Bengt Saltin's research while affiliated with University of Copenhagen and other places

Publications (173)

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As one of the most physically demanding sports in the Olympic Games, cross-country skiing poses considerable challenges with respect to both force generation and endurance during the combined upper- and lower-body effort of varying intensity and duration. The isoforms of myosin in skeletal muscle have long been considered not only to define the con...
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Key points: Although lipid droplets in skeletal muscle are an important energy source during endurance exercise, our understanding of lipid metabolism in this context remains incomplete. Using transmission electron microscopy, two distinct subcellular pools of lipid droplets can be observed in skeletal muscle - one beneath the sarcolemma and the o...
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Purpose: Animal studies suggest that the inhibition of nitric oxide synthase (NOS) affects blood flow differently in different skeletal muscles according to their muscle fibre type composition (oxidative vs glycolytic). Quadriceps femoris (QF) muscle consists of four different muscle parts: vastus intermedius (VI), rectus femoris (RF), vastus medi...
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The hypothesis that the adaptive capacity is higher in human upper- than lower-body skeletal muscle was tested. Furthermore, the hypothesis that more pronounced adaptations in upper-body musculature can be achieved by 'low-volume high-intensity' as compared to 'high-volume low-intensity' exercise training was evaluated. A group of sedentary premeno...
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This study compares the levels of algesic substances between subjects with trapezius myalgia (TM) and healthy controls (CON) and explores the multivariate correlation pattern between these substances, pain, and metabolic status together with relative blood flow changes reported in our previous paper (Eur J Appl Physiol 108:657–669, 2010). 43 female...
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In humans, skeletal muscle blood flow is regulated by an interaction between several locally formed vasodilators including nitric oxide (NO) and prostaglandins. In plasma, ATP is a potent vasodilator that stimulates the formation of NO and prostaglandins and very importantly can offset local sympathetic vasoconstriction. ATP is released into plasma...
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Aims: To determine the role played by adenosine, ATP and chemoreflex activation on the regulation of vascular conductance in chronic hypoxia. Methods: The vascular conductance response to low and high doses of adenosine and ATP was assessed in ten healthy men. Vasodilators were infused into the femoral artery at sea level and then after 8-12 day...
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Abstract The aim was to investigate performance variables and indicators of cardiovascular health profile in elderly soccer players (SP, n = 11) compared to endurance-trained (ET, n = 8), strength-trained (ST, n = 7) and untrained (UT, n = 7) age-matched men. The 33 men aged 65-85 years underwent a testing protocol including measurements of cycle p...
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Essential hypertension is linked to an increased sympathetic vasoconstrictor activity and reduced tissue perfusion. We investigated the role of exercise training on functional sympatholysis and postjunctional α-adrenergic responsiveness in individuals with essential hypertension. Leg haemodynamics were measured before and after 8 weeks of aerobic t...
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Aim: This study investigates consequences of chronic neck pain on muscle function and the rehabilitating effects of contrasting interventions. Methods: Women with trapezius myalgia (MYA, n = 42) and healthy controls (CON, n = 20) participated in a case-control study. Subsequently MYA were randomized to 10 weeks of specific strength training (SST...
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Aim: It is an ongoing discussion the extent to which oxygen delivery and oxygen extraction contribute to an increased muscle oxygen uptake during dynamic exercise. It has been proposed that local muscle factors including the capillary bed and mitochondrial oxidative capacity play a large role in prolonged low-intensity training of a small muscle g...
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To provide a large reference material on aerobic fitness and exercise physiology data in a healthy population of Norwegian men and women aged 20-90 years. Maximal and sub maximal levels of VO2, heart rate, oxygen pulse, and rating of perceived exertion (Borg scale: 6-20) were measured in 1929 men and 1881 women during treadmill running. The highest...
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The effects on left and right ventricular (LV, RV) volumes during physical exercise remains controversial. Furthermore, no previous study has investigated the effects of exercise on longitudinal contribution to stroke volume (SV) and the outer volume variation of the heart. The aim of this study was to determine if LV, RV and total heart volumes (T...
