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Biomedical subjects

B Sjödin

Publications and source records attributed to B Sjödin.

At least 55 records · Page 3Linked to original sources
PubMed1991

The relationship between body mass and oxygen uptake during running in humans.

Oxygen uptake during treadmill running was measured at submaximal and maximal intensities in six different groups of endurance athletes (N = 134) and in seven endurance-trained men. The relationship between body mass (M) and oxygen uptake (VO2) was evaluated by deriving the exponent b in the equation VO2 = a.Mb. Thus, if b = 1, the oxygen uptake increases in proportion to body mass and oxygen uptake per kg is independent of body mass; if b less than 1, than the oxygen uptake per kg is inversely related to body mass. The exponent b was found to be less than unity for all groups for both submaximal (b = 0.76, s = 0.06) and maximal oxygen uptake (b = 0.71, s = 0.05). These results indicate that neither submaximal nor maximal oxygen uptake increases in proportion to body mass during running. The relationship between submaximal oxygen uptake and body mass observed in this study may explain why the oxygen uptake per kg of body mass has been found to be higher for children than for adults.

Adolescent↗
PubMed1990

Lactate concentration differences in plasma, whole blood, capillary finger blood and erythrocytes during submaximal graded exercise in humans.

The aim of the study was to investigate the distribution of lactate in plasma, whole blood, erythrocytes, and capillary finger blood, before and during submaximal exercise. Ten healthy male subjects performed submaximal graded cycle ergometer exercise for 20-25 min. Venous blood samples and capillary finger blood samples were taken before exercise and every 5th min during exercise for lactate determination. The plasma lactate concentration was significantly higher (P less than 0.001, approximately 50%) than in the erythrocytes. This difference was not altered by the venous blood lactate concentration or exercise intensity. A significant difference (P less than 0.01) in lactate concentration was also found between capillary whole blood and venous whole blood. It was concluded that direct comparisons between lactate in capillary finger blood, venous whole blood and plasma could not be made.

Capillaries↗
PubMed1990

Changes in plasma concentration of hypoxanthine and uric acid in man with short-distance running at various intensities.

The relationship between running intensity and the accumulation of hypoxanthine and uric acid in plasma was studied in four well-trained runners. The runners each performed several 800-m runs at different velocities, each run being performed on separate days. Venous blood samples were collected before and at regular intervals after the runs. The concentration of hypoxanthine and uric acid was determined with high performance liquid chromatography (HPLC) in plasma extracts. A marked increase in the plasma concentration of both hypoxanthine and uric acid occurred simultaneously at intensities corresponding to 110, 108, 115 and 107% of VO2max for subject a, b, c and d, respectively. The sudden sharp increase in plasma concentration of hypoxanthine and uric acid may indicate that at a certain level of running intensity ATP catabolism exceeds the rate of ATP regeneration from the normal metabolic pathways.

Adolescent↗
PubMed1990

Periodontitis in the primary dentition associated with Actinobacillus actinomycetemcomitans infection and leukocyte dysfunction. A 3 1/2 year follow-up.

2 siblings, aged 5 years (girl) and 7 years (boy), with periodontitis in the primary dentition were studied. Actinobacillus actinomycetemcomitans was isolated from the gingival pockets of both children. The titers of IgG antibodies against A. actinomycetemcomitans were elevated, and the polymorphonuclear leukocytes had a decreased capacity to ingest IgG-coated latex particles. Other functions of the polymorphonuclear leukocytes were normal. After antibiotic therapy and for the 7-year-old boy, debridement of the gingival pockets A. actinomycetemcomitans was no longer detectable in the gingival pockets, and the phagocytic capacity of the polymorphonuclear leukocytes was normalized. After 2 1/2 years, A. actinomycetemcomitans was found again in the gingival pockets of the boy, and once more his polymorphonuclear leukocytes had a decreased capacity to ingest IgG-coated latex particles. The antibiotic therapy was repeated and 6 months later, the number of A. actinomycetemcomitans was very low and the phagocytic capacity of the polymorphonuclear leukocytes was back to normal. This case report suggests that A. actinomycetemcomitans may be involved in the etiology of periodontitis in the primary dentition, possibly by triggering a phagocytic dysfunction of polymorphonuclear leukocytes.

