https://www.sciencedaily.com/releases/2021/02/210217151031.htm

For instance, lactate, which is produced during the breakdown of glucose in the absence of oxygen in tissues, is an important biomarker present in both blood and sweat that reflects the intensity of physical exercise done as well as the oxygenation of muscles. During exercise, muscles requiring energy can rapidly run out of oxygen and fall back to a different metabolic pathway that provides energy at the 'cost' of accumulating lactate, which causes pain and fatigue. Lactate is then released into the bloodstream and part of it is eliminated through sweat. This means that a wearable chemical sensor could measure the concentration of lactate in sweat to give a real-time picture of the intensity of exercise or the condition of muscles.

Although lactate-measuring wearable sensors have already been proposed, most of them are composed of materials that can cause irritation of the skin. To address this problem, a team of scientists in Japan recently carried out a study to bring us a more comfortable and practical sensor. Their work, which was published in Electrochimica Acta, was led by Associate Professor Isao Shitanda, Mr. Masaya Mitsumoto, and Dr. Noya Loew from the Department of Pure and Applied Chemistry at the Tokyo University of Science, Japan.