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Biomedical subjects

B Sjödin

Publications and source records attributed to B Sjödin.

At least 37 records · Page 2Linked to original sources
PubMed1994

Body-mass-modified running economy and step length in elite male middle- and long-distance runners.

To minimize the influence of body mass on oxygen uptake (VO2) during running, submaximal and maximal VO2 should preferentially be expressed as ml.kg-0.75.min-1. In this study, the levels of such body-mass-modified running economy were investigated at different velocities in elite runners and related to step lengths and anthropometric measures. Twenty-six Swedish National Team middle- and long-distance runners performed submaximal (4 velocities) and maximal treadmill tests. In 17 runners repeated (2-4) tests were performed within 6 months. The maximal oxygen uptake (VO2max; 214 vs 202 ml.kg-0.75.min-1) and running velocity at 4 mmol.l-1 blood lactate were higher in the long- (n = 12) than in the middle-distance group (n = 14). The oxygen uptake at 15 km.h-1 (VO2 15) was lower (129 vs 138 ml.kg-0.75.min-1, p < 0.01) and the VO2/velocity slope higher in the long-distance runners, with similar VO2 18 in the two groups. Step lengths at 18 (168 vs 173 cm) and 15 km.h-1 did not differ significantly between the groups, but the increase in step length per km.h-1 velocity raise was greater in the middle-distance runners. Step lengths at these velocities were positively related to body mass and stature, negatively to relative leg length. Stature and leg length were greater in runners displaying low VO2 15, whereas no corresponding difference was seen for VO2 18. The figures for running economy at 15 and 18 km.h-1 were poorly related to the concomitantly determined step lengths at the respective velocities.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Marginal bone loss in the primary dentition. A survey of 7-9-year-old children in Sweden.

The present study was designed to determine the prevalence of bone loss in the primary dentition of children. Radiographs from children aged 7-9 were collected from 25 out of a total of 26 Public Dental Clinics in the County of Orebro, Sweden. These radiographs, representing 36.0%, 50.3% and 48.7% of all 7-, 8- and 9-year-old children (n = 8666) living in the districts of the participating clinics, constituted a primary sample. In addition, the 9-year-olds were subjected to a more comprehensive sampling procedure to obtain a more complete sample (sample of 9-year-olds), resulting in a group of 2017 children (71.9%). The radiographs were evaluated with respect to presence of marginal bone loss (CEJ-MBL: distance between the cemento-enamel junction and the marginal bone level > 2 mm), proximal calculus and number of decayed and filled proximal surfaces (dfsp) in the posterior areas of the primary dentition. In the primary sample, the prevalence of bone loss for > or = 1 proximal surfaces of the primary dentition in the 7-, 8- and 9-year-old children was 2.0%, 3.1% and 4.5%, respectively. The corresponding figures for proximal calculus were 2.5%, 3.1% and 4.2%. Mean number of dfsp amounted to 2.3, 2.5 and 3.0. The prevalences of bone loss and proximal calculus as well as the mean number of dfsp in the sample of 9-year-olds corresponded to the findings for the 9-year-old children in the primary sample.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar Bone Loss↗
PubMed1994

AMP deaminase in skeletal muscle of healthy males quantitatively determined by new assay.

A new, sensitive assay for the quantitative determination of AMP deaminase activity in human skeletal muscle is presented. The method is based on the determination of the direct product of the AMP deaminase reaction, the formed IMP, by high performance liquid chromatography (HPLC). In order to evaluate the relationship between AMP deaminase activity on the one hand and the contractile and metabolic characteristics of the muscle and the physical performance on the other, muscle biopsies were taken from 20 male subjects. The subjects also performed a 30 s sprint test on a cycle ergometer. The inter-individual variation in AMP deaminase activity was large, ranging from 5.4 to 27.4 microkat g-1 dry muscle. AMP deaminase was positively correlated with phosphofructokinase (PFK), the marker of the glycolytic capacity of the muscle, but there was no correlation with enzymes of oxidative metabolism, such as 3-hydroxyacyl-CoA dehydrogenase and citrate synthase, or with the activity of myokinase and lactate dehydrogenase. There was no significant correlation between AMP deaminase activity and the proportion of the different muscle fibre types. A weak positive correlation was found between the sprint performance and the AMP deaminase activity. In conclusion, the HPLC assay was found to be a fast, sensitive and reliable method for the quantitative determination of AMP deaminase activity in muscle. A direct relationship between AMP deaminase activity on the one hand and glycolytic capacity and sprint performance on the other was found. However, no relationship to oxidative capacity or contractile properties was found.

AMP Deaminase↗
PubMed1994

Reduced oxygen availability during high intensity intermittent exercise impairs performance.

