201
|
Shang Y, Gurley K, Yu G. Diffuse Correlation Spectroscopy (DCS) for Assessment of Tissue Blood Flow in Skeletal Muscle: Recent Progress. ACTA ACUST UNITED AC 2013; 3:128. [PMID: 24724043 PMCID: PMC3979478 DOI: 10.4172/2161-0940.1000128] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Near-infrared diffuse correlation spectroscopy (DCS) is an emerging technology for monitoring blood flow in various tissues. This article reviews the recent progress of DCS for the assessment of skeletal muscle blood flow, including the developments in technology allowing use during dynamic exercise and muscular electrical stimulation, the utilization for diagnosis of muscle vascular diseases, and the applications for evaluating treatment effects. The limitations of current DCS studies and future perspective are finally discussed.
Collapse
Affiliation(s)
- Yu Shang
- Department of Biomedical Engineering, University of Kentucky, Lexington, KY 40506, USA
| | - Katelyn Gurley
- Department of Biomedical Engineering, University of Kentucky, Lexington, KY 40506, USA ; Department of Neurological Surgery, University of Louisville, Louisville, KY 40202, USA
| | - Guoqiang Yu
- Department of Biomedical Engineering, University of Kentucky, Lexington, KY 40506, USA
| |
Collapse
|
202
|
The effect of venous and arterial occlusion of the arm on changes in tissue hemodynamics, oxygenation, and ultra-weak photon emission. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 765:257-264. [PMID: 22879042 DOI: 10.1007/978-1-4614-4989-8_36] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Ultra-weak photon emission (UPE) is a general feature of living -biological systems. To gain further insights into the origin of UPE and its physiological significance, the aim of the present study was to investigate the connection between hemodynamics (HD), oxygenation (OX), and UPE. Therefore, during venous and arterial occlusion (VO, AO), changes of UPE and surrogates of HD as well as OX were measured simultaneously using two photomultipliers and near-infrared spectroscopy, respectively. We showed that (1) changes in UPE correlate significantly nonlinearly with changes in oxyhemoglobin (Δ[O(2)Hb]), deoxyhemoglobin (Δ[HHb]), and hemoglobin difference (Δ[HbD] = Δ[O(2)Hb]-Δ[HHb]), indicating a complex association between UPE and tissue HD/OX; (2) UPE decreases significantly during AO but not during VO; (3) UPE increases significantly after AO; and (4) the view that ROS are the source of UPE is generally supported by the present study, although some findings remain unexplained in the context of the theory of ROS-mediated UPE generation. In conclusion, the present study revealed new insights into the interplay between HD, OX, and UPE and opens up new questions that have to be addressed by future studies.
Collapse
|
203
|
Waltz X, Pichon A, Lemonne N, Mougenel D, Lalanne-Mistrih ML, Lamarre Y, Tarer V, Tressières B, Etienne-Julan M, Hardy-Dessources MD, Hue O, Connes P. Normal muscle oxygen consumption and fatigability in sickle cell patients despite reduced microvascular oxygenation and hemorheological abnormalities. PLoS One 2012; 7:e52471. [PMID: 23285055 PMCID: PMC3527490 DOI: 10.1371/journal.pone.0052471] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Accepted: 11/13/2012] [Indexed: 11/21/2022] Open
Abstract
Background/Aim Although it has been hypothesized that muscle metabolism and fatigability could be impaired in sickle cell patients, no study has addressed this issue. Methods We compared muscle metabolism and function (muscle microvascular oxygenation, microvascular blood flow, muscle oxygen consumption and muscle microvascular oxygenation variability, which reflects vasomotion activity, maximal muscle force and local muscle fatigability) and the hemorheological profile at rest between 16 healthy subjects (AA), 20 sickle cell-hemoglobin C disease (SC) patients and 16 sickle cell anemia (SS) patients. Results Muscle microvascular oxygenation was reduced in SS patients compared to the SC and AA groups and this reduction was not related to hemorhelogical abnormalities. No difference was observed between the three groups for oxygen consumption and vasomotion activity. Muscle microvascular blood flow was higher in SS patients compared to the AA group, and tended to be higher compared to the SC group. Multivariate analysis revealed that muscle oxygen consumption was independently associated with muscle microvascular blood flow in the two sickle cell groups (SC and SS). Finally, despite reduced muscle force in sickle cell patients, their local muscle fatigability was similar to that of the healthy subjects. Conclusions Sickle cell patients have normal resting muscle oxygen consumption and fatigability despite hemorheological alterations and, for SS patients only, reduced muscle microvascular oxygenation and increased microvascular blood flow. Two alternative mechanisms can be proposed for SS patients: 1) the increased muscle microvascular blood flow is a way to compensate for the lower muscle microvascular oxygenation to maintain muscle oxygen consumption to normal values or 2) the reduced microvascular oxygenation coupled with a normal resting muscle oxygen consumption could indicate that there is slight hypoxia within the muscle which is not sufficient to limit mitochondrial respiration but increases muscle microvascular blood flow.
Collapse
Affiliation(s)
- Xavier Waltz
- Inserm 665, Université des Antilles et de la Guyane, Pointe-à-Pitre, Guadeloupe, France
- Laboratory of Excellence GR-Ex « The red cell : from genesis to death », PRES Sorbonne Paris Cité, Paris, France
- Laboratoire ACTES (EA 3596 - Département de Physiologie), Université des Antilles et de la Guyane, Pointe-à-Pitre, Guadeloupe, France
| | - Aurélien Pichon
- Laboratory of Excellence GR-Ex « The red cell : from genesis to death », PRES Sorbonne Paris Cité, Paris, France
- Laboratoire «Réponses cellulaires et fonctionnelles à l'hypoxie» EA2363, Université Paris 13 - PRES Sorbonne Paris Cité, Bobigny, France
| | - Nathalie Lemonne
- Unité Transversale de la Drépanocytose, Centre Hospitalier et Universitaire, Pointe-à-Pitre, Guadeloupe, France
| | - Danièle Mougenel
- Unité Transversale de la Drépanocytose, Centre Hospitalier et Universitaire, Pointe-à-Pitre, Guadeloupe, France
| | - Marie-Laure Lalanne-Mistrih
- Inserm 665, Université des Antilles et de la Guyane, Pointe-à-Pitre, Guadeloupe, France
- CIC-EC 802 Inserm, Centre Hospitalier Universitaire, Pointe-à-Pitre, Guadeloupe, France
| | - Yann Lamarre
- Inserm 665, Université des Antilles et de la Guyane, Pointe-à-Pitre, Guadeloupe, France
- Laboratory of Excellence GR-Ex « The red cell : from genesis to death », PRES Sorbonne Paris Cité, Paris, France
| | - Vanessa Tarer
- Centre de référence maladies rares pour la drépanocytose aux Antilles-Guyane, Centre Hospitalier et Universitaire, Pointe-à-Pitre, Guadeloupe, France
| | - Benoit Tressières
- CIC-EC 802 Inserm, Centre Hospitalier Universitaire, Pointe-à-Pitre, Guadeloupe, France
| | - Maryse Etienne-Julan
- Unité Transversale de la Drépanocytose, Centre Hospitalier et Universitaire, Pointe-à-Pitre, Guadeloupe, France
| | - Marie-Dominique Hardy-Dessources
- Inserm 665, Université des Antilles et de la Guyane, Pointe-à-Pitre, Guadeloupe, France
- Laboratory of Excellence GR-Ex « The red cell : from genesis to death », PRES Sorbonne Paris Cité, Paris, France
| | - Olivier Hue
- Laboratoire ACTES (EA 3596 - Département de Physiologie), Université des Antilles et de la Guyane, Pointe-à-Pitre, Guadeloupe, France
| | - Philippe Connes
- Inserm 665, Université des Antilles et de la Guyane, Pointe-à-Pitre, Guadeloupe, France
- Laboratory of Excellence GR-Ex « The red cell : from genesis to death », PRES Sorbonne Paris Cité, Paris, France
- Laboratoire ACTES (EA 3596 - Département de Physiologie), Université des Antilles et de la Guyane, Pointe-à-Pitre, Guadeloupe, France
- * E-mail:
| |
Collapse
|
204
|
Waltz X, Pichon A, Mougenel D, Lemonne N, Lalanne-Mistrih ML, Sinnapah S, Tarer V, Tressières B, Lamarre Y, Etienne-Julan M, Hue O, Hardy-Dessources MD, Connes P. Hemorheological alterations, decreased cerebral microvascular oxygenation and cerebral vasomotion compensation in sickle cell patients. Am J Hematol 2012; 87:1070-3. [PMID: 22911571 DOI: 10.1002/ajh.23318] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Accepted: 07/20/2012] [Indexed: 11/07/2022]
Abstract
Sickle cell anemia (SS) is characterized by a reduced cerebral microvascular oxygen saturation (cerebral TOI), which is not associated with hemoglobin concentration. Cerebral TOI has never been studied in sickle cell-hemoglobin C disease (SC). We focused on the relationships between hemorheological alterations and cerebral TOI in sickle cell patients with no cerebral vasculopathy and on the usefulness of TOI variability to assess the cerebral vasomotion activity. The blood rheological profile, the level of cerebral TOI (spatial resolved spectroscopy) and the cerebral TOI variability, which reflects vasomotion activity, were compared between 20 healthy subjects (AA), 21 SC patients, and 21 SS patients. Cerebral TOI exhibited the following order: AA > SC > SS. The low cerebral TOI in SS patients was related to red blood cell aggregation and deformability properties. The cerebral TOI variability of SS and SC patients was increased above healthy values and vasomotion activity was negatively associated with the reduced cerebral TOI in SS patients. We demonstrated that (1) blood rheology could be involved in the reduced cerebral TOI in SS patients but not in SC patients; (2) vasomotion activity is increased in SS and SC patients to compensate for the reduced cerebral TOI.
Collapse
Affiliation(s)
- Xavier Waltz
- UMR Inserm 665, Pointe-à-Pitre, F-97159 Guadeloupe, Université des Antilles et de la Guyane, Pointe-à-Pitre, F-97157, France
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
205
|
Ryan TE, Brizendine JT, McCully KK. A comparison of exercise type and intensity on the noninvasive assessment of skeletal muscle mitochondrial function using near-infrared spectroscopy. J Appl Physiol (1985) 2012; 114:230-7. [PMID: 23154991 DOI: 10.1152/japplphysiol.01043.2012] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Near-infrared spectroscopy (NIRS) can be used to measure muscle oxygen consumption (mVO(2)) using arterial occlusions. The recovery rate of mVO(2) after exercise can provide an index of skeletal muscle mitochondrial function. The purpose of this study was to test the influence of exercise modality and intensity on NIRS measurements of mitochondrial function. Three experiments were performed. Thirty subjects (age: 18-27 yr) were tested. NIRS signals were corrected for blood volume changes. The recovery of mVO(2) after exercise was fit to a monoexponential curve, and a rate constant was calculated (directly related to mitochondrial function). No differences were found in NIRS rate constants for VOL and ES exercises (2.04 ± 0.57 vs. 2.01 ± 0.59 min(-1) for VOL and ES, respectively; P = 0.317). NIRS rate constants were independent of the contraction frequency for both VOL and ES (VOL: P = 0.166 and ES: P = 0.780). ES current intensity resulted in significant changes to the normalized time-tension integral (54 ± 11, 82 ± 7, and 100 ± 0% for low, medium, and high currents, respectively; P < 0.001) but did not influence NIRS rate constants (2.02 ± 0.54, 1.95 ± 0.44, 2.02 ± 0.46 min(-1) for low, medium, and high currents, respectively; P = 0.771). In summary, NIRS measurements of skeletal muscle mitochondrial function can be compared between VOL and ES exercises and were independent of the intensity of exercise. NIRS represents an important new technique that is practical for testing in research and clinical settings.
