The effect of higher ATP cost of contraction on the metabolic response to graded exercise in patients with chronic obstructive pulmonary disease
To better understand the metabolic implications of a higher ATP cost of contraction in chronic obstructive pulmonary disease (COPD), we used 31 P-magnetic resonance spectroscopy ( 31 P-MRS) to examine muscle energetics and pH in response to graded exercise. Specifically, in six patients and six we...
| Main Authors: | , , |
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| Format: | Journal Article |
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The American Physiological Society
2012
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| Online Access: | http://hdl.handle.net/20.500.11937/63306 |
| _version_ | 1848761051447820288 |
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| author | Layec, G. Haseler, Luke Richardson, R. |
| author_facet | Layec, G. Haseler, Luke Richardson, R. |
| author_sort | Layec, G. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | To better understand the metabolic implications of a higher ATP cost of contraction in chronic obstructive pulmonary disease (COPD), we used 31 P-magnetic resonance spectroscopy ( 31 P-MRS) to examine muscle energetics and pH in response to graded exercise. Specifically, in six patients and six well-matched healthy controls, we determined the intracellular threshold for pH (T pH ) and inorganic phosphate-to-phosphocreatine ratio (T Pi/PCr ) during progressive dynamic plantar flexion exercise with work rate expressed as both absolute and relative intensity. Patients with COPD displayed a lower peak power output (WRmax) compared with controls (controls 25 ± 4 W, COPD 15 ± 5 W, P = 0.01) while end-exercise pH (controls 6.79 ± 0.15, COPD 6.76 ± 0.21, P = 0.87) and PCr consumption (controls 82 ± 10%, COPD 70 ± 18%, P = 0.26) were similar between groups. Both T pH and T Pi/PCr occurred at a significantly lower absolute work rate in patients with COPD compared with controls (controls: 14.7 ± 2.4 W for T pH and 15.3 ± 2.4W for T Pi/PCr ; COPD: 9.7 ± 4.5W for T pH and 10.0 ± 4.6Wfor T Pi/PCr , P > 0.05), but these thresholds occurred at the same percentage of WRmax (controls: 63 ± 11% WRmax for T pH and 67 ± 18% WRmax for T Pi/PCr ; COPD: 59 ± 9% WRmax for TpH and 61 ± 12% WRmax for T Pi/PCr , P > 0.05). Indexes of mitochondrial function, the PCr recovery time constant (controls 42 ± 7 s, COPD 45 ± 11 s, P = 0.66) and the PCr resynthesis rate (controls 105 ± 21%/min, COPD 91 ± 31%/min, P = 0.43) were similar between groups. In combination, these results reveal that when energy demand is normalized to WRmax, as a consequence of higher ATP cost of contraction, patients with COPD display the same metabolic pattern as healthy subjects, suggesting that skeletal muscle energy production is well preserved in these patients. |
| first_indexed | 2025-11-14T10:25:31Z |
| format | Journal Article |
| id | curtin-20.500.11937-63306 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T10:25:31Z |
| publishDate | 2012 |
| publisher | The American Physiological Society |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-633062023-02-22T06:24:20Z The effect of higher ATP cost of contraction on the metabolic response to graded exercise in patients with chronic obstructive pulmonary disease Layec, G. Haseler, Luke Richardson, R. To better understand the metabolic implications of a higher ATP cost of contraction in chronic obstructive pulmonary disease (COPD), we used 31 P-magnetic resonance spectroscopy ( 31 P-MRS) to examine muscle energetics and pH in response to graded exercise. Specifically, in six patients and six well-matched healthy controls, we determined the intracellular threshold for pH (T pH ) and inorganic phosphate-to-phosphocreatine ratio (T Pi/PCr ) during progressive dynamic plantar flexion exercise with work rate expressed as both absolute and relative intensity. Patients with COPD displayed a lower peak power output (WRmax) compared with controls (controls 25 ± 4 W, COPD 15 ± 5 W, P = 0.01) while end-exercise pH (controls 6.79 ± 0.15, COPD 6.76 ± 0.21, P = 0.87) and PCr consumption (controls 82 ± 10%, COPD 70 ± 18%, P = 0.26) were similar between groups. Both T pH and T Pi/PCr occurred at a significantly lower absolute work rate in patients with COPD compared with controls (controls: 14.7 ± 2.4 W for T pH and 15.3 ± 2.4W for T Pi/PCr ; COPD: 9.7 ± 4.5W for T pH and 10.0 ± 4.6Wfor T Pi/PCr , P > 0.05), but these thresholds occurred at the same percentage of WRmax (controls: 63 ± 11% WRmax for T pH and 67 ± 18% WRmax for T Pi/PCr ; COPD: 59 ± 9% WRmax for TpH and 61 ± 12% WRmax for T Pi/PCr , P > 0.05). Indexes of mitochondrial function, the PCr recovery time constant (controls 42 ± 7 s, COPD 45 ± 11 s, P = 0.66) and the PCr resynthesis rate (controls 105 ± 21%/min, COPD 91 ± 31%/min, P = 0.43) were similar between groups. In combination, these results reveal that when energy demand is normalized to WRmax, as a consequence of higher ATP cost of contraction, patients with COPD display the same metabolic pattern as healthy subjects, suggesting that skeletal muscle energy production is well preserved in these patients. 2012 Journal Article http://hdl.handle.net/20.500.11937/63306 10.1152/japplphysiol.00986.2011 The American Physiological Society unknown |
| spellingShingle | Layec, G. Haseler, Luke Richardson, R. The effect of higher ATP cost of contraction on the metabolic response to graded exercise in patients with chronic obstructive pulmonary disease |
| title | The effect of higher ATP cost of contraction on the metabolic response to graded exercise in patients with chronic obstructive pulmonary disease |
| title_full | The effect of higher ATP cost of contraction on the metabolic response to graded exercise in patients with chronic obstructive pulmonary disease |
| title_fullStr | The effect of higher ATP cost of contraction on the metabolic response to graded exercise in patients with chronic obstructive pulmonary disease |
| title_full_unstemmed | The effect of higher ATP cost of contraction on the metabolic response to graded exercise in patients with chronic obstructive pulmonary disease |
| title_short | The effect of higher ATP cost of contraction on the metabolic response to graded exercise in patients with chronic obstructive pulmonary disease |
| title_sort | effect of higher atp cost of contraction on the metabolic response to graded exercise in patients with chronic obstructive pulmonary disease |
| url | http://hdl.handle.net/20.500.11937/63306 |