1
|
Goulding RP, Burnley M, Wüst RCI. How Priming Exercise Affects Oxygen Uptake Kinetics: From Underpinning Mechanisms to Endurance Performance. Sports Med 2023; 53:959-976. [PMID: 37010782 PMCID: PMC10115720 DOI: 10.1007/s40279-023-01832-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2023] [Indexed: 04/04/2023]
Abstract
The observation that prior heavy or severe-intensity exercise speeds overall oxygen uptake ([Formula: see text]O2) kinetics, termed the "priming effect", has garnered significant research attention and its underpinning mechanisms have been hotly debated. In the first part of this review, the evidence for and against (1) lactic acidosis, (2) increased muscle temperature, (3) O2 delivery, (4) altered motor unit recruitment patterns and (5) enhanced intracellular O2 utilisation in underpinning the priming effect is discussed. Lactic acidosis and increased muscle temperature are most likely not key determinants of the priming effect. Whilst priming increases muscle O2 delivery, many studies have demonstrated that an increased muscle O2 delivery is not a prerequisite for the priming effect. Motor unit recruitment patterns are altered by prior exercise, and these alterations are consistent with some of the observed changes in [Formula: see text]O2 kinetics in humans. Enhancements in intracellular O2 utilisation likely play a central role in mediating the priming effect, probably related to elevated mitochondrial calcium levels and parallel activation of mitochondrial enzymes at the onset of the second bout. In the latter portion of the review, the implications of priming on the parameters of the power-duration relationship are discussed. The effect of priming on subsequent endurance performance depends critically upon which phases of the [Formula: see text]O2 response are altered. A reduced [Formula: see text]O2 slow component or increased fundamental phase amplitude tend to increase the work performable above critical power (i.e. W´), whereas a reduction in the fundamental phase time constant following priming results in an increased critical power.
Collapse
Affiliation(s)
- Richie P Goulding
- Laboratory for Myology, Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands.
| | - Mark Burnley
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Rob C I Wüst
- Laboratory for Myology, Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands
| |
Collapse
|
2
|
Jones S, Tillin T, Williams S, Rapala A, Chaturvedi N, Hughes AD. Skeletal Muscle Tissue Saturation Changes Measured Using Near Infrared Spectroscopy During Exercise Are Associated With Post-Occlusive Reactive Hyperaemia. Front Physiol 2022; 13:919754. [PMID: 35874520 PMCID: PMC9304617 DOI: 10.3389/fphys.2022.919754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 06/17/2022] [Indexed: 11/22/2022] Open
Abstract
Measuring local haemodynamics in skeletal muscle has the potential to provide valuable insight into the oxygen delivery to tissue, especially during high demand situations such as exercise. The aim of this study was to compare the skeletal muscle microvascular response during post-occlusive reactive hyperaemia (PORH) with the response to exercise, each measured using near-infrared spectroscopy (NIRS) and to establish if associations exist between muscle measures and exercise capacity or sex. Participants were from a population-based cohort study, the Southall and Brent Revisited (SABRE) study. Skeletal muscle measures included changes in tissue saturation index at the onset of exercise (∆TSIBL-INC) and across the whole of exercise (∆TSIBL-EE), time to 50%, 95% and 100% PORH, rate of PORH recovery, area under the curve (AUC) and total oxygenated Haemoglobin (oxy-Hb) change during PORH. Exercise capacity was measured using a 6-min stepper test (6MST). Analysis was by multiple linear regression. In total, 558 participants completed the 6MST with NIRS measures of TSI (mean age±SD: 73 ± 7years, 59% male). A sub-set of 149 participants also undertook the arterial occlusion. Time to 100% PORH, recovery rate, AUC and ∆oxy-Hb were all associated with ∆TSIBL-EE (β-coefficient (95%CI): 0.05 (0.01, 0.09), p = 0.012; -47 (-85, -9.9), p = 0.014; 1.7 (0.62, 2.8), p = 0.002; 0.04 (0.002.0.108), p = 0.041, respectively). Time to 95% & 100% PORH, AUC and ∆oxy-Hb were all associated with ∆TSIBL-INC (β-coefficient (95%CI): -0.07 (-0.12,-0.02), p = 0.02; -0.03 (-0.05, -0.003), p = 0.028; 0.85 (0.18, 1.5), p = 0.013 & 0.05 (0.02, 0.09), p = 0.001, respectively). AUC and ∆Oxy-Hb were associated with steps achieved (β-coefficient (95%CI): 18.0 (2.3, 33.7), p = 0.025; 0.86 (0.10, 1.6), p = 0.027). ∆TSIBL-EE was associated with steps and highest VO2 (1.7 (0.49, 2.9), p = 0.006; 7.7 (3.2, 12.3), p = 0.001). ∆TSIBL-INC was associated with steps and VO2 but this difference was attenuated towards the null after adjustment for age, sex and ethnicity. ∆TSIBL-EE was greater in women (3.4 (0.4, 8.9) versus 2.1 (0.3, 7.4), p = 0.017) and ∆TSIBL-INC was lower in women versus men (2.4 (0.2, 10.2) versus 3.2 (0.2, 18.2), p = 0.016). These Local microvascular NIRS-measures are associated with exercise capacity in older adults and several measures can detect differences in microvascular reactivity between a community-based sample of men and women.
Collapse
Affiliation(s)
- Siana Jones
- MRC Unit for Lifelong Health & Ageing at UCL, Department of Population Science and Experimental Medicine, Institute for Cardiovascular Science, University College London, London, United Kingdom
| | | | | | | | | | | |
Collapse
|
3
|
Salzmann K, Sanchez AMJ, Borrani F. Effects of Blood Flow Restriction on O 2 Muscle Extraction and O 2 Pulmonary Uptake Kinetics During Heavy Exercise. Front Physiol 2021; 12:722848. [PMID: 34539445 PMCID: PMC8441002 DOI: 10.3389/fphys.2021.722848] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 08/03/2021] [Indexed: 11/13/2022] Open
Abstract
This study aimed to determine the effects of three levels of blood flow restriction (BFR) on V˙O2 and O2 extraction kinetics during heavy cycling exercise transitions. Twelve healthy trained males completed two bouts of 10 min heavy intensity exercise without BFR (CON), with 40% or 50% BFR (BFR40 and BFR50, respectively). V˙O2 and tissue saturation index (TSI) were continuously measured and modelled using multiexponential functions. The time constant of the V˙O2 primary phase was significantly slowed in BFR40 (26.4 ± 2.0s; p < 0.001) and BFR50 (27.1 ± 2.1s; p = 0.001) compared to CON (19.0 ± 1.1s). The amplitude of the V˙O2 slow component was significantly increased (p < 0.001) with BFR in a pressure-dependent manner 3.6 ± 0.7, 6.7 ± 0.9 and 9.7 ± 1.0 ml·min−1·kg−1 for CON, BFR40, and BFR50, respectively. While no acceleration of the primary component of the TSI kinetics was observed, there was an increase (p < 0.001) of the phase 3 amplitude with BFR (CON −0.8 ± 0.3% VS BFR40 −2.9 ± 0.9%, CON VS BFR50 −2.8 ± 0.8%). It may be speculated that BFR applied during cycling exercise in the heavy intensity domain shifted the working muscles to an O2 dependent situation. The acceleration of the extraction kinetics could have reached a plateau, hence not permitting compensation for the slowdown of the blood flow kinetics, and slowing V˙O2 kinetics.
Collapse
Affiliation(s)
- Killian Salzmann
- Institute of Sport Sciences of University of Lausanne (ISSUL), University of Lausanne, Lausanne, Switzerland
| | - Anthony M J Sanchez
- University of Perpignan Via Domitia (UPVD), Faculty of Sports Sciences, Laboratoire Interdisciplinaire Performance Santé Environnement De Montagne (LIPSEM), Font-Romeu, France
| | - Fabio Borrani
- Institute of Sport Sciences of University of Lausanne (ISSUL), University of Lausanne, Lausanne, Switzerland
| |
Collapse
|
4
|
Salutary Acute Effects of Exercise on Central Hemodynamics in Heart Failure With Preserved Ejection Fraction. J Card Fail 2021; 27:1313-1320. [PMID: 33974969 DOI: 10.1016/j.cardfail.2021.04.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 04/27/2021] [Accepted: 04/28/2021] [Indexed: 11/21/2022]
Abstract
BACKGROUND A warmup period of priming exercise has been shown to improve peripheral oxygen transport in older adults. We sought to determine the acute effects of priming exercise on central hemodynamics at rest and during a repeat exercise in heart failure with preserved ejection fraction (HFpEF). METHODS AND RESULTS This is a post hoc analysis from 3 studies. Patients with HFpEF (n = 42) underwent cardiac catheterization with simultaneous expired gas analysis at rest and during exercise (20 W for 5 minutes, priming exercise). Measurements were then repeated at rest and during a second bout of exercise at a 20-W workload (second exercise). During the priming exercise, patients with HFpEF displayed dramatic increases in biventricular filling pressures and exercise-induced pulmonary hypertension. After the priming exercise at rest, biventricular filling pressures and pulmonary artery (PA) pressures were lower and lung tidal volume was increased. During the second bout of exercise, biventricular filling (PA wedge pressure, 29 ± 8 mm Hg at second exercise vs 32 ± 7 mm Hg at first exercise, P = .0003) and PA pressures were lower, and PA compliance increased. CONCLUSIONS This study shows that short duration, submaximal priming exercise attenuates the pathologic increases in filling pressures, improving pulmonary vascular hemodynamics at rest and during repeat exercise in patients with HFpEF.