Collapse
Affiliation(s)
- Terence E Ryan
- Department of Kinesiology, University of Georgia, Athens, Georgia 30602, USA.
| | | | | |
Collapse
|
206
|
Shoulder and forearm oxygenation and myoelectric activity in patients with work-related muscle pain and healthy subjects. Eur J Appl Physiol 2012; 113:1103-15. [PMID: 23108582 DOI: 10.1007/s00421-012-2530-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Accepted: 10/12/2012] [Indexed: 10/27/2022]
Abstract
We tested hypotheses of (a) reduced oxygen usage, oxygen recovery, blood flow and oxygen consumption; and (b) increased muscle activity for patients diagnosed with work-related muscle pain (WRMP) in comparison to healthy controls. Oxygenation was measured with near infrared spectroscopy (NIRS), and muscle activity with EMG for the extensor carpi radialis (ECR) and trapezius descendens (TD) muscles. Eighteen patients with diffuse neck-shoulder-arm pain and 17 controls (matched in age and sex) were equipped with NIRS and EMG probes. After determining an individual's maximum voluntary contraction (MVC) force, short-term (20 s) isometric contractions for the ECR and TD of 10, 30, 50 and 70 % MVC generated ∆StO₂ and StO₂% recovery (Rslope) from NIRS, and RMS%max from EMG signals. In addition, upper arm venous (VO) and arterial (AO) occlusions generated slopes of total hemoglobin (HbTslope) and deoxyhemoglobin (HHbslope) for the resting ECR as surrogates of blood flow and oxygen consumption, respectively. Mixed model analyses, t tests, and Mann-Whitney test were used to assess differences between groups. There was no significant difference in MVC between groups for either muscle. Also, ∆StO₂%, Rslope for either muscle, and ECR-HbTslope were not different between groups, thus our hypotheses of reduced oxygen use, recovery, and blood flow for patients were not confirmed. However, patients had a significantly lower ECR-HHbslope confirming our hypothesis of reduced consumption. Further, there was no difference in RMS%max during contractions meaning that the hypothesis of increased activity for patients was not confirmed. When taking into account the number of NIRS variables studied, differences we found between our patient group and healthy controls (i.e., in forearm oxygen consumption and shoulder oxygen saturation level) may be considered modest. Overall our findings may have been impacted by the fact that our patients and controls were similar in muscle strength, which is in contrast to previous studies.
Collapse
|
207
|
Vercruyssen F, Easthope C, Bernard T, Hausswirth C, Bieuzen F, Gruet M, Brisswalter J. The influence of wearing compression stockings on performance indicators and physiological responses following a prolonged trail running exercise. Eur J Sport Sci 2012; 14:144-50. [PMID: 24533521 DOI: 10.1080/17461391.2012.730062] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The objective of this study was to investigate the effects of wearing compression socks (CS) on performance indicators and physiological responses during prolonged trail running. Eleven trained runners completed a 15.6 km trail run at a competition intensity whilst wearing or not wearing CS. Counter movement jump, maximal voluntary contraction and the oxygenation profile of vastus lateralis muscle using near-infrared spectroscopy (NIRS) method were measured before and following exercise. Run time, heart rate (HR), blood lactate concentration and ratings of perceived exertion were evaluated during the CS and non-CS sessions. No significant difference in any dependent variables was observed during the run sessions. Run times were 5681.1 ± 503.5 and 5696.7 ± 530.7 s for the non-CS and CS conditions, respectively. The relative intensity during CS and non-CS runs corresponded to a range of 90.5-91.5% HRmax. Although NIRS measurements such as muscle oxygen uptake and muscle blood flow significantly increased following exercise (+57.7% and + 42.6%,+59.2% and + 32.4%, respectively for the CS and non-CS sessions, P<0.05), there was no difference between the run conditions. The findings suggest that competitive runners do not gain any practical or physiological benefits from wearing CS during prolonged off-road running.
Collapse
|
208
|
Wang CY, Chuang ML, Chuang CC, Hsieh YS, Sun CW. The utility of far-infrared illumination in oxygenation dynamics as measured with near-infrared spectroscopy. JOURNAL OF BIOPHOTONICS 2012; 5:719-723. [PMID: 22271704 DOI: 10.1002/jbio.201100108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Revised: 12/06/2011] [Accepted: 12/08/2011] [Indexed: 05/31/2023]
Abstract
Near-infrared spectroscopy (NIRS) is a noninvasive method for measuring the oxygenation in muscle and other tissues in vivo. For quantitative NIRS measurement of oxygenation dynamics, the vessel-occlusion test was usually applied as physiological intervention. There are several drawbacks of the vessel-occlusion method that include skin contact, uncomfortable and microcirculation block of patients. Thus, we propose the far-infrared (FIR) illumination as a new physiological intervention method in this paper. Our preliminary result shows a linear correlation of oxygenation dynamic signals between FIR illumination and arterial-occlusion test (AOT) that implies the FIR illumination could be applied for hemodynamic response measurement in clinical diagnosis.
Collapse
Affiliation(s)
- Chun-Yang Wang
- Biophotonics and Molecular Imaging Research Center and Institute of Biophotonics, National Yang-Ming University, Taipei 11221, Taiwan, R.O.C
| | | | | | | | | |
Collapse
|
209
|
Macnab AJ, Stothers LS, Shadgan B. Monitoring Detrusor Oxygenation and Hemodynamics Noninvasively during Dysfunctional Voiding. Adv Urol 2012; 2012:676303. [PMID: 23019422 PMCID: PMC3457593 DOI: 10.1155/2012/676303] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2012] [Revised: 07/03/2012] [Accepted: 07/17/2012] [Indexed: 12/02/2022] Open
Abstract
The current literature indicates that lower urinary tract symptoms (LUTSs) related to benign prostatic hyperplasia (BPH) have a heterogeneous pathophysiology. Pressure flow studies (UDSs) remain the gold standard evaluation methodology for such patients. However, as the function of the detrusor muscle depends on its vasculature and perfusion, the underlying causes of LUTS likely include abnormalities of detrusor oxygenation and hemodynamics, and available treatment options include agents thought to act on the detrusor smooth muscle and/or vasculature. Hence, near infrared spectroscopy (NIRS), an established optical methodology for monitoring changes in tissue oxygenation and hemodynamics, has relevance as a means of expanding knowledge related to the pathophysiology of BPH and potential treatment options. This methodological report describes how to conduct simultaneous NIRS monitoring of detrusor oxygenation and hemodynamics during UDS, outlines the clinical implications and practical applications of NIRS, explains the principles of physiologic interpretation of NIRS voiding data, and proposes an exploratory hypothesis that the pathophysiological causes underlying LUTS include detrusor dysfunction due to an abnormal hemodynamic response or the onset of oxygen debt during voiding.
Collapse
Affiliation(s)
- Andrew J. Macnab
- Near Infrared Spectroscopy Research Group, Department of Urology, Faculty of Medicine, University of British Columbia and UBC Hospital Bladder Care Centre, Unit IB—Room F329, 221 Wesbrook Mall, Vancouver, BC, Canada V6T 1Z3
- Stellenbosch Institute for Advanced Study, Wallenberg Research Centre, 10 Marais Street, Stellenbosch 7600, South Africa
| | - Lynn S. Stothers
- Near Infrared Spectroscopy Research Group, Department of Urology, Faculty of Medicine, University of British Columbia and UBC Hospital Bladder Care Centre, Unit IB—Room F329, 221 Wesbrook Mall, Vancouver, BC, Canada V6T 1Z3
| | - Babak Shadgan
- Near Infrared Spectroscopy Research Group, Department of Urology, Faculty of Medicine, University of British Columbia and UBC Hospital Bladder Care Centre, Unit IB—Room F329, 221 Wesbrook Mall, Vancouver, BC, Canada V6T 1Z3
| |
Collapse
|
210
|
Masschelein E, Van Thienen R, Wang X, Van Schepdael A, Thomis M, Hespel P. Dietary nitrate improves muscle but not cerebral oxygenation status during exercise in hypoxia. J Appl Physiol (1985) 2012; 113:736-45. [DOI: 10.1152/japplphysiol.01253.2011] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Exercise tolerance is impaired in hypoxia, and it has recently been shown that dietary nitrate supplementation can reduce the oxygen (O2) cost of muscle contractions. Therefore, we investigated the effect of dietary nitrate supplementation on arterial, muscle, and cerebral oxygenation status, symptoms of acute mountain sickness (AMS), and exercise tolerance at simulated 5,000 m altitude. Fifteen young, healthy volunteers participated in three experimental sessions according to a crossover study design. From 6 days prior to each session, subjects received either beetroot (BR) juice delivering 0.07 mmol nitrate/kg body wt/day or a control drink (CON). One session was in normoxia with CON (NORCON); the two other sessions were in hypoxia (11% O2), with either CON (HYPCON) or BR (HYPBR). Subjects first cycled for 20 min at 45% of peak O2 consumption (VO2peak; EX45%) and thereafter, performed a maximal incremental exercise test (EXmax). Whole-body VO2, arterial O2 saturation (%SpO2) via pulsoximetry, and tissue oxygenation index of both muscle (TOIM) and cerebral (TOIC) tissue by near-infrared spectroscopy were measured. Hypoxia per se substantially reduced VO2peak, %SpO2, TOIM, and TOIC (NORCON vs. HYPCON, P < 0.05). Compared with HYPCON, VO2 at rest and during EX45% was lower in HYPBR ( P < 0.05), whereas %SpO2 was higher ( P < 0.05). TOIM was ∼4-5% higher in HYPBR than in HYPCON both at rest and during EX45% and EXmax ( P < 0.05). TOIC as well as the incidence of AMS symptoms were similar between HYPCON and HYPBR at any time. Hypoxia reduced time to exhaustion in EXmax by 36% ( P < 0.05), but this ergolytic effect was partly negated by BR (+5%, P < 0.05). Short-term dietary nitrate supplementation improves arterial and muscle oxygenation status but not cerebral oxygenation status during exercise in severe hypoxia. This is associated with improved exercise tolerance against the background of a similar incidence of AMS.
