There is a vast range of options for wearable lactate sensors for sports and fitness, but there has been no advance in the awareness of this nascent technology—the debate still remains over the benefit of monitoring lactate in sweat.
A new study published in ACS Sensors, a journal of the American Chemical Society, reports that despite a recent record of contradictory—and incomplete—evidence, sports physiology is focusing on whether this technology can enhance performance while avoiding injury.
According to the co-authors of the study, Gaston Crespo and Maria Cuartero, associate and assistant professors at KTH Royal Institute of Technology, the potential of lactate sensor technology, of being able to identify in real-time if an athlete is exerting themselves too much or too little, remains just out of range for a few underlying reasons.
There isn’t enough evidence about the connection between sport performance and lactate concentration. There is also a lack of understanding about the link between lactate in the sweat and lactate in the bloodstream, as well as the connections with other biomarkers.
Gaston Crespo, Associate Professor, KTH Royal Institute of Technology
Lactate, or so-called lactic acid, is a byproduct of anaerobic respiration when muscle cells transform glucose to energy in the absence of oxygen. Sampling the blood of the athlete helps sports scientists and coaches to assess an athlete’s conditioning and fitness. However, the elusive gold standard would be a sensor that tracks lactate in real-time.
In the scientists’ review of the present study, they indicate that there are no universally-accepted methods so far for sweat collection and analysis that offer reliable data for determining a correlation between blood lactate and sweat lactate.
The study provides an analysis of the present state of electrochemical lactate sensors combined in wearables, and it lists main features to be enhanced or altered toward the final success of the technology.
Amongst these is the scientists’ technology, which was reported in the same journal during July: an epidermal patch consisting of a lactate biosensor, as well as pH and temperature sensors. The paper was highlighted in ACS Sensors as one of the journal’s most-read articles since its publication.
Temperature and pH essentially impact electrochemical readings of lactate, leading to measurements that are much lower than what would be expected. Hence, the scientists designed an approach to separate the lactate in sweat with the help of an exclusively designed polymer layer in the sensor’s outer part.
The polymer safeguards the reactive enzyme in the sensor from reacting to anything but lactate, and it allows the sensor to read higher lactate concentrations compared to what electrochemical sensors generally do.
The System’s Future is Two-Fold: Commercial and Experimental
According to Crespo, the sensor is being commercially developed through collaboration with a new company, IDRO BV, which the scientists founded with a grant from the European Institute of Innovation and Technology (EIT).
Moreover, collaboration with scientists from Dalarna University in Sweden has helped use the technology to perform on-body tests, where blood and sweat measurements are being linked with the sport performance of athletes. Besides, sweat samples are being gathered for a laboratory-based validation of the sensor performance.
Scientists from KTH are collaborating with Dalarna University in Sweden to perform full-body tests, where they aspire to answer the main questions that arise in their latest paper, for example, if lactate production relies on active muscles instead of passive ones.
Hoovels, K. V., et al. (2021) Can Wearable Sweat Lactate Sensors Contribute to Sports Physiology? ACS Sensors. doi.org/10.1021/acssensors.1c01403.