This study examined the influence of reduced oxygen availability on the ability to perform repeated bouts of high intensity exercise on a cycle ergometer. Seven male physical education students performed 10 exercise bouts (of 6 s each), interspersed with 30-s recovery periods, under hypoxic and normoxic conditions. The hypoxic condition was carried out in a low pressure chamber at 526 mmHg. Subjects were instructed to try to maintain a target pedalling speed of 140 rev min-1 during each exercise period. The mean power output of the first exercise bout was approximately 950 W. In both experimental conditions, all subjects were able to maintain the target speed for the first 3 s of each of the 10 exercise bouts. During the last 3-s interval of each exercise period the target speed was not maintained in both conditions over the 10 sprints. However, the reduction was greater in the hypoxic condition (P < 0.05). Post-exercise blood lactate accumulation was higher with hypoxia [10.3 (0.7) vs. 8.5 (0.8) mmol l-1, P < 0.05]. Oxygen uptake, measured during the exercise and recovery periods of sprints 6-9, was lower in the hypoxic condition [3.03 (0.2) vs. 3.19 (0.2) 1 min-1, P < 0.05]. These results indicate that a reduction in oxygen availability during high intensity intermittent exercise results in a higher accumulation of blood lactate and a lower oxygen uptake. The ability to maintain a high power output is impaired.

Adenosine Triphosphate↗
PubMed1994

Exchange of purines in human liver and skeletal muscle with short-term exhaustive exercise.

The exchange of purines in liver and active skeletal muscle with short-term exhaustive exercise was investigated. Eight male subjects performed two similar 10-min bouts of exhaustive supine cycling, separated by 75 min of rest. Immediately after termination of the second bout, a tourniquet was applied to the upper part of the thigh for 10 min. After the first bout, the arterial concentration of hypoxanthine and uric acid increased from 4.1 +/- 0.3 (SE) to a peak value of 36.3 +/- 7.9 mumol/l (P < 0.05) and from 335 +/- 23 to a peak value of 421 +/- 28 mumol/l (P < 0.05), respectively. There was a net release of hypoxanthine from the muscle at 12 and 45 min postexercise and an uptake of hypoxanthine and inosine in the liver at 7 and 42 min postexercise. Uric acid was released from the liver at 7 and 42 min after exercise. Before the second exercise bout and at 2 and 10 min after the release of the tourniquet, there was a significant net uptake of uric acid by the muscle. The present study demonstrates that, after strenuous short-term exercise, the main source of plasma hypoxanthine is the muscle, with no net contribution of this purine from the liver. Hypoxanthine in the blood is taken up by the liver where most of it is converted to uric acid. After exercise and a short period of ischemia, uric acid is taken up by the muscle.

Adult↗
PubMed1993

Marginal bone loss in the primary dentition of patients with juvenile periodontitis.

118 patients with juvenile periodontitis (JP), diagnosed when the patients were 13-19 years old, were studied retrospectively with respect to radiographic marginal bone loss in the primary dentition, experienced when the patients were 5-12 years old. 168 other 13-19 year old patients without any signs of bone loss in the permanent teeth were used as a reference group. The JP patients were classified into 2 groups according to the number of sites with bone loss in the permanent dentition: JP group I having 1 site with bone loss (n = 45) and JP group II having > or = 2 sites with bone loss (n = 73). It was found that 35 patients (52%) of JP group II displayed 1 or more sites with bone loss in the primary dentition during the age of 5-12 years. The corresponding numbers for JP group I and the reference group were 9 (20%) and 8 (5%) respectively. These findings indicate that juvenile periodontitis, at least in some individuals, may have its onset already in the primary dentition.

Adolescent↗
PubMed1993

The effect of high-intensity training on purine metabolism in man.

The effect of intermittent high-intensity training on the activity of enzymes involved in purine metabolism and on the concentration of plasma purines following acute short-term intense exercise was investigated. Eleven subjects performed sprint training three times per week for 6 weeks. Muscle biopsies for determination of enzyme activities were obtained prior to and 24 h after the training period. After training, the activity of adenosine 5'-phosphate (AMP) deaminase was lower (P < 0.001) whereas the activities of hypoxanthine phosphoribosyl transferase (HPRT) and phosphofructokinase were significantly higher compared with pre-training levels. The higher activity of HPRT with training suggests an improved potential for rephosphorylation of intracellular hypoxanthine to inosine monophosphate (IMP) in the trained muscle. Before and after the training period the subjects performed four independent 2-min tests at intensities from a mean of 106 to 135% of VO2max. Venous blood was drawn prior to and after each test. The accumulation of plasma hypoxanthine following the four tests was lower following training compared with prior to training (P < 0.05). The accumulation of uric acid was significantly lower (46% of pre-training value) after the test performed at 135% of VO2max (P < 0.05). Based on the observed alterations in muscle enzyme activities and plasma purine accumulation, it is suggested that high intensity intermittent training leads to a lower release of purines from muscle to plasma following intense exercise and, thus, a reduced loss of muscle nucleotides.