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Background The role of nitric oxide in controlling substrate metabolism in humans is incompletely understood. Methods The present study examined the effect of nitric oxide blockade on glucose uptake, and free fatty acid and lactate exchange in skeletal muscle of eight healthy young males. Exchange was determined by measurements of muscle perfusion...
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Endurance training lowers heart rate and blood pressure responses to exercise, but the mechanisms and consequences remain unclear. To determine the role of skeletal muscle for the cardioventilatory response to exercise, 8 healthy young men were studied before and after 5 weeks of 1-legged knee-extensor training and 2 weeks of deconditioning of the...
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The aim was to assess mRNA and/or protein levels of heat shock proteins, cytokines, growth regulating, and metabolic proteins in myalgic muscle at rest and in response to work tasks and prolonged exercise training. A randomized controlled trial included 28 females with trapezius myalgia and 16 healthy controls. Those with myalgia performed ~7 hrs r...
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Given recent technological developments, ultrasound Doppler can provide valuable measurements of blood velocity/flow in the conduit artery with high temporal resolution. In human-applied science such as exercise physiology, hemodynamic measurements in the conduit artery is commonly performed by blood flow feeding the exercising muscle, as the incre...
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Muscle mitochondrial respiratory capacity measured ex vivo provides a physiological reference to assess cellular oxidative capacity as a component in the oxygen cascade in vivo. In this article, the magnitude of muscle blood flow and oxygen uptake during exercise involving a small-to-large fraction of the body mass will be discussed in relation to...
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Contracting skeletal muscle can overcome sympathetic vasoconstrictor activity (functional sympatholysis), which allows for a blood supply that matches the metabolic demand. This ability is thought to be mediated by locally released substances that modulate the effect of noradrenaline (NA) on the α-receptor. Tyramine induces local NA release and can...
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Ageing is associated with an impaired ability to modulate sympathetic vasoconstrictor activity (functional sympatholysis) and a reduced exercise hypaeremia. The purpose of this study was to investigate whether a physically active lifestyle can offset the impaired functional sympatholysis and exercise hyperaemia in the leg and whether ATP signaling...
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Nitric oxide (NO) and prostaglandins (PG) together play a role in regulating blood flow during exercise. NO also regulates mitochondrial oxygen consumption through competitive binding to cytochrome-c oxidase. Indomethacin uncouples and inhibits the electron transport chain in a concentration-dependent manner, and thus, inhibition of NO and PG synth...
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To evaluate the effect of regular physical activity on metabolic risk factors and blood pressure in Inuit with high BMI consuming a western diet (high amount of saturated fatty acids and carbohydrates with a high glycemic index). Cross sectional study, comparing Inuit eating a western diet with Inuit eating a traditional diet. Two physically active...
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To elucidate the molecular mechanisms behind physical inactivity-induced insulin resistance in skeletal muscle, 12 young, healthy male subjects completed 7 days of bed rest with vastus lateralis muscle biopsies obtained before and after. In six of the subjects, muscle biopsies were taken from both legs before and after a 3-h hyperinsulinemic euglyc...
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Blood doping practices in sports have been around for at least half a century and will likely remain for several years to come. The main reason for the various forms of blood doping to be common is that they are easy to perform, and the effects on exercise performance are gigantic. Yet another reason for blood doping to be a popular illicit practic...
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The effects of physical training on the formation of vasodilating and vasoconstricting compounds, as well as on related proteins important for vascular function, were examined in skeletal muscle of individuals with essential hypertension (n=10). Muscle microdialysis samples were obtained from subjects with hypertension before and after 16 weeks of...
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The aim was to test the hypothesis that 7 days of bed rest reduces mitochondrial number and expression and activity of oxidative proteins in human skeletal muscle but that exercise-induced intracellular signaling as well as mRNA and microRNA (miR) responses are maintained after bed rest. Twelve young, healthy male subjects completed 7 days of bed r...