Actinobacillus Infections↗
PubMed1990

Biochemical mechanisms for oxygen free radical formation during exercise.

The biochemical mechanisms behind skeletal muscle soreness and damage with muscular overuse have remained unclear. Recently, however, a growing amount of evidence indicates that free radicals play an important role as mediators of skeletal muscle damage and inflammation. During exercise, two of the potentially harmful free radical generating sources are semiquinone in the mitochondria and xanthine oxidase in the capillary endothelial cells. During high intensity exercise the flow of oxygen through the skeletal muscle cells is greatly increased at the same time as the rate of ATP utilisation exceeds the rate of ATP generation. The metabolic stress in the cells causes several biochemical changes to occur, resulting in a markedly enhanced rate of production of oxygen free radicals from semiquinone and xanthine oxidase. During normal conditions free radicals are generated at a low rate and subsequently taken care of by the well developed scavenger and antioxidant systems. However, a greatly increased rate of free radical production may exceed the capacity of the cellular defence system. Consequently, a substantial attack of free radicals on the cell membranes may lead to a loss of cell viability and to cell necrosis and could initiate the skeletal muscle damage and inflammation caused by exhaustive exercise.

Adenosine Triphosphate↗
PubMed1989

A retrospective radiographic study of alveolar bone loss in the primary dentition in patients with localized juvenile periodontitis.

Lately, it has been questioned whether localized juvenile periodontitis (LJP) is restricted to the permanent dentition, or if it sometimes might have a prepubertal onset, involving the primary dentition. To clarify this question, 17 patients with LJP, together with 17 non-LJP matched controls, were retrospectively examined for radiographic signs of alveolar bone destruction in their primary dentitions. All LJP subjects but one showed localized marginal bone loss, whereas no bone loss was observed among the controls. The results suggest that at least some cases of LJP start in the primary dentition prior to the involvement of the permanent teeth.

Adolescent↗
PubMed1989

The metabolic relation between hypoxanthine and uric acid in man following maximal short-distance running.

This study was performed to assess the metabolic relation between hypoxanthine and uric acid following short-distance maximal running. Eleven trained males, mean age 22 years (16-31), were instructed to run 800 m in the shortest time possible. Blood samples were collected before warm-up, before the run, immediately after the run and periodically up to 24 h following the run. Blood lactate was determined after warm-up, and at 5, 10, and 30 min following the run. Mean VO2 max for the subjects was 65.8 (4.7) (SD) ml kg-1 min-1 and mean oxygen demand for the running was 118 (8)% of VO2 max. Plasma hypoxanthine levels rose from 3.3 (1.4) to a peak of 48.2 (19.0) mumol l-1 at 20 min following the run and at 180 min had almost returned to pre-run levels. Plasma uric acid levels rose from a pre-run value of 267 (34) to a peak value of 431 (87) mumol l-1 at 45 min following the run. Uric acid concentrations had not returned to normal at 10 h following the run. The blood lactate level peaked at 5 min with 13.7 (2.0) mmol l-1. The results obtained in this study indicate a metabolic relationship between the formation of hypoxanthine and the formation of uric acid. The data also indicate that xanthine oxidase is active following short-distance intensive running.

Adult↗
PubMed1987

Alveolar bone levels in a geriatric Swedish population.

A random sample of non-institutionalized elderly people in Orebro County, Sweden, has been examined. The present report studies marginal bone levels in this population. Measurements were made on intra-oral radiographs. The marginal bone levels of the teeth were measured in fifths between the apex and a point 1 mm apical to the cemento-enamel junction. More than 87% of the teeth received a bone score 1 or 2, which indicates that more than 60% of the original bone level was remaining. About half of the teeth were given the bone score of 1, i.e., having more than 80% of the original bone level intact. For those subjects receiving regular dental treatment, the average bone level index (mean bone score for the subject) was lower than for the others. The general bone level of a subject is described by a classification which takes into consideration only the best 70% of the teeth. Using these bone level classes, people aged 65-74 years positively differ from older groups. The % of subjects belonging to the better bone level classes increases with increasing number of remaining teeth. In a multiple stepwise regression analysis, the number of teeth is the only predictor having significant correlation to bone level index. A variable such as regular treatment in itself seems to have little influence.

