participant completed staged cycling tests, beginning at 100 watts and increasing every three minutes until exhaustion. Sweat was collected from the chest throughout, while fingertip blood samples were taken at each stage. Thresholds for sodium and potassium were identified at the point of their first significant rise above baseline.
What The Results Showed
The study found the sensors to be effective for predicting anaerobic threshold in medium- and high-fitness groups, where sweat-based measures showed strong alignment with blood lactate levels.
Correlations were moderate but statistically significant in the highly trained group. In those with a medium training history, the relationship was even stronger, with sweat thresholds closely tracking blood lactate thresholds.
The results obtained from the lower-fitness group were less reliable. Some correlation between blood lactate and sweat thresholds was observed, but it was inconsistent and failed to reach statistical significance in certain measures. This indicates the approach is less effective in individuals with limited training experience.
Further analysis confirmed these findings, with medium- and high-fitness participants showing close agreement between sweat and blood lactate measures, while the low-fitness group displayed weaker consistency.
Potential Impact
The findings show wearable sweat sensors could provide a practical, non-invasive alternative to traditional blood lactate testing for trained and moderately trained athletes.
While the technology is not yet suitable for all fitness levels, it has significant potential for endurance monitoring, performance assessment, and, in the future, everyday fitness and health.
Journal Reference
Luo, Z., Cao, M., Yan, L., Wang, J. (2025). Feasibility study of a novel wearable sweat sensor for anaerobic threshold determination. Scientific Reports, 15(1), 1-7. DOI: 10.1038/s41598-025-16559-4, https://www.nature.com/articles/s41598-025-16559-4
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