Using Near-Infrared Spectroscopy Wearable Devices to Identify Central Versus Peripheral Limitations During Exercise

Summary

This protocol integrates near-infrared spectroscopy (NIRS) technology to assess localized hematological and oxygenation changes at the prefrontal cortex, respiratory (m.Intercostales), and locomotor (m.Vastus Lateralis) muscles during cardiopulmonary exercise testing, enabling the identification of central and peripheral limiting factors affecting exercise performance.

Abstract

The gold standard to assess the aerobic capacity in physically active subjects and athletes is the maximal oxygen consumption test (VO_2–max), which involves analysis of exhaled–gases and cardiorespiratory variables obtained via the breath-by-breath method in an ergospirometer during an incremental exercise. However, this method cannot elucidate metabolic changes at the muscular level. Near-infrared spectroscopy (NIRS) has emerged as a valuable technology to evaluate local oxygen levels (Tissular Saturation Index, TSI) by quantifying the concentrations of oxygenated (O₂-Hb) and deoxygenated (H-Hb) hemoglobin in the microvasculature of tissues. NIRS applications extend to respiratory and locomotor muscles, assessing metabolic changes associated with the cost of breathing (COB) and peripheral workload, respectively. Additionally, cerebral regions, such as the prefrontal cortex, have been explored with NIRS technology to assess physiological changes related to cognitive demand associated with planning or ideation of motor tasks linked to sports performance. Thus, by analyzing exercise-induced changes (D) in O₂-Hb, H-Hb, and TSI, it is possible to identify central and peripheral exercise limitations, particularly when endurance training is the main component of physical fitness (e.g., running, cycling, triathlon, etc.). Addressing these factors is paramount for coaches and exercise physiologists to optimize athletic performance, incorporating training strategies focused on the primary exercise-limiting factors. This study outlines a protocol for utilizing wearables devices equipped with NIRS technology to analyze exercise changes in TSI, O₂-Hb, and H-Hb, alongside cardiorespiratory variables typically registered in athletes during VO_2–max tests. This approach offers a comprehensive method for identifying the primary systems involved in stopping exercise progression and sports performance improvement.

Introduction

Endurance athletes rely on an efficient balance of oxygen delivery and uptake to sustain high–intensity exercise and enhance their athletic performance^1,2. The maximal oxygen uptake test (VO_2-max) is a vital physiological assessment that determines sports performance by analyzing exhaled–gases and cardiorespiratory variables during incremental exercise intensity¹. This assessment, known as ergospirometry or Cardiopulmonary Exercise Testing (CPET), reflects the exercise response of the cardiovascular, respiratory, and muscular systems³. Alon....

Protocol

The protocol was approved by the Institutional Review Board of the Pontificia Universidad Católica de Chile (projects nº 210525001 and 220608010), and the study was conducted in accordance with the Declaration of Helsinki. All participants provided written informed consent before participating in the testing described.

1. Placement and setup of NIRS wearables

NOTE: Various NIRS wearables and data acquisition software can be utilized. Researc.......

Discussion

There is significant potential in using NIRS wearables as a complementary tool to CPET for evaluating athletic performance and identifying central and peripheral exercise–limiting factors in aerobic or endurance athletes, given that NIRS technology has proven its validity and reliability in assessing microvascular hemodynamics in both cerebral and muscular regions^37,38. However, to maximize the benefits of this technology, several considerations must be add.......

Materials

Name	Company	Catalog Number	Comments
Column Scale	SECA	711	There are numerous alternatives to this item
Portable Stadiometer	SECA	217	There are numerous alternatives to this item
12-lead ECG	COSMED	Quark T12x	A 12-lead ECG provides a better understanding of HR during exercise and facilitates the detection of arrhythmias.
Pulse Oxymeter	COSMED		Integrated pulse oxymeter
Ergoespirometer	COSMED	Quark-CPET	Calibration gases and calibration syringe are included
Cycle-ergometer	Ergoline GmH	ViaSprint 150P	There are numerous alternatives to this item. Must ensure compatibility with provided software
NIRS weareable	Artinis Medical Systems	Portalite	Articulated NIRS weareable fits the surface where it's placed upon.
NIRS weareable	Artinis Medical Systems	Portamon	Portamon device provides better results on high adipose-tissue surfaces.
Metabolic Data Management Software (OMNIA)	COSMED		Software will vary upon system choice
NIRS Data Management Software (Oxysoft)	Artinis Medical Systems		Software will vary upon device choice
Wireless Probe Type Ultrasound Scanner	SONUS	Duo LC	There are numerous alternatives to this item