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To test the hypothesis that physical inactivity impairs the exercise-induced modulation of pyruvate dehydrogenase (PDH), six healthy normally physically active male subjects completed 7 days of bed rest. Before and immediately after the bed rest, the subjects completed an oral glucose tolerance test (OGTT) and a one-legged knee extensor exercise bo...
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Although glycogen is known to be heterogeneously distributed within skeletal muscle cells, there is presently little information available about the role of fibre types, utilization and resynthesis during and after exercise with respect to glycogen localization. Here, we tested the hypothesis that utilization of glycogen with different subcellular...
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During exercise involving a small muscle mass, peak oxygen uptake is thought to be limited by peripheral factors, such as the degree of oxygen extraction from the blood and/or mitochondrial oxidative capacity. Previously, the maximal activity of the Krebs cycle enzyme oxoglutarate dehydrogenase has been shown to provide a quantitative measure of ma...
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The aim of this study was to test the hypotheses that 1) skeletal muscles of elderly subjects can adapt to a single endurance exercise bout and 2) endurance trained elderly subjects have higher expression/activity of oxidative and angiogenic proteins in skeletal muscle than untrained elderly people. To investigate this, lifelong endurance trained e...
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The aim of the present study was to determine the effect of nitric oxide and prostanoids on microcirculation and oxygen uptake, specifically in the active skeletal muscle by use of positron emission tomography (PET). Healthy males performed three 5-min bouts of light knee-extensor exercise. Skeletal muscle blood flow and oxygen uptake were measured...
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Exercising muscle releases interleukin-6 (IL-6), but the mechanisms controlling this process are poorly understood. This study was performed to test the hypothesis that the IL-6 release differs in arm and leg muscle during whole-body exercise, owing to differences in muscle metabolism. Sixteen subjects (10 men and six women, with body mass index 24...
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Across a wide range of species and body mass a close matching exists between maximal conductive oxygen delivery and mitochondrial respiratory rate. In this study we investigated in humans how closely in-vivo maximal oxygen consumption (VO(2) max) is matched to state 3 muscle mitochondrial respiration. High resolution respirometry was used to quanti...
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Sympathetic vasoconstriction is blunted in contracting human skeletal muscles (functional sympatholysis). In young subjects, infusion of adenosine and ATP increases blood flow, and the latter compound also attenuates α-adrenergic vasoconstriction. In patients with type 2 diabetes and age-matched healthy subjects, we tested 1) the sympatholytic capa...
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Intraluminal ATP could play an important role in the local regulation of skeletal muscle blood flow, but the stimuli that cause ATP release and the levels of plasma ATP in vessels supplying and draining human skeletal muscle remain unclear. To gain insight into the mechanisms by which ATP is released into plasma, we measured plasma [ATP] with the i...
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Little is known about the precise mechanism that relates skeletal muscle glycogen to muscle fatigue. The aim of the present study was to examine the effect of glycogen on sarcoplasmic reticulum (SR) function in the arm and leg muscles of elite cross-country skiers (n = 10, (V) over dot(O2 max) 72 +/- 2 ml kg(-1) min(-1)) before, immediately after,...
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As a consequence to hypobaric hypoxic exposure skeletal muscle atrophy is often reported. The underlying mechanism has been suggested to involve a decrease in protein synthesis in order to conserve O(2). With the aim to challenge this hypothesis, we applied a primed, constant infusion of 1-(13)C-leucine in nine healthy male subjects at sea level an...
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One major unresolved issue in muscle blood flow regulation is that of the role of circulating versus interstitial vasodilatory compounds. The present study determined adenosine-induced formation of NO and prostacyclin in the human muscle interstitium versus in femoral venous plasma to elucidate the interaction and importance of these vasodilators i...
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It was investigated whether skeletal muscle K(+) release is linked to the degree of anaerobic energy production. Six subjects performed an incremental bicycle exercise test in normoxic and hypoxic conditions prior to and after 2 and 8 wk of acclimatization to 4,100 m. The highest workload completed by all subjects in all trials was 260 W. With acut...