Collapse
Affiliation(s)
- Evi Masschelein
- Research Center for Exercise and Health, Department of Biomedical Kinesiology, KU Leuven, Leuven, Belgium; and
| | - Ruud Van Thienen
- Research Center for Exercise and Health, Department of Biomedical Kinesiology, KU Leuven, Leuven, Belgium; and
| | - Xu Wang
- Laboratory for Pharmaceutical Analysis, Faculty of Pharmaceutical Sciences, KU Leuven, Leuven, Belgium
| | - Ann Van Schepdael
- Laboratory for Pharmaceutical Analysis, Faculty of Pharmaceutical Sciences, KU Leuven, Leuven, Belgium
| | - Martine Thomis
- Research Center for Exercise and Health, Department of Biomedical Kinesiology, KU Leuven, Leuven, Belgium; and
| | - Peter Hespel
- Research Center for Exercise and Health, Department of Biomedical Kinesiology, KU Leuven, Leuven, Belgium; and
| |
Collapse
|
211
|
Keramidas ME, Kounalakis SN, Geladas ND, Eiken O, Mekjavic IB. Heterogeneous sensitivity of cerebral and muscle tissues to acute normobaric hyperoxia at rest. Microvasc Res 2012; 84:205-10. [DOI: 10.1016/j.mvr.2012.05.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 04/22/2012] [Accepted: 05/25/2012] [Indexed: 11/28/2022]
|
212
|
Lacroix S, Gayda M, Gremeaux V, Juneau M, Tardif JC, Nigam A. Reproducibility of near-infrared spectroscopy parameters measured during brachial artery occlusion and reactive hyperemia in healthy men. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:077010. [PMID: 22894522 DOI: 10.1117/1.jbo.17.7.077010] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Near-infrared spectroscopy (NIRS) is a noninvasive technique evaluating microvascular function. The aim of this study was to assess the reproducibility of NIRS parameters during reactive hyperemia induced by a 5 min brachial artery occlusion. Twenty-four healthy young males (mean 34 ± 8 years old) had two microvascular function evaluations by NIRS over a 7 to 30-day period (mean 16 ± 10 days). Intra-subject and inter-observer reproducibility were evaluated with intraclass correlation coefficient (ICC), coefficient of variation (CV), and standard error of measurement (SEM%) for every parameter. Mean NIRS parameters did not differ between both evaluations. Reproducibility was greatest for muscle oxygen consumption (ICC: 0.84; CV: 6.51%; SEM: 7.11%), time to basal O(2)Hb (ICC: 0.63, CV: 20.04%, SEM 27.22%), time to maximal O(2)Hb (ICC: 0.71; CV: 15.61%; SEM: 19.27%), peak of O(2)Hb (ICC: 0.63, CV: 6.68%, SEM 8.53%), time to maximal tHb (ICC: 0.73, CV: 19,61%, SEM 24.56%) and area under the O(2)Hb and tHb curves (ICC: 0.68, CV: 16.15%, SEM 22.93% and ICC: 0.62, CV: 18.59%, SEM 26.64%, respectively). Moreover, inter-observer reproducibility ranged from excellent to perfect (ICC from 0.85 to 1.00) for every parameter. NIRS parameters during reactive hyperemia are highly reproducible which enables their repeated measurement to study microvascular function in healthy subjects.
Collapse
Affiliation(s)
- Sébastien Lacroix
- Montreal Heart Institute Montreal, Cardiovascular Rehabilitation and Prevention Centre (ÉPIC), Quebec, Canada
| | | | | | | | | | | |
Collapse
|
213
|
Gurley K, Shang Y, Yu G. Noninvasive optical quantification of absolute blood flow, blood oxygenation, and oxygen consumption rate in exercising skeletal muscle. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:075010. [PMID: 22894482 PMCID: PMC3395077 DOI: 10.1117/1.jbo.17.7.075010] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 06/11/2012] [Accepted: 06/13/2012] [Indexed: 05/19/2023]
Abstract
This study investigates a method using novel hybrid diffuse optical spectroscopies [near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS)] to obtain continuous, noninvasive measurement of absolute blood flow (BF), blood oxygenation, and oxygen consumption rate (V̇O(2)) in exercising skeletal muscle. Healthy subjects (n=9) performed a handgrip exercise to increase BF and V̇O(2) in forearm flexor muscles, while a hybrid optical probe on the skin surface directly monitored oxy-, deoxy-, and total hemoglobin concentrations ([HbO(2)], [Hb], and THC), tissue oxygen saturation (S(t)O(2)), relative BF (rBF), and relative oxygen consumption rate (rV̇O(2)). The rBF and rV̇O(2) signals were calibrated with absolute baseline BF and V̇O(2) obtained through venous and arterial occlusions, respectively. Known problems with muscle-fiber motion artifacts in optical measurements during exercise were mitigated using a novel gating algorithm that determined muscle contraction status based on control signals from a dynamometer. Results were consistent with previous findings in the literature. This study supports the application of NIRS/DCS technology to quantitatively evaluate hemodynamic and metabolic parameters in exercising skeletal muscle and holds promise for improving diagnosis and treatment evaluation for patients suffering from diseases affecting skeletal muscle and advancing fundamental understanding of muscle and exercise physiology.
Collapse
Affiliation(s)
- Katelyn Gurley
- University of Kentucky, Center for Biomedical Engineering, Lexington, Kentucky 40506
| | - Yu Shang
- University of Kentucky, Center for Biomedical Engineering, Lexington, Kentucky 40506
| | - Guoqiang Yu
- University of Kentucky, Center for Biomedical Engineering, Lexington, Kentucky 40506
- Address all correspondence to: Guoqiang Yu, University of Kentucky, Center for Biomedical Engineering, 204 Wenner-Gren Research Lab, 600 Rose Street, Lexington, Kentucky 40506-0070. Tel: +859 257 9110; Fax: 859 257 1856; E-mail:
| |
Collapse
|
214
|
Hesford CM, Laing SJ, Cardinale M, Cooper CE. Asymmetry of quadriceps muscle oxygenation during elite short-track speed skating. Med Sci Sports Exerc 2012; 44:501-8. [PMID: 21900848 DOI: 10.1249/mss.0b013e31822f8942] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE It has been suggested that, because of the low sitting position in short-track speed skating, muscle blood flow is restricted, leading to decreases in tissue oxygenation. Therefore, wearable wireless-enabled near-infrared spectroscopy (NIRS) technology was used to monitor changes in quadriceps muscle blood volume and oxygenation during a 500-m race simulation in short-track speed skaters. METHODS Six elite skaters, all of Olympic standard (age = 23 ± 1.8 yr, height = 1.8 ± 0.1 m, mass = 80.1 ± 5.7 kg, midthigh skinfold thickness = 7 ± 2 mm), were studied. Subjects completed a 500-m race simulation time trial (TT). Whole-body oxygen consumption was simultaneously measured with muscle oxygenation in right and left vastus lateralis as measured by NIRS. RESULTS Mean time for race completion was 44.8 ± 0.4 s. VO2 peaked 20 s into the race. In contrast, muscle tissue oxygen saturation (TSI%) decreased and plateaued after 8 s. Linear regression analysis showed that right leg TSI% remained constant throughout the rest of the TT (slope value = 0.01), whereas left leg TSI% increased steadily (slope value = 0.16), leading to a significant asymmetry (P < 0.05) in the final lap. Total muscle blood volume decreased equally in both legs at the start of the simulation. However, during subsequent laps, there was a strong asymmetry during cornering; when skaters traveled solely on the right leg, there was a decrease in its muscle blood volume, whereas an increase was seen in the left leg. CONCLUSIONS NIRS was shown to be a viable tool for wireless monitoring of muscle oxygenation. The asymmetry in muscle desaturation observed on the two legs in short-track speed skating has implications for training and performance.
Collapse
|
215
|
Microcirculation and macrocirculation in cardiac surgical patients. Crit Care Res Pract 2012; 2012:654381. [PMID: 22720146 PMCID: PMC3374942 DOI: 10.1155/2012/654381] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Revised: 03/08/2012] [Accepted: 03/27/2012] [Indexed: 11/18/2022] Open
Abstract
Background. The aim of our study was to investigate the relationship between microcirculatory alterations after open cardiac surgery, macrohemodynamics, and global indices of organ perfusion. Methods. Patients' microcirculation was assessed with near-infrared spectroscopy (NIRS) and the vascular occlusion technique (VOT). Results. 23 patients undergoing open cardiac surgery (11 male/12 female, median age 68 (range 28-82) years, EuroSCORE 6 (1-12)) were enrolled in the study. For pooled data, CI correlated with the tissue oxygen consumption rate as well as the reperfusion rate (r = 0.56, P < 0.001 and r = 0.58, P < 0.001, resp.). In addition, both total oxygen delivery (DO(2), mL/min per m(2)) and total oxygen consumption (VO(2), mL/min per m(2)) also correlated with the tissue oxygen consumption rate and the reperfusion rate. The tissue oxygen saturation of the thenar postoperatively correlated with the peak lactate levels during the six hour monitoring period (r = 0.50, P < 0.05). The tissue oxygen consumption rate (%/min) and the reperfusion rate (%/min), as derived from the VOT, were higher in survivors compared to nonsurvivors for pooled data [23 (4-54) versus 20 (8-38) P < 0.05] and [424 (27-1215) versus 197 (57-632) P < 0.01], respectively. Conclusion. Microcirculatory alterations after open cardiac surgery are related to macrohemodynamics and global indices of organ perfusion.
Collapse
|
216
|
Kounalakis SN, Geladas ND. Cardiovascular drift and cerebral and muscle tissue oxygenation during prolonged cycling at different pedalling cadences. Appl Physiol Nutr Metab 2012; 37:407-17. [DOI: 10.1139/h2012-011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We hypothesized that a faster cycling cadence could exaggerate cardiovascular drift and affect muscle and cerebral blood volume and oxygenation. Twelve healthy males (mean age, 23.4 ± 3.8 years) performed cycle ergometry for 90 min on 2 separate occasions, with pedalling frequencies of 40 and 80 r·min–1, at individual workloads corresponding to 60% of their peak oxygen consumption. The main measured variables were heart rate, ventilation, cardiac output, electromyographic activity of the vastus lateralis, and regional muscle and cerebral blood volume and oxygenation. Cardiovascular drift developed at both cadences, but it was more pronounced at the faster than at the slower cadence, as indicated by the drop in cardiac output by 1.0 ± 0.2 L·min–1, the decline in stroke volume by 9 ± 3 mL·beat–1, and the increase in heart rate by 9 ± 1 beats·min–1 at 80 r·min–1. At the faster cadence, minute ventilation was higher by 5.0 ± 0.5 L·min–1, and end-tidal CO2 pressure was lower by 2.0 ± 0.1 torr. Although higher electromyographic activity in the vastus lateralis was recorded at 80 r·min–1, muscle blood volume did not increase at this cadence, as it did at 40 r·min–1. In addition, muscle oxygenation was no different between cadences. In contrast, cerebral regional blood volume and oxygenation at 80 r·min–1 were not as high as at 40 r·min–1 (p < 0.05). Faster cycling cadence exaggerates cardiovascular drift and seems to influence muscle and cerebral blood volume and cerebral oxygenation, without muscle oxygenation being radically affected.
