PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “muscle oxygenation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2006

Relating pulmonary oxygen uptake to muscle oxygen consumption at exercise onset: in vivo and in silico studies.

Assessment of the rate of muscle oxygen consumption, UO(2m), in vivo during exercise involving a large muscle mass is critical for investigating mechanisms regulating energy metabolism at exercise onset. While UO(2m) is technically difficult to obtain under these circumstances, pulmonary oxygen uptake, VO(2p), can be readily measured and used as a proxy to UO(2m). However, the quantitative relationship between VO(2p) and UO(2m) during the nonsteady phase of exercise in humans, needs to be established. A computational model of oxygen transport and utilization--based on dynamic mass balances in blood and tissue cells--was applied to quantify the dynamic relationship between model-simulated UO(2m) and measured VO(2p) during moderate (M), heavy (H), and very heavy (V) intensity exercise. In seven human subjects, VO(2p) and muscle oxygen saturation, StO(2m), were measured with indirect calorimetry and near infrared spectroscopy (NIRS), respectively. The dynamic responses of VO(2p) and StO(2m) at each intensity were in agreement with previously published data. The response time of muscle oxygen consumption, tauUO(2m) estimated by direct comparison between model results and measurements of StO(2m) was significantly faster (P < 0.001) than that of pulmonary oxygen uptake, tauVO(2p) (M: 13 +/- 4 vs. 65 +/- 7 s; H: 13 +/- 4 vs. 100 +/- 24 s; V: 15 +/- 5 vs. 82 +/- 31 s). Thus, by taking into account the dynamics of oxygen stores in blood and tissue and determining muscle oxygen consumption from muscle oxygenation measurements, this study demonstrates a significant temporal dissociation between UO(2m) and VO(2p) at exercise onset.

Adolescent↗
PubMed2003

Cardiac output, oxygen consumption and muscle oxygen delivery in submaximal exercise. Normal and low O2 states.

Cardiac output (Q) changes linearly with oxygen consumption (VO2) in normal subjects undertaking submaximal exercise (Q = A + B x VO2 where A is the y intercept and B the slope). If (hypothesis 1) the increase in cardiac output above the resting state represents the blood flow to exercising muscle (qm) and the increase in VO2 represents the oxygen consumption of exercising muscle (VO2m) then, where CaO2 is the arterial oxygen content, oxygen extraction, Em = 1/(B x CaO2). Secondly, exercising muscle venous oxygen content, CvO2m = CaO2 - 1/B. Limiting the hypothesis just to the calculation of VO2m (hypothesis 2) allows calculation of qm if CaO2 and CvO2m are available. From Koskolov et al. (Am. J. Physiol.: Heart and Circ. Physiol. 273, H1787-H1793, 1997), exercising muscle blood flow (qm) is equal to the increment in cardiac output when CaO2 is normal but exceeds it when CaO2 is low. Muscle Oxygen extraction (Em) is found to be 68% in submaximal exercise. Hence, muscle oxygen delivery (DaO2m) for a given metabolic rate is sustained in low O2 states (at 1.48 ml DaO2m per ml VO2m), confirmed by analysis of Roach et al. (Am. J. Physiol.: Heart and Circ. Physiol. 276, H438-H445, 1999).

Anemia↗
PubMed2004

The influence of allogeneic red blood cell transfusion compared with 100% oxygen ventilation on systemic oxygen transport and skeletal muscle oxygen tension after cardiac surgery.