Collapse
|
5
|
Short-Term Changes in Quality of Life in Patients with Advanced Lung Cancer during In-Hospital Exercise Training and Chemotherapy Treatment: A Randomized Controlled Trial. J Clin Med 2021; 10:jcm10081761. [PMID: 33919571 PMCID: PMC8073323 DOI: 10.3390/jcm10081761] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 04/13/2021] [Accepted: 04/16/2021] [Indexed: 12/24/2022] Open
Abstract
The aim of this study was to assess the impact of exercise training on the quality of life (QoL) of patients diagnosed with stage IIIB and stage IV non–small cell lung cancer (NSCLC) compared to a passive control group (CG). The exercise-trained group (ETG) consisted of 18 patients, and the CG consisted of 8 patients. The training program in the ETG consisted of two 2-week running cycles interspersed with consecutive rounds of chemotherapy with cytostatic drugs. A comparison of the changes in the Short Form (36) Health Survey (SF-36), St. George’s Respiratory Questionnaire (SGRQ), and the Functional Assessment of Cancer Therapy-Lung (FACT-L) was the primary outcome. Analysis of the results of the SGRQ and the SF-36 questionnaire did not reveal any statistically significant differences in the assessment of QoL between the examined groups. The analysis of FACT-L questionnaires showed statistically significant changes, indicating deterioration of QoL in domains describing physical well-being in the CG. Therefore, the analysis of the results of the QoL assessment did not show any significant improvements in the group of patients undergoing comprehensive exercise training, although deterioration of QoL was noted in the CG.
Collapse
|
6
|
Iannetta D, de Almeida Azevedo R, Ingram CP, Keir DA, Murias JM. Evaluating the suitability of supra-PO peak verification trials after ramp-incremental exercise to confirm the attainment of maximum O 2 uptake. Am J Physiol Regul Integr Comp Physiol 2020; 319:R315-R322. [PMID: 32697652 DOI: 10.1152/ajpregu.00126.2020] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
During exhaustive ramp-incremental cycling tests, the incidence of O2 uptake (V̇o2) plateaus is low. To verify the attainment of maximum V̇o2 (V̇o2max), it is recommended that a trial at a power output (PO) corresponding to 110% of the ramp-derived peak (POpeak) is performed. It remains unclear whether verification trials set at this PO can be tolerated for long enough to allow attainment of V̇o2max. Eleven recreationally trained individuals performed five ramp tests of varying slope (5, 10, 15, 25, and 30 W/min), each followed, in series, by two verification trials: the first at 110% POpeak of the 25 W/min ramp and the second at 110% POpeak attained in the preceding ramp test. Exercise duration of the first verification trial was on average 81 ± 15 s (CV = 9 ± 3%) versus 162 ± 32, 121 ± 24, 103 ± 15, and 73 ± 10 s for the second verification trials at 110% of POpeak of the 5, 10, 15, and 30 W/min ramp tests, respectively (P < 0.05). Compared with the highest V̇o2 recorded during ramp tests, V̇o2 from the subsequent verification trials was not different for the 5, 10, and 15 W/min ramp tests (P > 0.05) but was lower for the 25 and 30 W/min ramp tests (P < 0.05). Verification trials at 110% POpeak of rapidly incrementing ramp tests (i.e., 25 W/min) were not sustained for long enough to allow the attainment of V̇o2max. With commonly used rapidly incrementing ramp tests engendering exhaustion within 8-12 min, verification trials less than POpeak should be preferred as they can be sustained sufficiently long to allow the attainment of V̇o2max.
Collapse
Affiliation(s)
- Danilo Iannetta
- Faculty of Kinesiology, University of Calgary, Calgary, Canada
| | | | | | - Daniel A Keir
- Department of Medicine, University Health Network, Toronto, Canada
| | - Juan M Murias
- Faculty of Kinesiology, University of Calgary, Calgary, Canada
| |
Collapse
|
7
|
Goulart CDL, Arêas GPT, Caruso FR, Araújo ASG, de Moura SCG, Catai AM, Beltrame T, Junior LCDC, Dos Santos PB, Roscani MG, Mendes RG, Arena R, Borghi-Silva A. Effect of high-intensity exercise on cerebral, respiratory and peripheral muscle oxygenation of HF and COPD-HF patients. Heart Lung 2020; 50:113-120. [PMID: 32709499 DOI: 10.1016/j.hrtlng.2020.06.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 05/15/2020] [Accepted: 06/29/2020] [Indexed: 01/09/2023]
Abstract
OBJECTIVE To investigate cerebral oxygenation (Cox) responses as well as respiratory (Res) and active peripheral muscle (Pm) O2 delivery during high-intensity cycling exercise and contrast responses between patients with coexistent chronic obstructive pulmonary disease (COPD)-heart failure (HF) and HF alone. METHODS Cross-sectional study involving 11 COPD-HF and 11 HF patients. On two different days, patients performed maximal incremental cardiopulmonary exercise testing (CPET) and constant load exercise on a cycle ergometer until the limit of tolerance (Tlim). The high-intensity exercise session was 80% of the peak CPET work rate. Relative blood concentrations of oxyhemoglobin ([O2Hb]), deoxyhemoglobin ([HHb]) of Res, Pm (right vastus lateralis) and Cox (pre-frontal) were measured using near infrared spectroscopy. RESULTS We observed a greater decrease in [O2Hb] at a lower Tlim in COPD-HF when compared to HF (P < 0.05). [HHb] of Res was higher (P < 0.05) and Tlim was lower in COPD-HF vs. HF. Pm and Cox were lower and Tlim was higher in (P < 0.05) HF vs. COPD-HF. In HF, there was a lower ∆[O2Hb] and higher ∆ [HHb] of Pm when contrasted to Cox observed during exercise, as well as a lower ∆ [O2Hb] and higher ∆ [HHb] of Res when contrasted with Cox (P < 0.05). However, COPD-HF patients presented with a higher ∆ [HHb] of Res and Pm when contrasted with Cox (P < 0.05). CONCLUSION The coexistence of COPD in patients with HF produces negative effects on Cox, greater deoxygenation of the respiratory and peripheral muscles and higher exertional dyspnea, which may help to explain an even lower exercise tolerance in this multimorbidity phenotype.
