The effect of severe intensity bouts on muscle oxygen saturation responses in trained cyclists

Abstract

Near-infrared spectroscopy (NIRS) quantifies muscle oxygenation (SmO2) during exercise. Muscle oxygenation response to self-paced, severe-intensity cycling remains unclear. Observing SmO2 can provide cycling professionals with the ability to assess muscular response, helping optimize decision-making. We aimed to describe the effect of self-paced severe intensity bouts on SmO2, measured noninvasively by a wearable NIRS sensor on the vastus lateralis (VL) muscle, and examine its reliability. We hypothesized a greater desaturation response with each bout, whereas, between trials, good reliability would be observed. Fourteen recreationally trained, and trained cyclists completed a ramp test to determine the power output (PO) at the respiratory compensation point (RCP). Athletes completed two subsequent visits of 50-minute sessions that included four severe-intensity bouts done at 5% above RCP PO. Muscle oxygenation in the VL was monitored using a wearable NIRS device. Measures included mean PO, heart-rate (HR), cadence, and SmO2 at bout onset, during work (work SmO2), and ΔSmO2. The bouts were compared using a one-way repeated measures ANOVA. For significant differences, a Fisher's least square difference post-hoc analysis was used. A two-way repeated measures ANOVA was used using trial and bout as main factors. Intraclass correlations (ICC) were used to quantify relative reliability for mean work, and standard error of the measurement (SEM) was used to quantify absolute agreement of mean work SmO2. Both PO and cadence showed no effect of bout or trial. Heart-rate at bout 2 (168 ± 8 bpm) and 4 (170 ± 7 bpm) were higher than bout 1 (160 ± 6 bpm). Onset SmO2 (%) response significantly increased in the final two bouts of the session. Mean work SmO2 increased across bouts, with the highest value displayed in bout 4 (36 ± 22%). ΔSmO2 showed a smaller desaturation response during bout 4 (27 ± 10%) compared to bout 3 (31 ± 10%). Mean work SmO2 ICC showed good reliability (ICC = 0.87), and SEM was 12% (CI 9-15%). We concluded that a non-invasive, affordable, wearable NIRS sensor demonstrated the heterogeneous muscle oxygenation response during severe intensity cycling bouts with good reliability in trained cyclists.

Wearable near-infrared spectroscopy: reliability and sensitivity among different endurance cycling exercise intensities

“…However, V̇O 2 measurement is extremely costly and requires highly skilled technicians to collect and interpret the data, ultimately limiting its broad utilization in simple clinical and sport testing facilities. Among the most promising alternative approaches for tracking muscle metabolic demands during exercise, near-infrared spectroscopy (NIRS) is of utmost interest since it provides noninvasive continuous monitoring of O 2 saturation in the microvasculature surrounding the active musculature ( 4 , 5 ). Recent evidence has suggested that NIRS is a valid tool for characterizing the dynamics of muscle O 2 changes (i.e., the balance between O 2 delivery and extraction by the skeletal muscles) among different exercise intensities ( 6 , 7 ).…”

Side differences and reproducibility of the Moxy muscle oximeter during cycling in trained men

“…Although the Moxy has been used in various studies in applied settings (e.g. Olcina et al 2019;Paquette et al 2021;Pratt 2018;Yogev et al 2023b), its reliability has not yet been adequately studied. In order to meaningfully implement the Moxy in training, reproducibility of SmO 2 , bilateral side differences and between-device measurement error need to be known.…”

“…This is vital for the decision if a change between two tests is "real" or due to measurement or biological error (Chrzanowski-Smith et al 2020). The validation study from Feldmann et al (2019) and a few others investigated the test-retest reliability during different activities such as rest, sitting, walking and endurance exercise (Contreras-Briceño et al 2019;Crum et al 2017;Gandia-Soriano et al 2022;McManus et al 2018;Scholkmann and Scherer-Vrana 2020;Yogev et al 2023bYogev et al , 2023a. Two of those studies looked at the test-retest reliability during cycling and came to different conclusions.…”

Comparative Bilateral Measurements of Vastus Lateralis Muscle Oxygen Desaturation Kinetics during 30 S Sprint Cycling Exercise: Effects of Age and Performance

“…When measuring local oxygen utilisation with the NIRS system, it is often used only on one leg—either on the dominant or non-dominant leg [ 13 , 14 ]. Recent studies [ 9 , 15 ] have introduced new findings regarding the importance of bilateral signal recording for a comprehensive understanding of the processes contributing to power output.…”