AMP Deaminase↗
PubMed1993

Decreased resting levels of adenine nucleotides in human skeletal muscle after high-intensity training.

The effect of high-intensity intermittent training on the adenine nucleotide content of skeletal muscle was studied. Eleven male subjects (group A) performed high-intensity intermittent training on a cycle ergometer three times per week for 6 wk, followed by 1 wk of the same kind of training with two sessions per day. Nine males (group B) exclusively performed 1 wk of training with two sessions per day. In group A, skeletal muscle total adenine nucleotide (TAN) levels decreased from 25.1 +/- 0.7 (SE) to 22.0 +/- 0.6 mmol/kg dry wt over the 6-wk period (P < 0.01). The subsequent intensive week did not further alter TAN levels. In group B, the intensive week of training reduced TAN levels from 25.1 +/- 0.5 to 19.4 +/- 0.6 mmol/kg dry wt (P < 0.001). The decrease was sustained 72 h after training (P < 0.001). During the intensive week, there was no change in plasma creatine kinase activity in either group A or group B. The plasma activity was, however, higher in group B than in group A on days 4 and 7 of the intensive week (P < 0.05). The results from this study indicate that high-intensity intermittent exercise causes a decrease in resting levels of skeletal muscle adenine nucleotide without a concomitant indication of muscle damage. A training-induced adaptation appears to occur with training by which a further loss of adenine nucleotides is prevented despite an increased training dose.

Adenine Nucleotides↗
PubMed1992

Physiological responses to maximal intensity intermittent exercise.

Physiological responses to repeated bouts of short duration maximal-intensity exercise were evaluated. Seven male subjects performed three exercise protocols, on separate days, with either 15 (S15), 30 (S30) or 40 (S40) m sprints repeated every 30 s. Plasma hypoxanthine (HX) and uric acid (UA), and blood lactate concentrations were evaluated pre- and postexercise. Oxygen uptake was measured immediately after the last sprint in each protocol. Sprint times were recorded to analyse changes in performance over the trials. Mean plasma concentrations of HX and UA increased during S30 and S40 (P less than 0.05), HX increasing from 2.9 (SEM 1.0) and 4.1 (SEM 0.9), to 25.4 (SEM 7.8) and 42.7 (SEM 7.5) mumol.l-1, and UA from 372.8 (SEM 19) and 382.8 (SEM 26), to 458.7 (SEM 40) and 534.6 (SEM 37) mumol.l-1, respectively. Postexercise blood lactate concentrations were higher than pretest values in all three protocols (P less than 0.05), increasing to 6.8 (SEM 1.5), 13.9 (SEM 1.7) and 16.8 (SEM 1.1) mmol.l-1 in S15, S30 and S40, respectively. There was no significant difference between oxygen uptake immediately after S30 [3.2 (SEM 0.1) l.min-1] and S40 [3.3 (SEM 0.4) l.min-1], but a lower value [2.6 (SEM 0.1) l.min-1] was found after S15 (P less than 0.05). The time of the last sprint [2.63 (SEM 0.04) s] in S15 was not significantly different from that of the first [2.62 (SEM 0.02) s]. However, in S30 and S40 sprint times increased from 4.46 (SEM 0.04) and 5.61 (SEM 0.07) s (first) to 4.66 (SEM 0.05) and 6.19 (SEM 0.09) s (last), respectively (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Oxygen uptake during running as related to body mass in circumpubertal boys: a longitudinal study.

To investigate the effect of endurance training on physiological characteristics during circumpubertal growth, eight young runners (mean starting age 12 years) were studied every 6 months for 8 years. Four other boys served as untrained controls. Oxygen uptake (VO2) and blood lactate concentrations were measured during submaximal and maximal treadmill running. The data were aligned with each individual's age of peak height velocity. The maximal oxygen uptake (VO2max; ml.kg-1.min-1) decreased with growth in the untrained group but remained almost constant in the training group. The oxygen cost of running at 15 km.h-1 (VO2 15, ml.kg-1.min-1) was persistently lower in the trained group but decreased similarly with age in both groups. The development of VO2max and VO2 15 (l.min-1) was related to each individual's increase in body mass so that power functions were obtained. The mean body mass scaling factor was 0.78 (SEM 0.07) and 1.01 (SEM 0.04) for VO2max and 0.75 (SEM 0.09) and 0.75 (SEM 0.02) for VO2 15 in the untrained and trained groups, respectively. Therefore, expressed as ml.kg-0.75.min-1, VO2 15 was unchanged in both groups and VO2max increased only in the trained group. The running velocity corresponding to 4 mmol.l-1 of blood lactate (nu la4) increased only in the trained group. Blood lactate concentration at exhaustion remained constant in both groups over the years studied. In conclusion, recent and the present findings would suggest that changes in the oxygen cost of running and VO2max (ml.kg-1.min-1) during growth may mainly be due to an overestimation of the body mass dependency of VO2 during running.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Maximal-intensity intermittent exercise: effect of recovery duration.