Collapse
Affiliation(s)
- Cássia da Luz Goulart
- Cardiopulmonary Physiotherapy Laboratory, Physiotherapy Department, Federal University of Sao Carlos, UFSCar, Rodovia Washington Luis, KM 235, Monjolinho, CEP: 13565-905, Sao Carlos, SP, Brazil
| | - Guilherme Peixoto Tinoco Arêas
- Cardiopulmonary Physiotherapy Laboratory, Physiotherapy Department, Federal University of Sao Carlos, UFSCar, Rodovia Washington Luis, KM 235, Monjolinho, CEP: 13565-905, Sao Carlos, SP, Brazil; Human Physiology Laboratory, Physiology Department, Federal University of Amazonas, UFAM, v. General Rodrigo Octávio, 6200, Coroado I, CEP: 69080-900, Manaus, AM, Brazil
| | - Flávia Rossi Caruso
- Cardiopulmonary Physiotherapy Laboratory, Physiotherapy Department, Federal University of Sao Carlos, UFSCar, Rodovia Washington Luis, KM 235, Monjolinho, CEP: 13565-905, Sao Carlos, SP, Brazil
| | - Adriana S Garcia Araújo
- Cardiopulmonary Physiotherapy Laboratory, Physiotherapy Department, Federal University of Sao Carlos, UFSCar, Rodovia Washington Luis, KM 235, Monjolinho, CEP: 13565-905, Sao Carlos, SP, Brazil
| | - Sílvia Cristina Garcia de Moura
- Cardiovascular Physical Therapy Laboratory, Physiotherapy Department, Federal University of São Carlos, Rod Washington Luis, KM 235, Monjolinho, CEP: 13565-905, Sao Carlos, SP, Brazil
| | - Aparecida Maria Catai
- Cardiovascular Physical Therapy Laboratory, Physiotherapy Department, Federal University of São Carlos, Rod Washington Luis, KM 235, Monjolinho, CEP: 13565-905, Sao Carlos, SP, Brazil
| | - Thomas Beltrame
- Cardiovascular Physical Therapy Laboratory, Physiotherapy Department, Federal University of São Carlos, Rod Washington Luis, KM 235, Monjolinho, CEP: 13565-905, Sao Carlos, SP, Brazil
| | - Luiz Carlos de Carvalho Junior
- Cardiopulmonary Physiotherapy Laboratory, Physiotherapy Department, Federal University of Sao Carlos, UFSCar, Rodovia Washington Luis, KM 235, Monjolinho, CEP: 13565-905, Sao Carlos, SP, Brazil
| | - Polliana Batista Dos Santos
- Cardiopulmonary Physiotherapy Laboratory, Physiotherapy Department, Federal University of Sao Carlos, UFSCar, Rodovia Washington Luis, KM 235, Monjolinho, CEP: 13565-905, Sao Carlos, SP, Brazil
| | | | - Renata Gonçalves Mendes
- Cardiopulmonary Physiotherapy Laboratory, Physiotherapy Department, Federal University of Sao Carlos, UFSCar, Rodovia Washington Luis, KM 235, Monjolinho, CEP: 13565-905, Sao Carlos, SP, Brazil
| | - Ross Arena
- Department of Physical Therapy, College of Applied Health Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Audrey Borghi-Silva
- Cardiopulmonary Physiotherapy Laboratory, Physiotherapy Department, Federal University of Sao Carlos, UFSCar, Rodovia Washington Luis, KM 235, Monjolinho, CEP: 13565-905, Sao Carlos, SP, Brazil.
| |
Collapse
|
8
|
Goulding RP, Roche DM, Scott SN, Koga S, Weston PJ, Marwood S. Limitations to exercise tolerance in type 1 diabetes: the role of pulmonary oxygen uptake kinetics and priming exercise. J Appl Physiol (1985) 2020; 128:1299-1309. [PMID: 32213117 DOI: 10.1152/japplphysiol.00892.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
We compared the time constant (τV̇O2) of the fundamental phase of pulmonary oxygen uptake (V̇o2) kinetics between young adult men with type 1 diabetes and healthy control subjects. We also assessed the impact of priming exercise on τV̇O2, critical power, and muscle deoxygenation in a subset of participants with type 1 diabetes. Seventeen men with type 1 diabetes and 17 healthy male control subjects performed moderate-intensity exercise to determine τV̇O2. A subset of seven participants with type 1 diabetes performed an additional eight visits, in which critical power, τV̇O2, and muscle deoxyhemoglobin + myoglobin ([HHb+Mb], via near-infrared spectroscopy) kinetics (described by a time constant, τ[HHb+Mb]) were determined with (PRI) and without (CON) a prior 6-min bout of heavy exercise. τV̇O2 was greater in participants with type 1 diabetes compared with control subjects (type 1 diabetes 50 ± 13 vs. control 32 ± 12 s; P < 0.001). Critical power was greater in PRI compared with CON (PRI 161 ± 25 vs. CON 149 ± 22 W; P < 0.001), whereas τV̇O2 (PRI 36 ± 15 vs. CON 50 ± 21 s; P = 0.006) and τ[HHb+Mb] (PRI 10 ± 5 vs. CON 17 ± 11 s; P = 0.037) were reduced in PRI compared with CON. Type 1 diabetes patients showed slower pulmonary V̇o2 kinetics compared with control subjects; priming exercise speeded V̇o2 and [HHb + Mb] kinetics and increased critical power in a subgroup with type 1 diabetes. These data therefore represent the first characterization of the power-duration relationship in type 1 diabetes and the first experimental evidence that τV̇O2 is an independent determinant of critical power in this population.NEW & NOTEWORTHY Patients with type 1 diabetes demonstrated slower oxygen uptake (V̇o2) kinetics compared with healthy control subjects. Furthermore, a prior bout of high-intensity exercise speeded V̇o2 kinetics and increased critical power in people with type 1 diabetes. Prior exercise speeded muscle deoxygenation kinetics, indicating that V̇o2 kinetics in type 1 diabetes are limited primarily by oxygen extraction and/or intracellular factors. These findings highlight the potential for interventions that decrease metabolic inertia for enhancing exercise tolerance in this condition.
Collapse
Affiliation(s)
- Richie P Goulding
- School of Health Sciences, Liverpool Hope University, Liverpool, United Kingdom.,Japan Society for Promotion of Science, Tokyo, Japan.,Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| | - Denise M Roche
- School of Health Sciences, Liverpool Hope University, Liverpool, United Kingdom
| | - Sam N Scott
- University Department of Diabetes, Endocrinology, Nutritional Medicine, and Metabolism, University Hospital and University of Bern, Bern, Switzerland.,Team Novo Nordisk Professional Cycling Team, Atlanta, Georgia
| | - Shunsaku Koga
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| | - Philip J Weston
- Royal Liverpool and Broadgreen University Hospitals NHS Trust, Liverpool, United Kingdom
| | - Simon Marwood
- School of Health Sciences, Liverpool Hope University, Liverpool, United Kingdom
| |
Collapse
|
9
|
Garnham JO, Roberts LD, Espino-Gonzalez E, Whitehead A, Swoboda PP, Koshy A, Gierula J, Paton MF, Cubbon RM, Kearney MT, Egginton S, Bowen TS, Witte KK. Chronic heart failure with diabetes mellitus is characterized by a severe skeletal muscle pathology. J Cachexia Sarcopenia Muscle 2020; 11:394-404. [PMID: 31863644 PMCID: PMC7113493 DOI: 10.1002/jcsm.12515] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 10/07/2019] [Accepted: 10/17/2019] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Patients with coexistent chronic heart failure (CHF) and diabetes mellitus (DM) demonstrate greater exercise limitation and worse prognosis compared with CHF patients without DM, even when corrected for cardiac dysfunction. Understanding the origins of symptoms in this subgroup may facilitate development of targeted treatments. We therefore characterized the skeletal muscle phenotype and its relationship to exercise limitation in patients with diabetic heart failure (D-HF). METHODS In one of the largest muscle sampling studies in a CHF population, pectoralis major biopsies were taken from age-matched controls (n = 25), DM (n = 10), CHF (n = 52), and D-HF (n = 28) patients. In situ mitochondrial function and reactive oxygen species, fibre morphology, capillarity, and gene expression analyses were performed and correlated to whole-body exercise capacity. RESULTS Mitochondrial respiration, content, coupling efficiency, and intrinsic function were lower in D-HF patients compared with other groups (P < 0.05). A unique mitochondrial complex I dysfunction was present in D-HF patients only (P < 0.05), which strongly correlated to exercise capacity (R2 = 0.64; P < 0.001). Mitochondrial impairments in D-HF corresponded to higher levels of mitochondrial reactive oxygen species (P < 0.05) and lower gene expression of anti-oxidative enzyme superoxide dismutase 2 (P < 0.05) and complex I subunit NDUFS1 (P < 0.05). D-HF was also associated with severe fibre atrophy (P < 0.05) and reduced local fibre capillarity (P < 0.05). CONCLUSIONS Patients with D-HF develop a specific skeletal muscle pathology, characterized by mitochondrial impairments, fibre atrophy, and derangements in the capillary network that are linked to exercise intolerance. These novel preliminary data support skeletal muscle as a potential therapeutic target for treating patients with D-HF.