Collapse
Affiliation(s)
- Stylianos N. Kounalakis
- Human Performance–Rehabilitation Laboratory, Faculty of Physical and Cultural Education, Evelpidon Hellenic Military University, Vari 16672, Greece
| | - Nickos D. Geladas
- Department of Sports Medicine and Biology of Exercise, Faculty of Physical Education, and Sport Science, University of Athens, 17237 Dafne, Greece
| |
Collapse
|
217
|
Ryan TE, Erickson ML, Brizendine JT, Young HJ, McCully KK. Noninvasive evaluation of skeletal muscle mitochondrial capacity with near-infrared spectroscopy: correcting for blood volume changes. J Appl Physiol (1985) 2012; 113:175-83. [PMID: 22582211 DOI: 10.1152/japplphysiol.00319.2012] [Citation(s) in RCA: 151] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Near-infrared spectroscopy (NIRS) is a well-known method used to measure muscle oxygenation and hemodynamics in vivo. The application of arterial occlusions allows for the assessment of muscle oxygen consumption (mVo(2)) using NIRS. The aim of this study was to measure skeletal muscle mitochondrial capacity using blood volume-corrected NIRS signals that represent oxygenated hemoglobin/myoglobin (O(2)Hb) and deoxygenated hemoglobin/myoglobin (HHb). We also assessed the reliability and reproducibility of NIRS measurements of resting oxygen consumption and mitochondrial capacity. Twenty-four subjects, including four with chronic spinal cord injury, were tested using either the vastus lateralis or gastrocnemius muscles. Ten healthy, able-bodied subjects were tested on two occasions within a period of 7 days to assess the reliability and reproducibility. NIRS signals were corrected for blood volume changes using three different methods. Resting oxygen consumption had a mean coefficient of variation (CV) of 2.4% (range 1-32%). The recovery of oxygen consumption (mVo(2)) after electrical stimulation at 4 Hz was fit to an exponential curve, which represents mitochondrial capacity. The time constant for the recovery of mVo(2) was reproducible with a mean CV of 10% (range 1-22%) only when correcting for blood volume changes. We also examined the effects of adipose tissue thickness on measurements of mVo(2). We found the mVo(2) measurements using absolute units to be influenced by adipose tissue thickness (ATT), and this relationship was removed when an ischemic calibration was performed, supporting its use to compare mVo(2) between individuals of varying ATT. In conclusion, in vivo oxidative capacity can be assessed using blood volume-corrected NIRS signals with a high degree of reliability and reproducibility.
Collapse
Affiliation(s)
- Terence E Ryan
- Department of Kinesiology, University of Georgia, Athens, GA 30602, USA.
| | | | | | | | | |
Collapse
|
218
|
Lipcsey M, Woinarski NC, Bellomo R. Near infrared spectroscopy (NIRS) of the thenar eminence in anesthesia and intensive care. Ann Intensive Care 2012; 2:11. [PMID: 22569165 PMCID: PMC3488540 DOI: 10.1186/2110-5820-2-11] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 03/26/2012] [Indexed: 01/20/2023] Open
Abstract
Near infrared spectroscopy of the thenar eminence (NIRSth) is a noninvasive bedside method for assessing tissue oxygenation. The NIRS probe emits light with several wavelengths in the 700- to 850-nm interval and measures the reflected light mainly from a predefined depth. Complex physical models then allow the measurement of the relative concentrations of oxy and deoxyhemoglobin, and thus tissue saturation (StO2), as well as an approximation of the tissue hemoglobin, given as tissue hemoglobin index. Here we review of current knowledge of the application of NIRSth in anesthesia and intensive care. We performed an analytical and descriptive review of the literature using the terms “near-infrared spectroscopy” combined with “anesthesia,” “anesthesiology,” “intensive care,” “critical care,” “sepsis,” “bleeding,” “hemorrhage,” “surgery,” and “trauma” with particular focus on all NIRS studies involving measurement at the thenar eminence. We found that NIRSth has been applied as clinical research tool to perform both static and dynamic assessment of StO2. Specifically, a vascular occlusion test (VOT) with a pressure cuff can be used to provide a dynamic assessment of the tissue oxygenation response to ischemia. StO2 changes during such induced ischemia-reperfusion yield information on oxygen consumption and microvasculatory reactivity. Some evidence suggests that StO2 during VOT can detect fluid responsiveness during surgery. In hypovolemic shock, StO2 can help to predict outcome, but not in septic shock. In contrast, NIRS parameters during VOT increase the diagnostic and prognostic accuracy in both hypovolemic and septic shock. Minimal data are available on static or dynamic StO2 used to guide therapy. Although the available data are promising, further studies are necessary before NIRSth can become part of routine clinical practice.
Collapse
Affiliation(s)
- Miklos Lipcsey
- Department of Intensive Care, Austin Hospital, Melbourne, VIC, Australia.
| | | | | |
Collapse
|
219
|
Ufland P, Lapole T, Ahmaidi S, Buchheit M. Muscle force recovery in relation to muscle oxygenation. Clin Physiol Funct Imaging 2012; 32:380-7. [PMID: 22856345 DOI: 10.1111/j.1475-097x.2012.01141.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2012] [Accepted: 03/23/2012] [Indexed: 11/29/2022]
Abstract
The aim of this study was to investigate the relative contribution of human muscle reoxygenation on force recovery following a maximal voluntary contraction (MVC). Ten athletes (22·9 ± 4·0 years) executed a plantar-flexion sequence including two repeated MVCs [i.e. a 30-s MVC (MVC(30)) followed by a 10-s MVC (MVC(10))] separated by 10, 30, 60, 120 or 300 s of passive recovery. A 10-min passive recovery period was allowed between each MVC sequence. This procedure was randomly repeated with two different recovery conditions: without (CON) or with (OCC) arterial occlusion of the medial gastrocnemius. During OCC, the occlusion was maintained from the end of MVC(30) to the end of MVC(10). Muscle oxygenation (Near-infrared spectroscopy, NIRS, [Hb(diff) ]) was continuously measured during all MVC sequences and expressed as a percentage of the maximal changes in optical density observed during MVC(30). Maximal Torque was analysed at the start of each contraction. Torque during each MVC(10) was expressed as a percentage of the Torque during the previous MVC(30). Torque recovery was complete within 300 s after MVC(30) during CON (MVC(10) = 101·8 ± 5·0%); 88·6 ± 8·9% of the Torque was recovered during OCC (P = 0·005). There was also a moderate correlation between absolute level of muscle oxygenation and Torque (r = 0·32 (90% CI, 0·09;0·52), P = 0·02). Present findings confirm the role of human muscle oxygenation in muscular force recovery during repeated-maximal efforts. However, the correlation between absolute muscle oxygenation and force level during recovery is only moderate, suggesting that other mechanisms are likely involved in the force recovery process.
Collapse
Affiliation(s)
- Pierre Ufland
- Faculty of Sport Sciences, Laboratory of Exercise Physiology and Rehabilitation, University of Picardie Jules Verne, Amiens, France.
| | | | | | | |
Collapse
|
220
|
Reading SA, Yeomans M. Oxygen absorption by skin exposed to oxygen supersaturated water. Can J Physiol Pharmacol 2012; 90:515-24. [PMID: 22494481 DOI: 10.1139/y2012-020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study tests the hypothesis that skin on the plantar surface of the foot absorbs oxygen (O(2)) when immersed in water that has a high dissolved O(2) content. Healthy male and female subjects (24.2 ± 1.4 years) soaked each foot in tap water (1.7 ± 0.1 mg O(2)·L(-1); 30.7 ± 0.3 °C) or O(2)-infused water (50.2 ± 1.7 mg O(2)·L(-1); 32.1 ± 0.5 °C) for up to 30 min in 50 different experiments. Transcutaneous oximetry and near infrared spectroscopy were used to evaluate changes in skin PO(2), oxygenated haemoglobin, and cytochrome oxidase aa(3) that resulted from treatment. Compared with the tap water condition, tissue oxygenation index was 3.5% ± 1.3% higher in feet treated for 30 min with O(2)-infused water. This effect persisted after treatment, as skin PO(2) was higher in feet treated with O(2)-infused water at 2 min (237 ± 9 vs. 112 ± 5 mm HG) and 15 min (131 ± 1 vs. 87 ± 4 mm HG) post-treatment. When blood flow to the foot was occluded for 5 min, feet resting in O(2)-infused water maintained a 3-fold higher O(2) consumption rate than feet treated with tap water (9.1 ± 1.4 vs. 3.0 ± 1.0 µL·100 g(-1)·min(-1)). We estimate that skin absorbs 4.5 mL of O(2)·m(-2)·min(-1) from O(2)-infused water. Thus, skin absorbs appreciable amounts of O(2) from O(2)-infused water. This finding may prove useful and assist development of treatments targeting skin diseases with ischemic origin.
Collapse
Affiliation(s)
- Stacey A Reading
- Faculty of Kinesiology, University of New Brunswick, Fredericton, Canada.
| | | |
Collapse
|
221
|
Nagasawa T. Effect of exercise intensity on oxygen consumption kinetics in non-exercising muscle during exercise. Clin Physiol Funct Imaging 2012; 32:172-8. [PMID: 22487150 DOI: 10.1111/j.1475-097x.2011.01073.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This study examined the effect of exercise intensity on the kinetics of muscle oxygen consumption in non-exercising forearm flexor muscles (VO(2mf)) during exercise. Seven healthy male subjects performed cycling exercise for 60 min at 30% of maximal oxygen consumption (%VO(2max)) and 30 min at 50% VO(2max) on separate days. The VO(2mf) values at rest and during exercise were measured by near-infrared spectroscopy. The VO(2mf) at 30% VO(2max) significantly increased to 1·2 ± 0·1-fold over resting value at 20 min after the beginning of exercise (P<0·05) and remained constant within 1·2- to 1·3-fold over resting value until 60 min during exercise. The VO(2mf) at 50% VO(2max) significantly increased to 1·2 ± 0·1-fold over resting value at 15 min after the beginning of exercise (P<0·05). Subsequently, the VO(2mf) at 50% VO(2max) increased with time to 1·3 ± 0·1-fold over resting value at 20 min after the beginning of exercise and to 1·5 ± 0·2-fold over resting value at 30 min. The VO(2mf) 15-30 min of exercise at 50% VO(2max) was significantly higher than that at 30% VO(2max) (P<0·05). These data suggest that the increase in VO(2mf) has a time lag from the beginning of exercise, and the kinetics of VO(2mf) during exercise differs with exercise intensity. Therefore, we conclude that the kinetics of VO(2mf) during exercise is dependent on exercise intensity.