In this study we investigated the effects of allogeneic red blood cell (RBC) transfusion on tissue oxygenation compared with those of 100% oxygen ventilation by using systemic oxygen transport variables and skeletal muscle oxygen tension (PtiO2). Fifty-one volume-resuscitated, mechanically ventilated patients with a nadir hemoglobin concentration in the range from 7.5 to 8.5 g/dL after elective coronary artery bypass grafting were allocated randomly to receive 1 unit (transfusion 1; n = 17) or 2 units (transfusion 2; n = 17) of allogeneic RBCs and ventilation with 40% oxygen or pure oxygen ventilation (100% oxygen; n = 17) and no allogeneic blood for 3 hours. Invasive arterial and pulmonary artery pressures and calculations of oxygen delivery (oxygen delivery index) and consumption indices (oxygen consumption index) were documented at 30-min intervals. PtiO2 was measured continuously by using implantable polarographic microprobes. Systemic oxygen transport variables and PtiO2 were similar between groups at baseline. The oxygen delivery index increased significantly with transfusion of allogeneic RBCs and 100% oxygen ventilation, whereas the oxygen consumption index remained unchanged. Oxygen 100% ventilation increased PtiO2 significantly (from 24.0 +/- 5.1 mm Hg to 34.2 +/- 6.2 mm Hg), whereas no change was found after transfusion of allogeneic RBCs. Peak PtiO2 values were 25.2 +/- 5.2 mm Hg and 26.3 +/- 6.5 mm Hg in the transfusion 1 and 2 groups, respectively. Transfusion of stored allogeneic RBCs was effective only in improving systemic oxygen delivery index, whereas 100% oxygen ventilation improved systemic oxygen transport and PtiO2. This improved oxygenation status was most likely due to an increase in convective oxygen transport with a large driving gradient for diffusion of plasma-dissolved oxygen into the tissue.

Aged↗
PubMed2002

Body fatness, insulin sensitivity and muscle oxygen supply in adolescents.

Muscle blood flow can be reduced in insulin-resistant states. The present study examined the importance of body fatness and insulin sensitivity as variables that may be associated with muscle oxygen supply. We studied 38 adolescents (22 males, 16 females; age 15.3-18.6 years; body mass index 17.7-34.7 kg/m(2)) and used near-IR spectroscopy to measure the muscle re-oxygenation rate after ischaemic finger flexion exercise. Total body fat content was estimated by bioelectrical impedance analysis, and insulin sensitivity was assessed by homoeostasis model assessment. Regional lipid compartments were also assessed for potential associations with muscle oxygen supply. Abdominal adiposity (visceral and subcutaneous) was assessed by magnetic resonance imaging, and soleus intramyocellular lipid levels were determined by magnetic resonance spectroscopy. Total body fat content ( r =0.67, P <0.001), abdominal subcutaneous fat area ( r =0.78, P <0.001), abdominal visceral fat area ( r =0.54, P <0.001) and intramyocellular lipid levels ( r =0.68, P <0.001) were significantly related to forearm re-oxygenation half-time. After adjusting for insulin sensitivity, both total body fat content ( r =0.395, P =0.02) and abdominal subcutaneous fat area ( r =0.543, P =0.001) remained positively associated with relatively reduced muscle oxygen supply in adolescent subjects. After adjusting for body fat content, abdominal subcutaneous fat area ( r =0. 511, P =0.002) was significantly associated with muscle oxygen supply. Thus muscle oxygen supply is associated with body fat content, and certain fat compartments may be more influential than others.

Abdomen↗
PubMed1981

Increased hemoglobin-oxygen affinity does not decrease skeletal muscle oxygen consumption.

The importance of hemoglobin-oxygen affinity (HOA) in affecting skeletal muscle oxygen consumption (VO2) was reevaluated using an isolated canine gracilis muscle. HOA of the blood [normal O2 half-saturation pressure of hemoglobin (P50) = 30 Torr] was increased by refrigerated storage (P50 = 22 Torr), incubation in sodium metabisulfite (P50 = 24 Torr), or in sodium cyanate (P50 = 14 Torr). Stored blood caused a significant fall in VO2 to 80% of control, with no change in venous O2 partial pressure (PvO2), substantiating previous studies. However, in contrast, blood incubated in sodium metabisulfite or sodium cyanate resulted in no impairment of VO2, with a fall in PvO2 in the latter case indicating that a critical PvO2 did not cause the reduction in VO2 with stored blood. To substantiate further the lack of existence of a critical PO2, fresh and increased HOA blood was perfused at constant flow rates and varying arterial oxygen saturations. Stored blood showed a marked reduction in VO2 as compared with normal blood over a wide range of saturations. However, carbamylated blood VO2 was identical to fresh blood VO2 values. The data suggest that the position of the oxygen dissociation curve may not be as important as originally thought in determining skeletal muscle oxygen delivery. The drop in VO2 caused by perfusion with stored blood is due to some other factor unrelated to HOA.

