Regional tissue oxygenation during high-intensity exercise following voluntary isocapnic hyperpnea versus inspiratory threshold loading in endurance–trained individuals: a randomized controlled trial
Year: 2026
Type: article
Study designs: Randomized Controlled Trial, Clinical Trial
Abstract: This study contrasted the effects of five weeks of voluntary isocapnic hyperpnea (VIH) versus inspiratory threshold loading (ITL) on tissue oxygenation at the prefrontal cortex (PFC), respiratory muscles (m.Intercostales), and locomotor muscles (m.Vastus Lateralis) during high intensity constant load cycling (CLT) in endurance trained individuals. Twenty participants (14 men, 6 women) were randomly assigned to VIH (n = 10) or ITL (n = 10) training. Before and after intervention, participants completed a CLT at 80% of peak power output until exhaustion. Tissue oxygenation was continuously monitored using near–infrared spectroscopy (NIRS) at three sites. Changes in oxygenated (Δ[O2Hb]), deoxygenated (Δ[HHb]), and total hemoglobin (Δ[tHb]), along with tissue saturation index (TSI), were analyzed using a three–way ANOVA. VIH significantly improved peak oxygen–uptake (p = 0.016), maximal lung ventilation (p = 0.004), respiratory rate (p = 0.030), and tidal volume (p = 0.022), whereas ITL significantly increased maximal inspiratory pressure (p = 0.003). A significant main effect of time (%CLT) was observed for all NIRS variables at the three measurement sites (p < 0.05), except TSI at the PFC and Δ[O2Hb] at the m.Vastus Lateralis. A main effect of training was detected only for TSI at the m.Vastus Lateralis (p = 0.036, η²p = 0.22; mean difference 3.2%, 95% CI: 0.3 to 6.1%), though direct physiological interpretation requires caution given the modest effect magnitude. No significant group effects or interactions were observed. VIH and ITL elicit distinct adaptations in respiratory function and aerobic capacity without modifying regional tissue oxygenation dynamics during high intensity exercise. The observed locomotor muscle TSI trend warrants confirmation in future studies.
Source: Scientific Reports
Authors: Daniel Ramos–López, Raúl Caulier–Cisterna, Andrés Vega–Moraga, Fúlvia B. Manchado–Gobatto, Luigi Gabrielli–Nervi, Hugo E. Verdejo, Vitor A. Lira, Maximiliano Espinosa–Ramírez, Karol Ramírez–Parada, Matías Crisosto–Ramos, Antonio Escobar–Neicun, Amalia Matus–Santa Cruz, Savka Miranda–Osorio, Kevin Parra–Huenchuleo, Aracelly Pérez–Caro, Sebastián Podestá–Oyarzun, Oscar F. Araneda, Felipe Contreras–Briceño
Institutions: Pontificia Universidad Católica de Chile, Metropolitan University of Technology, Universidade Estadual de Campinas (UNICAMP), Hospital Clínico de la Universidad Católica, Advanced Center for Chronic Diseases, University of Iowa, Universidad Andrés Bello, Universidad de Los Andes, Chile, University of O'Higgins
Language: English
Subfield: Physiology (medical)
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $2,690
OpenAlex ID: W7142244516