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Muscle Oxygenation (muscle + oxygenation)
Selected AbstractsLactate kinetics in human tissues at rest and during exerciseACTA PHYSIOLOGICA, Issue 4 2010Gerrit Van Hall Abstract Lactate production in skeletal muscle has now been studied for nearly two centuries and still its production and functional role at rest and during exercise is much debated. In the early days skeletal muscle was mainly seen as the site of lactate production during contraction and lactate production associated with a lack of muscle oxygenation and fatigue. Later it was recognized that skeletal muscle not only played an important role in lactate production but also in lactate clearance and this led to a renewed interest, not the least from the Copenhagen School in the 1930s, in the metabolic role of lactate in skeletal muscle. With the introduction of lactate isotopes muscle lactate kinetics and oxidation could be studied and a simultaneous lactate uptake and release was observed, not only in muscle but also in other tissues. Therefore, this review will discuss in vivo human: (1) skeletal muscle lactate metabolism at rest and during exercise and suggestions are put forward to explain the simultaneous lactate uptake and release; and (2) lactate metabolism in the heart, liver, kidneys, brain, adipose tissue and lungs will be discussed and its potential importance in these tissues. [source] Dynamics of skeletal muscle oxygenation during sequential bouts of moderate exerciseEXPERIMENTAL PHYSIOLOGY, Issue 3 2005Leonardo F. Ferreira In rat muscle, faster dynamics of microvascular PO2 (approximately blood flowto O2 uptakeratio) after prior contractions that did not alter blood [lactate] have been considered to be a consequence of fasterkinetics. However, in humans, prior exercise below the lactate threshold does not affect the pulmonarykinetics. To clarify this apparent discrepancy, we examined the effects of prior moderate exercise on the kinetics of muscle oxygenation (deoxyhaemoglobin, [HHb],) and pulmonaryin humans. Eight subjects performed two bouts (6 min each) of moderate-intensity cycling separated by 6 min of baseline pedalling. Muscle (vastus lateralis) oxygenation was evaluated by near-infrared spectroscopy andwas measured breath-by-breath. The time constant (,) of the primary component ofwas not significantly affected by prior exercise (21.5 ± 9.2 versus 25.6 ± 9.7 s; Bout 1 versus 2, P= 0.49). The time delay (TD) of [HHb] decreased (11.6 ± 2.6 versus 7.7 ± 1.5 s; Bout 1 versus 2, P < 0.05) and ,[HHb] increased (7.0 ± 3.5 versus 10.2 ± 4.6 s; Bout 1 versus 2, P < 0.05), while the mean response time (TD +,) did not change (18.6 ± 2.7 versus 17.9 ± 3.9 s) after prior moderate exercise. Thus, prior moderate exercise resulted in shorter onset and slower rate of increase in [HHb] during subsequent exercise. These data suggest that prior exercise altered the dynamic interaction betweenandfollowing the onset of exercise. [source] Influence of gum-chewing on the haemodynamics in female masseter muscleJOURNAL OF ORAL REHABILITATION, Issue 4 2009N. ABE Summary, Blood flow in active skeletal muscles provides energy substrate, oxygen and reduction of excessive heat and metabolic by-products. Although cyclic jaw motions such as those during mastication and speech articulation are the primitive oro-facial functions, possible effects of the cyclic muscle contractions on the intramuscular haemodynamics of the jaw muscles remains scarcely known. We investigated the masseteric haemodynamics during and after gum-chewing. Ten healthy female adults participated in the study. Electromyography, kinetics of masseter muscle oxygenation, electrocardiogram and blood pressure were recorded simultaneously. The subjects were asked to perform gum-chewing and cyclic jaw motion without gum bolus (empty-chewing task). The haemodynamics parameters were compared between the two experimental conditions. During gum-chewing task, deoxygenated haemoglobin and sympathetic nerve activity increased, while tissue blood oxygen saturation decreased. Blood pressure and parasympathetic nerve activity did not change. The overall behaviour of haemodynamic parameters during empty-chewing task was similar to that observed during gum-chewing task. However, the latency periods from the end of chewing until significant changes in the haemodynamic parameters were notably shorter (P < 0·05) in gum-chewing task as compared with those associated with empty-chewing task. The duration of the changes was shorter with empty-chewing than with gum-chewing. Fluctuations in masseter muscle haemodynamics associated with chewing jaw movement differed depending on the level of muscle contraction during movement. The differences became statistically significant immediately after the commencement of chewing and after the cessation movement. During the chewing movement, automatic nerve activities increased in response to the level of muscle contraction during movement. [source] Near-infrared spectroscopy grades the severity of intermittent claudication in diabetics more accurately than ankle pressure measurement,BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 4 2000Dr T. Komiyama Background: The aim of this study was to evaluate near-infrared spectroscopy (NIRS), combined with a treadmill-walking test, as a method of assessment of intermittent claudication (IC) in diabetic patients. Methods: Some 208 symptomatic legs in 153 consecutive patients who complained of calf IC due to atherosclerotic disease were studied with NIRS and resting ankle: brachial pressure index (ABPI). Results: There was good reproducibility of NIRS measurements. Three distinct types of IC were detected by NIRS. ABPI was significantly different between these three types in non-diabetic patients, but could not grade the severity of IC in diabetic patients. Recovery time (RT) of muscle oxygenation differentiated more accurately between severe and moderate claudication than ABPI in diabetics, although RT and ABPI had similar accuracy in non-diabetics. There was a significant correlation between RT and ABPI in non-diabetic patients and patients who had been diabetic for less than 10 years, while there was no correlation in patients who had had diabetes for over 10 years. Conclusion: Measurement of muscle oxygenation during exercise by NIRS graded the severity of IC in diabetic patients more accurately than resting ABPI. © 2000 British Journal of Surgery Society Ltd [source] Relationship between muscle oxygenation and electromyography activity during sustained isometric contractionCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 4 2008Eiji Yamada Summary The purpose of this study was to clarify the relationship between electromyography (EMG) spectrum changes and muscle oxygenation measured by near-infrared time-resolved spectroscopy (TRS). Each subject performed sustained isometric knee extension at 50% of the maximal voluntary contraction load for 1 min. Surface EMG and TRS were simultaneously recorded from the right vastus lateralis muscle. Mean power frequency (MPF) of the power spectrum was calculated every 5 s during isometric contraction using fast Fourier transform, and decrease in the slope of MPF for 1 min was calculated using the least squares method. The maximal changes in oxygenated haemoglobin and myoglobin (Oxy Hb/Mb) and in deoxygenated haemoglobin and myoglobin (Deoxy Hb/Mb) from pre-contraction values of 1 min were calculated. There were significant relationships between the decrease in the slope of MPF and the maximal changes in Oxy Hb/Mb and Deoxy Hb/Mb (P < 0·05). These findings suggested that changes in Oxy Hb/Mb and Deoxy Hb/Mb indicate muscle fatigue assessed by EMG. [source] | |||||||||||||