Collapse
Affiliation(s)
- Jack O Garnham
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Lee D Roberts
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Ever Espino-Gonzalez
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Anna Whitehead
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Peter P Swoboda
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Aaron Koshy
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - John Gierula
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Maria F Paton
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Richard M Cubbon
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Mark T Kearney
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Stuart Egginton
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - T Scott Bowen
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Klaus K Witte
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| |
Collapse
|
10
|
Garnham JO, Roberts LD, Caspi T, Al-Owais MM, Bullock M, Swoboda PP, Koshy A, Gierula J, Paton MF, Cubbon RM, Kearney MT, Bowen TS, Witte KK. Divergent skeletal muscle mitochondrial phenotype between male and female patients with chronic heart failure. J Cachexia Sarcopenia Muscle 2020; 11:79-88. [PMID: 31430834 PMCID: PMC7015245 DOI: 10.1002/jcsm.12488] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 06/23/2019] [Accepted: 07/22/2019] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Previous studies in heart failure with reduced ejection fraction (HFrEF) suggest that skeletal muscle mitochondrial impairments are associated with exercise intolerance in men. However, the nature of this relationship in female patients remains to be elucidated. This study aimed to determine the relationship between skeletal muscle mitochondrial impairments and exercise intolerance in male and female patients with HFrEF. METHODS Mitochondrial respiration, enzyme activity, and gene expression were examined in pectoralis major biopsies from age-matched male (n = 45) and female (n = 11) patients with HFrEF and healthy-matched male (n = 24) and female (n = 11) controls. Mitochondrial variables were compared between sex and related to peak exercise capacity. RESULTS Compared with sex-matched controls, complex I mitochondrial oxygen flux was 17% (P = 0.030) and 29% (P = 0.013) lower in male and female patients with HFrEF, respectively, which correlated to exercise capacity (r = 0.71; P > 0.0001). Female HFrEF patients had a 32% (P = 0.023) lower mitochondrial content compared with controls. However, after adjusting for mitochondrial content, male patients demonstrated lower complex I function by 15% (P = 0.030). Expression of key mitochondrial genes regulating organelle dynamics and maintenance (i.e. optic atrophy 1, peroxisome proliferator-activated receptor γ coactivator-1α, NADH:ubiquinone oxidoreductase core subunit S1/S3, and superoxide dismutase 2) were selectively lower in female HFrEF patients. CONCLUSIONS These data provide novel evidence that HFrEF induces divergent sex-specific mitochondrial phenotypes in skeletal muscle that predispose towards exercise intolerance, impacting mitochondrial 'quantity' in female patients and mitochondrial 'quality' in male patients. Therapeutic strategies to improve exercise tolerance in HFrEF should consider targeting sex-specific mitochondrial abnormalities in skeletal muscle.
Collapse
Affiliation(s)
- Jack O Garnham
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Lee D Roberts
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Talia Caspi
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Moza M Al-Owais
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Max Bullock
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Peter P Swoboda
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Aaron Koshy
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - John Gierula
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Maria F Paton
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Richard M Cubbon
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - Mark T Kearney
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| | - T Scott Bowen
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Klaus K Witte
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, UK
| |
Collapse
|
11
|
Van Iterson EH. Left Ventricular Assist Device Support Complicates the Exercise Physiology of Oxygen Transport and Uptake in Heart Failure. Card Fail Rev 2019; 5:162-168. [PMID: 31768273 PMCID: PMC6848979 DOI: 10.15420/cfr.2019.10.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 07/15/2019] [Indexed: 11/05/2022] Open
Abstract
Low-output forward flow and impaired maximal exercise oxygen uptake (VO2 max) are hallmarks of patients in advanced heart failure. The continuous-flow left ventricular assist device is a cutting-edge therapy proven to increase forward flow, yet this therapy does not yield consistent improvements in VO2 max. The science of how adjustable artificial forward flow impacts the exercise physiology of heart failure and physical O2 transport between the central and peripheral systems is unclear. This review focuses on the exercise physiology of axial continuous-flow left ventricular assist device support and the impact that pump speed has on the interactive convective and diffusive components of whole-body physical O2 transport and VO2.
Collapse
Affiliation(s)
- Erik H Van Iterson
- Section of Preventive Cardiology and Rehabilitation, Heart and Vascular Institute, Cleveland Clinic, Cleveland OH, US
| |
Collapse
|
12
|
Boyes NG, Eckstein J, Pylypchuk S, Marciniuk DD, Butcher SJ, Lahti DS, Dewa DMK, Haykowsky MJ, Wells CR, Tomczak CR. Effects of heavy-intensity priming exercise on pulmonary oxygen uptake kinetics and muscle oxygenation in heart failure with preserved ejection fraction. Am J Physiol Regul Integr Comp Physiol 2019; 316:R199-R209. [PMID: 30601707 DOI: 10.1152/ajpregu.00290.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Exercise intolerance is a hallmark feature in heart failure with preserved ejection fraction (HFpEF). Prior heavy exercise ("priming exercise") speeds pulmonary oxygen uptake (V̇o2p) kinetics in older adults through increased muscle oxygen delivery and/or alterations in mitochondrial metabolic activity. We tested the hypothesis that priming exercise would speed V̇o2p on-kinetics in patients with HFpEF because of acute improvements in muscle oxygen delivery. Seven patients with HFpEF performed three bouts of two exercise transitions: MOD1, rest to 4-min moderate-intensity cycling and MOD2, MOD1 preceded by heavy-intensity cycling. V̇o2p, heart rate (HR), total peripheral resistance (TPR), and vastus lateralis tissue oxygenation index (TOI; near-infrared spectroscopy) were measured, interpolated, time-aligned, and averaged. V̇o2p and HR were monoexponentially curve-fitted. TPR and TOI levels were analyzed as repeated measures between pretransition baseline, minimum value, and steady state. Significance was P < 0.05. Time constant (τ; tau) V̇o2p (MOD1 49 ± 16 s) was significantly faster after priming (41 ± 14 s; P = 0.002), and the effective HR τ was slower following priming (41 ± 27 vs. 51 ± 32 s; P = 0.025). TPR in both conditions decreased from baseline to minimum TPR ( P < 0.001), increased from minimum to steady state ( P = 0.041) but remained below baseline throughout ( P = 0.001). Priming increased baseline ( P = 0.003) and minimum TOI ( P = 0.002) and decreased the TOI muscle deoxygenation overshoot ( P = 0.041). Priming may speed the slow V̇o2p on-kinetics in HFpEF and increase muscle oxygen delivery (TOI) at the onset of and throughout exercise. Microvascular muscle oxygen delivery may limit exercise tolerance in HFpEF.
Collapse
Affiliation(s)
- Natasha G Boyes
- College of Kinesiology, University of Saskatchewan , Saskatoon, SK , Canada
| | - Janine Eckstein
- College of Medicine, University of Saskatchewan , Saskatoon, SK , Canada
| | - Stephen Pylypchuk
- College of Medicine, University of Saskatchewan , Saskatoon, SK , Canada
| | - Darcy D Marciniuk
- College of Medicine, University of Saskatchewan , Saskatoon, SK , Canada
| | - Scotty J Butcher
- School of Physical Therapy, University of Saskatchewan , Saskatoon, SK , Canada
| | - Dana S Lahti
- College of Kinesiology, University of Saskatchewan , Saskatoon, SK , Canada
| | - Dalisizwe M K Dewa
- College of Medicine, University of Saskatchewan , Saskatoon, SK , Canada
| | - Mark J Haykowsky
- Integrated Cardiovascular Exercise Physiology and Rehabilitation Laboratory, College of Nursing and Health Innovation, University of Texas at Arlington , Arlington, Texas
| | - Calvin R Wells
- College of Medicine, University of Saskatchewan , Saskatoon, SK , Canada
| | - Corey R Tomczak
- College of Kinesiology, University of Saskatchewan , Saskatoon, SK , Canada
| |
Collapse
|
13
|
Slow V˙O 2 kinetics in acute hypoxia are not related to a hyperventilation-induced hypocapnia. Respir Physiol Neurobiol 2018; 251:41-49. [PMID: 29477729 DOI: 10.1016/j.resp.2018.02.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 02/01/2018] [Accepted: 02/16/2018] [Indexed: 11/21/2022]
Abstract
We examined whether slower pulmonary O2 uptake (V˙O2p) kinetics in hypoxia is a consequence of: a) hypoxia alone (lowered arterial O2 pressure), b) hyperventilation-induced hypocapnia (lowered arterial CO2 pressure), or c) a combination of both. Eleven participants performed 3-5 repetitions of step-changes in cycle ergometer power output from 20W to 80% lactate threshold in the following conditions: i) normoxia (CON; room air); ii) hypoxia (HX, inspired O2 = 12%; lowered end-tidal O2 pressure [PETO2] and end-tidal CO2 pressure [PETCO2]); iii) hyperventilation (HV; increased PETO2 and lowered PETCO2); and iv) normocapnic hypoxia (NC-HX; lowered PETO2 and PETCO2 matched to CON). Ventilation was increased (relative to CON) and matched between HX, HV, and NC-HX conditions. During each condition VO2p˙ was measured and phase II V˙O2p kinetics were modeled with a mono-exponential function. The V˙O2p time constant was different (p < 0.05) amongst all conditions: CON, 26 ± 11s; HV, 36 ± 14s; HX, 46 ± 14s; and NC-HX, 52 ± 13s. Hypocapnia may prevent further slowing of V˙O2p kinetics in hypoxic exercise.