2,3-Diphosphoglycerate↗
PubMed2006

Knee extensor muscle oxygen consumption in relation to muscle activation.

Recently, fatigability and muscle oxygen consumption (mVO(2)) during sustained isometric contractions were found to be less at shorter (30 degrees knee angle; 0 degrees = full extension) compared to longer knee extensor muscle lengths (90 degrees ) and, at low torques, less in the rectus femoris (RF) muscle than in the vastus lateralis and medialis. In the present study we hypothesized that these findings could be accounted for by a knee angle- and a muscle-dependent activation respectively. On two experimental days rectified surface EMG (rsEMG) was obtained as a measure of muscle activation in nine healthy young males. In addition, on day 1 maximal torque capacity (MTC) was carefully determined using superimposed nerve stimulation on brief high intensity contractions (> 70%MVC) at 30, 60 and 90 degrees knee angles. On day 2, subjects performed longer lasting isometric contractions (10-70%MTC) while mVO(2) was measured using near-infrared spectroscopy (NIRS). At 30 degrees , maximal mVO(2) was reached significantly later (11.0 s +/- 6.5 s) and was 57.9 +/- 8.3% less (average +/- SD, across intensities and muscles) than mVO(2) at 60 and 90 degrees (p < 0.05). However, rsEMG was on average only 18.0 +/- 11.8% (p = 0.062) less at the start of the contraction at 30 degrees . At 10%MTC at all knee angles, maximal mVO(2) of the RF occurred significantly later (28.8 +/- 36.0 s) and showed a significantly smaller increase in rsEMG compared to both vasti. In conclusion, it is unlikely that the tendency for less intense muscle activation could fully account for the approximately 60% lower oxygen consumption at 30 degrees , but the later increase in RFmVO(2) seemed to be caused by a less strong activation of the RF.

Adult↗
PubMed2006

The effects of work experience, lift frequency and exposure duration on low back muscle oxygenation.

BACKGROUND: Previous studies have shown changes in low back muscle oxygenation after static muscle contractions or short-term dynamic lifting exertions. The aim of this study was to document the changes in low back muscle oxygenation during prolonged lifting activity over an entire workday as of function of work experience and lift frequency. METHODS: Four novice and six experienced subjects participated in a lifting study in which they lifted load with a given weight at one of five different frequencies (2, 4, 8, 10, 12 lifts/min) for an 8-h period. Oxygen saturation of the left and right erector spinae was measured continuously and non-invasively using near-infrared spectroscopy during each lifting session. FINDINGS: Exposure duration had a statistically significant effect on muscle oxygenation level (P<0.0001). Oxygen saturation in the erector spinae increased during the 8-h lifting period. As lift frequency increased, back muscle oxygenation in experienced subjects also increased. In general, the increase in muscle oxygenation for experienced subjects was less than that for novice subjects. INTERPRETATION: This study suggested that the requirement of oxygen for the low back muscle in a typical industrial lifting job increased over time and experienced workers responded differently from the novice subjects. These findings may provide more insight into the physiological changes of the working muscle and the potential risks of developing muscle injury.

Back↗
PubMed1999

Hyperoxia does not increase peak muscle oxygen uptake in small muscle group exercise.

