Journal article
Vasoconstrictor responsiveness in contracting human muscle: influence of contraction frequency, contractile work, and metabolic rate
European journal of applied physiology, Vol.117(8), pp.1697-1706
08/2017
DOI: 10.1007/s00421-017-3660-7
PMID: 28624852
Abstract
The aim of this study was to examine whether independent effects exist between contractile work and metabolic demand (VO
) on vasoconstrictor responsiveness (i.e., functional sympatholysis) under different contraction durations matched for total contractile work in exercising human skeletal muscle.
Ten young men performed rhythmic forearm contractions at 10 and 15% of maximum voluntary contraction (MVC) which consisted of muscle contractions using the same duty cycle but altering the duration of the contraction-relaxation cycles of exercise and included: 1) fast frequency contractions at 10% MVC (FFC
) using a contraction relaxation cycle at 1:2 s; 2) slow frequency contractions at 10% MVC (SFC
) at 2:4 s; and 3) SFC at 15% MVC (SFC
) at 2:4 s. Lower body negative pressure (LBNP) was applied to increase sympathetic vasoconstriction during forearm exercise. Brachial artery diameter and blood velocities (measured via Doppler ultrasound) determined forearm blood flow (FBF), and forearm vascular conductance (FVC) was calculated from FBF (ml min
) and mean arterial blood pressure.
Results revealed that steady-state indices of FBF, FVC, and VO
were greater (P < 0.05) in FFC
and SFC
vs. SFC
. In addition, the magnitude of vasoconstriction (percent reduction in FVC) in response to reflex increases in sympathetic activity during LBNP was greater with SFC
vs. FFC
(-20.6 ± 3.0 vs. -11.1 ± 2.0%; P < 0.05), whereas there was no difference with FFC
vs. SFC
(-11.1 ± 2.0 vs. -11.8 ± 1.8%; P = 0.91).
Our data indicate that faster work-matched muscle contractions increase blood flow and metabolism, leading to improved functional sympatholysis as compared to slower work-matched muscle contractions in humans.
Details
- Title: Subtitle
- Vasoconstrictor responsiveness in contracting human muscle: influence of contraction frequency, contractile work, and metabolic rate
- Creators
- Nicholas T Kruse - Abboud Cardiovascular Research Center, Iowa, IA, USA. Nicholas-kruse-1@uiowa.eduWilliam E Hughes - Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, University of Iowa, Iowa, IA, 52242, USAKenichi Ueda - Department of Anesthesia, Carver College of Medicine, University of Iowa, Iowa, IA, USADarren P Casey - Fraternal Order of Eagles Diabetes Research, Iowa, IA, USA
- Resource Type
- Journal article
- Publication Details
- European journal of applied physiology, Vol.117(8), pp.1697-1706
- Publisher
- Germany
- DOI
- 10.1007/s00421-017-3660-7
- PMID
- 28624852
- ISSN
- 1439-6319
- eISSN
- 1439-6327
- Grant note
- R00 HL105467 / NHLBI NIH HHS
- Language
- English
- Date published
- 08/2017
- Academic Unit
- Anesthesia; Physical Therapy and Rehabilitation Science; Fraternal Order of Eagles Diabetes Research Center; Internal Medicine
- Record Identifier
- 9984047677102771
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