Collapse
|
14
|
Poole DC, Richardson RS, Haykowsky MJ, Hirai DM, Musch TI. Exercise limitations in heart failure with reduced and preserved ejection fraction. J Appl Physiol (1985) 2017; 124:208-224. [PMID: 29051336 DOI: 10.1152/japplphysiol.00747.2017] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The hallmark symptom of chronic heart failure (HF) is severe exercise intolerance. Impaired perfusive and diffusive O2 transport are two of the major determinants of reduced physical capacity and lowered maximal O2 uptake in patients with HF. It has now become evident that this syndrome manifests at least two different phenotypic variations: heart failure with preserved or reduced ejection fraction (HFpEF and HFrEF, respectively). Unlike HFrEF, however, there is currently limited understanding of HFpEF pathophysiology, leading to a lack of effective pharmacological treatments for this subpopulation. This brief review focuses on the disturbances within the O2 transport pathway resulting in limited exercise capacity in both HFpEF and HFrEF. Evidence from human and animal research reveals HF-induced impairments in both perfusive and diffusive O2 conductances identifying potential targets for clinical intervention. Specifically, utilization of different experimental approaches in humans (e.g., small vs. large muscle mass exercise) and animals (e.g., intravital microscopy and phosphorescence quenching) has provided important clues to elucidating these pathophysiological mechanisms. Adaptations within the skeletal muscle O2 delivery-utilization system following established and emerging therapies (e.g., exercise training and inorganic nitrate supplementation, respectively) are discussed. Resolution of the underlying mechanisms of skeletal muscle dysfunction and exercise intolerance is essential for the development and refinement of the most effective treatments for patients with HF.
Collapse
|
15
|
Benson AP, Bowen TS, Ferguson C, Murgatroyd SR, Rossiter HB. Data collection, handling, and fitting strategies to optimize accuracy and precision of oxygen uptake kinetics estimation from breath-by-breath measurements. J Appl Physiol (1985) 2017; 123:227-242. [PMID: 28450551 DOI: 10.1152/japplphysiol.00988.2016] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 03/20/2017] [Accepted: 04/19/2017] [Indexed: 11/22/2022] Open
Abstract
Phase 2 pulmonary oxygen uptake kinetics (ϕ2 τV̇o2P) reflect muscle oxygen consumption dynamics and are sensitive to changes in state of training or health. This study identified an unbiased method for data collection, handling, and fitting to optimize V̇o2P kinetics estimation. A validated computational model of V̇o2P kinetics and a Monte Carlo approach simulated 2 × 105 moderate-intensity transitions using a distribution of metabolic and circulatory parameters spanning normal health. Effects of averaging (interpolation, binning, stacking, or separate fitting of up to 10 transitions) and fitting procedures (biexponential fitting, or ϕ2 isolation by time removal, statistical, or derivative methods followed by monoexponential fitting) on accuracy and precision of V̇o2P kinetics estimation were assessed. The optimal strategy to maximize accuracy and precision of τV̇o2P estimation was 1-s interpolation of 4 bouts, ensemble averaged, with the first 20 s of exercise data removed. Contradictory to previous advice, we found optimal fitting procedures removed no more than 20 s of ϕ1 data. Averaging method was less critical: interpolation, binning, and stacking gave similar results, each with greater accuracy compared with analyzing repeated bouts separately. The optimal procedure resulted in ϕ2 τV̇o2P estimates for transitions from an unloaded or loaded baseline that averaged 1.97 ± 2.08 and 1.04 ± 2.30 s from true, but were within 2 s of true in only 47-62% of simulations. Optimized 95% confidence intervals for τV̇o2P ranged from 4.08 to 4.51 s, suggesting a minimally important difference of ~5 s to determine significant changes in τV̇o2P during interventional and comparative studies.NEW & NOTEWORTHY We identified an unbiased method to maximize accuracy and precision of oxygen uptake kinetics (τV̇o2P) estimation. The optimum number of bouts to average was four; interpolation, bin, and stacking averaging methods gave similar results. Contradictory to previous advice, we found that optimal fitting procedures removed no more than 20 s of phase 1 data. Our data suggest a minimally important difference of ~5 s to determine significant changes in τV̇o2P during interventional and comparative studies.
Collapse
Affiliation(s)
- Alan P Benson
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom; .,Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, United Kingdom
| | - T Scott Bowen
- Heart Centre, University of Leipzig, Leipzig, Germany
| | - Carrie Ferguson
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom.,Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, United Kingdom
| | - Scott R Murgatroyd
- Neurosciences Intensive Care Unit, Wessex Neurological Centre, University Hospital Southampton, Southampton, United Kingdom; and
| | - Harry B Rossiter
- Rehabilitation Clinical Trials Center, Division of Respiratory and Critical Care Physiology and Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California.,School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| |
Collapse
|
16
|
Niemeijer VM, Jansen JP, van Dijk T, Spee RF, Meijer EJ, Kemps HMC, Wijn PFF. The influence of adipose tissue on spatially resolved near-infrared spectroscopy derived skeletal muscle oxygenation: the extent of the problem. Physiol Meas 2017; 38:539-554. [PMID: 28151429 DOI: 10.1088/1361-6579/aa5dd5] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Near-infrared spectroscopy (NIRS) measurements of tissue oxygen saturation (StO2) are useful for the assessment of skeletal muscle perfusion and function during exercise, however, they are influenced by overlying skin and adipose tissue. This study explored the extent and nature of the influence of adipose tissue thickness (ATT) on StO2. APPROACH NIR spatially resolved spectroscopy (SRS) derived oxygenation was measured on vastus lateralis in 56 patients with chronic heart failure (CHF) and 20 healthy control (HC) subjects during rest and moderate intensity exercise with simultaneous assessment of oxygen uptake kinetics (τ [Formula: see text]). In vitro measurements were performed on a flow cell with a blood mixture with full oxygen saturation (100%), which was gradually decreased to 0% by adding sodium metabisulfite. Experiments were repeated with 2 mm increments of porcine fat layer between the NIRS device and flow cell up to 14 mm. MAIN RESULTS Lower ATT, higher τ [Formula: see text], and CHF were independently associated with lower in vivo StO2 in multiple regression analysis, whereas age and gender showed no independent relationship. With greater ATT, in vitro StO2 was reduced from 100% to 74% for fully oxygenated blood and increased from 0% to 68% for deoxygenated blood. SIGNIFICANCE This study shows that ATT independently confounds NIR-SRS derived StO2 by overestimating actual skeletal muscle oxygenation and by decreasing its sensitivity for deoxygenation. Because physiological properties (e.g. presence of disease and slowing of τ [Formula: see text]) also influence NIR-SRS, a correction based on optical properties is needed to interpret calculated values as absolute StO2.
Collapse
Affiliation(s)
- Victor M Niemeijer
- Department of Cardiology, Máxima Medical Centre, PO Box 7777, 5500 MB Veldhoven, Netherlands. Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, Netherlands
| | | | | | | | | | | | | |
Collapse
|
17
|
Hirai DM, Zelt JT, Jones JH, Castanhas LG, Bentley RF, Earle W, Staples P, Tschakovsky ME, McCans J, O’Donnell DE, Neder JA. Dietary nitrate supplementation and exercise tolerance in patients with heart failure with reduced ejection fraction. Am J Physiol Regul Integr Comp Physiol 2017; 312:R13-R22. [DOI: 10.1152/ajpregu.00263.2016] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 10/03/2016] [Accepted: 10/26/2016] [Indexed: 11/22/2022]
Abstract
Endothelial dysfunction and reduced nitric oxide (NO) signaling are key abnormalities leading to skeletal muscle oxygen delivery-utilization mismatch and poor physical capacity in patients with heart failure with reduced ejection fraction (HFrEF). Oral inorganic nitrate supplementation provides an exogenous source of NO that may enhance locomotor muscle function and oxygenation with consequent improvement in exercise tolerance in HFrEF. Thirteen patients (left ventricular ejection fraction ≤40%) were enrolled in a double-blind, randomized crossover study to receive concentrated nitrate-rich (nitrate) or nitrate-depleted (placebo) beetroot juice for 9 days. Low- and high-intensity constant-load cardiopulmonary exercise tests were performed with noninvasive measurements of central hemodynamics (stroke volume, heart rate, and cardiac output via impedance cardiography), arterial blood pressure, pulmonary oxygen uptake, quadriceps muscle oxygenation (near-infrared spectroscopy), and blood lactate concentration. Ten patients completed the study with no adverse clinical effects. Nitrate-rich supplementation resulted in significantly higher plasma nitrite concentration compared with placebo (240 ± 48 vs. 56 ± 8 nM, respectively; P < 0.05). There was no significant difference in the primary outcome of time to exercise intolerance between nitrate and placebo (495 ± 53 vs. 489 ± 58 s, respectively; P > 0.05). Similarly, there were no significant differences in central hemodynamics, arterial blood pressure, pulmonary oxygen uptake kinetics, skeletal muscle oxygenation, or blood lactate concentration from rest to low- or high-intensity exercise between conditions. Oral inorganic nitrate supplementation with concentrated beetroot juice did not present with beneficial effects on central or peripheral components of the oxygen transport pathway thereby failing to improve exercise tolerance in patients with moderate HFrEF.