We examined the influence of hyperoxia on peak oxygen uptake (VO2peak) and peripheral gas exchange during exercise with the quadriceps femoris muscle. Young, trained men (n=5) and women (n=3) performed single-leg knee-extension exercise at 70% and 100% of maximum while inspiring normal air (NOX) or 60% O2 (HiOX). Blood was sampled from the femoral vein of the exercising limb and from the contralateral artery. In comparison with NOX, hyperoxic arterial O2 tension (PaO2) increased from 13.5 +/- 0.3 (x +/- SE) to 41.6 +/- 0. 3 kPa, O2 saturation (SaO2) from 98 +/- 0.1 to 100 +/- 0.1%, and O2 concentration (CaO2) from 177 +/- 4 to 186 +/- 4 mL L-1 (all P < 0. 01). Peak exercise femoral venous PO2 (PvO2) was also higher in HiOX (3.68 +/- 0.06 vs. 3.39 +/- 0.7 kPa; P < 0.05), indicating a higher O2 diffusion driving pressure. HiOX femoral venous O2 saturation averaged 36.8 +/- 2.0% as opposed to 33.4 +/- 1.5% in NOX (P < 0.05) and O2 concentration 63 +/- 6 vs. 55 +/- 4 mL L-1 (P < 0.05). Peak exercise quadriceps blood flow (Qleg), measured by the thermo-dilution technique, was lower in HiOX than in NOX, 6.4 +/- 0. 5 vs. 7.3 +/- 0.9 L min-1 (P < 0.05); mean arterial blood pressure at inguinal height was similar in NOX and HiOX at 144 and 142 mmHg, respectively. O2 delivery to the limb (Qleq times CaO2) was not significantly different in HiOX and NOX. VO2peak of the exercising limb averaged 890 mL min-1 in NOX and 801 mL min-1 in HiOX (n.s.) corresponding to 365 and 330 mL min-1 per kg active muscle, respectively. The VO2peak-to-PvO2 ratio was lower (P < 0.05) in HiOX than in NOX suggesting a lower O2 conductance. We conclude that the similar VO2peak values despite higher O2 driving pressure in HiOX indicates a peripheral limitation for VO2peak. This may relate to saturation of the rate of O2 turnover in the mitochondria during exercise with a small muscle group but can also be caused by tissue diffusion limitation related to lower O2 conductance.

Acid-Base Equilibrium↗
PubMed2007

Related trends in locomotor and respiratory muscle oxygenation during exercise.

PURPOSE: We investigated the potential effect of respiratory muscle work on leg muscle oxygenation without artificial intervention in non-endurance-trained young subjects and searched for the range of intensity when this effect could occur. METHODS: We simultaneously monitored accessory respiratory and leg muscle oxygenation patterns with near-infrared spectroscopy (NIRS) in 15 healthy young men performing maximal incremental exercise on a cycle ergometer. Pulmonary gas exchange was measured. The respiratory compensation point (RCP) was determined. Oxygenation (RMO2) and blood volume (RMBV) of the serratus anterior (accessory respiratory muscle) and of the vastus lateralis (LegO2 and LegBV) were monitored with NIRS. The breakdown point of accessory respiratory muscle oxygenation (BPRMO2) and the accelerated (BP1LegO2) and attenuated fall (BP2LegO2) in leg muscle oxygenation were detected. RESULTS: BPRMO2 occurred at approximately 85% .VO2max and was related to RCP (r = 0.88, P < 0.001). BP2LegO2 appeared at approximately 83% .VO2max and was related to RCP (r = 0.57, P < 0.05) and with BPRMO2 (r = 0.64, P = 0.01). From BP2LegO2 to maximal exercise, LegBV was significantly reduced (P < 0.05). CONCLUSION: In active subjects exercising at heavy exercise intensities, we observed that the appearance of the accelerated drop in accessory respiratory muscle oxygenation-associated with high ventilatory level-was related with the attenuated fall in leg muscle oxygenation detected with near-infrared spectroscopy. This suggests that the high oxygen requirement of respiratory muscle leads to limited oxygen use by locomotor muscles as demonstrated in endurance-trained subjects. The phenomenon observed was associated with reduced leg blood volume, supporting the occurrence of leg vasoconstriction. These events appeared not only at maximal exercise but onward above the respiratory compensation point.

Adolescent↗
PubMedDate not supplied

Do the kinetics of peripheral muscle oxygenation reflect systemic oxygen intake?