Collapse
Affiliation(s)
- Takeshi Nagasawa
- Department of Health Science, Hiroshima Institute of Technology, Hiroshima, Japan.
| |
Collapse
|
222
|
Keramidas ME, Kounalakis SN, Eiken O, Mekjavic IB. Carbon monoxide exposure during exercise performance: muscle and cerebral oxygenation. Acta Physiol (Oxf) 2012; 204:544-54. [PMID: 21933352 DOI: 10.1111/j.1748-1716.2011.02363.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIM To investigate the effect of carbon monoxide (CO) in the inspired air as anticipated during peak hours of traffic in polluted megalopolises on cerebral, respiratory and leg muscle oxygenation during a constant-power test (CPT). In addition, since O(2) breathing is used to hasten elimination of CO from the blood, we examined the effect of breathing O(2) following exposure to CO on cerebral and muscle oxygenation during a subsequent exercise test under CO conditions. METHODS Nine men participated in three trials: (i) 3-h air exposure followed by a control CPT, (ii) 1-h air and 2-h CO (18.9 ppm) exposure succeeded by a CPT under CO conditions (CPT(COA)), and (iii) 2-h CO and 1-h 100% normobaric O(2) exposure followed by a CPT under CO conditions (CPT(COB)). All exercise tests were performed at 85% of peak power output to exhaustion. Oxygenated (Δ[O(2)Hb]), deoxygenated (Δ[HHb]) and total (Δ[tHb]) haemoglobin in cerebral, intercostal and vastus lateralis muscles were monitored with near-infrared spectroscopy throughout the CPTs. RESULTS Performance time did not vary between trials. However, the vastus lateralis and intercostal Δ[O(2)Hb] and Δ[tHb] were lower in CPT(COA) than in CPT. During the CPT(COB), the intercostal Δ[O(2) Hb] and Δ[tHb] were higher than in the CPT(COA). There were no differences in cerebral oxygenation between the trials. CONCLUSION Inspiration of 18.9 ppm CO decreases oxygenation in the vastus lateralis and serratus anterior muscles, but does not affect performance. Breathing normobaric O(2) moderates the CO-induced reductions in muscle oxygenation, mainly in the intercostals, but does not affect endurance.
Collapse
Affiliation(s)
- M E Keramidas
- Department of Automation, Biocybernetics and Robotics, Jozef Stefan Institute, Ljubljana, Slovenia.
| | | | | | | |
Collapse
|
223
|
Debevec T, Mekjavic IB. Short intermittent hypoxic exposures augment ventilation but do not alter regional cerebral and muscle oxygenation during hypoxic exercise. Respir Physiol Neurobiol 2012; 181:132-42. [DOI: 10.1016/j.resp.2012.02.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Revised: 02/20/2012] [Accepted: 02/23/2012] [Indexed: 11/25/2022]
|
224
|
Bilateral changes in forearm oxygen consumption at rest and after exercise in patients with unilateral repetitive strain injury: a case-control study. J Orthop Sports Phys Ther 2012; 42:371-8. [PMID: 22466007 DOI: 10.2519/jospt.2012.3751] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
STUDY DESIGN Case-control study. OBJECTIVES To investigate whether oxygen consumption and blood flow at rest and after exercise are lower in the affected arm of patients with repetitive strain injury (RSI) compared to controls, and lower in the healthy nonaffected forearm within patients with unilateral RSI. BACKGROUND RSI is considered an upper extremity overuse injury. Despite the local presentation of complaints, RSI may be represented by systemic adaptations. Insight into the pathophysiology of RSI is important to better understand the development of RSI complaints and to develop effective treatment and prevention strategies. METHODS Twenty patients with unilateral RSI and 20 gender-matched control subjects participated in this study. Forearm muscle blood flow and oxygen consumption were measured using near-infrared spectroscopy at baseline and immediately after isometric handgrip exercises at 10%, 20%, and 40% of the individual maximal voluntary contraction. RESULTS Unilateral RSI resulted in a lower oxygen consumption and blood flow in the affected forearm at baseline and lower oxygen consumption after incremental handgrip exercises compared to controls (P<.05). In addition, exercise-induced blood flow and oxygen consumption in the nonaffected forearm in patients with RSI were similarly reduced. CONCLUSION Blood flow and oxygen consumption after exercise are similarly attenuated in the affected and nonaffected arms of patients with unilateral RSI. Our findings suggest that, despite the unilateral character in clinical symptoms, RSI demonstrates systemic adaptations in forearm blood flow and oxygen consumption at rest and after exercise.
Collapse
|
225
|
Exercise thermoregulatory responses following a 28-day sleep-high train-low regimen. Eur J Appl Physiol 2012; 112:3881-91. [DOI: 10.1007/s00421-012-2374-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Accepted: 02/27/2012] [Indexed: 11/26/2022]
|
226
|
Cole AL, Herman RA, Heimlich JB, Ahsan S, Freedman BA, Shuler MS. Ability of near infrared spectroscopy to measure oxygenation in isolated upper extremity muscle compartments. J Hand Surg Am 2012; 37:297-302. [PMID: 22189186 DOI: 10.1016/j.jhsa.2011.10.037] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 10/18/2011] [Accepted: 10/19/2011] [Indexed: 02/02/2023]
Abstract
PURPOSE Near infrared spectroscopy (NIRS), a noninvasive means for monitoring muscle oxygenation, may be useful in the diagnosis of acute compartment syndrome, a condition characterized by poor tissue perfusion. This study used the decrease in muscle oxygenation caused by exercise to investigate the ability of anatomic placement of NIRS sensor pads over compartments of the forearm to isolate perfusion values of a specific compartment. METHODS We recruited 63 uninjured volunteers from a private clinic-based setting and placed NIRS sensor pads over the dorsal, volar, and mobile wad compartments of 1 forearm. A total of 49 participants also had the contralateral forearm monitored, which served as an internal control. Participants performed a series of 3 exercises designed to sequentially activate the muscles of each compartment. A washout period separated each exercise to allow perfusion to return to baseline. We compared NIRS values of each compartment recorded during muscle contraction with baseline values. RESULTS Mean NIRS values decreased significantly from baseline during muscle contraction for all compartments, whereas mean NIRS values of muscle compartments that remained at rest showed little or no change. We observed no changes in NIRS values of the contralateral arm, which remained at rest during the entire data collection period. CONCLUSIONS Although lack of an existing method for quantifying muscle perfusion precludes validation of this technique against a reference standard, this study suggests that NIRS can provide oxygenation values that are both sensitive and specific to muscle compartments of the forearm. Future studies should investigate NIRS among patients with upper extremity injuries. TYPE OF STUDY/LEVEL OF EVIDENCE Diagnostic III.
Collapse
Affiliation(s)
- Ashley L Cole
- Department of Upper Extremity and Micro Surgery, Athens Orthopedic Clinic, PA, USA
| | | | | | | | | | | |
Collapse
|
227
|
Álvares TS, Conte CA, Paschoalin VMF, Silva JT, Meirelles CDM, Bhambhani YN, Gomes PSC. Acute l-arginine supplementation increases muscle blood volume but not strength performance. Appl Physiol Nutr Metab 2012; 37:115-26. [DOI: 10.1139/h11-144] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
l-Arginine (L-arg) is an amino acid precursor to nitric oxide (NO). Dietary supplements containing L-arg have been marketed with the purpose of increasing vasodilation, thereby elevating blood flow to the exercising muscle and enhancing the metabolic response to exercise. Our goal was to identify the acute effect of L-arg supplementation on biceps strength performance, indicators of NO production (nitrite and nitrate – NOx), and muscle blood volume (Mbv) and oxygenation (Mox) during recovery from 3 sets of resistance exercise. Fifteen males participated in a randomized, double-blind, placebo-controlled study. After withdrawing resting blood samples, the subjects were supplemented with 6 g of L-arg (ARG) or placebo (PLA). Monitoring of Mbv and Mox with near-infrared spectroscopy began 30 min after supplementation and lasted for 60 min. The exercise protocol (3 sets of 10 maximal voluntary contractions of isokinetic concentric elbow extension at 60°·s–1, 2-min rest between sets) was initiated 80 min after supplementation. Blood samples were drawn at 30, 60, 90, and 120 min after supplementation. Repeated measures ANOVA showed that Mbv significantly (p ≤ 0.05) increased in ARG compared with the PLA during the recovery period of each set of resistance exercise. NOx, Mox, peak torque, total work, and set total work were not significantly different between groups. We found that acute L-arg supplementation increases Mbv during recovery from sets of resistance exercise with no increase in strength performance. It is still premature to recommend nutritional supplements containing L-arg as an ergogenic aid to increase muscle strength during resistance training in healthy subjects.
Collapse
Affiliation(s)
- Thiago Silveira Álvares
- Laboratory Crossbridges, Physical Education Postgraduate Program, Gama Filho University, Rio de Janeiro, Brazil
- Department of Biochemistry, Chemistry Institute, Federal University of Rio de Janeiro, Brazil
- Laboratório de Análises Avançadas em Bioquímica e Biologia Molecular, Universidade Federal do Rio de Janeiro, Av. Athos da Silveira Ramos, 149 Rio de Janeiro, Rio de Janeiro 21941-909, Brazil
| | - Carlos Adam Conte
- Department of Biochemistry, Chemistry Institute, Federal University of Rio de Janeiro, Brazil
| | | | - Joab Trajano Silva
- Department of Biochemistry, Chemistry Institute, Federal University of Rio de Janeiro, Brazil
| | - Cláudia de Mello Meirelles
- Laboratory Crossbridges, Physical Education Postgraduate Program, Gama Filho University, Rio de Janeiro, Brazil
- School of Physical Education of the Army, Rio de Janeiro, Brazil
| | - Yagesh N. Bhambhani
- Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB T6G 2G4, Canada
| | - Paulo Sergio Chagas Gomes
- Laboratory Crossbridges, Physical Education Postgraduate Program, Gama Filho University, Rio de Janeiro, Brazil
| |
Collapse
|
228
|
Gussakovsky E, Yang Y, Rendell J, Jilkina O, Kupriyanov V. NIR spectroscopic imaging to map hemoglobin + myoglobin oxygenation, their concentration and optical pathlength across a beating pig heart during surgery. JOURNAL OF BIOPHOTONICS 2012; 5:128-39. [PMID: 21688399 DOI: 10.1002/jbio.201100031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Revised: 05/25/2011] [Accepted: 05/27/2011] [Indexed: 05/07/2023]
Abstract
The purpose of this paper is to demonstrate that near-infrared (NIR) spectroscopic imaging can provide spatial distribution (maps) of the absolute concentration of hemoglobin + myoglobin, oxygen saturation parameter and optical pathlength, reporting on the biochemico-physiological status of a beating heart in vivo. The method is based on processing the NIR spectroscopic images employing a first-derivative approach. Blood-pressure-controlled gating compensated the effect of heart motion on the imaging. All the maps are available simultaneously and noninvasively at a spatial resolution in the submillimeter range and can be obtained in a couple of minutes. The equipment has no mechanical contact with the tissue, thereby leaving the heart unaffected during the measurement.
