| 1. |
- Malm, Christer, et al.
(författare)
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Immune system alteration in response to two consecutive soccer games.
- 2004
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Ingår i: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 180:2, s. 143-55
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Tidskriftsartikel (refereegranskat)abstract
- AIM: Changes in leucocyte and monocyte subpopulations were investigated in 10 elite male soccer players aged 16-19 years. The purpose was to perform a descriptive study of immunological alterations in elite soccer players in response to two consecutive games separated by 20 h. It was hypothesized that in response to two games the players would show signs of short-term immunosuppression. METHODS: Blood samples were taken before the first soccer game, immediately after the second game and after 6, 24, 48 and 72 h. Cell surface antigens, testosterone and cortisol were investigated. RESULTS: During the first 6 h after the second game there was a significant increase in number of circulating neutrophils, mature (CD20+ CD5+) B cells and CD4/CD8 ratio. A significant decrease was observed in the number of natural killer (NK) cells, monocytes and adhesion on lymphocytes and monocytes. In a delayed phase, 48 h after the second game the expression of both adhesion and signalling molecules increased on lymphocytes and monocytes. Changes in adhesion and signalling molecules at 48 h correlated negatively to the subjects VO2max, suggesting larger immunological response to similar exercise in subjects with lower aerobic exercise capacity. CONCLUSION: In response to competitive soccer exercise some immunological variables are enhanced while others are depressed. Observed changes may serve a purpose in adaptation to exercise by signalling via adhesion.
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| 2. |
- Andersson, Eva A, et al.
(författare)
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Intramuscular EMG from the hip flexor muscles during human locomotion.
- 1997
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 161:3, s. 361-70
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Tidskriftsartikel (refereegranskat)abstract
- The purpose was to investigate the activation pattern of five major hip flexor muscles and its adaptation to changing speed and mode of progression. A total of 11 healthy subjects performed walking and running on a motor-driven treadmill at speeds ranging from 1.0 to 6.0 m s-1. Intramuscular fine-wire electrodes were used to record myoelectric signals from the iliacus, psoas, sartorius, rectus femoris and tensor fascia latae muscles. The basic pattern, with respect to number of activation periods, remained the same irrespective of speed and mode of progression. However, differences in the relative duration and timing of onset of activation occurred between individual muscles. Over the speed range in walking, a progressively earlier onset was generally seen for the activation period related to hip flexion. Changes in EMG amplitude were measured in the iliacus and psoas muscles and showed a marked increase and difference between walking and running at speeds above 2.0 m s-1. Thus, the alternating flexion-extension movements at the hip during locomotion appear to be governed by a rather fixed 'neural program' which normally only needs minor modulations to accomplish the adjustments accompanying an increase in speed of progression as well as a change from walking to running.
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| 3. |
- Bakkman, L., et al.
(författare)
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Quantitative and qualitative adaptation of human skeletal muscle mitochondria to hypoxic compared to normoxic training at the same relative work rate
- 2007
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Ingår i: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X .- 1748-1708 .- 1748-1716. ; 190:3, s. 243-251
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Tidskriftsartikel (refereegranskat)abstract
- Aim: To investigate if training during hypoxia (H) improves the adaptation of muscle oxidative function compared with normoxic (N) training performed at the same relative intensity.Method: Eight untrained volunteers performed one-legged cycle training during 4 weeks in a low-pressure chamber. One leg was trained under N conditions and the other leg under hypobaric hypoxia (526 mmHg) at the same relative intensity as during N (65% of maximal power output, Wmax). Muscle biopsies were taken from vastus lateralis before and after the training period. Muscle samples were analysed for the activities of oxidative enzymes [citrate synthase (CS) and cytochrome c oxidase (COX)] and mitochondrial respiratory function.Results: W max increased with more than 30% over the training period during both N and H. CS activity increased significantly after training during N conditions (+20.8%, P < 0.05) but remained unchanged after H training (+4.5%, ns) with a significant difference between conditions (P < 0.05 H vs. N). COX activity was not significantly changed by training and was not different between exercise conditions [+14.6 (N) vs. -2.3% (H), ns]. Maximal ADP stimulated respiration (state 3) expressed per weight of muscle tended to increase after N (+31.2%, P < 0.08) but not after H training (+3.2%, ns). No changes were found in state four respiration, respiratory control index, P/O ratio, mitochondrial Ca2+ resistance and apparent Km for oxygen.Conclusion: The training-induced increase in muscle oxidative function observed during N was abolished during H. Altitude training may thus be disadvantageous for adaptation of muscle oxidative function.