To examine whether the kinetics of local muscle oxygenation reflect systemic oxygen intake, we measured the kinetics of local muscle oxygenation and systemic oxygen consumption (VO2). This study included 16 healthy males who performed an exercise tolerance test on a bicycle ergometer. During the exercise test, expiratory gas analysis was performed with an expiratory gas analyzer, and the kinetics of vastus lateralis muscle oxygenation were determined by near-infrared spectroscopy (NIRS). Oxygenated hemoglobin (OxyHb) and tissue blood oxygen saturation (StO2) gradually decreased during the exercise test, while deoxygenated hemoglobin (DeoxyHb) gradually increased. We examined correlations between the mean values of these parameters, which were calculated by time-integrating the values obtained using NIRS and dividing them by the integral time, and VO2. There was a marked positive correlation between DeoxyHb and VO2 (r = 0.893-0.986), and a marked negative correlation between StO2 and VO2 (r = 0.859-0.995). There was a negative correlation between VO2 and OxyHb (r = 0.726-0.978), and no correlation between TotalHb and VO2. These results suggest that the kinetics of peripheral muscle oxygenation reflect systemic VO2.

Adult↗
PubMed2006

The effects of lumbar massage on muscle fatigue, muscle oxygenation, low back discomfort, and driver performance during prolonged driving.

An increasing dependence of society on automobiles for both work and leisure and the corresponding increase in time spent seated in the car has been correlated with a greater risk of low back pain and absence from work (Porter and Gyi 2002). This study examined the effects of three types of lumbar massage units on seating comfort, muscle fatigue, muscle oxygenation, muscle blood flow and driving performance during a 1 h simulated driving task. Electromyographic (EMG) signals were recorded from the right and left thoracic and lumbar erector spinae musculature. Average EMG (AEMG), mean power frequency (MPF), gaps and amplitude probability distribution function (APDF) parameters were analysed from the three massage seats and compared to a control seat. Near infrared spectroscopy (NIRS) and skin temperature from the right thoracic and lumbar erector spinae were used as an indication of muscle oxygenation and blood flow throughout the driving task. Ratings of perceived discomfort were used to assess driver discomfort, and driving performance was assessed by calculating mean lap times for the duration of each driving trial. The results showed statistically significant increases in skin temperature compared with the control seat after 60 min of driving. The NIRS results reflected these trends although the results were not statistically significant. AEMG and MPF measures showed no significant differences between the seats. MPF measures were found to increase over time, effects attributed to increases in muscle temperature. Gaps and APDF analyses revealed greater rest times and lower activation levels, respectively, with the control seat, which could result in increased loading of passive structures. This study demonstrated the beneficial effects of lumbar massage systems in increasing muscle blood flow and oxygenation. Although EMG parameters were not significantly different, the trends support the significant blood flow results. Future research should include longer driving times and adjustments in EMG measures to account for the effects of increasing muscle temperature on AEMG and MPF measures.

Adult↗
PubMed1998

Evaluation of polarographic measurements of basal muscle oxygen tension in type I diabetic patients.

Microcirculatory changes occur early in insulin-dependent diabetes mellitus (IDDM) and are believed to be an early feature of late diabetic complications, leading to reduced oxygen pressure and hypoxia in the skin and other tissues. Whether muscle oxygen supply is also altered is unknown. Therefore, the authors analyzed polarographic measurements of muscle oxygen tension in 44 healthy type I diabetic patients (mean age 28 years; mean diabetes duration 7 years) and in 57 healthy controls, matched for age, sex, and body mass index, and the corresponding influencing factors. Two measurements were taken at rest 60 minutes apart in the anterior tibial muscle. Muscle oxygen tensions did not differ between IDDM patients and controls (23.0 +/- 8.6 vs 25.3 +/- 9.0 mmHg) and were reproducible on repeated measurements (25.3 +/- 9.7 vs 25.5 +/- 7.4 mmHg). Coefficients of variation were 13.5 +/- 10.8% in IDDM patients and 13.1 +/- 9.3% in controls. Compared with controls, in IDDM patients hemoglobin A1c (HbA1c) and blood glucose concentrations were elevated, and arterial oxygen pressure was significantly lower. Muscle oxygen tensions were positively correlated with blood glucose concentrations in IDDM patients (Rho=0.48, P=0.002) but not with HbA1c or with insulin concentrations. The authors conclude that the polarographic measurement of muscle oxygen tension is a reliable method with good reproducibility. Hypoxia in the anterior tibial muscle of type I diabetic patients can be excluded. In IDDM patients the level of muscle oxygen tension is correlated with the level of blood glucose concentration.

