| 1. |
- Ainegren, Mats, 1963-, et al.
(författare)
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Breathing resistance in automated metabolic systems is high in comparison with the Douglas Bag method and previous recommendations
- 2018
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part P. - : SAGE Publications. - 1754-3371. ; 232:2, s. 122-130
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to investigate the resistance (RES) to breathing in metabolic systems used for the distribution and measurement of pulmonary gas exchange. A mechanical lung simulator was used to standardize selected air flow rates ( , L/s). The delta pressure (∆p, Pa) between ambient air and the air inside the equipment was measured in the breathing valve’s mouthpiece adapter for four metabolic systems and four types of breathing valves. RES for the inspiratory and expiratory sides was calculated as RES = ∆p / , Pa/L/s. The results for RES showed significant (p < 0.05) between-group variance among the tested metabolic systems, as well as the breathing valves and between most of the completed . The lowest RES among the metabolic systems was found for a Douglas Bag system, with approximately half of the RES compared to the automated metabolic systems. The automated systems were found to have higher RES already at low in comparison to previous recommendations. For the hardware components, the highest RES was found for the breathing valves while the lowest RES was found for the hoses. Conclusion: The results showed that RES in metabolic systems can be minimized through conscious choices of system design and hardware components.
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| 2. |
- Ainegren, Mats, 1963-, et al.
(författare)
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Breathing resistance in metabolic systems : Its effects on pulmonary ventilation and oxygen uptake in elite athletes with high aerobic power
- 2020
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part P. - : Sage Publications. - 1754-3371. ; 234:3, s. 217-226
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the effects on pulmonary ventilation and oxygen uptake ( (V) over dot athletes with a very high maximal oxygen uptake (V) over dotO(2)max) and corresponding high ventilation capacity when using a modern metabolic system with relatively high resistance to breathing (HIGH(RES)), compared to a traditional system with low resistance to breathing (LOWRES). Four rowers and three cross-country skiers (without asthma), competing at a high international level, performed in experimental conditions with LOWRE (S)and HIGH(RES) using a rowing ergometer and roller skis on a treadmill. The results showed that (V) over dotO(2), blood lactate, heart rate and respiratory exchange ratio were not different between the LOWRES and HIGH(RES) test conditions during both submaximal and maximal exercise. Also, the athlete's time to exhaustion (treadmill) and mean power (rowing ergometer) from maximal tests were no different between the two conditions. However, ventilation and expiratory O-2 and CO2 concentrations were different for both submaximal and maximal exercise. Thus, the authors have concluded that the differences in resistance to breathing of metabolic systems influence elite endurance athletes (V) over dot(E)at low to very high workloads, thus affecting the expired gas fractions, but not the submaximal (V) over dotO(2), (V) over dotO(2)maxand performance in a laboratory setting at sea level.
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| 3. |
- Calbet, J, et al.
(författare)
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Maximal vascular conductances during whole body upright exercise in humans
- 2004
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Ingår i: The Journal of Physiology. - : Wiley. - 0022-3751 .- 1469-7793. ; 558:1, s. 319-331
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Tidskriftsartikel (refereegranskat)abstract
- That muscular blood flow may reach 2.5 l kg�1 min�1 in the quadriceps muscle has led to the suggestion that muscular vascular conductance must be restrained during whole body exercise to avoid hypotension. The main aim of this study was to determine the maximal arm and leg muscle vascular conductances (VC) during leg and arm exercise, to find out if the maximal muscular vasodilatory response is restrained during maximal combined arm and leg exercise. If during maximal exercise arms and legs had been vasodilated to the observed maximal levels then mean arterial pressure would have dropped at least to 75�77 mmHg in our experimental conditions. It is concluded that skeletal muscle vascular conductance is restrained during whole body exercise in the upright position to avoid hypotension. AVKORTAT ABSTRACT
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| 4. |
- Calbet, J, et al.
(författare)
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Why do the arms extract less oxygen than the legs during exercise?