Collapse
Affiliation(s)
- Daniel M. Hirai
- Department of Medicine, Division of Respirology, Laboratory of Clinical Exercise Physiology, Queen’s University, Kingston, Ontario, Canada
- Department of Medicine, Respiratory Division, Pulmonary Function and Clinical Exercise Physiology Unit, Federal University of Sao Paulo, Sao Paulo, Brazil
| | - Joel T. Zelt
- Department of Medicine, Division of Respirology, Laboratory of Clinical Exercise Physiology, Queen’s University, Kingston, Ontario, Canada
| | - Joshua H. Jones
- Department of Medicine, Division of Respirology, Laboratory of Clinical Exercise Physiology, Queen’s University, Kingston, Ontario, Canada
| | - Luiza G. Castanhas
- Department of Medicine, Division of Respirology, Laboratory of Clinical Exercise Physiology, Queen’s University, Kingston, Ontario, Canada
| | - Robert F. Bentley
- School of Kinesiology and Health Studies, Human Vascular Control Laboratory, Queen’s University, Kingston, Ontario, Canada
| | - Wendy Earle
- Department of Medicine, Division of Cardiology, Queen’s University, Kingston, Ontario, Canada; and
| | - Patti Staples
- Department of Medicine, Division of Cardiology, Queen’s University, Kingston, Ontario, Canada; and
| | - Michael E. Tschakovsky
- School of Kinesiology and Health Studies, Human Vascular Control Laboratory, Queen’s University, Kingston, Ontario, Canada
| | - John McCans
- Department of Medicine, Division of Cardiology, Queen’s University, Kingston, Ontario, Canada; and
| | - Denis E. O’Donnell
- Department of Medicine, Division of Respirology, Respiratory Investigation Unit, Queen’s University, Kingston, Ontario, Canada
| | - J. Alberto Neder
- Department of Medicine, Division of Respirology, Laboratory of Clinical Exercise Physiology, Queen’s University, Kingston, Ontario, Canada
| |
Collapse
|
18
|
Niemeijer VM, Spee RF, Schoots T, Wijn PFF, Kemps HMC. Limitations of skeletal muscle oxygen delivery and utilization during moderate-intensity exercise in moderately impaired patients with chronic heart failure. Am J Physiol Heart Circ Physiol 2016; 311:H1530-H1539. [DOI: 10.1152/ajpheart.00474.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 09/28/2016] [Indexed: 11/22/2022]
Abstract
The extent and speed of transient skeletal muscle deoxygenation during exercise onset in patients with chronic heart failure (CHF) are related to impairments of local O2 delivery and utilization. This study examined the physiological background of submaximal exercise performance in 19 moderately impaired patients with CHF (Weber class A, B, and C) compared with 19 matched healthy control (HC) subjects by measuring skeletal muscle oxygenation (SmO2) changes during cycling exercise. All subjects performed two subsequent moderate-intensity 6-min exercise tests (bouts 1 and 2) with measurements of pulmonary oxygen uptake kinetics and SmO2 using near-infrared spatially resolved spectroscopy at the vastus lateralis for determination of absolute oxygenation values, amplitudes, kinetics (mean response time for onset), and deoxygenation overshoot characteristics. In CHF, deoxygenation kinetics were slower compared with HC (21.3 ± 5.3 s vs. 16.7 ± 4.4 s, P < 0.05, respectively). After priming exercise (i.e., during bout 2), deoxygenation kinetics were accelerated in CHF to values no longer different from HC (16.9 ± 4.6 s vs. 15.4 ± 4.2 s, P = 0.35). However, priming did not speed deoxygenation kinetics in CHF subjects with a deoxygenation overshoot, whereas it did reduce the incidence of the overshoot in this specific group ( P < 0.05). These results provide evidence for heterogeneity with respect to limitations of O2 delivery and utilization during moderate-intensity exercise in patients with CHF, with slowed deoxygenation kinetics indicating a predominant O2 utilization impairment and the presence of a deoxygenation overshoot, with a reduction after priming in a subgroup, indicating an initial O2 delivery to utilization mismatch.
Collapse
Affiliation(s)
- Victor M. Niemeijer
- Department of Cardiology, Máxima Medical Centre, Veldhoven, the Netherlands
- Department of Applied Physics, Eindhoven University of Technology, Eindhoven, the Netherlands; and
| | - Ruud F. Spee
- Department of Cardiology, Máxima Medical Centre, Veldhoven, the Netherlands
| | - Thijs Schoots
- Department of Cardiology, Máxima Medical Centre, Veldhoven, the Netherlands
| | - Pieter F. F. Wijn
- Department of Applied Physics, Eindhoven University of Technology, Eindhoven, the Netherlands; and
- Department of Medical Physics, Máxima Medical Centre, Veldhoven, the Netherlands
| | - Hareld M. C. Kemps
- Department of Cardiology, Máxima Medical Centre, Veldhoven, the Netherlands
| |
Collapse
|
19
|
Spee RF, Niemeijer VM, Wijn PF, Doevendans PA, Kemps HM. Effects of high-intensity interval training on central haemodynamics and skeletal muscle oxygenation during exercise in patients with chronic heart failure. Eur J Prev Cardiol 2016; 23:1943-1952. [DOI: 10.1177/2047487316661615] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Ruud F Spee
- Department of Cardiology, Máxima Medical Center, Veldhoven, The Netherlands
- ICIN, Netherlands Heart Institute, Utrecht, The Netherlands
| | - Victor M Niemeijer
- Department of Cardiology, Máxima Medical Center, Veldhoven, The Netherlands
| | - Pieter F Wijn
- Department of Clinical Physics and Clinical Informatics, Máxima Medical Center, Veldhoven, The Netherlands
- Department of Applied Physics, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Pieter A Doevendans
- ICIN, Netherlands Heart Institute, Utrecht, The Netherlands
- Department of Cardiology, University Medical Center, Utrecht, The Netherlands
| | - Hareld M Kemps
- Department of Cardiology, Máxima Medical Center, Veldhoven, The Netherlands
| |
Collapse
|
20
|
Abstract
Pulmonary rehabilitation, as a quality of life intervention, has a role to play in palliative care for lung cancer patients. Combining the art and skills of clinical care, physiological, and behavioral tools, pulmonary rehabilitation can serve to rebuild the functional capacity of patients limited by breathlessness and deconditioning. Exercise programs are the primary tool used to restore and rebuild the patient's endurance by challenging the entire pathway of oxygen transport and improving gas exchange. Other tools of pulmonary rehabilitation include breathing retraining, self-management skills, airway clearance techniques, bronchodilitation, smoking cessation and oxygen therapy. Pulmonary rehabilitation is now becoming a part of supportive care for patients undergoing chemotherapy and radiation therapy. The ability to be more active without suffering the consequences of dyspnea on exertion boosts the patient's self-efficacy and allows for an improved quality of life, so that lung cancer patients can participate in their family lives during this therapeutic challenge.
