Assessing the feasibility of near-infrared spectroscopy for evaluating physiological exercise thresholds

Iskra, Simon (author), Paravlić, Armin (author)

To examine the feasibility of using near-infrared spectroscopy (NIRS) for physiological threshold detection and whether NIRS-derived parameters differ between highly-trained and less-trained cyclists. Twenty-seven male cyclists were divided into: highly trained endurance cyclists (EA) and recreational cyclists (RA). Participants performed a step-incremental cycling test to exhaustion. Ventilatory thresholds (VT$_1$ and VT$_2$) were determined using gas-exchange variables. NIRS sensor was placed on the vastus lateralis muscle to identify breakpoints corresponding to ventilatory thresholds. No significant differences were observed between NIRS-derived thresholds, compared to VT$_1$ and VT$_2$ (F = 1.04–1.33, p= 0.26–0.36). Moderate to strong correlations were found between NIRS-derived thresholds and ventilatory thresholds (r = 0.65–0.9, p< 0.01). A moderate correlation was found between maximal oxygen uptake and minimal tissue saturation index (TSI) value during the test (r =−0.411, p= 0.037). EA group showed tendency towards lower minimal TSI values compared to RA group (MD = 5.46% TSI, p= 0.081). NIRS is a feasible tool for non-invasive assessment of ventilatory thresholds during incremental exercise. TSI, in particular, showed lower variability compared to other NIRS-derived parameters, and may therefore be more suitable for practical applications in sport science. Highly trained athletes demonstrated distinct physiological responses compared to recreational athletes, suggesting enhanced peripheral oxygen extraction.

• Language: English
• Keywords: sport, NIRS, ventilatory threshold, cycling, gas-exchange, incremental test
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FŠ - Faculty of Sport
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: 11 str.
• Numbering: Vol. 15, art. 33349
• PID: 20.500.12556/RUL-181164
• UDC: 796.01
• ISSN on article: 2045-2322
• DOI: 10.1038/s41598-025-14920-1
• COBISS.SI-ID: 252983043
• Publication date in RUL: 26.03.2026

Record is a part of a journal

• Title: Scientific reports
• Shortened title: Sci. rep.
• Publisher: Springer Nature
• ISSN: 2045-2322
• COBISS.SI-ID: 18727432

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: šport, kolesarstvo, NIRS, prag ventilacije, izmenjava plinov, inkrementalni test