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- Laaksonen, Marko, et al.
(författare)
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Regional differences in blood flow, glucose uptake and fatty acid uptake within quadriceps femoris muscle during dynamic knee-extension exercise
- 2013
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 113:7, s. 1775-1782
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the present study was to investigate the regional differences in glucose and fatty acid uptake within skeletal muscle during exercise. Blood flow (BF), glucose uptake (GU) and free fatty acid uptake (FFAU) were measured in four different regions (vastus lateralis, VL; rectus femoris, RF; vastus intermedius, VI; and vastus medialis, VM) of the quadriceps femoris (QF) muscle during low-intensity, knee-extension exercise using positron emission tomography. BF was higher in VI than in VL, RF and VM (P < 0.05). FFAU was higher in VI (P < 0.001) but also in VM (P < 0.05) compared with VL and RF. In contrast, GU was higher in RF compared with VL (P < 0.05) but was not significantly different to VM or VI (both P = NS). FFAU within these four muscle regions correlated significantly with BF (r = 0.951, P < 0.05), whereas no significant relationship was observed between GU and BF (r = 0.352, P = NS). Therefore, skeletal muscle FFAU, but not GU, appears to be associated with BF during low-intensity exercise. The present results also indicate considerable regional differences in substrate use within working QF muscle. As such, an important methodological outcome from these results is that one sample from a specific part of the QF muscle does not represent the response in the entire QF muscle group.
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- Kalliokoski, K.K, et al.
(författare)
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Muscle fractal vascular branching pattern and microvascular perfusion heterogeneity in endurance-trained and untrained men
- 2003
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Ingår i: Journal of Physiology. - : Wiley. - 0022-3751 .- 1469-7793. ; 546:pt2, s. 529-35
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Tidskriftsartikel (refereegranskat)abstract
- Less heterogeneous skeletal muscle perfusion has recently been reported in endurance-trained compared to untrained men at macrovascular level. The causes of this difference in perfusion heterogeneity are unknown as is whether the same difference is observed in microvasculature. We hypothesised that the difference could be caused by changes in muscle vascular branching pattern. Perfusion was measured in resting and exercising muscle in 14 endurance-trained and seven untrained men using [(15)O]water and positron emission tomography. Fractal dimension (D) of perfusion distribution was calculated as a measure of fractal characteristics of muscle vascular branching pattern. Perfusion heterogeneity in microvascular units (1 mm(3) samples) was estimated using the measured heterogeneity in voxels of positron emission tomography (PET) images (relative dispersion, RD = S.D./mean) and corresponding D values. D was similar between the groups (exercising muscle 1.11 +/- 0.07 and 1.14 +/- 0.06, resting muscle 1.12 +/- 0.06 and 1.14 +/- 0.03, trained and untrained, respectively). Trained men had lower perfusion (151 +/- 44 vs. 218 +/- 87 ml min(-1) kg(-1), P < 0.05) and macrovascular perfusion heterogeneity (relative dispersion 21 +/- 5 vs. 25 +/- 5 %, P < 0.05) in exercising muscle than untrained men. Furthermore, estimated perfusion heterogeneity in microvascular units in exercising muscle was also lower in trained men (33 +/- 7 vs.48 +/- 19 %, P < 0.05). These results show that fractal vascular branching pattern is similar in endurance-trained and untrained men but perfusion is less heterogeneous at both the macro- and the microvascular level in endurance-trained men. Thus, changes in fractal branching pattern do not explain the differences in perfusion heterogeneity between endurance-trained and untrained men.
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- Kalliokoski, K K, et al.
(författare)
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Perfusion distribution between and within muscles during intermittent static exercise in endurance-trained and untrained men
- 2003
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Ingår i: International Journal of Sports Medicine. - : Georg Thieme Verlag KG. - 0172-4622 .- 1439-3964. ; 24, s. 400-403
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Tidskriftsartikel (refereegranskat)abstract
- We have recently shown that muscle perfusion varies between different quadriceps femoris muscles during submaximal exercise in humans. In animals, endurance training changes perfusion distribution between muscles during exercise. Whether the same is observed in humans is currently unknown. Therefore, we compared perfusion levels between different parts of the quadriceps femoris muscle group during one-legged intermittent static exercise in seven endurance-trained and seven untrained men. Muscle perfusion was measured using positron emission tomography with [ 15O]-H 2 O. In addition, relative dispersion of perfusion (standard deviation within a region/mean within a region x 100 %) within each muscle region was calculated as an index of perfusion heterogeneity within the muscles. Muscle perfusion tended to be lower in endurance-trained men (p = 0.16) and it was also different between the regions (p < 0.001). However, perfusion distributed similarly between the groups (p = 0.51). Relative dispersion of perfusion within the muscles was lower in endurance-trained men (p = 0.01) and it was also different between muscles (p < 0.001). These results suggest that endurance training does not alter perfusion distribution between muscles, but it decreases perfusion heterogeneity within the muscles.
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- Laaksonen, Marko, et al.
(författare)
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Effects of exhaustive stretch-shortening cycle exercise on muscle blood flow during exercise
- 2006
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Ingår i: Acta Physiologica. - : Wiley. - 1748-1708 .- 1748-1716. ; 186:4, s. 261-270
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Aim: The influence of exhaustive stretch-shortening cycle exercise (SSC) on skeletal muscle blood flow (BF) during exercise is currently unknown. Methods: Quadriceps femoris (QF) BF was measured in eight healthy men using positron emission tomography before and 3 days after exhaustive SSC exercise. The SSC protocol consisted of maximal and submaximal drop jumps with one leg. Needle biopsies of the vastus lateralis muscles were taken immediately and 2 days after SSC for muscle endothelial nitric oxide synthase (eNOS) and interleukin-1-beta (IL-1beta) mRNA level determinations. Results: All subjects reported subjective muscle soreness after SSC (P < 0.001), which was well in line with a decrease in maximal isometric contraction force (MVC) and increase in serum creatine kinase activity (CK) (P = 0.018). After SSC muscle BF was 25% higher in entire QF (P = 0.043) and in its deep and superficial muscle regions, whereas oxygen uptake remained unchanged (P = 0.893). Muscle biopsies revealed increased IL-1beta (30 min: 152 +/- 75%, P = 0.012 and 2 days: 108 +/- 203%, P = 0.036) but decreased or unchanged eNOS (30 min; -21 +/- 57%, P = 0.050 and 2 days: +101 +/- 204%, P = 0.779) mRNA levels after SSC. Conclusion: It was concluded that fatiguing SSC exercise induces increased muscle BF during exercise, which is likely to be associated with pro-inflammatory processes in the exercised muscle.
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