Collapse
Affiliation(s)
- Eugene Gussakovsky
- National Research Council Institute for Biodiagnostics, 435 Ellice Ave., Winnipeg, Manitoba, Canada R3B 1Y6.
| | | | | | | | | |
Collapse
|
229
|
Endofibrosis and Kinking of the Iliac Arteries in Athletes: A Systematic Review. Eur J Vasc Endovasc Surg 2012; 43:208-17. [DOI: 10.1016/j.ejvs.2011.11.019] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Accepted: 11/28/2011] [Indexed: 11/19/2022]
|
230
|
Munk N, Symons B, Shang Y, Cheng R, Yu G. Noninvasively measuring the hemodynamic effects of massage on skeletal muscle: A novel hybrid near-infrared diffuse optical instrument. J Bodyw Mov Ther 2012; 16:22-8. [DOI: 10.1016/j.jbmt.2011.01.018] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Revised: 12/30/2010] [Accepted: 01/14/2011] [Indexed: 11/15/2022]
|
231
|
Keramidas ME, Kounalakis SN, Geladas ND. The effect of interval training combined with thigh cuffs pressure on maximal and submaximal exercise performance. Clin Physiol Funct Imaging 2011; 32:205-13. [PMID: 22487155 DOI: 10.1111/j.1475-097x.2011.01078.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The purpose of the study was to investigate the effect of interval training combined with a thigh cuffs pressure of +90 mmHg on maximal and submaximal cycling performance. Twenty untrained individuals were assigned either to a control (CON) or to an experimental (CUFF) training group. Both groups trained 3 days per week for 6 weeks at the same relative intensity; each training session consisted of 2-min work bout at 90% of VO(2max): 2-min active recovery bout at 50% of VO(2max). An incremental exercise test to exhaustion, a 6-min constant-power test at 80% of VO(2max) (Sub(80)) and a maximal constant-power test to exhaustion (TF(150)) were performed pre- and post-training. Despite the unchanged VO(2max), both groups significantly increased peak power output (CON: ∼12%, CUFF: ∼20%) that was accompanied by higher deoxygenation (ΔStO(2)) measured with near-infrared muscle spectroscopy. These changes were more pronounced in the CUFF group. Moreover, both groups reduced VO(2) during the Sub(80) test without concomitant changes in ΔStO(2). TF(150) was enhanced in both groups. Thus, an interval exercise training protocol under moderate restricted blood flow conditions does not provide any additive effect on maximal and submaximal cycling performance. However, it seems to induce peripheral muscular adaptations, despite the lower absolute training intensity.
Collapse
Affiliation(s)
- Michail E Keramidas
- Department of Sport Medicine and Biology of Physical Activity, Faculty of Physical Education and Sport Science, National and Kapodistrian University of Athens, Athens, Greece.
| | | | | |
Collapse
|
232
|
Fu TC, Wang CH, Lin PS, Hsu CC, Cherng WJ, Huang SC, Liu MH, Chiang CL, Wang JS. Aerobic interval training improves oxygen uptake efficiency by enhancing cerebral and muscular hemodynamics in patients with heart failure. Int J Cardiol 2011; 167:41-50. [PMID: 22197120 DOI: 10.1016/j.ijcard.2011.11.086] [Citation(s) in RCA: 158] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Revised: 10/10/2011] [Accepted: 11/27/2011] [Indexed: 12/17/2022]
Abstract
BACKGROUND Abnormal ventilatory/hemodynamic responses to exercise contribute to functional impairment in patients with heart failure (HF). This study investigates how interval and continuous exercise regimens influence functional capacity by modulating ventilatory efficiency and hemodynamic function in HF patients. METHODS Forty-five HF patients were randomized to perform either aerobic interval training (AIT; 3-minute intervals at 40% and 80% VO(2peak)) or moderate continuous training (MCT; sustained 60% VO()for 30 min/day, 3 days/week for 12 weeks, or to a control group that received general healthcare (GHC). A noninvasive bio-reactance device was adopted to measure cardiac hemodynamics, whereas a near-infrared spectroscopy was employed to assess perfusion/O2 extraction in frontal cerebral lobe (∆[THb]FC/∆[HHb]FC) and vastus lateralis (∆[THb]VL/∆[HHb]VL), respectively. RESULTS Following the 12-week intervention, the AIT group exhibited higher oxygen uptake efficiency slope (OUES) and lower VE-VCO2 slope than the MCT and GHC groups. Furthermore, AIT, but not MCT, boosted cardiac output (CO) and increased ∆[THb]FC, ∆[THb]VL, and ∆[HHb]VL during exercise. In multivariate analyses, CO was the dominant predictor of VO(2peak). ∆[THb]FC and ∆[THb]VL, which modulated the correlation between CO and OUES, were significantly correlated with OUES. Simultaneously, ∆[THb]VL was the only factor significantly associated with VE-VCO2 slope. Additionally, AIT reduced plasma brain natriuretic peptide, myeloperoxidase, and interleukin-6 levels and increased the Short Form-36 physical/mental component scores and decreased the Minnesota Living with Heart Failure questionnaire score. CONCLUSIONS AIT effectively improves oxygen uptake efficiency by enhancing cerebral/muscular hemodynamics and suppresses oxidative stress/inflammation associated with cardiac dysfunction, and also promotes generic/disease-specific qualities of life in patients with HF.
Collapse
Affiliation(s)
- Tieh-Cheng Fu
- Department of Physical Medicine and Rehabilitation, Chang Gung Memorial Hospital, Keelung, Taiwan
| | | | | | | | | | | | | | | | | |
Collapse
|
233
|
Jabre JF, Squintani GM, Chui KK. Oxyneurography: A new technique for the measurement of nerve oxygenation. Muscle Nerve 2011; 45:75-80. [DOI: 10.1002/mus.22251] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
234
|
Kacin A, Strazar K. Frequent low-load ischemic resistance exercise to failure enhances muscle oxygen delivery and endurance capacity. Scand J Med Sci Sports 2011; 21:e231-41. [PMID: 21385216 DOI: 10.1111/j.1600-0838.2010.01260.x] [Citation(s) in RCA: 139] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This study investigated the effects of frequent low-load ischemic resistance exercise performed to failure on quadriceps size and performance, muscle activation, oxygen kinetics and cardiovascular responses. Ten healthy males performed knee-extension exercise for 4 weeks (4 sessions/week) at 15% maximal voluntary muscle contraction (MVC). One leg was trained with free blood flow (C-leg) while in the other leg (I-leg) ischemia was induced by an inflatable cuff (≥230 mmHg). Quadriceps cross-sectional area (CSA) of the I-leg increased by 3.4% (P<0.05). A tendency for smaller increase in muscle CSAs at the cuff level was observed. MVC force did not change in either leg, whereas the number of repetitions during exercise test to failure increased (P<0.01) by 63% in I-leg and 36% in C-leg. The decrease in muscle oxygenated hemoglobin concentration acquired by NIRS was attenuated (P<0.01) by 56% in I-leg and 21% in C-leg. Electromyographic amplitude of rectus femoris in I-leg was ∼45% lower (P<0.025) during the ischemic test. Also, ∼9% increase (P<0.05) in pre-exercise diastolic pressure was observed. In conclusion, substantial gains in muscle endurance capacity were induced, which were associated with enhanced muscle oxygen delivery. The potential negative effects of ischemic exercise with high cuff pressure on muscle and nerve and on arterial pressure regulation need further investigation.
Collapse
Affiliation(s)
- A Kacin
- Department of Physiotherapy, Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia.
| | | |
Collapse
|
235
|
Hamaoka T, McCully KK, Niwayama M, Chance B. The use of muscle near-infrared spectroscopy in sport, health and medical sciences: recent developments. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:4591-604. [PMID: 22006908 DOI: 10.1098/rsta.2011.0298] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Near-infrared spectroscopy (NIRS) has been shown to be one of the tools that can measure oxygenation in muscle and other tissues in vivo. This review paper highlights the progress, specifically in this decade, that has been made for evaluating skeletal muscle oxygenation and oxidative energy metabolism in sport, health and clinical sciences. Development of NIRS technologies has focused on improving quantification of the signal using multiple wavelengths to solve for absorption and scattering coefficients, multiple pathlengths to correct for the influence of superficial skin and fat, and time-resolved and phase-modulated light sources to determine optical pathlengths. In addition, advances in optical imaging with multiple source and detector pairs as well as portability using small wireless detectors have expanded the usefulness of the devices. NIRS measurements have provided information on oxidative metabolism in various athletes during localized exercise and whole-body exercise, as well as training-induced adaptations. Furthermore, NIRS technology has been used in the study of a number of chronic health conditions. Future developments of NIRS technology will include enhancing signal quantification. In addition, advances in NIRS imaging and portability promise to transform how measurements of oxygen utilization are obtained in the future.
Collapse
Affiliation(s)
- Takafumi Hamaoka
- Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan.
| | | | | | | |
Collapse
|
236
|
Reliability of near-infrared spectroscopy for measuring forearm and shoulder oxygenation in healthy males and females. Eur J Appl Physiol 2011; 112:2703-15. [PMID: 22109701 DOI: 10.1007/s00421-011-2244-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Accepted: 11/08/2011] [Indexed: 10/15/2022]
Abstract
This study determined the day-to-day reliability of NIRS-derived oxygenation responses (∆StO(2)%) for isometric contractions and for cuff occlusion. Twenty-four subjects (12 males and 12 females) were tested for 2 days (4-6 days interval). Variables generated were: (1) ∆StO(2)% for isometric contractions (10, 30, 50 and 70% MVC) for descending trapezius (TD) and extensor carpi radialis (ECR) muscles; (2) slope changes in total haemoglobin (HbTslope) and deoxyhaemoglobin (HHbslope) for the ECR using upper arm venous (VO, 50 mmHg) and arterial occlusion (AO, 250 mmHg); (3) recovery slopes (Rslope) for oxygen saturation (StO(2)) following isometric contractions and AO. For each variable, an intraclass correlation (ICC) was calculated to assess the ability to differentiate between subjects, and limits of agreement (LOA) were computed to assess day-to-day consistency of the measurement. ICCs for ΔStO(2)% were lowest at 10% MVC for both ECR (0.58) and TD (0.55), and highest at 30% MVC for ECR (0.95) and at 70% MVC for TD (0.79). For both muscles, LOA for ΔStO(2)% was lowest at 10% and highest at 50 and 70% MVC. ICC for HbTslope was 0.17. For HHbslope ICC was higher for AO (0.83) than for VO (0.73), and LOA was lower for AO. For the ECR Rslope ICCs ranged from 0.88 to 0.90 for contraction, but was lower for AO (0.33); LOA was lowest at 70% MVC. For trapezius Rslope ICCs ranged from 0.63 to 0.73 and LOA was lowest at 30% MVC. For this study, establishing reliability data for the ECR and TD and including variables commonly reported are expected to have meaning for future NIRS studies of work-related upper-extremity pain as well as for other NIRS research and clinical applications.