Collapse
|
21
|
Niemeijer VM, Spee RF, Jansen JP, Buskermolen ABC, van Dijk T, Wijn PFF, Kemps HMC. Test-retest reliability of skeletal muscle oxygenation measurements during submaximal cycling exercise in patients with chronic heart failure. Clin Physiol Funct Imaging 2015; 37:68-78. [DOI: 10.1111/cpf.12269] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 04/27/2015] [Indexed: 01/26/2023]
Affiliation(s)
| | - Ruud F. Spee
- Department of Cardiology; Máxima Medical Centre; Veldhoven The Netherlands
| | - Jasper P. Jansen
- Department of Biomedical Engineering; Eindhoven University of Technology; Eindhoven The Netherlands
| | | | - Thomas van Dijk
- Department of Medical Physics; Máxima Medical Centre; Veldhoven The Netherlands
| | - Pieter F. F. Wijn
- Department of Applied Physics; Eindhoven University of Technology; Eindhoven The Netherlands
- Department of Medical Physics; Máxima Medical Centre; Veldhoven The Netherlands
| | - Hareld M. C. Kemps
- Department of Cardiology; Máxima Medical Centre; Veldhoven The Netherlands
| |
Collapse
|
22
|
Oliveira MF, Zelt JTJ, Jones JH, Hirai DM, O'Donnell DE, Verges S, Neder JA. Does impaired O2 delivery during exercise accentuate central and peripheral fatigue in patients with coexistent COPD-CHF? Front Physiol 2015; 5:514. [PMID: 25610401 PMCID: PMC4285731 DOI: 10.3389/fphys.2014.00514] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 12/15/2014] [Indexed: 02/04/2023] Open
Abstract
Impairment in oxygen (O2) delivery to the central nervous system ("brain") and skeletal locomotor muscle during exercise has been associated with central and peripheral neuromuscular fatigue in healthy humans. From a clinical perspective, impaired tissue O2 transport is a key pathophysiological mechanism shared by cardiopulmonary diseases, such as chronic obstructive pulmonary disease (COPD) and chronic heart failure (CHF). In addition to arterial hypoxemic conditions in COPD, there is growing evidence that cerebral and muscle blood flow and oxygenation can be reduced during exercise in both isolated COPD and CHF. Compromised cardiac output due to impaired cardiopulmonary function/interactions and blood flow redistribution to the overloaded respiratory muscles (i.e., ↑work of breathing) may underpin these abnormalities. Unfortunately, COPD and CHF coexist in almost a third of elderly patients making these mechanisms potentially more relevant to exercise intolerance. In this context, it remains unknown whether decreased O2 delivery accentuates neuromuscular manifestations of central and peripheral fatigue in coexistent COPD-CHF. If this holds true, it is conceivable that delivering a low-density gas mixture (heliox) through non-invasive positive pressure ventilation could ameliorate cardiopulmonary function/interactions and reduce the work of breathing during exercise in these patients. The major consequence would be increased O2 delivery to the brain and active muscles with potential benefits to exercise capacity (i.e., ↓central and peripheral neuromuscular fatigue, respectively). We therefore hypothesize that patients with coexistent COPD-CHF stop exercising prematurely due to impaired central motor drive and muscle contractility as the cardiorespiratory system fails to deliver sufficient O2 to simultaneously attend the metabolic demands of the brain and the active limb muscles.
Collapse
Affiliation(s)
- Mayron F Oliveira
- Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Respiratory Division, Department of Medicine, School of Medicine, Federal University of São Paulo (UNIFESP) São Paulo, Brazil
| | - Joel T J Zelt
- Laboratory of Clinical Exercise Physiology, Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University Kingston, ON, Canada
| | - Joshua H Jones
- Laboratory of Clinical Exercise Physiology, Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University Kingston, ON, Canada
| | - Daniel M Hirai
- Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Respiratory Division, Department of Medicine, School of Medicine, Federal University of São Paulo (UNIFESP) São Paulo, Brazil ; Laboratory of Clinical Exercise Physiology, Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University Kingston, ON, Canada
| | - Denis E O'Donnell
- Respiratory Investigation Unit, Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University Kingston, ON, Canada
| | - Samuel Verges
- HP2 Laboratory, Grenoble Alpes University Grenoble, France
| | - J Alberto Neder
- Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Respiratory Division, Department of Medicine, School of Medicine, Federal University of São Paulo (UNIFESP) São Paulo, Brazil ; Laboratory of Clinical Exercise Physiology, Division of Respiratory and Critical Care Medicine, Department of Medicine, Queen's University Kingston, ON, Canada
| |
Collapse
|
23
|
Bowen TS, Rossiter HB, Benson AP, Amano T, Kondo N, Kowalchuk JM, Koga S. Slowed oxygen uptake kinetics in hypoxia correlate with the transient peak and reduced spatial distribution of absolute skeletal muscle deoxygenation. Exp Physiol 2013; 98:1585-96. [DOI: 10.1113/expphysiol.2013.073270] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
24
|
Layec G, Haseler LJ, Trinity JD, Hart CR, Liu X, Le Fur Y, Jeong EK, Richardson RS. Mitochondrial function and increased convective O2 transport: implications for the assessment of mitochondrial respiration in vivo. J Appl Physiol (1985) 2013; 115:803-11. [PMID: 23813526 DOI: 10.1152/japplphysiol.00257.2013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although phosphorus magnetic resonance spectroscopy (31P-MRS)-based evidence suggests that in vivo peak mitochondrial respiration rate in young untrained adults is limited by the intrinsic mitochondrial capacity of ATP synthesis, it remains unknown whether a large, locally targeted increase in convective O2 delivery would alter this interpretation. Consequently, we examined the effect of superimposing reactive hyperemia (RH), induced by a period of brief ischemia during the last minute of exercise, on oxygen delivery and mitochondrial function in the calf muscle of nine young adults compared with free-flow conditions (FF). To this aim, we used an integrative experimental approach combining 31P-MRS, Doppler ultrasound imaging, and near-infrared spectroscopy. Limb blood flow [area under the curve (AUC), 1.4 ± 0.8 liters in FF and 2.5 ± 0.3 liters in RH, P < 0.01] and convective O2 delivery (AUC, 0.30 ± 0.16 liters in FF and 0.54 ± 0.05 liters in RH, P < 0.01), were significantly increased in RH compared with FF. RH was also associated with significantly higher capillary blood flow (P < 0.05) and faster tissue reoxygenation mean response times (70 ± 15 s in FF and 24 ± 15 s in RH, P < 0.05). This resulted in a 43% increase in estimated peak mitochondrial ATP synthesis rate (29 ± 13 mM/min in FF and 41 ± 14 mM/min in RH, P < 0.05) whereas the phosphocreatine (PCr) recovery time constant in RH was not significantly different (P = 0.22). This comprehensive assessment of local skeletal muscle O2 availability and utilization in untrained subjects reveals that mitochondrial function, assessed in vivo by 31P-MRS, is limited by convective O2 delivery rather than an intrinsic mitochondrial limitation.
Collapse
Affiliation(s)
- Gwenael Layec
- Department of Medicine, Division of Geriatrics, University of Utah, Salt Lake City, Utah
| | | | | | | | | | | | | | | |
Collapse
|
25
|
Benson AP, Grassi B, Rossiter HB. A validated model of oxygen uptake and circulatory dynamic interactions at exercise onset in humans. J Appl Physiol (1985) 2013; 115:743-55. [PMID: 23766506 DOI: 10.1152/japplphysiol.00184.2013] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
At the onset of muscular exercise, the kinetics of pulmonary O2 uptake (Vo2P) reflect the integrated dynamic responses of the ventilatory, circulatory, and neuromuscular systems for O2 transport and utilization. Muscle O2 uptake (Vo2m) kinetics, however, are dissociated from Vo2P kinetics by intervening O2 capacitances and the dynamics of the circulation and ventilation. We developed a multicompartment computational model (MCM) to investigate these dynamic interactions and optimized and validated the MCM using previously published, simultaneously measured Vo2m, alveolar O2 uptake (Vo2A), and muscle blood flow (Qm) in healthy young men during cycle ergometry. The model was used to show that 1) the kinetics of Vo2A during exercise transients are very sensitive to preexercise blood flow distribution and the absolute value of Qm, 2) a low preexercise Qm exaggerates the magnitude of the transient fall in venous O2 concentration for any given Vo2m kinetics, necessitating a tighter coupling of Qm/Vo2m (or a reduction in the available work rate range) during the exercise transient to avoid limits to O2 extraction, and 3) information regarding exercise-related alterations in O2 uptake and blood flow in nonexercising tissues and their effects on mixed venous O2 concentration is required to accurately predict Vo2A kinetics from knowledge of Vo2m and Qm dynamics. Importantly, these data clearly demonstrate that Vo2A kinetics are nonexponential, nonlinear distortions of Vo2m kinetics that can be explained in a MCM by interactions among circulatory and cellular respiratory control processes before and during exercise.
Collapse
Affiliation(s)
- Alan P Benson
- School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | | | | |
Collapse
|
26
|
Hamaoka T. Muscle oxygenation monitoring using near-infrared spectroscopy. THE JOURNAL OF PHYSICAL FITNESS AND SPORTS MEDICINE 2013. [DOI: 10.7600/jpfsm.2.203] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
27
|
Sperandio PA, Oliveira MF, Rodrigues MK, Berton DC, Treptow E, Nery LE, Almeida DR, Neder JA. Sildenafil improves microvascular O2 delivery-to-utilization matching and accelerates exercise O2 uptake kinetics in chronic heart failure. Am J Physiol Heart Circ Physiol 2012; 303:H1474-80. [PMID: 23023868 DOI: 10.1152/ajpheart.00435.2012] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nitric oxide (NO) can temporally and spatially match microvascular oxygen (O(2)) delivery (Qo(2mv)) to O(2) uptake (Vo(2)) in the skeletal muscle, a crucial adjustment-to-exercise tolerance that is impaired in chronic heart failure (CHF). To investigate the effects of NO bioavailability induced by sildenafil intake on muscle Qo(2mv)-to-O(2) utilization matching and Vo(2) kinetics, 10 males with CHF (ejection fraction = 27 ± 6%) undertook constant work-rate exercise (70-80% peak). Breath-by-breath Vo(2), fractional O(2)extraction in the vastus lateralis {∼deoxygenated hemoglobin + myoglobin ([deoxy-Hb + Mb]) by near-infrared spectroscopy}, and cardiac output (CO) were evaluated after sildenafil (50 mg) or placebo. Sildenafil increased exercise tolerance compared with placebo by ∼20%, an effect that was related to faster on- and off-exercise Vo(2) kinetics (P < 0.05). Active treatment, however, failed to accelerate CO dynamics (P > 0.05). On-exercise [deoxy-Hb + Mb] kinetics were slowed by sildenafil (∼25%), and a subsequent response "overshoot" (n = 8) was significantly lessened or even abolished. In contrast, [deoxy-Hb + Mb] recovery was faster with sildenafil (∼15%). Improvements in muscle oxygenation with sildenafil were related to faster on-exercise Vo(2) kinetics, blunted oscillations in ventilation (n = 9), and greater exercise capacity (P < 0.05). Sildenafil intake enhanced intramuscular Qo(2mv)-to-Vo(2) matching with beneficial effects on Vo(2) kinetics and exercise tolerance in CHF. The lack of effect on CO suggests that improvement in blood flow to and within skeletal muscles underlies these effects.