- 2005
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Ingår i: American Journal of Physiology. Regulatory Integrative and Comparative Physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 289, s. 1448-1458
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Tidskriftsartikel (refereegranskat)abstract
- To determine whether conditions for O2 utilization and O2 off-loading from the hemoglobin are different in exercising arms and legs, six cross-country skiers participated in this study. Femoral and subclavian vein blood flow and gases were determined during skiing on a treadmill at 76% maximal O2 uptake (O2 max) and at O2 max with different techniques: diagonal stride (combined arm and leg exercise), double poling (predominantly arm exercise), and leg skiing (predominantly leg exercise). The percentage of O2 extraction was always higher for the legs than for the arms. At maximal exercise (diagonal stride), the corresponding mean values were 93 and 85% (n = 3; P < 0.05). During exercise, mean arm O2 extraction correlated with the PO2 value that causes hemoglobin to be 50% saturated (P50: r = 0.93, P < 0.05), but for a given value of P50, O2 extraction was always higher in the legs than in the arms. Mean capillary muscle O2 conductance of the arm during double poling was 14.5 (SD 2.6) ml·min–1·mmHg–1, and mean capillary PO2 was 47.7 (SD 2.6) mmHg. Corresponding values for the legs during maximal exercise were 48.3 (SD 13.0) ml·min–1·mmHg–1 and 33.8 (SD 2.6) mmHg, respectively. Because conditions for O2 off-loading from the hemoglobin are similar in leg and arm muscles, the observed differences in maximal arm and leg O2 extraction should be attributed to other factors, such as a higher heterogeneity in blood flow distribution, shorter mean transit time, smaller diffusing area, and larger diffusing distance, in arms than in legs. diffusing capacity; fatigue; oxygen extraction; performance; training
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| 5. |
- Fuchi, Tokio, et al.
(författare)
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Microdialysis of rat skeletal muscle and adipose tissue : dynamics of the interstitial glucose pool.
- 1994
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 151:2, s. 249-60
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Tidskriftsartikel (refereegranskat)abstract
- Microdialysis was evaluated as a method for studying glucose metabolism in skeletal muscle. Dialysis probes (0.5 x 10 mm) were perfused at 0.5 or 1.0 microliter min-1. Based upon perfusion with glucose, the muscle interstitial glucose concentration was estimated to be 6.9 +/- 0.3 mM (n = 14), which was not significantly different from the blood glucose level. With insulin infusion (1200 mU kg-1 body wt i.v.), the insulin-induced change in the glucose concentration of the interstitial space of muscle was of equal magnitude to that of blood and adipose tissue. In spite of this, when the perfusion medium was not supplemented with glucose, the glucose concentration decreased more in skeletal muscle dialysates (to 36.7 +/- 4.9% of the initial level) than in blood (to 29.7 +/- 5.0%) but less than in adipose tissue (to 17.7 +/- 4.9% of the initial level) (P < 0.05). The results indicate that these differences are due to tissue-specific differences in the dynamic balance between the supply to, and removal from, the interstitial glucose pool. This balance is revealed as a result of the constant glucose drainage by the microdialysis probe. The present results show that, in skeletal muscle, increases in glucose uptake occur with a concomitant increase in tissue blood flow as revealed by the microdialysis ethanol technique, whereas in adipose tissue the glucose uptake increases in the absence of a corresponding increase in blood flow.
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| 6. |
- Grigorenko, Anatoli, et al.
(författare)
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Sitting balance and effects of kayak training in paraplegics.
- 2004
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Ingår i: Journal of Rehabilitation Medicine. - : Medical Journals Sweden AB. - 1650-1977 .- 1651-2081. ; 36:3, s. 110-6
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: The objectives of this study were to evaluate biomechanical variables related to balance control in sitting, and the effects of kayak training, in individuals with spinal cord injury. SUBJECTS: Twelve individuals with spinal cord injury were investigated before and after an 8-week training period in open sea kayaking, and 12 able-bodied subjects, who did not train, served as controls. METHODS: Standard deviation and mean velocity of centre of pressure displacement, and median frequency of centre of pressure acceleration were measured in quiet sitting in a special chair mounted on a force plate. RESULTS: All variables differed between the group with spinal cord injury, before training, and the controls; standard deviation being higher and mean velocity and median frequency lower in individuals with spinal cord injury. A significant training effect was seen only as a lowering of median frequency. CONCLUSION: The results indicate that individuals with spinal cord injury may have acquired and consolidated an alternative strategy for balance control in quiet sitting allowing for only limited further adaptation even with such a vigorous training stimulus as kayaking.
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| 7. |
- Hamrin, Kerstin, et al.
(författare)
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Microdialysis in human skeletal muscle : effects of adding a colloid to the perfusate.
