For an athlete, understanding and knowing your lactate threshold is key to knowing if your training is working or not. But in order for you to know what yours is, you'd have to get strapped up to machines like these:
With BSX Insight, you wear something that looks like a compression sock
and it periodically shines a low-power LED into your skin to analyze the composition of the underlying muscle. Using the right algorithms and a sensor, it can detect minute changes in light. The device then tells you how much lactic acid is in your muscle tissue at any given moment.