Collapse
Affiliation(s)
- Priscila A Sperandio
- Pulmonary Function and Clinical Exercise Physiology Unit, Division of Respiratory Diseases, Department of Medicine, Federal University of São Paulo, Brazil
| | | | | | | | | | | | | | | |
Collapse
|
28
|
Effect of moderate-intensity work rate increment on phase II τVO₂, functional gain and Δ[HHb]. Eur J Appl Physiol 2012; 113:545-57. [PMID: 22829340 DOI: 10.1007/s00421-012-2460-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 07/07/2012] [Indexed: 10/27/2022]
Abstract
This study systematically examined the role of work rate (WR) increment on the kinetics of pulmonary oxygen uptake (VO(2p)) and near-infrared spectroscopy (NIRS)-derived muscle deoxygenation (Δ[HHb]) during moderate-intensity (Mod) cycling. Fourteen males (24 ± 5 years) each completed four to eight repetitions of Mod transitions from 20 to 50, 70, 90, 110 and 130 W. VO(2p) and Δ[HHb] responses were modelled as a mono-exponential; responses were then scaled to a relative % of the respective response (0-100 %). The Δ[HHb]/VO(2) ratio was calculated as the average Δ[HHb]/VO(2) during the 20-120 s period of the on-transient. When considered as a single group, neither the phase II VO(2p) time constant (τVO(2p); 27 ± 9, 26 ± 11, 25 ± 10, 27 ± 14, 29 ± 13 s for 50-130 W transitions, respectively) nor the Δ[HHb]/VO(2) ratio (1.04 ± 0.13, 1.10 ± 0.13, 1.08 ± 0.07, 1.09 ± 0.11, 1.09 ± 0.09, respectively) was affected by WR (p > 0.05); yet, the VO(2) functional gain (G; ΔVO(2)/ΔWR) increased with increasing WR transitions (8.6 ± 1.3, 9.1 ± 1.2, 9.5 ± 1.0, 9.5 ± 1.0, 9.9 ± 1.0 mL min(-1) W(-1); p < 0.05). When subjects were stratified into two groups [Fast (n = 6), τVO(2p130W) < 25 s < τVO(2p130W), Slower (n = 8)], a group by WR interaction was observed for τVO(2p). The increasing functional G persisted (p < 0.05) and did not differ between groups (p > 0.05). The Δ[HHb]/VO(2) ratio was smaller (p < 0.05) in the Fast than Slower group, but was unaffected by WR. In conclusion, the present study demonstrated (1) a non-uniform effect of Mod WR increment on τVO(2p); (2) that τVO(2p) in the Slower group is likely determined by an O(2) delivery limitation; and (3) that increasing Mod WR increments elicits an increased functional G, regardless of the τVO(2p) response.
Collapse
|
29
|
Gandra PG, Nogueira L, Hogan MC. Mitochondrial activation at the onset of contractions in isolated myofibres during successive contractile periods. J Physiol 2012; 590:3597-609. [PMID: 22711953 DOI: 10.1113/jphysiol.2012.232405] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
At the onset of skeletal muscle repetitive contractions, there is a significant delay in the time to achieve oxidative phosphorylation steady state. The purpose of the present study was to examine the factors that limit oxidative phosphorylation at the onset of contractions. NAD(P)H was measured in real time during two contractile periods (2 min each) separated by 5 min of rest in intact single muscle fibres (n = 7) isolated from Xenopus laevis. The fibres were then loaded with the dye tetramethylrhodamine methyl ester perchlorate (TMRM) to evaluate the kinetics of the mitochondrial membrane potential (Δψ (m)) during two further successive contractile periods. At the onset of contractions in the first period, NAD(P)H exhibited a time delay (14.1 ± 1.3 s) before decreasing toward a steady state. In contrast, Δψ(m) decreased immediately after the first contraction and started to be reestablished after 10.7 ± 0.9 s, with restoration to the pre-stimulation values after approximately 32 s. In the second contractile period (5 min after the first), NAD(P)H decreased immediately (i.e. no time delay) after the first contraction and had a significantly shorter time constant compared to the first contractile bout (3.3 ± 0.3 vs. 5.0 ± 0.2 s, P < 0.05). During the second bout, Δψ(m) remained unchanged from pre-stimulation values. These results suggest: (1) that at the onset of contractions, oxidative phosphorylation is primarily limited by the activity of the electron transport chain complexes rather than by a limited level of substrates; and (2) when the muscle is 'primed' by previous contractile activity, the faster enhancement of the cellular respiratory rate is due to intrinsic factors within the myofibre.
Collapse
Affiliation(s)
- Paulo G Gandra
- Department of Medicine-0623, University of California, San Diego, 9500 Gilman Drive La Jolla, CA 92093-0623, USA
| | | | | |
Collapse
|
30
|
Bowen TS, Cannon DT, Begg G, Baliga V, Witte KK, Rossiter HB. A novel cardiopulmonary exercise test protocol and criterion to determine maximal oxygen uptake in chronic heart failure. J Appl Physiol (1985) 2012; 113:451-8. [PMID: 22653993 DOI: 10.1152/japplphysiol.01416.2011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Cardiopulmonary exercise testing for peak oxygen uptake (Vo(2peak)) can evaluate prognosis in chronic heart failure (CHF) patients, with the peak respiratory exchange ratio (RER(peak)) commonly used to confirm maximal effort and maximal oxygen uptake (Vo(2max)). We determined the precision of RER(peak) in confirming Vo(2max), and whether a novel ramp-incremental (RI) step-exercise (SE) (RISE) test could better determine Vo(2max) in CHF. Male CHF patients (n = 24; NYHA class I-III) performed a symptom-limited RISE-95 cycle ergometer test in the format: RI (4-18 W/min; ∼10 min); 5 min recovery (10 W); SE (95% peak RI work rate). Patients (n = 18) then performed RISE-95 tests using slow (3-8 W/min; ∼15 min) and fast (10-30 W/min; ∼6 min) ramp rates. Pulmonary gas exchange was measured breath-by-breath. Vo(2peak) was compared within patients by unpaired t-test of the highest 12 breaths during RI and SE phases to confirm Vo(2max) and its 95% confidence limits (CI(95)). RER(peak) was significantly influenced by ramp rate (fast, medium, slow: 1.21 ± 0.1 vs. 1.15 ± 0.1 vs. 1.09 ± 0.1; P = 0.001), unlike Vo(2peak) (mean n = 18; 14.4 ± 2.6 ml·kg(-1)·min(-1); P = 0.476). Group Vo(2peak) was similar between RI and SE (n = 24; 14.5 ± 3.0 vs. 14.7 ± 3.1 ml·kg(-1)·min(-1); P = 0.407); however, within-subject comparisons confirmed Vo(2max) in only 14 of 24 patients (CI(95) for Vo(2max) estimation averaged 1.4 ± 0.8 ml·kg(-1)·min(-1)). The RER(peak) in CHF was significantly influenced by ramp rate, suggesting its use to determine maximal effort and Vo(2max) be abandoned. In contrast, the RISE-95 test had high precision for Vo(2max) confirmation with patient-specific CI(95) (without secondary criteria), and showed that Vo(2max) is commonly underestimated in CHF. The RISE-95 test was well tolerated by CHF patients, supporting its use for Vo(2max) confirmation.
Collapse
Affiliation(s)
- T Scott Bowen
- Institute of Membrane and Systems Biology, University of Leeds, Leeds, United Kingdom
| | | | | | | | | | | |
Collapse
|