Oxygenation Threshold Derived from Near-Infrared Spectroscopy: Reliability and Its Relationship with the First Ventilatory Threshold

Abstract

BackgroundNear-infrared spectroscopy (NIRS) measurements of oxygenation reflect O2 delivery and utilization in exercising muscle and may improve detection of a critical exercise threshold.PurposeFirst, to detect an oxygenation breakpoint (Δ[O2HbMb-HHbMb]-BP) and compare this breakpoint to ventilatory thresholds during a maximal incremental test across sexes and training status. Second, to assess reproducibility of NIRS signals and exercise thresholds and investigate confounding effects of adipose tissue thickness on NIRS measurements.MethodsForty subjects (10 trained male cyclists, 10 trained female cyclists, 11 endurance trained males and 9 recreationally trained males) performed maximal incremental cycling exercise to determine Δ[O2HbMb-HHbMb]-BP and ventilatory thresholds (VT1 and VT2). Muscle haemoglobin and myoglobin O2 oxygenation ([HHbMb], [O2HbMb], SmO2) was determined in m. vastus lateralis. Δ[O2HbMb-HHbMb]-BP was determined by double linear regression. Trained cyclists performed the maximal incremental test twice to assess reproducibility. Adipose tissue thickness (ATT) was determined by skinfold measurements.ResultsΔ[O2HbMb-HHbMb]-BP was not different from VT1, but only moderately related (r = 0.58–0.63, p<0.001). VT1 was different across sexes and training status, whereas Δ[O2HbMb-HHbMb]-BP differed only across sexes. Reproducibility was high for SmO2 (ICC = 0.69–0.97), Δ[O2HbMb-HHbMb]-BP (ICC = 0.80–0.88) and ventilatory thresholds (ICC = 0.96–0.99). SmO2 at peak exercise and at occlusion were strongly related to adipose tissue thickness (r2 = 0.81, p<0.001; r2 = 0.79, p<0.001). Moreover, ATT was related to asymmetric changes in Δ[HHbMb] and Δ[O2HbMb] during incremental exercise (r = -0.64, p<0.001) and during occlusion (r = -0.50, p<0.05).ConclusionAlthough the oxygenation threshold is reproducible and potentially a suitable exercise threshold, VT1 discriminates better across sexes and training status during maximal stepwise incremental exercise. Continuous-wave NIRS measurements are reproducible, but strongly affected by adipose tissue thickness.

Reliability of Near-Infrared Spectroscopy for Measuring Intermittent Handgrip Contractions in Sport Climbers

“…Previously, cw-NIRS derived parameters during exercise have been shown to be a valid tool for determination of local muscle oxygen consumption, oxygenation threshold, tissue deoxygenation and O2 recovery rate (3,27,29). The use of cw-NIRS is, therefore, promising as a diagnostic tool in sports where muscular hypoxia is common such as local isometric contractions or high intensity exercise seen in rock climbing.…”

Evaluación de parámetros fisiológicos en función de la saturación de oxigeno muscular en mujeres con sobrepeso y obesidad. [Evaluation physiological parameters depending on muscle oxygen saturation in overweight and obesity].

“…Si bien la Smo2% medida con NIRS puede estimar el nivel de fatiga del ser humano (Halim, Salikin, Rusop, Laili, Aziz y Laili, 2016), sus mediciones de onda continua son reproducibles, pero el espesor del tejido adiposo afecta en gran medida la amplitud de las señales de la hemoglobina oxigenada en un grado diferente y por lo tanto también puede afectar a la cinética de señales combinadas con el oxígeno del musculo. (Nasseri, Kleiser, Ostojic, Karen, y Wolf, 2016;van der Zwaard, 2016) Una de la razones puede ser la intensidad del ejercicio se relaciona con la disponibilidad de los carbohidratos con el flujo sanguíneo lo cual puede afectar al grupo de normopeso que tuvo más tiempo durante la prueba de esfuerzo, también hay otros factores como el tipo y cantidad de carbohidrato ingerido, el horario de alimentación, el glucógeno la disponibilidad (Jeukendrup y Jentjens, 2000). Al igual que el calor producido en musculo durante el ejercicio puede reducir el flujo sanguíneo en consecuencia la entrega de glucosa al músculo puede ser dañado.…”

Near-Infrared Spectroscopy for Monitoring Sternocleidomastoid Muscular Oxygenation during Isometric Flexion for Patients with Mild Nonspecific Neck Pain: A Pilot Study

“…In this investigation, the characteristics of sternocleidomastoid muscular oxygenation were continuously monitored during isometric flexion by a commercial frequency-domain NIRS system (Imagent, ISS Inc., Champaign, IL, USA) in real time at a 25 Hz sample rate. On the other hand, as previous work had mentioned that the frequency-domain multiple-distance system with over distances in the range of 1.5 to 4.5 cm could minimize the influence of between-subjects variations in adipose tissue thickness on NIRS signals and accurately quantify the optical properties of the superficial muscle [51], the multiple-channel NIRS probe was adopted to attenuate the confounding effects of adipose tissue thickness on NIRS measurements [52,53] and attached on the sternal head of the dominant or affected sternocleidomastoid muscle. The system had four sources and one detector with interoptode distances of 2.05, 2.55, 3.05 and 3.55 cm.…”

“…Table 2 summarizes the muscular oxygenation variables of interest for both groups. Only the half-deoxygenation time of oxygen saturation (StO 2 ), which means the flection time taken to reach 50% of the maximal oxygen consumption during the contraction phase [53] in patients with nonspecific neck pain is shorter than asymptomatic individuals (10.43 ± 1.79 s vs. 13.82 ± 1.42 s, p < 0.001), but no any statistically significant differences in other muscular oxygenation variables (p > 0.05) were observed between these two groups. On the other hand, there were also no any differences between males (pooled data of neck pain and asymptomatic individuals) and females (pooled data of neck pain and asymptomatic individuals) in adipose tissue thickness, and muscular oxygenation variables (Table S1 of Supplementary Material).…”