Identificador persistente para citar o vincular este elemento: http://hdl.handle.net/10553/52631
Título: Task failure during exercise to exhaustion in normoxia and hypoxia is due to reduced muscle activation caused by central mechanisms while muscle metaboreflex does not limit performance
Autores/as: Torres-Peralta, Rafael 
Morales Alamo, David 
González-Izal, Miriam
Losa-Reyna, José
Pérez-Suárez, Ismael
Calbet, Jose A. L. 
Izquierdo, Mikel
Clasificación UNESCO: 2411 Fisiología humana
Palabras clave: Electromyography
EMG
Exhaustion
Fatigue
High-intensity, et al.
Fecha de publicación: 2016
Publicación seriada: Frontiers in Physiology 
Resumen: To determine whether task failure during incremental exercise to exhaustion (IE) is principally due to reduced neural drive and increased metaboreflex activation eleven men (22 ± 2 years) performed a 10 s control isokinetic sprint (IS; 80 rpm) after a short warm-up. This was immediately followed by an IE in normoxia (Nx, PIO2:143 mmHg) and hypoxia (Hyp, PIO2:73 mmHg) in random order, separated by a 120 min resting period. At exhaustion, the circulation of both legs was occluded instantaneously (300 mmHg) during 10 or 60 s to impede recovery and increase metaboreflex activation. This was immediately followed by an IS with open circulation. Electromyographic recordings were obtained from the vastus medialis and lateralis. Muscle biopsies and blood gases were obtained in separate experiments. During the last 10 s of the IE, pulmonary ventilation, VO2, power output and muscle activation were lower in hypoxia than in normoxia, while pedaling rate was similar. Compared to the control sprint, performance (IS-Wpeak) was reduced to a greater extent after the IE-Nx (11% lower P < 0.05) than IE-Hyp. The root mean square (EMGRMS) was reduced by 38 and 27% during IS performed after IE-Nx and IE-Hyp, respectively (Nx vs. Hyp: P < 0.05). Post-ischemia IS-EMGRMS values were higher than during the last 10 s of IE. Sprint exercise mean (IS-MPF) and median (IS-MdPF) power frequencies, and burst duration, were more reduced after IE-Nx than IE-Hyp (P < 0.05). Despite increased muscle lactate accumulation, acidification, and metaboreflex activation from 10 to 60 s of ischemia, IS-Wmean (+23%) and burst duration (+10%) increased, while IS-EMGRMS decreased (-24%, P < 0.05), with IS-MPF and IS-MdPF remaining unchanged. In conclusion, close to task failure, muscle activation is lower in hypoxia than in normoxia. Task failure is predominantly caused by central mechanisms, which recover to great extent within 1 min even when the legs remain ischemic. There is dissociation between the recovery of EMGRMS and performance. The reduction of surface electromyogram MPF, MdPF and burst duration due to fatigue is associated but not caused by muscle acidification and lactate accumulation. Despite metaboreflex stimulation, muscle activation and power output recovers partly in ischemia indicating that metaboreflex activation has a minor impact on sprint performance.
URI: http://hdl.handle.net/10553/52631
ISSN: 1664-042X
DOI: 10.3389/fphys.2015.00414
Fuente: Frontiers in Physiology [EISSN 1664-042X], v. 6 (JAN), (Enero 2016)
Colección:Artículos
miniatura
pdf
Adobe PDF (2,25 MB)
Vista completa

Citas SCOPUSTM   

27
actualizado el 24-mar-2024

Citas de WEB OF SCIENCETM
Citations

27
actualizado el 25-feb-2024

Visitas

67
actualizado el 09-dic-2023

Descargas

78
actualizado el 09-dic-2023

Google ScholarTM

Verifica

Altmetric


Comparte



Exporta metadatos



Los elementos en ULPGC accedaCRIS están protegidos por derechos de autor con todos los derechos reservados, a menos que se indique lo contrario.