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Alternatives to the six-minute walk test in pulmonary arterial hypertension.

Mainguy V, Malenfant S, Neyron AS, Saey D, Maltais F, Bonnet S, Provencher S - PLoS ONE (2014)

Bottom Line: The physiological response during the endurance shuttle walk test (ESWT), the cycle endurance test (CET) and the incremental shuttle walk test (ISWT) remains unknown in PAH.However, the trends overtime differed.Endurance tests induce a maximal physiological demand in PAH.

View Article: PubMed Central - PubMed

Affiliation: Pulmonary Hypertension Research Group, Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec (Québec), Canada.

ABSTRACT

Introduction: The physiological response during the endurance shuttle walk test (ESWT), the cycle endurance test (CET) and the incremental shuttle walk test (ISWT) remains unknown in PAH. We tested the hypothesis that endurance tests induce a near-maximal physiological demand comparable to incremental tests. We also hypothesized that differences in respiratory response during exercise would be related to the characteristics of the exercise tests.

Methods: Within two weeks, twenty-one PAH patients (mean age: 54(15) years; mean pulmonary arterial pressure: 42(12) mmHg) completed two cycling exercise tests (incremental cardiopulmonary cycling exercise test (CPET) and CET) and three field tests (ISWT, ESWT and six-minute walk test (6MWT)). Physiological parameters were continuously monitored using the same portable telemetric device.

Results: Peak oxygen consumption (VO(2peak)) was similar amongst the five exercise tests (p = 0.90 by ANOVA). Walking distance correlated markedly with the VO(2peak) reached during field tests, especially when weight was taken into account. At 100% exercise, most physiological parameters were similar between incremental and endurance tests. However, the trends overtime differed. In the incremental tests, slopes for these parameters rose steadily over the entire duration of the tests, whereas in the endurance tests, slopes rose sharply from baseline to 25% of maximum exercise at which point they appeared far less steep until test end. Moreover, cycling exercise tests induced higher respiratory exchange ratio, ventilatory demand and enhanced leg fatigue measured subjectively and objectively.

Conclusion: Endurance tests induce a maximal physiological demand in PAH. Differences in peak respiratory response during exercise are related to the modality (cycling vs. walking) rather than the progression (endurance vs. incremental) of the exercise tests.

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Related in: MedlinePlus

Comparison of the physiological parameters between cycling and walking constant work rate exercise tests.Physiological response during the cycle endurance test (CET) and the endurance shuttle walk test (ESWT) at the same relative time (e.g. 0%, 25%, 50%, 75% and 100%) from maximal exercise duration. The ESWT was characterized by a higher oxygen consumption (VO2) and a lower respiratory exchange ratio (RER) throughout the exercise. Conversely, carbon dioxide output (VCO2), minute ventilation (VE) and oxygen pulse (VO2/HR) slopes were slightly steeper in the early phase of the CET (from baseline to 25% of exercise duration), to end up with similar end-exercise values. Similarly, heart rate (HR) slopes, although statistically significant, were virtually the same during the CET and the ESWT. The shaded zone represents the initial warm-up period of the ESWT. #p≤0.01 between CET and ESWT. Values are means (SE). *p<0.05; **p<0.01; ***p<0.001 for the comparison of the slopes of each parameter from baseline to 25% of exercise duration, and from 25% to 100% (test end).
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pone-0103626-g003: Comparison of the physiological parameters between cycling and walking constant work rate exercise tests.Physiological response during the cycle endurance test (CET) and the endurance shuttle walk test (ESWT) at the same relative time (e.g. 0%, 25%, 50%, 75% and 100%) from maximal exercise duration. The ESWT was characterized by a higher oxygen consumption (VO2) and a lower respiratory exchange ratio (RER) throughout the exercise. Conversely, carbon dioxide output (VCO2), minute ventilation (VE) and oxygen pulse (VO2/HR) slopes were slightly steeper in the early phase of the CET (from baseline to 25% of exercise duration), to end up with similar end-exercise values. Similarly, heart rate (HR) slopes, although statistically significant, were virtually the same during the CET and the ESWT. The shaded zone represents the initial warm-up period of the ESWT. #p≤0.01 between CET and ESWT. Values are means (SE). *p<0.05; **p<0.01; ***p<0.001 for the comparison of the slopes of each parameter from baseline to 25% of exercise duration, and from 25% to 100% (test end).