Aged↗
PubMed1985

The influence of muscle metabolic characteristics on physical performance.

This study describes the influence of muscle fiber type composition, enzyme activities and capillary supply on muscle strength, local muscle endurance or aerobic power and capacity. Muscle biopsies were obtained from m. vastus lateralis in thirteen physically active men. Histochemical staining procedures were applied to assess the percentage of fast twitch (FT) fibers, muscle fiber area, and capillary density. Also, the activity of citrate synthase (CS), creatine kinase (CK), hexokinase (HK), lactate dehydrogenase (LDH), and phosphofructokinase (PFK) were analysed using fluorometrical assays. Peak torque at 'low' and 'high' angular velocities was measured during leg extension. Similarly, muscle fatigue (e.g. peak torque decline) and recovery from a short-term exercise task were measured during maximal, voluntary consecutive leg extensions. Aerobic power (VO2max) and aerobic capacity (e.g. onset of blood lactate concentration; OBLA), as defined by a blood lactate concentration of 4 mol X 1(-1) were measured during cycling. Peak torque at a high angular velocity was positively correlated with % FT area (p less than 0.001). Fatigue and recovery were correlated with LDH X CS-1 (p less than 0.001). WOBLA was best correlated with PFK and PFK X CS-1 (p less than 0.001). Hence, muscle strength was partly determined by fiber type composition whereas local muscle endurance, recovery and aerobic capacity reflect mainly capillary supply and the activity of key enzymes involved in aerobic and anaerobic metabolism.

Adult↗
PubMed1985

Blood lactate vs. exhaustive exercise to evaluate aerobic fitness.

This study compared the predictive power of a lactate-related index determined during submaximal cycle exercise to that of an exhaustive cycle ergometer test for evaluating the endurance exercise capacity of soldiers. The subjects (n = 48 males) performed a continuous exercise test to voluntary exhaustion on the cycle ergometer. Power output (PO) increased by 50 W steps each fourth min, with determinations of heart rate (HR), RPE and blood lactate concentrations (HLa) just prior to each PO increase. The PO at a 4 mmol L(-1) HLa concentration (WOBLA) was interpolated; based on the time to exhaustion the maximal PO that could be maintained for 6 min (Wmax6) was calculated from previously documented formulae. Subjects were timed during a 3000 m cross-country run. Both the cycle test and the run were performed again 3 months later, as was an additional 3000 m run with full military equipment weighing about 21 kg. All 3000 m times were significantly correlated (p less than 0.05) with both Wmax6 and WOBLA; similar predictive power was demonstrated for both Wmax6 and WOBLA, suggesting that accuracy in evaluation would not be sacrificed by substituting the submaximal for the exhaustive exercise test. HR and RPE-related indices showed markedly lower predictive power. The results extend the previously documented relationship between HLa during treadmill ergometry and running performance to include the use of cycle ergometry for the evaluation of running performance. The results also proved applicable to running performance while load carrying.

Adult↗
PubMed1985

Relationship of ergometer-specific VO2 max and muscle enzymes to blood lactate during submaximal exercise.

This study compared the relationship of maximum oxygen uptake and skeletal muscle enzyme activities to the submaximal exercise intensity eliciting 4 mM blood lactate (OBLA). Twelve subjects performed both cycle (Cy) and treadmill (Tr) submaximal exercise with step-wise increments each fourth minute. Blood lactate concentration and oxygen uptake (VO2) were determined during the final minute of each step. Peak VO2 during exhaustive exercise was also measured on each ergometer. Biopsies were taken from the gastrocnemius (gast) and vastus lateralis (vl) muscles as representatives of muscles recruited during Tr and Cy exercise, respectively. Citrate synthase (CS), phosphofructokinase (PFK), and lactate dehydrogenase (LDH) activities were assayed. Peak VO2 was 10% greater and the VO2 at OBLA was 16% greater during Tr compared to Cy exercise. The percent of peak VO2 at OBLA was 85% and 79% for Tr and Cy exercise, respectively. The absolute enzyme activities were not different in the two muscles, however the ratio LDH/CS was greater in the vl than in the gast. The results indicate that the absolute differences between Cy and Tr exercise in peak VO2 are not commensurate with the differences in the relative exercise intensity at which OBLA occurs.

