Portable biosensor warns when athletes are about to 'hit the wall'

Scientists have reportedly developed a biosensor which when applied to the human skin can alert marathoners, competitive bikers and other 'extreme' athletes that they're about to 'bonk' or 'hit the wall', a new study has revealed.

According to the study, the first human tests of the sensor could also help soldiers and others who engage in intense exercise along with their trainers monitor stamina and fitness.

Researcher Joseph Wang and colleagues explained that the sensor monitors lactate, a form of lactic acid released in sweat. Lactate forms when the muscles need more energy than the body can supply from the 'aerobic' respiration that suffices during mild exercise. The body shifts to "anaerobic" metabolism, producing lactic acid and lactate.

The researchers found that it helps for a while, but lactate builds up in the body, causing extreme fatigue and the infamous 'bonking out', where an athlete just cannot continue.

Wang's team sought to develop a better approach as the current methods of measuring lactate are cumbersome, require blood samples or do not give instant results.

The researchers described the first human tests of a lactate sensor applied to the skin like a temporary tattoo that stays on and flexes with body movements showed that the sensor accurately measured lactate levels in sweat during exercise.

Wang said that such skin-worn metabolite biosensors could lead to useful insights into physical performance and overall physiological status, hence offering considerable promise for diverse sport, military, and biomedical applications adding that the future research will further correlate sweat lactate levels with fitness, performance and blood lactate levels.