Collapse
|
237
|
Assessing running economy during field running with changes of direction: application to 20 m shuttle runs. Int J Sports Physiol Perform 2011; 6:380-95. [PMID: 21911863 DOI: 10.1123/ijspp.6.3.380] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
PURPOSE To examine physiological responses to submaximal field running with changes of direction (COD), and to compare two approaches to assess running economy (RE) with COD, ie, during square-wave (SW) and incremental (INC) exercises. METHODS Ten male team-sport athletes performed, in straight-line or over 20 m shuttles, one maximal INC and four submaximal SW (45, 60, 75 and 90% of the velocity associated with maximal pulmonary O2 uptake [vVO2pmax]). Pulmonary (VO2p) and gastrocnemius (VO2m) O2 uptake were computed for all tests. For both running mode, RE was estimated as the O2 cost per kilogram of bodyweight, per meter of running during all SW and INC. RESULTS Compared with straight-line runs, shuttle runs were associated with higher VO2p (eg, 33 ± 6 vs 37 ± 5 mL O2·min-1·kg-1 at 60%, P < .01) and VO2m (eg, 1.1 ± 0.5 vs 1.3 ± 0.8 mL O2·min-1·100 g-1 at 60%, P = .18, Cohen's d = 0.32). With COD, RE was impaired during SW (0.26 ± 0.02 vs 0.24 ± 0.03 mL O2·kg-1·m-1, P < .01) and INC (0.23 ± 0.04 vs 0.16 ± 0.03 mL O2·kg-1·m-1, P < .001). For both SW and INC tests, the changes in RE with COD were related to height (eg, r = .56 [90%CL, 0.01;0.85] for SW) and weekly training/competitive volume (eg, r = -0.58 [-0.86;-0.04] for SW). For both running modes, RE calculated from INC was better than that from SW (both P < .001). CONCLUSION Although RE is impaired during field running with COD, team-sport players of shorter stature and/or presenting greater training/competitive volumes may present a lower RE deterioration with COD. Present results do not support the use of INC to assess RE in the field, irrespective of running mode.
Collapse
|
238
|
Troitzsch D, Moosdorf R, Vogt S. Microvascular tissue oxygenation and oxidative metabolism changes in the pedicled latissimus dorsi muscle during graded hypoxia: correlation between near infrared and 31P nuclear magnetic resonance spectroscopy. J Surg Res 2011; 176:337-42. [PMID: 21705019 DOI: 10.1016/j.jss.2011.04.064] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 04/05/2011] [Accepted: 04/28/2011] [Indexed: 11/18/2022]
Abstract
BACKGROUND In this study, the microvascular tissue oxygenation and oxidative muscle metabolism during graded hypoxia and reoxygenation were examined in a rabbit model by near-infrared (NIR) spectroscopy and correlated with high-energy phosphates measured by (31)P nuclear magnetic resonance (NMR) spectroscopy. MATERIALS AND METHODS Graded hypoxia was performed in a New Zealand rabbit model (n = 20, 2.0 ± 0.4 kg) by a stepwise reduction of the fraction of inspired oxygen (FiO(2)) from 0.3 to 0.05 (intervention group versus control group). Recovery and reoxygenation were achieved using FiO(2) of 0.3. A noninvasive NIR spectroscopy sensor and NMR probe was positioned on the surface of the prepared pedicled latissimus dorsi muscle. Microvascular tissue oxygenation (oxyhemoglobin, HbO(2); deoxyhemoglobin, HHb) and redox state of cytochrome oxidase (CytOx) were measured by NIR spectroscopy and correlated with standard values of oxidative muscle metabolism (phosphocreatine, PCr; adenosine triphosphate, ATP) measured by time-resolved (31)P NMR spectroscopy (4.7T). RESULTS Significant correlation was found between PCr and HbO(2) (r = 0.85, P < 0.001) and HHb (r = -0.75, P < 0.001). β-ATP levels correlated significantly with CytOx (r = 0.87, P < 0.001). CONCLUSIONS The data suggest that changes in high-energy phosphates (PCr- and ATP-levels) correlate closely with microvascular tissue oxygenation (HbO(2), HHb, CytOx) measured by NIR spectroscopy.
Collapse
Affiliation(s)
- Dirk Troitzsch
- Biomedical Research Center, Cardiovascular Research Lab, Department of Cardiac and Thoracic Vascular Surgery, University Medical Center, Philipps-University of Marburg/Lahn, Marburg/Lahn, Germany
| | | | | |
Collapse
|
239
|
Wang CY, Chuang ML, Liang SJ, Tsai JC, Chuang CC, Hsieh YS, Lu CW, Lee PL, Sun CW. Diffuse optical multipatch technique for tissue oxygenation monitoring: clinical study in intensive care unit. IEEE Trans Biomed Eng 2011; 59:87-94. [PMID: 21536517 DOI: 10.1109/tbme.2011.2147315] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Diffuse optical multipatch technique is used to assess spatial variations in absorption and scattering in biological tissue, by monitoring changes in the concentration of oxyhemoglobin and deoxyhemoglobin. In our preliminary study, the temporal tracings of tissue oxygenation are measured using diffuse optical multipatch measurement and a venous occlusion test, employing normal subjects and ICU patients suffering from sepsis and heart failure. In experiments, obvious differences in tissue oxygenation signals were observed among all three groups. This paper discusses the physiological relevance of tissue oxygenation with respect to disease.
Collapse
Affiliation(s)
- Chun-Yang Wang
- Department of Photonics, National Chiao Tung University, Hsinchu 30010, Taiwan
| | | | | | | | | | | | | | | | | |
Collapse
|
240
|
Wu YT, Chiou A, Sun CW. Correlation between tissue oxygenation and erythrocytes elasticity. JOURNAL OF BIOPHOTONICS 2011; 4:224-228. [PMID: 20803533 DOI: 10.1002/jbio.201000082] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 08/07/2010] [Accepted: 08/09/2010] [Indexed: 05/29/2023]
Abstract
In this paper, near-infrared spectroscopy (NIRS) and jumping optical tweezers were used to measure the tissue oxygenation and the elasticity of erythrocytes, respectively. The correlation between tissue oxygenation induced by arterial occlusion test (AOT) and the mechanical properties of individual erythrocytes from a blood sample obtained after AOT was studied. The experimental results show a linear correlation between the oxygenation signal caused by AOT and the elasticity of erythrocytes.
Collapse
Affiliation(s)
- Yu-Tsung Wu
- Institute of Biophotonics and Biophotonics Interdisciplinary Research Center, National Yang-Ming University, Taipei, Taiwan, R.O.C
| | | | | |
Collapse
|
241
|
Buchheit M, Ufland P, Haydar B, Laursen PB, Ahmaidi S. Reproducibility and sensitivity of muscle reoxygenation and oxygen uptake recovery kinetics following running exercise in the field. Clin Physiol Funct Imaging 2011; 31:337-46. [PMID: 21771251 DOI: 10.1111/j.1475-097x.2011.01020.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The purpose of this study was to assess the reliability of postexercise near-infrared spectroscopy (NIRS)-derived measurements and their sensitivity to different exercise intensities in the field. Seventeen athletes (24·1 ± 5·6 year) repeated, on three occasions, two 2-min submaximal shuttle-runs at 40% and 60% of V(IFT) (final speed of the 30-15 intermittent fitness test) and a 50-m shuttle-run sprint (Sprint), with (OCC) or without (CON) repeated transient arterial occlusions of the medial gastrocnemius during the postexercise period. NIRS variables (i.e. oxyhaemoglobin [HbO(2)], deoxyhaemoglobin [HHb] and their difference [Hb(diff)]) were measured continuously for 3 min after each exercise. Half-recovery (½Rec) and mean response (MRT; monoexponential curve fitting) times of muscle reoxygenation and muscle oxygen uptake (mVO(2)) recovery were calculated. Reliability was assessed using the typical error of measurement, expressed as a coefficient of variation (CV). Postexercise recovery of muscle reoxygenation revealed CVs ranging from 16·8% to 37·3%; CV for mVO(2) recovery ranged from 6·2% to 20·9%, with no substantial differences shown between NIRS variables and exercise intensities. While running, intensity did not affect MRT or ½Rec for muscle reoxygenation, and differences were found for mVO(2) recovery (e.g. [Hb(diff)]-mVO(2) MRT = 28·7 ± 5·2, 34·2 ± 5·1 and 37·3 ± 6·2 s for 40%, 60% and Sprint, respectively, P<0·01). To conclude, the kinetics of postexercise NIRS measurements showed CV values ranging from 6% to 37%, with no substantial differences between exercise intensities or NIRS-derived variables. However, exercise intensity did influence mVO(2) recovery kinetics, but not that of muscle reoxygenation in an occlusion-free condition.
Collapse
Affiliation(s)
- Martin Buchheit
- Laboratory of Exercise Physiology and Rehabilitation, EA 3300, Faculty of Sport Sciences, University of Picardie, Amiens, France.
| | | | | | | | | |
Collapse
|
242
|
Aerobic exercise training preceded by respiratory muscle endurance training: a synergistic action enhances the hypoxic aerobic capacity. Eur J Appl Physiol 2011; 111:2629-30. [PMID: 21373865 DOI: 10.1007/s00421-011-1887-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Accepted: 02/18/2011] [Indexed: 10/18/2022]
|
243
|
Keramidas ME, Kounalakis SN, Eiken O, Mekjavic IB. Muscle and cerebral oxygenation during exercise performance after short-term respiratory work. Respir Physiol Neurobiol 2011; 175:247-54. [DOI: 10.1016/j.resp.2010.11.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2010] [Revised: 11/19/2010] [Accepted: 11/19/2010] [Indexed: 11/25/2022]
|
244
|
Owens GE, King K, Gurney JG, Charpie JR. Low renal oximetry correlates with acute kidney injury after infant cardiac surgery. Pediatr Cardiol 2011; 32:183-8. [PMID: 21085945 DOI: 10.1007/s00246-010-9839-x] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Accepted: 11/01/2010] [Indexed: 01/11/2023]
Abstract
Acute kidney injury (AKI) is a frequent complication after cardiopulmonary bypass surgery during infancy. Standard methods for evaluating renal function are not particularly sensitive nor are proximate indicators of renal dysfunction that allow intervention in real time. Near-infrared spectroscopy (NIRS) is a newer noninvasive technology that continuously evaluates regional oximetry and may correlate with renal injury and adverse outcomes after cardiac surgery in infants. This prospective observational study enrolled 40 infants (age, <12 months) undergoing biventricular repair. Continuous renal oximetry data were collected for the first 48 postoperative hours and correlated with postoperative course, standard laboratory data, and the occurrence of acute renal injury. Subjects with low renal oximetry (below 50% for >2 h) had significantly higher postoperative peak creatinine levels by 48 h (0.8 ± 0.4 vs. 0.52 ± 0.2; p = 0.003) and a higher incidence of AKI (50 vs. 3.1%; p = 0.003) than those with normal renal oximetry. These subjects also required more ventilator days and greater vasoactive support, and they had elevated lactate levels. Prolonged low renal near-infrared oximetry appears to correlate with renal dysfunction, decreased systemic oxygen delivery, and the overall postoperative course in infants with congenital heart disease undergoing biventricular repair.
