(This article was originally published on BikeRadar)
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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.”
While the company recommends using the unit for lactate threshold tests every few weeks, BSXinsight can also give daily feedback on muscle oxygenation levels. And, very much unlike lab LT test equipment, the unit is designed to be worn while riding outside.
But what exactly would a cyclist do with muscle oxygenation data? Freckleton and other physiologists admit that this is still exploratory, “similar to where heart-rate and power data were when they first came out,” Freckleton said. “There are no clear guidelines as to how to use it.”
The main premise and selling point of the device for now, however, is a way to measure or at least approximate a rider’s lactate threshold. In rough terms, lactate threshold is closely associated with the maximum level of sustainable output. If you can quantify this point, either in power output or in heart rate, you can more effectively train to improve it.
A common way to approximate a lactate threshold test without lab gear is to ride as hard as you can for an hour, then look at your average power and/or heart rate for the last 20min of the effort. This could be called your LT power or heart rate.
Traditional LT tests involve pricking a rider’s finger every few minutes to measure lactic concentration as power is incrementally increased
In the lab, lactate threshold tests typically involve ramping up power (usually by 20 watts every four minutes), and measuring lactic acid by taking small blood samples from the fingertip, looking for the point when lactic acid starts to spike.
The team behind BSXinsight are hoping that having a portable consumer unit that calculates lactate threshold without the pin pricks — or the lab costs — could find a market among cyclists, runners and triathletes.
The US$299 running version will pair with heart-rate monitors. The US$369 cycling version will pair with heart-rate monitors and power meters, via ANT+, but not cadence sensors, at least for now. And there is also a US$419 multisport version. All come with a 30-day money-back guarantee. BSXinsight is still awaiting product certification approval outside the US, but Freckleton expects to have that soon.