Adult↗
PubMed2001

Influence of training on NIRS muscle oxygen saturation during submaximal exercise.

PURPOSE: Endurance training improves the oxygen delivery and muscle metabolism. Muscle oxygen saturation measured by near infrared spectroscopy (IR-SO(2)), which is primarily influenced by the local delivery/demand balance, should thus be modified by training. We examined this effect by determining the influence of change in blood lactate and muscle capillary density with training on IR-SO(2) in seven healthy young subjects. METHODS: Two submaximal exercise tests at 50% (Ex1) and 80% pretraining VO(2max) (Ex2) were performed before and after a 4-wk endurance-training program. RESULTS: VO(2max) increased only slightly (+8%, NS) with training but the training effect was confirmed by the increased capillary density (+31%, P < 0.01) and citrate synthase activity (50%, P < 0.01), determined from muscle biopsy samples. Before training, blood lactate increased during the first 5 min of Ex1 and then remained constant (3.8 +/- 0.5 mmol x L(-1), P < 0.01), whereas it increased continuously during Ex2 (8.9 +/- 1.8 mmol x L(-1), P < 0.001). After training, lactate decreased significantly and remained constant during the two bouts of exercise (2.0 +/- 0.4 and 3.7 +/- 1.2 at the end of Ex1 and Ex2, respectively, both P < 0.001). During Ex1, IR-SO(2) dropped initially at the onset of exercise and recovered progressively without reaching the resting level. Training did not change this pattern of IR-SO(2). During Ex2, IR-SO(2) decreased progressively during the 15 min of exercise (P < 0.05); IR-SO2 kept constant after the initial drop after training. We found a significant relationship (r = 0.42, P = 0.03) between blood lactate and IR-SO(2) at the end of both bouts of exercise; this relationship was closer before training. By contrast, IR-SO(2) or IR-BV was not related to the capillary density. CONCLUSION: The training-induced adaptation in blood lactate influences IR-SO(2) during mild- to hard-intensity exercise. Thus, NIRS could be used as a noninvasive monitoring of training-induced adaptations.

Adult↗
PubMed1981

Increased muscle oxygen consumption during electrical stimulation following endotoxin administration.

In this study, skeletal muscle oxygen demand was increased by electrical stimulation to determine if restricted oxygen supply to skeletal muscle in endotoxin-treated dogs was limiting oxygen consumption. Skeletal muscle blood flow was measured directly and arterio-venous differences of oxygen were determined in hindlimb muscles by obtaining blood samples simultaneously from the carotid artery and profunda femoris veins. Hindlimb muscle stimulation did not influence the systemic hemodynamic parameters monitored in either saline or endotoxin treated animals, although endotoxin treated animals demonstrated the well-characterized hemodynamic changes. During stimulation, skeletal muscle oxygen consumption was elevated due to increased oxygen extraction and blood flow in both treatment groups. No significant difference in oxygen consumption by nonstimulated muscle was observed between treatment groups. However, muscle oxygen extraction following endotoxin was greater than either pre-treatment or saline extraction values. This study demonstrates that following endotoxin administration, oxygen extraction by skeletal muscle is not maximal, and the muscle can further increase oxygen extraction with greater oxygen demand. Thus, skeletal muscle oxygen supply is not limiting the oxygen consumption following endotoxin treatment.

Animals↗
PubMed2005

Examination of the reproducibility of grip force and muscle oxygenation kinetics on maximal repeated rhythmic grip exertion.