Collapse
Affiliation(s)
- Gabe E Owens
- Division of Pediatric Cardiology, Department of Pediatrics, University of Michigan, 1500 East Medical Center Drive, Ann Arbor, MI 48109-5204, USA.
| | | | | | | |
Collapse
|
245
|
Fu TC, Wang CH, Hsu CC, Cherng WJ, Huang SC, Wang JS. Suppression of cerebral hemodynamics is associated with reduced functional capacity in patients with heart failure. Am J Physiol Heart Circ Physiol 2011; 300:H1545-55. [PMID: 21278137 DOI: 10.1152/ajpheart.00867.2010] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This investigation elucidated the underlying mechanisms of functional impairments in patients with heart failure (HF) by simultaneously comparing cardiac-cerebral-muscle hemodynamic and ventilatory responses to exercise among HF patients with various functional capacities. One hundred one patients with HF [New York Heart Association HF functional class II (HF-II, n = 53) and functional class III (HF-III, n = 48) patients] and 71 normal subjects [older control (O-C, n = 39) and younger control (Y-C, n = 32) adults] performed an incremental exercise test using a bicycle ergometer. A recently developed noninvasive bioreactance device was adopted to measure cardiac hemodynamics, and near-infrared spectroscopy was employed to assess perfusions in the frontal cerebral lobe (Δ[THb](FC)) and vastus lateralis muscle (Δ[THb](VL)). The results demonstrated that the Y-C group had higher levels of cardiac output, Δ[THb](FC), and Δ[THb](VL) during exercise than the O-C group. Moreover, these cardiac/peripheral hemodynamic responses to exercise in HF-III group were smaller than those in both HF-II and O-C groups. Although the change of cardiac output caused by exercise was normalized, the amounts of blood distributed to frontal cerebral lobe and vastus lateralis muscle in the HF-III group significantly declined during exercise. The HF-III patients had lower oxygen-uptake efficiency slopes (OUES) and greater Ve-Vo(2) slopes than the HF-II patients and age-matched controls. However, neither hemodynamic nor ventilatory response to exercise differed significantly between the HF-II and O-C groups. Cardiac output, Δ[THb](FC), and Δ[THb](VL) during exercise were directly related to the OUES and Vo(2peak) and inversely related to the Ve-Vco(2) slope. Moreover, cardiac output or Δ[THb](FC) was an effect modifier, which modulated the correlation status between Δ[THb](VL) and Ve-Vco(2) slope. We concluded that the suppression of cerebral/muscle hemodynamics during exercise is associated with ventilatory abnormality, which reduces functional capacity in patients with HF.
Collapse
Affiliation(s)
- Tieh-Cheng Fu
- Department of Physical Medicine and Rehabilitation, Gung Memorial Hospital, Keelung, Taiwan
| | | | | | | | | | | |
Collapse
|
246
|
Bremmer RH, Kanick SC, Laan N, Amelink A, van Leeuwen TG, Aalders MCG. Non-contact spectroscopic determination of large blood volume fractions in turbid media. BIOMEDICAL OPTICS EXPRESS 2011; 2:396-407. [PMID: 21339884 PMCID: PMC3038454 DOI: 10.1364/boe.2.000396] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Revised: 01/21/2011] [Accepted: 01/23/2011] [Indexed: 05/08/2023]
Abstract
We report on a non-contact method to quantitatively determine blood volume fractions in turbid media by reflectance spectroscopy in the VIS/NIR spectral wavelength range. This method will be used for spectral analysis of tissue with large absorption coefficients and assist in age determination of bruises and bloodstains. First, a phantom set was constructed to determine the effective photon path length as a function of μ(a) and μ(s)' on phantoms with an albedo range: 0.02-0.99. Based on these measurements, an empirical model of the path length was established for phantoms with an albedo > 0.1. Next, this model was validated on whole blood mimicking phantoms, to determine the blood volume fractions ρ = 0.12-0.84 within the phantoms (r = 0.993; error < 10%). Finally, the model was proved applicable on cotton fabric phantoms.
Collapse
Affiliation(s)
- Rolf H. Bremmer
- Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Stephen C. Kanick
- Center for Optical Diagnostics and Therapy, Department of Radiation Oncology,Erasmus Medical Center, Rotterdam, The Netherlands
| | - Nick Laan
- Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Arjen Amelink
- Center for Optical Diagnostics and Therapy, Department of Radiation Oncology,Erasmus Medical Center, Rotterdam, The Netherlands
| | - Ton G. van Leeuwen
- Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
- Biomedical Photonic Imaging, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | - Maurice C. G. Aalders
- Biomedical Engineering and Physics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| |
Collapse
|
247
|
Combining microdialysis and near-infrared spectroscopy for studying effects of low-load repetitive work on the intramuscular chemistry in trapezius myalgia. J Biomed Biotechnol 2010; 2010:513803. [PMID: 20625491 PMCID: PMC2896692 DOI: 10.1155/2010/513803] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Revised: 03/31/2010] [Accepted: 03/31/2010] [Indexed: 11/30/2022] Open
Abstract
Epidemiological research provides strong evidence for a link between repetitive work (RW) and the development of chronic trapezius myalgia (TM). The aims were to further elucidate if an accumulation of sensitising substances or impaired oxygenation is evident in painful muscles during RW. Females with TM (n = 14) were studied during rest, 30 minutes RW and 60 minutes recovery. Microdialysate samples were obtained to determine changes in intramuscular microdialysate (IMMD) [glutamate], [PGE2], [lactate], and [pyruvate] (i.e., [concentration]) relative to work. Muscle oxygenation (%StO2) was assessed using near-infrared spectroscopy. During work, all investigated substances, except PGE2, increased significantly: [glutamate] (54%, P < .0001), [lactate] (26%, P < .005), [pyruvate] (19%, P < .0001), while the %StO2 decreased (P < .05). During recovery [PGE2] decreased (P < .005), [lactate] remained increased (P < .001), [pyruvate] increased progressively (P < .0001), and %StO2 had returned to baseline. Changes in substance concentrations and oxygenation in response to work indicate normal increase in metabolism but no ongoing inflammation in subjects with TM.
Collapse
|
248
|
Abstract
Acute compartment syndrome (ACS) is a surgical emergency requiring urgent fasciotomy to save the limb. However, time is of the essence and diagnostic uncertainty can lead to unnecessary surgery. Measurement of intracompartmental pressure (ICP) to aid decision making is becoming commonplace, particularly in unconscious or confused patients. However, inaccurate readings can result from misplacement of the probe, subjecting patients to a needless fasciotomy in the event of an overreading. Similarly, underestimated readings create a false sense of security. Screening tools, criteria-led systems of clinical decision making, are used by some to assist in diagnosis and management planning, but do they work? Here, we review current diagnostic strategies and question whether screening tools can make rapid diagnosis more accurate. Furthermore, in the absence of a standardized tool, we analyze the practice of a sample of vascular surgeons with the aim of moving toward a management consensus useful to junior doctors.
Collapse
Affiliation(s)
| | - Ashok Handa
- John Radcliffe Hospital, Oxford, United Kingdom
| |
Collapse
|
249
|
Green JG, Stannard SR. Active recovery strategies and handgrip performance in trained vs. untrained climbers. J Strength Cond Res 2010; 24:494-501. [PMID: 20072048 DOI: 10.1519/jsc.0b013e3181c06af3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Isometric contractions, such as occurring during rock climbing, occlude blood flow to the active musculature. The ability to maximize forearm blood flow between such contractions is a likely determinant of intermittent handgrip performance. This study aimed to test the hypothesis that intermittent isometric handgrip performance is improved by 2 common active recovery strategies suggested to increase muscle blood flow. On 6 separate occasions, 9 trained indoor rock climbers and 9 untrained participants undertook a fatiguing, intermittent, isometric handgrip exercise bout consisting of sets of 6 contractions (approximately 33% of maximal voluntary contraction [MVC] force), each 3-second long separated by a 1-second rest. Between sets, participants were allowed 9-second recovery performing passive rest, "shaking out" (vigorously shaking the hand), or grasping a handgrip vibration machine, each with or without forearm occlusion. Performance was assessed by pre- and post-exercise MVC trials and a 20-contraction post-exercise handgrip time trial (TT20). Trained climbers exhibited significantly greater handgrip MVC force and intermittent exercise capacity than untrained (p < 0.01). There was no effect of recovery strategy on any measure (p > 0.05). Trained climbers were more affected by occlusion than untrained in MVC (p < 0.05) and TT20 (p < 0.01). Shaking out and low-frequency vibration are unlikely to affect rock climbing performance. It is recommended that rock climbers and their coaches focus on optimizing body position rather than compromising body position to allow for shaking out.
Collapse
Affiliation(s)
- Jackson G Green
- Institute of Food, Nutrition and Human Health, Massey University, Palmerston, New Zealand.
| | | |
Collapse
|
250
|
Wang JS, Wu MH, Mao TY, Fu TC, Hsu CC. Effects of normoxic and hypoxic exercise regimens on cardiac, muscular, and cerebral hemodynamics suppressed by severe hypoxia in humans. J Appl Physiol (1985) 2010; 109:219-29. [PMID: 20431021 DOI: 10.1152/japplphysiol.00138.2010] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Hypoxic preconditioning prevents cerebrovascular/cardiovascular disorders by increasing resistance to acute ischemic stress, but severe hypoxic exposure disturbs vascular hemodynamics. This study compared how various exercise regimens with/without hypoxia affect hemodynamics and oxygenation in cardiac, muscle, and cerebral tissues during severe hypoxic exposure. Sixty sedentary males were randomly divided into five groups. Each group (n = 12) received one of five interventions: 1) normoxic (21% O(2)) resting control, 2) hypoxic (15% O(2)) resting control, 3) normoxic exercise (50% maximum work rate under 21% O(2); N-E group), 4) hypoxic-relative exercise (50% maximal heart rate reserve under 15% O(2); H-RE group), or 5) hypoxic-absolute exercise (50% maximum work rate under 15% O(2); H-AE group) for 30 min/day, 5 days/wk, for 4 wk. A recently developed noninvasive bioreactance device was used to measure cardiac hemodynamics, and near-infrared spectroscopy was used to assess perfusion and oxygenation in the vastus lateralis (VL)/gastrocnemius (GN) muscles and frontal cerebral lobe (FC). Our results demonstrated that the H-AE group had a larger improvement in aerobic capacity compared with the N-E group. Both H-RE and H-AE ameliorated the suppression of cardiac stroke volume and the GN hyperemic response (Delta total Hb/min) and reoxygenation rate by acute 12% O(2) exposure. Simultaneously, the two hypoxic interventions enhanced perfusion (Delta total Hb) and O(2) extraction [Delta deoxyHb] of the VL muscle during the 12% O(2) exercise. Although acute 12% O(2) exercise decreased oxygenation (Delta O(2)Hb) of the FC, none of the 4-wk interventions influenced the cerebral perfusion and oxygenation during normoxic/hypoxic exercise tests. Therefore, we conclude that moderate hypoxic exercise training improves cardiopulmonary fitness and increases resistance to disturbance of cardiac hemodynamics by severe hypoxia, concurrence with enhancing O(2) delivery/utilization in skeletal muscles but not cerebral tissues.
Collapse
Affiliation(s)
- Jong-Shyan Wang
- Graduate Institute of Rehabilitation Science, Chang Gung University, 259 Wen-Hwa 1st Rd., Kwei-Shan, Tao-Yuan 333, Taiwan.
| | | | | | | | | |
Collapse
|