Ventilatory responses to dynamic exercise elicited by intramuscular sensors.
Med Sci Sports Exerc
; 31(2): 277-86, 1999 Feb.
Article
en En
| MEDLINE
| ID: mdl-10063818
ABSTRACT
PURPOSE:
Eight subjects, aged 27.0+/-1.6 yr, performed incremental workload cycling to investigate the contribution of skeletal muscle mechano- and metaboreceptors to ventilatory control during dynamic exercise.METHODS:
Each subject performed four bouts of exercise exercise with no intervention (CON); exercise with bilateral thigh cuffs inflated to 90 mm Hg (CUFF); exercise with application of lower-body positive pressure (LBPP) to 45 torr (PP); and exercise with 90 mm Hg thigh cuff inflation and 45 torr LBPP (CUFF+PP). Ventilatory responses and pulmonary gas exchange variables were collected breath-by-breath with concomitant measurement of leg intramuscular pressure.RESULTS:
Ventilation (VE) was significantly elevated from CON during PP and CUFF+PP at workloads corresponding to > or = 60% CON peak oxygen uptake (VO2peak) and during CUFF at workloads > or = 80% CON VO2peak, P < 0.05. The VO2 at which ventilatory threshold occurred was significantly reduced from CON (2.17+/-0.28 L x min(-1)) to 1.60+/-0.19 L x min(-1), 1.45+/-0.15 L x min(-1), and 1.15+/-0.11 L x min(-1) during CUFF, PP, and CUFF+PP, respectively. The slope of the linear regression describing the VE/CO2 output relationship was increased from CON by approximately 22% during CUFF, 40% during PP, and 41% during CUFF+PP.CONCLUSIONS:
As intramuscular pressure was significantly elevated immediately upon application of LBPP during PP and CUFF+PP without a concomitant increase in VE, it seems unlikely that LBPP-induced increases in VE can be attributed to activation of the mechanoreflex. These findings suggest that LBPP-induced reductions in perfusion pressure and decreases in venous outflow resulting from inflation of bilateral thigh cuffs may generate a metabolite sensitive intramuscular ventilatory stimulus.Palabras clave
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Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Presión
/
Respiración
/
Ejercicio Físico
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Músculo Esquelético
/
Mecanorreceptores
Límite:
Adult
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Female
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Humans
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Male
Idioma:
En
Revista:
Med Sci Sports Exerc
Año:
1999
Tipo del documento:
Article
País de afiliación:
Estados Unidos