BSXinsight is the product of many years of research to develop a noninvasive technique for measuring lactate threshold. Our work actually started in the medical space as we worked with local university and hospital research centers to develop translational technologies.
Our efforts build on over a decade of scientific effort that has demonstrated the viability of using optical techniques (specifically near-infrared spectroscopy- aka NIRS) to noninvasively monitor athletic performance. NIRS uses light to measure and record activity inside living tissue in a safe manner. A light source shines a signal into the target which then passes through as it returns back to a detector. By changing the wavelengths of the light source, you can interrogate different molecules and chemical reactions. Depending on the physical and chemical properties of that tissue, the signal is distorted in measurable ways along its path. These distortions (also known as absorption spectra) are what contain the information we are able to process afterwards. For example, oxygenated and deoxygenated hemoglobin have very predictable and very distinct absorption spectra from each other. This allows us to measure their relative and absolute ratios as well as the total amount of blood flow through the target region.
At BSX Research Laboratories we have perfected both the front-end electronics as well as the post processing intelligence to do this with much higher quality and exponentially lower cost than other products. These oxygenation parameters are just some of the important predictors, along with others simultaneously collected by BSXinsight that feed into the algorithms for noninvasively measuring lactate threshold events.
Using NIRS to measure muscle oxygenation is a very standard practice which has been well documented in the scientific community for many years. As exercise physiologists though, we were further interested in understanding how changes to these oxygenation and other predictor variables occurred in real-time during exercise in peripheral muscle tissue, and how (if at all) these changes could be used to correlate with actionable training decisions that would benefit athletes of all levels.
We knew that lactate threshold was the gold standard for quantifying endurance performance and the best way for an athlete to personalize their training intensities for best outcomes. The problem with traditional lactate threshold measurement techniques, however, was it is a blood test and very expensive to complete. We wondered if we could somehow correlate the blood measurements we were noninvasively recording with the blood measurements of a traditional finger stick lactate threshold test.
In short, we hypothesized that there must be a predictable correlation between local blood oxygenation concentrations and lactate levels. The rationale went as such: during increasing intensity workloads the muscles are delivered and subsequently extract increasing quantities of oxygen in order to sustain their metabolic demands. As long as muscle oxygen delivery matches or is in excess of oxygen demand (ie extraction into the tissue) then muscle oxygenation levels remain relatively constant. But when demand exceeds delivery, the balance tips which leads to recordable desaturation event. At the same time, increased workloads begin to stress cellular aerobic machinery beyond their capacity to produce sufficient energy. This leads to an increased reliance on the anaerobic energy producing systems and increasing lactate production. As soon as production exceeds clearance, the measurable concentration of lactic acid increases. We believed there must be a predictable correlation between the downward flexion of blood oxygenation and upward flexion of lactate levels. Our hypothesized relationship looked something like this:
In this hypothesized graph the blue line represents SmO2 and the red line represents blood lactate over the course of an incremental exercise protocol. Raw data samples look like this:
For over three years, intensive R&D efforts at BSX Laboratories has successfully identified the relationship between muscle oxygenation events and blood lactate dynamics. Additionally, we have found ways to significantly improve these models using complimentary indicators which are collected and analyzed during and Assessment Protocol. Through these efforts we have overcome many of the major hurdles faced by other research groups to make a NIRS based approach feasible for use in a consumer electronic device. For the first time ever athletes can know what is essentially their redline and know if they need to speed up or slow down for optimal results.