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Inspiratory muscle training attenuates the human respiratory muscle metaboreflex Witt, Jonathan Derek
Abstract
PURPOSE: High-resistance inspiratory muscle work results in inspiratory muscle fatigue and sympathetically mediated increases in heart rate (HR) and mean arterial pressure (MAP). We hypothesized that 5 wks of inspiratory muscle training (IMT) would attenuate such a response. METHODS: An experimental group (EXP, n = 8) performed IMT 6 days/wk for 5-wks at 50% of maximal inspiratory pressure (MIP), while a mock training group (SHAM, n = 8) performed IMT at 10% MIP. Pre- and post- training, subjects underwent a eucapnic resistive breathing protocol (RBT) at a resistance of approx. 50% MIP (breathing frequency = 15 breaths/min, duty cycle = 0.70) while HR and MAP were continuously monitored. RBT duration was matched within each subject pre and post. MIP was assessed weekly. RESULTS: MIP increased significantly (p < 0.05) in the EXP group (-125.0 ± 28.4 to - 145.5 ± 33.3 cm H₂0, mean ± SD) but not in the SHAM group (-141.2 ± 31.8 to -147.5 ± 32.0 cm H₂0) . Mean RBT duration was significantly shorter in the SHAM group (392 ± 93.7 sec vs. 677 ± 197 sec). Prior to IMT, the RBT resulted in significant, rises in HR (SHAM: 58.7 ± 5.2 to 82.9 ± 11.6 beats/min; EXP : 61.7 ± 9.3 to 82.7 ± 12.1 beats/min) and MAP (SHAM: 88.1 ± 4.6 to 106.2 ± 7.3 mmHg; EXP : 84.5 ± 4.0 to 99.2 ± 8.1 mmHg) in both groups. The SHAM group responded similarly to the RBT post-training (HR: 56.9 ± 6.2 to 76.8 ± 8.5 beats/min; MAP : 89.3 ± 9.0 to 102.5 ± 8.0 mmHg). Following IMT in the EXP group, the RBT failed to increase HR and MAP to the same extent as before training (HR: 58.6 ± 8.7 to 73.8 ± 7.1 beats/min; MAP : 84.5 ± 3.3 to 88.7 ± 6.1 mmHg). MIP measured before and after the RBT did not change in either group pre or post training. CONCLUSIONS: IMT reduces the HR and MAP response to resistive inspiratory muscle work. This may indicate a reduction in sympatho-excitation due to either reduced accumulation of, or reduced responsiveness to, metabolites within the inspiratory muscles.
Item Metadata
Title |
Inspiratory muscle training attenuates the human respiratory muscle metaboreflex
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2007
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Description |
PURPOSE: High-resistance inspiratory muscle work results in inspiratory muscle fatigue
and sympathetically mediated increases in heart rate (HR) and mean arterial pressure (MAP).
We hypothesized that 5 wks of inspiratory muscle training (IMT) would attenuate such a
response. METHODS: An experimental group (EXP, n = 8) performed IMT 6 days/wk for
5-wks at 50% of maximal inspiratory pressure (MIP), while a mock training group (SHAM,
n = 8) performed IMT at 10% MIP. Pre- and post- training, subjects underwent a eucapnic
resistive breathing protocol (RBT) at a resistance of approx. 50% MIP (breathing frequency
= 15 breaths/min, duty cycle = 0.70) while HR and MAP were continuously monitored.
RBT duration was matched within each subject pre and post. MIP was assessed weekly.
RESULTS: MIP increased significantly (p < 0.05) in the EXP group (-125.0 ± 28.4 to -
145.5 ± 33.3 cm H₂0, mean ± SD) but not in the SHAM group (-141.2 ± 31.8 to -147.5 ±
32.0 cm H₂0) . Mean RBT duration was significantly shorter in the SHAM group (392 ±
93.7 sec vs. 677 ± 197 sec). Prior to IMT, the RBT resulted in significant, rises in HR
(SHAM: 58.7 ± 5.2 to 82.9 ± 11.6 beats/min; EXP : 61.7 ± 9.3 to 82.7 ± 12.1 beats/min) and
MAP (SHAM: 88.1 ± 4.6 to 106.2 ± 7.3 mmHg; EXP : 84.5 ± 4.0 to 99.2 ± 8.1 mmHg) in
both groups. The SHAM group responded similarly to the RBT post-training (HR: 56.9 ±
6.2 to 76.8 ± 8.5 beats/min; MAP : 89.3 ± 9.0 to 102.5 ± 8.0 mmHg). Following IMT in the
EXP group, the RBT failed to increase HR and MAP to the same extent as before training
(HR: 58.6 ± 8.7 to 73.8 ± 7.1 beats/min; MAP : 84.5 ± 3.3 to 88.7 ± 6.1 mmHg). MIP
measured before and after the RBT did not change in either group pre or post training.
CONCLUSIONS: IMT reduces the HR and MAP response to resistive inspiratory muscle
work. This may indicate a reduction in sympatho-excitation due to either reduced
accumulation of, or reduced responsiveness to, metabolites within the inspiratory muscles.
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Genre | |
Type | |
Language |
eng
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Date Available |
2011-02-22
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0077015
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.