Biopsy↗
PubMed1985

Physiological characteristics of elite male runners in and off-season.

The seasonal variation in physiological characteristics of elite male runners was studied. Five middle distance (mean age 21 yrs) and 5 long distance runners (23 yrs), all members of the Swedish national track and field team, participated in treadmill tests on 4 occasions over a period of one year: in January, in May, during the highly competitive summer period and the following January. The maximal oxygen uptake (VO2 max, ml X kg-1 X min-1) increased successively during the season and was significantly (p less than 0.01) higher during the summer than in the winter (74.2 to 77.4 ml X kg-1 X min-1). From the competitive summer period to the second winter the VO2 max (ml X kg-1 X min-1) showed a significant decrease. The absolute value of VO2 max (1/min) was not significantly changed during this one-year period, however. Running economy was evaluated from oxygen uptake determinations at 15 km/h (VO2 15) and 20 km/h (VO2 20). Slightly lower values of VO2 15 and VO2 20 were noted during the season, and after one year VO2 20 was significantly decreased. Such an improvement in running economy with time was also found in a larger group of elite runners (n = 16) when determined from an average of 7 treadmill tests. The running velocity corresponding to a blood lactate concentration of 4 mmol/l increased from January to the summer season. The blood lactate concentration after exhaustion (VO2 max test) increased significantly from January to May.

Adolescent↗
PubMed1984

Maximal and submaximal oxygen uptakes and blood lactate levels in elite male middle- and long-distance runners.

Physiological characteristics of elite runners from different racing events were studied. Twenty-seven middle- and long-distance runners and two 400-m runners belonging to the Swedish national team in track and field were divided, according to their distance preferences, into six groups from 400 m up to the marathon. The maximal oxygen uptake (VO2 max, ml X kg-1 X min-1) on the treadmill was higher the longer the main distance except for the marathon runners (e.g., 800-1500-m group, 72.1; 5000-10,000-m group, 78.7 ml X kg-1 X min-1). Running economy evaluated from oxygen uptake measurements at 15 km/h (VO2 15) and 20 km/h (VO2 20) did not differ significantly between the groups even though VO2 15 tended to be lower in the long-distance runners. The running velocity corresponding to a blood lactate concentration of 4 mmol/l (vHla 4.0) differed markedly between the groups with the highest value (5.61 m/s) in the 5000-10,000-m group. The oxygen uptake (VO2) at vHla 4.0 in percentage of VO2 max did not differ significantly between the groups. The blood lactate concentration after exhaustion (VO2 max test) was lower in the long-distance runners. In summary, the present study demonstrates differences in physiological characteristics of elite runners specializing in different racing events. The two single (but certainly inter-related) variables in which this was most clearly seen were the maximal oxygen uptake (ml X kg-1 X min-1) and the running velocity corresponding to a blood lactate concentration of 4 mmol/l.

Adult↗
PubMed1983

Semi-automatic blood lactate assay: experiences from an exercise laboratory.

A semi-automatic system based on flow injection analysis (FIA) for the transportation of small sample aliquots has been combined with fluorometric, enzymatic methods for blood lactate determination and has been described earlier. In the present study duplicate blood samples were obtained from exercising subjects to enable a comparison of lactate concentrations between neutralized and non-neutralized samples. Duplicate samples were also obtained to enable FIA lactate values to be compared to those obtained with a manual enzymatic method, and with a colorimetric method. No significant change was observed if the sample was not neutralized, enabling a more rapid sample turnover. The FIA method was reliable, with a coefficient of variation of 4.9% between duplicate blood samples. FIA lactate values were valid when compared to two other manual assays. FIA has been shown to be a rapid (60 samples x h-1) means of accurately determining blood lactate concentrations with 25 microliter blood samples and is of particular relevance to the exercise laboratory.

Automation↗