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| 4. |
- Balsom, Paul D, et al.
(författare)
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High-intensity exercise and muscle glycogen availability in humans.
- 1999
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Ingår i: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 165:4, s. 337-45
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the effects of muscle glycogen availability on performance and selected physiological and metabolic responses during high-intensity intermittent exercise. Seven male subjects completed a regimen of exercise and dietary intake (48 h) to either lower and keep low (LOW-CHO) or lower and then increase (HIGH-CHO) muscle glycogen stores, on two separate occasions at least a week apart. On each occasion the subjects completed a short-term (<10 min) and prolonged (>30 min) intermittent exercise (IEX) protocol, 24 h apart, which consisted of 6-s bouts of high-intensity exercise performed at 30-s intervals on a cycle ergometer. Glycogen concentration (mean +/- SEM) in m. vastus lateralis before both IEx(short) and IEx(long) was significantly lower following LOW-CHO [180 (14), 181 (17) mmol kg (dw)(-1)] compared with HIGH-CHO [397 (35), 540 (25) mmol kg (dw)(-1)]. In both IEx(short) and IEx(long), significantly less work was performed following LOW-CHO compared with HIGH-CHO. In IEx(long), the number of exercise bouts that could be completed at a pre-determined target exercise intensity increased by 265% from 111 (14) following LOW-CHO to 294 (29) following HIGH-CHO (P < 0.05). At the point of fatigue in IEx(long), glycogen concentration was significantly lower with the LOW-CHO compared with HIGH-CHO [58 (25) vs. 181 (46) mmol kg (dw)(-1), respectively]. The plasma concentrations of adrenaline and nor-adrenaline (in IEx(short) and IEx(long)), and FFAand glycerol (in IEx(long)), increased several-fold above resting values with both experimental conditions. Oxygen uptake during the exercise periods in IEx(long), approached 70% of Vo2max. These results suggest that muscle glycogen availability can affect performance during both short-term and more prolonged high-intensity intermittent exercise and that with repeated exercise periods as short as 6 s, there can be a relatively high aerobic contribution.
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| 5. |
- Blomstrand, Eva, et al.
(författare)
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Changes in plasma concentrations of aromatic and branched-chain amino acids during sustained exercise in man and their possible role in fatigue.
- 1988
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Ingår i: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 133:1, s. 115-21
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Tidskriftsartikel (refereegranskat)abstract
- The plasma concentrations of branched-chain and aromatic amino acids have been measured in two different types of sustained dynamic exercise. Twenty-two subjects participated in the 1986 Stockholm Marathon and eight subjects took part in an army training programme of approximately 1.5-h duration. Both types of exercise caused a significant decrease in the plasma concentration of branched-chain amino acids, while there was no change in the concentration of total (free plus bound to albumin) tryptophan. The plasma concentration of free tryptophan, which was measured in the marathon runners, was found to increase 2.4-fold during the race. This increase is probably caused by a pronounced elevation in the concentration of plasma free fatty acids during exercise, since these are known to displace tryptophan from albumin. The observed increase in plasma free tryptophan concentration, together with the decrease in plasma concentration of branched-chain amino acids, gives rise to a marked increase in the plasma concentration ratio of free tryptophan/branched-chain amino acids. This should lead to an increase in the rate of transport of tryptophan across the blood-brain barrier and hence to an increase in the rate of synthesis of 5-hydroxytryptamine (5-HT) in the brain. An elevated concentration of 5-HT in specific areas of the brain may be responsible, at least in part, for the development of physical, and/or mental fatigue during prolonged exercise.
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| 6. |
- Blomstrand, Eva, et al.
(författare)
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Effect of carbohydrate ingestion on brain exchange of amino acids during sustained exercise in human subjects.