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The effect of low blood flow at onset of moderate-intensity exercise on the rate of rise in muscle oxygen uptake was examined. Seven male subjects performed a 3.5-min one-legged knee-extensor exercise bout (24 +/- 1 W, mean +/- SD) without (Con) and with (double blockade; DB) arterial infusion of inhibitors of nitric oxide synthase (N(G)-monomethyl...
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Vascular endothelial growth factor (VEGF) protein and capillarization were determined in muscle vastus lateralis biopsy samples in individuals with essential hypertension (n = 10) and normotensive controls (n = 10). The hypertensive individuals performed exercise training for 16 weeks. Muscle samples as well as muscle microdialysis fluid samples we...
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The aim of this investigation was to study female workers active in the labour market for differences between those with trapezius myalgia (MYA) and without (CON) during repetitive pegboard (PEG) and stress (STR) tasks regarding (1) relative muscle load, (2) trapezius muscle blood flow, (3) metabolite accumulation, (4) oxygenation, and (5) pain dev...
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ATP has been proposed to play multiple roles in local skeletal muscle blood flow regulation by inducing vasodilation and modulating sympathetic vasoconstrictor activity, but the mechanisms remain unclear. Here we evaluated the effects of arterial ATP infusion and exercise on leg muscle interstitial ATP and norepinephrine (NE) concentrations to gain...
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Extracellular nucleotides and nucleosides are involved in regulation of skeletal muscle blood flow. Diabetes induces cardiovascular dysregulation, but the extent to which the vasodilatatory capacity of nucleotides and nucleosides is affected in type 2 diabetes is unknown. The present study investigated 1) the vasodilatatory effect of ATP, uridine-t...
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To test the hypothesis that free fatty acid (FFA) and muscle glycogen modify exercise-induced regulation of PDH (pyruvate dehydrogenase) in human skeletal muscle through regulation of PDK4 expression. On two occasions, healthy male subjects lowered (by exercise) muscle glycogen in one leg (LOW) relative to the contra-lateral leg (CON) the day befor...
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To assess the benefit and harm of exercise training in adults with clinical depression. The DEMO trial is a randomized pragmatic trial for patients with unipolar depression conducted from January 2005 through July 2007. Patients were referred from general practitioners or psychiatrists and were eligible if they fulfilled the International Classific...
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Adenosine can induce vasodilation in skeletal muscle, but to what extent adenosine exerts its effect via formation of other vasodilators and whether there is redundancy between adenosine and other vasodilators remain unclear. We tested the hypothesis that adenosine, prostaglandins, and NO act in synergy to regulate skeletal muscle hyperemia by dete...
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Three classical problems in the field of man's adaptive response to exercise are reviewed. A case is made for the pump capacity of the heart limiting maximal oxygen uptake in man. This conclusion is based on findings that the capacity of skeletal muscle of man markedly surpasses that of the heart supplying it with a flow and thereby oxygen. It is s...
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Plasma ATP is thought to contribute to the local regulation of skeletal muscle blood flow. Intravascular ATP infusion can induce profound limb muscle vasodilatation, but the purinergic receptors and downstream signals involved in this response remain unclear. This study investigated: 1) the role of nitric oxide (NO), prostaglandins, and adenosine a...
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Peak aerobic power in humans (VO2,peak) is markedly affected by inspired O2 tension (FIO2). The question to be answered in this study is what factor plays a major role in the limitation of muscle peak VO2 in hypoxia: arterial O2 partial pressure (Pa,O2) or O2 content (Ca,O2)? Thus, cardiac output (dye dilution with Cardio-green), leg blood flow (th...
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The muscle glycogen content of the quadriceps femoris muscle was determined in 9 healthy subjects with the aid of the needle biopsy technique. The glycogen content could be varied in the individual subjects by instituting different diets after exhaustion of the glycogen store by hard exercise. Thus, the glycogen content after a fat ± protein (P) an...
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The effect of training on the skeletal muscle metabolism of 11-to 13-year-old boys was examined. In one experiment changes in blood lactate, and muscle lactate, CP, ATP, and glycogen were determined at rest and following exercise before and after 4 months of training. The concentrations of glycogen, CP and ATP at rest were higher (P<0.01) following...