Inspiratory muscle fatigue increases sympathetic vasomotor outflow and blood pressure during submaximal exercise

Abstract

Katayama K, Iwamoto E, Ishida K, Koike T, Saito M. Inspiratory muscle fatigue increases sympathetic vasomotor outflow and blood pressure during submaximal exercise. Am J Physiol Regul Integr Comp Physiol 302: R1167-R1175, 2012. First published March 28, 2012 doi:10.1152/ajpregu.00006.2012.-The purpose of this study was to elucidate the influence of inspiratory muscle fatigue on muscle sympathetic nerve activity (MSNA) and blood pressure (BP) response during submaximal exercise. We hypothesized that inspiratory muscle fatigue would elicit increases in sympathetic vasoconstrictor outflow and BP during dynamic leg exercise. The subjects carried out four submaximal exercise tests: two were maximal inspiratory pressure (PImax) tests and two were MSNA tests. In the PI max tests, the subjects performed two 10-min exercises at 40% peak oxygen uptake using a cycle ergometer in a semirecumbent position [spontaneous breathing for 5 min and with or without inspiratory resistive breathing for 5 min (breathing frequency: 60 breaths/min, inspiratory and expiratory times were each set at 0.5 s)]. Before and immediately after exercise, PImax was estimated. In MSNA tests, the subjects performed two 15-min exercises (spontaneous breathing for 5 min, with or without inspiratory resistive breathing for 5 min, and spontaneous breathing for 5 min). MSNA was recorded via microneurography of the right median nerve at the elbow. PImax decreased following exercise with resistive breathing, whereas no change was found without resistance. The time-dependent increase in MSNA burst frequency (BF) appeared during exercise with inspiratory resistive breathing, accompanied by an augmentation of diastolic BP (DBP) (with resistance: MSNA, BF ϩ83.4%; DBP, ϩ23.8%; without resistance: MSNA BF, ϩ19.2%; DBP, Ϫ0.4%, from spontaneous breathing during exercise). These results suggest that inspiratory muscle fatigue induces increases in muscle sympathetic vasomotor outflow and BP during dynamic leg exercise at mild intensity. respiratory muscle; sympathetic outflow; metaboreflex; dynamic leg exercise

The effect of feedback respiratory exercise on muscle activity, craniovertebral angle, and neck disability index of the neck flexors of patients with forward head posture

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The 400- and 800-m Track Running Induces Inspiratory Muscle Fatigue in Trained Female Middle-Distance Runners

“…Maximal inspiratory pressure, which is commonly used to measure inspiratory muscle strength, was assessed according to the published guidelines (2). Maximal inspiratory pressure was measured before whole-body warm-up and within 2 minutes after completion of the 400-and 800-m running tests, using a portable autospirometer (AS-507; Minato Medical Science, Osaka, Japan) with a handheld mouth pressure meter (AAM377; Minato Medical Science) (18). All measurements were made while the participants sat with their nose occluded.…”

“…Pulmonary function was assessed using a portable autospirometer (AS-507; Minato Medical Science) (18) to determine forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV 1 ). All measurements were performed according to the published guidelines (22).…”

Prolonged Intermittent Running Induces Inspiratory-Muscle Fatigue in Female Runners

“…MIP was measured before the whole-body warm-up, and within 2 min after completion of the MART and maximal intermittent graded exercise tests, using a portable autospirometer (AS-507; Minato Medical Science) with a handheld mouth-pressure meter (AAM377; Minato Medical Science) [14]. All measurements were made while the participant sat with her nose occluded.…”

“…Pulmonary function was assessed using a portable autospirometer (AS-507; Minato Medical Science) [14] to determine forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV 1 ). All measurements were performed according to published guidelines [16].…”