- 2005
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 185:3, s. 203-9
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Tidskriftsartikel (refereegranskat)abstract
- AIM: This study investigated the effect of prolonged exercise with and without carbohydrate intake on the brain exchange of amino acids, especially focussing on tryptophan and branched-chain amino acids (BCAA). METHODS: Five male subjects exercised for 3 h on a cycle ergometer at 200 +/- 7 W on two occasions; either supplemented with a 6% carbohydrate solution or with flavoured water (placebo). Catheters were inserted into the right internal jugular vein and the radial artery of the non-dominant arm. The brain exchange of amino acids during exercise was calculated from the arterial-jugular venous concentration difference multiplied by plasma flow. RESULTS: About 106 micromol (22 mg) of tryptophan was taken up by the brain during exercise in the placebo trial, whereas no significant uptake was observed in the carbohydrate trial. In accordance, the arterial concentration of free tryptophan increased from 12 +/- 1 to 20 +/- 2 micromol L(-1) during the placebo trial and was significantly higher compared with the glucose trial (14 +/- 1 micromol L(-1) at the end of exercise). Also, the arterial concentration of total tryptophan (free and albumin-bound) increased during the first 30 min of exercise in both trials, but returned to the basal level at 180 min of exercise. In both trials, BCAA were taken up by the brain while glutamine was released. CONCLUSION: The present data show that both tryptophan and BCAA are taken up by the brain during prolonged exercise, and we suggest that the cerebral uptake of tryptophan may relate to increased synthesis of serotonin (5-HT) in the brain.
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| 7. |
- Blomstrand, Eva, et al.
(författare)
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Influence of ingesting a solution of branched-chain amino acids on perceived exertion during exercise.
- 1997
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 159:1, s. 41-9
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Tidskriftsartikel (refereegranskat)abstract
- On two occasions, seven male endurance-trained cyclists performed exhaustive exercise on a cycle ergometer in the morning after they had performed a bout of exercise the preceding evening in an attempt to lower the muscle glycogen stores. The subjects exercised at a work rate corresponding to approximately 70% of their maximal oxygen uptake for 60 min, followed by another 20 min of maximal exercise. During exercise the subjects were given either a solution of branched-chain amino acids (BCAAs) or flavoured water (placebo). Every 10 min during exercise the subjects rated their perceived exertion and mental fatigue on two different Borg scales. During the 60 min exercise at a given work rate the subjects ratings of perceived exertion when they were given BCAAs were 7% lower, and their ratings of mental fatigue were 15% lower than when they were given placebo. In addition, the performance in the colour task of Stroops Colour Word Test performed after exercise was improved when BCAAs had been ingested during exercise, compared with the results from the placebo trial. There was no difference in the physical performance between the two trials measured as the amount of work done during the last 20 min of exercise when the subjects performed at their maximum. The plasma concentration ratio of free tryptophan/BCAAs, which increased by 45% during exercise and by 150% 5 min after exercise in the placebo trial, remained unchanged or even decreased when BCAAs were ingested.
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| 8. |
- Blomstrand, Eva, et al.
(författare)
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Influence of reduced muscle temperature on metabolism in type I and type II human muscle fibres during intensive exercise.
- 1987
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Ingår i: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 131:4, s. 569-74
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Tidskriftsartikel (refereegranskat)abstract
- Six male subjects performed intensive cycle exercise to exhaustion after cooling their legs in water at 10-12 degrees C (muscle temperature (Tm) 28 +/- 2.6 degrees C, mean +/- SD). Exercise at exactly the same rate and duration (370 +/- 34 W, 1.5 +/- 0.2 min) was then repeated by each subject 2-5 weeks later at normal Tm (35 +/- 1.0 degrees C). Muscle biopsies were taken from the vastus lateralis muscle at rest and after exercise. The muscle tissue was freeze-dried and fragments of single fibres were dissected out. The fibres were classified and pooled into groups of type I and type II. Analyses of glycogen, glucose 6-phosphate, lactate and phosphagens were performed on pools of type-identified fibres. After exercise at reduced Tm, all subjects had higher concentrations of glucose 6-phosphate and lactate in both type I and type II fibres, and in most subjects the concentrations of ATP and phosphocreatine were lower as compared with the findings after exercise at normal Tm. During exercise the glycogen content of both fibre types decreased to a greater extent at reduced than at normal Tm in most subjects. The results suggest that during intensive dynamic exercise at reduced Tm there is a higher degree of glycolysis from glycogen in the muscle than in the normal situation. In some subjects the cause of fatigue may be related to a more rapid accumulation of lactate in the cold muscle, while in others fatigue may be related to alternative factors, e.g. low levels of ATP and phosphocreatine.