The contribution of physiological mechanisms involving force-exertion value during maximal repeated rhythmic muscle contraction work changes over time. The purpose of this study was to examine the reproducibility of grip force and muscle oxygenation kinetics with a decrease of the gripping force during maximal repeated rhythmic grip (RRG). Subjects were 10 males, aged 20-26 years (height 173.9+/-7.3 cm, body weight 71.5+/-11.2 kg). Each subject performed maximal repeated rhythmic grip as a target value with a target frequency of 30 grips.min(-1) for 6 min. The trial-to-trial reproducibility of Oxygenated haemoglobin (Oxy-Hb), Deoxygenated haemoglobin (Deoxy-Hb), Total haemoglobin (Total Hb) and grip force during the RRG (6 min) was very high (r(xy)=0.919-0.966) and the decreasing pattern of the force-time curve was consistent. The cross correlation coefficients of the grip force (r(xy)=0.985) and muscle oxygenation kinetics (Total Hb: 0.996, Oxy-Hb: 0.992, Deoxy-Hb: 0.995) in the pre-inflection phase (marked force decreasing phase) were very high, while these coefficients in the post-inflection phase (almost steady state phase) were low as compared with those in the pre-inflection phase. The trial-to-trial reliabilities of any parameter regarding grip were fair or high (ICC=0.686-0.927). The changing points of muscle oxygenation kinetics appeared before reaching an almost steady state, which showed a high reliability and they were considered to reflect the shift of physiological mechanisms. In particular, the intraclass correlation coefficients (ICC) for the time to reach maximum Deoxy-Hb and Oxy-Hb values and regression coefficient in an increasing phase of Oxy-Hb were very high (ICC=0.894-0.947). It was found that the trial-to-trial reproducibility of grip force and muscle oxygenation kinetics is very high during the whole 6 min in RRG, but is poor during the post-inflection phase. The reproducibility of the grip force and muscle oxygenation kinetics in the phase before reaching an almost steady state during RRG is fair, and the decrease of the grip force in this phase may be influenced by the muscle oxygenation kinetics.

Adult↗
PubMed2005

[Relationship between respiration exchange ratio and muscle oxygen content measured by near-infrared spectroscopy].

OBJECTIVE: To study the relationship between respiration exchange ratio (RER) and tissue oxygen content in human skeletal muscle. METHOD: Using a portable tissue oximeter based on near-infrared spectroscopy (NIRS), the relative changes of skeletal muscle oxygen content were measured non-invasively and in vivo when healthy volunteers were performing an incremental intensity running protocol. The results were compared with heart rate (HR), VO2, VCO2, and RER. RESULT: In the experiment, the change in skeletal muscle oxygenation content of the volunteers was regular and has a significant close relationship to HR, VO2 and RER (P=0.01). CONCLUSION: It shows that NIRS is a new photonic technology which provides a measurable biomedical parameter for the evaluation of athlete's physique and training effect. It offers reference for monitoring and assessing training effect in vivo, real-time and non-invasively.

Adult↗
PubMed2000

A modular NIRS system for clinical measurement of impaired skeletal muscle oxygenation.

Near-infrared spectrometry (NIRS) is a well-known method used to measure in vivo tissue oxygenation and hemodynamics. This method is used to derive relative measures of hemoglobin (Hb) + myoglobin (Mb) oxygenation and total Hb (tHb) accumulation from measurements of optical attenuation at discrete wavelengths. We present the design and validation of a new NIRS oxygenation analyzer for the measurement of muscle oxygenation kinetics. This design optimizes optical sensitivity and detector wavelength flexibility while minimizing component and construction costs. Using in vitro validations, we demonstrate 1) general optical linearity, 2) system stability, and 3) measurement accuracy for isolated Hb. Using in vivo validations, we demonstrate 1) expected oxygenation changes during ischemia and reactive hyperemia, 2) expected oxygenation changes during muscle exercise, 3) a close correlation between changes in oxyhemoglobin and oxymyoglobin and changes in deoxyhemoglobin and deoxymyoglobin and limb volume by venous occlusion plethysmography, and 4) a minimal contribution from movement artifact on the detected signals. We also demonstrate the ability of this system to detect abnormal patterns of tissue oxygenation in a well-characterized patient with a deficiency of skeletal muscle coenzyme Q(10). We conclude that this is a valid system design for the precise, accurate, and sensitive detection of changes in bulk skeletal muscle oxygenation, can be constructed economically, and can be used diagnostically in patients with disorders of skeletal muscle energy metabolism.

Coenzymes↗