Extreme athletes often hit a point during competition wherein their bodies simply can't produce the requisite amount of energy to sustain their current output, commonly known as "hitting the wall". While much research has been done towards countering this event (looking at you, Gatorade), actively estimating when the wall will hit remains a cumbersome exercise. But this new biosensor has a non-invasive way of knowing exactly when you'll run out of steam.
The sensor sticks onto your skin like a temporary tattoo and measures the amount of lactate that your body produces in its sweat. Unlike its better-known cousin lactic acid, which only forms during strenuous anaerobic exertion, lactate forms during both mild aerobic exercises and strenuous anaerobic variety. Once your body reaches a specific lactate threshold, it shuts down regardless of your steeled willpower, and you hit the proverbial wall. By measuring how long and how hard you work before your body quits, the sensor can help athletes train more effectively and keep soldiers on patrol from over exerting themselves.
The research team recently published their findings in the journal, Analytical Chemistry, and hope to further refine the device by correlating lactate levels in the sweat with lactate levels in the blood. [ACS via R&D Mag]