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| 9. |
- Carlson, H, et al.
(författare)
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Lumbar back muscle activity during locomotion : effects of voluntary modifications of normal trunk movements.
- 1988
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 133:3, s. 343-53
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Tidskriftsartikel (refereegranskat)abstract
- The mechanisms of adaptation of the trunk to changed mechanical conditions were studied during locomotion in man. The myoelectrical (EMG) activity in lumbar back muscles and the movements of the trunk were recorded in nine healthy subjects during walking and running on a motor-driven treadmill. Two different types of voluntary modifications of the movement pattern were used: (1) The trunk was kept in an extreme forward or backward tilted position. In both these situations the basic EMG pattern with two periods of activity per stride cycle was maintained during walking, whereas a major shift relative to the stride cycle (25% of the stride cycle duration) occurred in running with the trunk tilted backwards. The synchrony of the back muscle activation at both sides increased when locomotion was performed with the trunk tilted forwards. The relative duration of the EMG bursts was similar to normal locomotion and corresponded to 15-26% of the stride cycle duration in walking and 23-37% in running. (2) In the other type of modification the subjects were instructed to exaggerate the angular trunk movements either in the sagittal or in the frontal plane. The basic EMG pattern and phase relationships remained in most cases unchanged. One exception was running with exaggerated lateral movements, in which only one period of back muscle activity per stride cycle was observed. The relative duration of the bursts was longer in trials with exaggerated trunk movements as compared to normal locomotion. In walking and running with the trunk tilted forwards or backwards the lumbar back muscles were not always involved as prime movers of the trunk. This was in contrast to the more dynamic situations, in which the back muscle activity appeared to be directly involved in braking and reversing the exaggerated trunk movements.
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| 10. |
- Cresswell, A G, et al.
(författare)
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Observations on intra-abdominal pressure and patterns of abdominal intra-muscular activity in man.
- 1992
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 144:4, s. 409-18
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Tidskriftsartikel (refereegranskat)abstract
- The aim was to investigate possible relationships between activities of the individual muscles of the ventrolateral abdominal wall and the development of pressure within the abdominal cavity. Intra-muscular activity was recorded bilaterally from transversus abdominis, obliquus internus, obliquus externus and rectus abdominis with fine-wire electrodes guided into place using real-time ultrasound. Intra-abdominal pressure was measured intragastrically using a micro tip pressure transducer. Six males were studied during loading and movement tasks with varied levels of intra-abdominal pressure. During both maximal voluntary isometric trunk flexion and extension, transversus abdominis activity and intra-abdominal pressure remained constant, while all other abdominal muscles showed a marked reduction during extension. When maximal isometric trunk flexor or extensor torques were imposed upon a maximal Valsalva manoeuvre, transversus abdominis activity and intra-abdominal pressure remained comparable within and across conditions, whereas obliquus internus, obliquus externus and rectus abdominis activities either markedly increased (flexion) or decreased (extension). Trunk twisting movements showed reciprocal patterns of activity between the left and right sides of transversus abdominis, indicating an ability for torque development. During trunk flexion--extension, transversus abdominis showed less distinguished changes of activity possibly relating to a general stabilizing function. In varied pulsed Valsalva manoeuvres, changes in peak intra-abdominal pressure were correlated with mean amplitude electromyograms of all abdominal muscles, excluding rectus abdominis. It is concluded that the co-ordinative patterns shown between the muscles of the ventrolateral abdominal wall are task specific based upon demands of movement, torque and stabilization. It appears that transversus abdominis is the abdominal muscle whose activity is most consistently related to changes in intra-abdominal pressure.
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