(This article was originally published on BikeRadar)


In mid-December the first BSXinsight wearable lactate threshold monitors will begin shipping.

Announced back in March via a Kickstarter campaign, the US$369 devices slip inside a calf compression sleeve, where data is recorded for post-workout upload via a smartphone app.

The end result, the company claims, is lactate threshold data that can inform training, previously only available to athletes via pin-prick blood tests done in medical centres and high-end training facilities.

Instead of the lab-standard model of measuring lactic acid in the blood every few minutes, the BSXinsight monitors muscle oxygenation via a light array shined into the calf. BSXinsight then runs an algorithm to give users lactate threshold (LT) power and heart rate numbers, plus training zones based on percentages of those figures. 

“Lactate threshold is the gold standard of performance testing, and the blood-testing method has been around for 50 years,” said Dustin Freckleton, president and co-founder of BSXinsight.

“Researchers discovered that by doing these incremental testings [as power and/or pace ramps up], taking blood samples along the way, and plotting results of lactate concentrations, you see this thick hockey stick curve towards the end. What that spike represents is the point at which the athlete moves from a predominantly aerobic state to an anaerobic state.” 

The original idea for BSXinsight was to beam real-time data to Garmin or other cycling computers via an ANT+ signal, and that may still come in version 2.0. The current unit, however, will be started and stopped by a smartphone app, and information will be transmitted to BSXinsight.com for analysis. The app walks riders through a progressive LT test, as well, to be done on a trainer with a power meter.

The BSXinsight measurement is done with standard LED bulbs.

“Each type of light interacts differently with different type of tissues,” Freckleton said. “Some reflect light, some are absorbed. Based on those interactions of distortion and absorption, we are able to determine what is going on inside the muscle.”