RT info:eu-repo/semantics/article
T1 Limitations to oxygen transport and utilization during sprint exercise in humans: evidence for a functional reserve in muscle O2 diffusing capacity
A1 Calbet, José A. L.
A1 Losa Reyna, José
A1 Torres Peralta, Rafael
A1 Rasmussen, Peter
A1 Ponce González, Jesús Gustavo
A1 Sheel, A. William
A1 Calle Herrero, Jaime de la
A1 Guadalupe Grau, Amelia
A1 Morales Álamo, David
A1 Fuentes Nieto, Teresa
A1 Rodríguez García, Lorena
A1 Siebenmann, Christoph
A1 Boushel, Robert
A1 Lundby, Carsten
AB 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.
SN 0022-3751
YR 2015
FD 2015
LK https://uvadoc.uva.es/handle/10324/72646
UL https://uvadoc.uva.es/handle/10324/72646
LA eng
NO Journal of Physiology, 2015, vol. 593, n. 20, p. 4649-4664
NO Producción Científica
DS UVaDOC
RD 04-abr-2025