Mentions: Cardiac and ventilatory responses for each exercise test are described in Table 2 and Figures 1–3, respectively. At 100% exercise, VO2peak was similar for all exercise modalities (p = 0.90 by ANOVA). As expected, the slope of the physiological parameters during the tests significantly differed between exercise modalities (Figure 1). In the incremental tests, slopes for oxygen consumption, heart rate (HR), minute ventilation (VE), respiratory exchange ratio (RER), as well as carbon dioxide output and VE/VCO2 (data not shown) rose steadily over the entire duration of the tests. Conversely, in the endurance tests, slopes rose sharply from baseline to 25% of maximum exercise (all p≤0.001 compared to the slopes of incremental tests using the longitudinal mixed model), at which point they appeared far less steep until test end (all p<0.05 compared to the slopes of incremental tests using the longitudinal mixed model). The work rate achieved during CPET and CET significantly correlated with VO2peak reached during these tests (R2 = 0.62 and 0.74, respectively, both p<0.01). The mean 6MWT distance was 447(96) meters, as compared to 384(87) and 460(258) meters for the ISWT and ESWT respectively. While the distance walked during the 6MWT, ISWT and ESWT correlated with the VO2peak reached during these tests (R2 = 0.25, 0.41 and 0.33, all p<0.01), this correlation was markedly increased when the work of walking was taken into account (R2 = 0.75, 0.75 and 0.47, all p<0.01) or when the distance walked during the 6MWT and the ISWT was correlated with the VO2peak/kg reached during these tests (R2 = 0.67 and 0.75, all p<0.01). Note that these adjustments minimally influenced these correlations for the ESWT (0.47 and 0.20, p<0.01, for the work of walking and the VO2peak/kg).


Alternatives to the six-minute walk test in pulmonary arterial hypertension.

Mainguy V, Malenfant S, Neyron AS, Saey D, Maltais F, Bonnet S, Provencher S - PLoS ONE (2014)

