Identificador persistente para citar o vincular este elemento: http://hdl.handle.net/10553/44474
Título: Limitations to oxygen transport and utilization during sprint exercise in humans: evidence for a functional reserve in muscle O-2 diffusing capacity
Autores/as: Calbet, José A.L. 
Losa Reyna,Jose 
Torres-Peralta, Rafael 
Rasmussen, Peter
Ponce González,Jesús Gustavo 
Sheel, A. William
de la Calle-Herrero, Jaime
Guadalupe-Grau, Amelia 
Morales-Alamo, David 
Fuentes, Teresa 
Rodríguez García,Lorena 
Siebenmann, Christoph
Boushel, Robert
Lundby, Carsten
Clasificación UNESCO: 32 Ciencias médicas
Palabras clave: Intense Dynamic Exercise
Anaerobic Energy-Release
Severe Acute-Hypoxia
Skeletal-Muscle
Blood-Flow, et al.
Fecha de publicación: 2015
Proyectos: Oxygenación Cerebral y Fatiga Durante El Ejercicio en Hipoxia Aguda 
Publicación seriada: Journal of Physiology 
Resumen: To determine the contribution of convective and diffusive limitations to V̇(O2peak) during exercise in humans, oxygen transport and haemodynamics were measured in 11 men (22 ± 2 years) during incremental (IE) and 30 s all-out cycling sprints (Wingate test, WgT), in normoxia (Nx, P(IO2): 143 mmHg) and hypoxia (Hyp, P(IO2): 73 mmHg). Carboxyhaemoglobin (COHb) was increased to 6-7% before both WgTs to left-shift the oxyhaemoglobin dissociation curve. Leg V̇(O2) was measured by the Fick method and leg blood flow (BF) with thermodilution, and muscle O2 diffusing capacity (D(MO2)) was calculated. In the WgT mean power output, leg BF, leg O2 delivery and leg V̇(O2) were 7, 5, 28 and 23% lower in Hyp than Nx (P < 0.05); however, peak WgT D(MO2) was higher in Hyp (51.5 ± 9.7) than Nx (20.5 ± 3.0 ml min(-1) mmHg(-1), P < 0.05). Despite a similar P(aO2) (33.3 ± 2.4 and 34.1 ± 3.3 mmHg), mean capillary P(O2) (16.7 ± 1.2 and 17.1 ± 1.6 mmHg), and peak perfusion during IE and WgT in Hyp, D(MO2) and leg V̇(O2) were 12 and 14% higher, respectively, during WgT than IE in Hyp (both P < 0.05). D(MO2) was insensitive to COHb (COHb: 0.7 vs. 7%, in IE Hyp and WgT Hyp). At exhaustion, the Y equilibration index was well above 1.0 in both conditions, reflecting greater convective than diffusive limitation to the O2 transfer in both Nx and Hyp. In conclusion, muscle V̇(O2) during sprint exercise is not limited by O2 delivery, O2 offloading from haemoglobin or structure-dependent diffusion constraints in the skeletal muscle. These findings reveal a remarkable functional reserve in muscle O2 diffusing capacity.
URI: http://hdl.handle.net/10553/44474
ISSN: 0022-3751
DOI: 10.1113/JP270408
Fuente: Journal of Physiology [ISSN 0022-3751], v. 593 (20), p. 4649-4664
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