- 2002
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Ingår i: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 92:1, s. 385-93
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Tidskriftsartikel (refereegranskat)abstract
- Microdialysis catheters (CMA-60 with a polyamide dialysis membrane; 20,000-molecular wt cutoff) were either immersed in an external medium or were inserted in the quadriceps femoris muscle of healthy subjects, using perfusate with or without dextran 70. Varying the position of the outflow tubing induced changes in hydrostatic pressure. The sample volumes were significantly smaller in catheters perfused without a colloid compared with those perfused with a colloid [11-50% (in vitro) and 8-59% (in vivo) lower than in colloid-perfused catheters with the same position of the outflow tubing]. The sample volumes were also significantly smaller when the dialysis membrane was influenced by maximal hydrostatic pressure (above position) compared with minimal hydrostatic pressure (below position) [7-38% (in vitro) and 3-46% (in vivo) lower than in catheters in the below position with the same perfusion fluid]. In vivo, glucose concentration at a perfusion flow rate of 0.33 microl/min was higher when the catheters were perfused without a colloid [18-28% higher than in colloid-perfused catheters with the same position of the outflow tubing (P < 0.001)] than with a colloid. A corresponding difference also tended to occur with lactate, glycerol, and urea. At 0.16 microl/min, the glucose concentration was the same irrespective of whether fluid loss had been counteracted by colloid inclusion or by lowering of outlet tubing. The mechanism behind the observed concentration difference is thought to be a higher effective perfusion flow rate when fluid loss is prevented at low-perfusion flows. This study shows that fluid imbalances can have important implications for microdialysis results at low-perfusion flow rates.
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| 8. |
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| 9. |
- Henriksson, Jan, et al.
(författare)
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Per-Olof Åstrand : Nekrolog
- 2015
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Annan publikation (populärvet., debatt m.m.)abstract
- Nekrolog över Per-Olof ÅstrandProfessor emeritus Per-Olof Åstrand har avlidit i en ålder av 92 år. Hans närmaste anhöriga är makan Irma och barnen Elin och Per med familjer.Per-Olof Åstrand föddes i Bredaryd i Småland den 21 oktober 1922, och avled den 2 januari 2015 i Näsby Park norr om Stockholm. Efter värnplikt och beredskapstjänstgöring i pansartrupperna under andra världskriget kom han 1944 till Kungl. Gymnastiska Centralinstitutet (GCI/GIH) för studier till gymnastiklärare. Vid sluttentamen i fysiologi var hans svar så avancerade att den ansvarige läraren bad professorn, Erik Hohwü Christensen, att rätta dem. Kort därefter fick GCI:s fysiologiska institution en ny amanuens.Efter gymnastikdirektörsexamen 1946 följde läkarstudier, och parallellt med dessa inleddes avhandlingsarbetet ”Experimental studies of physical working capacity in relation to sex and age”, som försvarades 1952. Genom detta utvecklades en metodik för att mäta maximal syreupptagning. Det blev en avgörande variabel att relatera till i hans senare forskning om den cirkulatoriska och respiratoriska anpassningen till fysiskt arbete och träning. Det submaximala konditionstest som P.-O., och hans blivande hustru Irma Ryhming, publicerade år 1954 bidrog till att göra GCI känt över världen. Det finns fog att benämna honom som ”den vetenskapligt baserade konditionsträningens fader”. 1970 blev han professor i kroppsövningarnas fysiologi vid GIH.P.-O. visade tidigt ett stort intresse för undervisning, och många mötte honom i populärvetenskapliga skrifter såsom ”Kondition och hälsa” och ”Bättre kondition”, men det var genom den omfattande läroboken ”Textbook of Work Physiology: Physiological Bases for Exercise”, skriven tillsammans med Kaare Rodahl, som han blev det riktigt stora namnet inom internationell arbetsfysiologi. Där framträdde holisten Åstrand med en bredd och ett djup som ingen förr hade fångat och skrivit fram. Denna bok, P.-O:s pedagogiska förmåga och engagemang har haft avgörande betydelse för många studenter och kolleger.Hans gärningar gjorde honom till ledamot i många lärda sällskap och hedersdoktor vid ett antal universitet ute i världen. Därtill var han en hedersman, med en personlighet präglad av en stor omtanke, slagkraftig humor och generös spiritualitet, ofta med inslag av en särpräglad musikalisk förmåga. För oss som studenter och lärare vid GIH kom samvaron med P.-O. ofta att formas till högtidsstunder. En legendar har nu lämnat oss i djupaste sorg, men också i tacksamhet över allt han bidrog med i våra liv.Jan HenrikssonHans RosdahlPeter SchantzHarriet Wallberg
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