Comparison of the physiological parameters between cycling and walking constant work rate exercise tests.Physiological response during the cycle endurance test (CET) and the endurance shuttle walk test (ESWT) at the same relative time (e.g. 0%, 25%, 50%, 75% and 100%) from maximal exercise duration. The ESWT was characterized by a higher oxygen consumption (VO2) and a lower respiratory exchange ratio (RER) throughout the exercise. Conversely, carbon dioxide output (VCO2), minute ventilation (VE) and oxygen pulse (VO2/HR) slopes were slightly steeper in the early phase of the CET (from baseline to 25% of exercise duration), to end up with similar end-exercise values. Similarly, heart rate (HR) slopes, although statistically significant, were virtually the same during the CET and the ESWT. The shaded zone represents the initial warm-up period of the ESWT. #p≤0.01 between CET and ESWT. Values are means (SE). *p<0.05; **p<0.01; ***p<0.001 for the comparison of the slopes of each parameter from baseline to 25% of exercise duration, and from 25% to 100% (test end).
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pone-0103626-g003: Comparison of the physiological parameters between cycling and walking constant work rate exercise tests.Physiological response during the cycle endurance test (CET) and the endurance shuttle walk test (ESWT) at the same relative time (e.g. 0%, 25%, 50%, 75% and 100%) from maximal exercise duration. The ESWT was characterized by a higher oxygen consumption (VO2) and a lower respiratory exchange ratio (RER) throughout the exercise. Conversely, carbon dioxide output (VCO2), minute ventilation (VE) and oxygen pulse (VO2/HR) slopes were slightly steeper in the early phase of the CET (from baseline to 25% of exercise duration), to end up with similar end-exercise values. Similarly, heart rate (HR) slopes, although statistically significant, were virtually the same during the CET and the ESWT. The shaded zone represents the initial warm-up period of the ESWT. #p≤0.01 between CET and ESWT. Values are means (SE). *p<0.05; **p<0.01; ***p<0.001 for the comparison of the slopes of each parameter from baseline to 25% of exercise duration, and from 25% to 100% (test end).
Mentions: Cardiac and ventilatory responses for each exercise test are described in Table 2 and Figures 1–3, respectively. At 100% exercise, VO2peak was similar for all exercise modalities (p = 0.90 by ANOVA). As expected, the slope of the physiological parameters during the tests significantly differed between exercise modalities (Figure 1). In the incremental tests, slopes for oxygen consumption, heart rate (HR), minute ventilation (VE), respiratory exchange ratio (RER), as well as carbon dioxide output and VE/VCO2 (data not shown) rose steadily over the entire duration of the tests. Conversely, in the endurance tests, slopes rose sharply from baseline to 25% of maximum exercise (all p≤0.001 compared to the slopes of incremental tests using the longitudinal mixed model), at which point they appeared far less steep until test end (all p<0.05 compared to the slopes of incremental tests using the longitudinal mixed model). The work rate achieved during CPET and CET significantly correlated with VO2peak reached during these tests (R2 = 0.62 and 0.74, respectively, both p<0.01). The mean 6MWT distance was 447(96) meters, as compared to 384(87) and 460(258) meters for the ISWT and ESWT respectively. While the distance walked during the 6MWT, ISWT and ESWT correlated with the VO2peak reached during these tests (R2 = 0.25, 0.41 and 0.33, all p<0.01), this correlation was markedly increased when the work of walking was taken into account (R2 = 0.75, 0.75 and 0.47, all p<0.01) or when the distance walked during the 6MWT and the ISWT was correlated with the VO2peak/kg reached during these tests (R2 = 0.67 and 0.75, all p<0.01). Note that these adjustments minimally influenced these correlations for the ESWT (0.47 and 0.20, p<0.01, for the work of walking and the VO2peak/kg).

Bottom Line: The physiological response during the endurance shuttle walk test (ESWT), the cycle endurance test (CET) and the incremental shuttle walk test (ISWT) remains unknown in PAH.However, the trends overtime differed.Endurance tests induce a maximal physiological demand in PAH.

View Article: PubMed Central - PubMed

Affiliation: Pulmonary Hypertension Research Group, Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Université Laval, Québec (Québec), Canada.

ABSTRACT

Introduction: The physiological response during the endurance shuttle walk test (ESWT), the cycle endurance test (CET) and the incremental shuttle walk test (ISWT) remains unknown in PAH. We tested the hypothesis that endurance tests induce a near-maximal physiological demand comparable to incremental tests. We also hypothesized that differences in respiratory response during exercise would be related to the characteristics of the exercise tests.

Methods: Within two weeks, twenty-one PAH patients (mean age: 54(15) years; mean pulmonary arterial pressure: 42(12) mmHg) completed two cycling exercise tests (incremental cardiopulmonary cycling exercise test (CPET) and CET) and three field tests (ISWT, ESWT and six-minute walk test (6MWT)). Physiological parameters were continuously monitored using the same portable telemetric device.

Results: Peak oxygen consumption (VO(2peak)) was similar amongst the five exercise tests (p = 0.90 by ANOVA). Walking distance correlated markedly with the VO(2peak) reached during field tests, especially when weight was taken into account. At 100% exercise, most physiological parameters were similar between incremental and endurance tests. However, the trends overtime differed. In the incremental tests, slopes for these parameters rose steadily over the entire duration of the tests, whereas in the endurance tests, slopes rose sharply from baseline to 25% of maximum exercise at which point they appeared far less steep until test end. Moreover, cycling exercise tests induced higher respiratory exchange ratio, ventilatory demand and enhanced leg fatigue measured subjectively and objectively.

Conclusion: Endurance tests induce a maximal physiological demand in PAH. Differences in peak respiratory response during exercise are related to the modality (cycling vs. walking) rather than the progression (endurance vs. incremental) of the exercise tests.

Show MeSH
Related in: MedlinePlus