Seven male subjects performed 15 x 40m sprints, on three occasions, with rest periods of either 120 s (R120), 60 s (R60) or 30 s (R30) between each sprint. Sprint times were recorded with four photo cells placed at 0, 15, 30 and 40 m. The performance data indicated that whereas running speed over the last 10 m of each sprint decreased in all three protocols (after 11 sprints in R120, 7 sprints in R60 and 3 sprints in R30), performance during the initial acceleration period from 0-15 m was only affected with the shortest rest periods increasing from (mean +/- SEM) 2.58 +/- .03 (sprint 1) to 2.78 +/- .04 s (spring 15) (p < .05). Post-exercise blood lactate concentration was not significantly different in R120 (12.1 +/- 1.3 mmol.l-1) and R60 (13.9 +/- 1.2 mmol.l-1), but a higher concentration was found in R30 (17.2 +/- .7 mmol.l-1) (p < .05). After 6 sprints there was no significant difference in blood lactate concentration with the different recovery durations, however, there were significant differences in sprint times at this point, suggesting that blood lactate is a poor predictor of performance during this type of exercise. Although the work bouts could be classified primarily as anaerobic exercise, oxygen uptake measured during rest periods increased to 52, 57 and 66% of maximum oxygen uptake in R120, R60 and R30, respectively. Evidence of adenine nucleotide degradation was provided by plasma hypoxanthine and uric acid concentrations elevated post-exercise in all three protocols. Post-exercise uric acid concentration was not significantly affected by recovery duration.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗
PubMed1992

Marginal bone level in the normal primary dentition.

The aim of the present study was to establish the normal range for the radiographic distance between the cemento-enamel junction (CEJ) and the marginal bone level (MBL) in the primary dentition, and to relate this distance to various physiological and pathological factors. 128 children at the ages 7, 8 and 9 years took part in the study. Clinical and radiographic examinations of the mesial and distal surfaces of all primary molars and the distal surface of the primary canines were performed. The clinical examination included measurements of the amounts of plaque, bleeding on probing, probing depth and probing attachment loss. In addition, increased mobility of the primary teeth and stage of eruption of the neighbouring permanent teeth were recorded. The radiographic examination included measurements of the CEJ-MBL distance and the remaining root length. Also, exfoliating teeth, presence of proximal dentin caries, restorations and calculus were recorded from the radiographs. Associations between various explanatory variables and the CEJ-MBL distance were tested with both a chi 2 test and a variance components analysis. The mean CEJ-MBL distance for all primary tooth surfaces was 1.0 mm. Individual surfaces displayed distances ranging from 0.0-4.0 mm. Of the variables tested for association with the CEJ-MBL distance, eruption of neighbouring permanent tooth and exfoliation of neighbouring primary tooth seemed to be associated with large CEJ-MBL distances. When surfaces with these characteristics were excluded, a CEJ-MBL range of 0.0-2.0 mm was obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar Process↗
PubMed1991

Plasma accumulation of hypoxanthine, uric acid and creatine kinase following exhausting runs of differing durations in man.

During exhausting exercise adenylate kinase in the muscle cells is activated and a degradation of adenosine 5'-diphosphate occurs. Consequently, degradation products of adenosine 5'-monophosphate including hypoxanthine and uric acid, accumulate in plasma. The aim of this study was to compare the concentration changes of hypoxanthine and uric acid in plasma following running of varying duration and intensity. In addition, plasma creatine kinase activity was measured to assess the possible relationship between metabolic stress and protein release. Four groups of competitive male runners ran 100 m (n = 7), 800 m (n = 11), 5000 m (n = 7) and 42,000 m (n = 7), respectively, at an exhausting pace. Subsequent to the 100 m event (mean running time 11 s) plasma concentrations of hypoxanthine and uric acid increased by 364% and 36% respectively (P less than 0.05), indicating a very high rate of adenine nucleotide degradation during the event. Following the 800-m event (mean running time 125 s), hypoxanthine and uric acid concentrations had increased by 1598% and 66%, respectively (P less than 0.05). Both the events of longer duration, 5000 m and 42,000 m, also caused a significant increase in plasma concentration of hypoxanthine (742% and 237% respectively, P less than 0.05) and plasma uric acid (54% and 34% respectively, P less than 0.05). Plasma activities of creatine kinase were significantly increased at 24 h only following the 5000 m and 42,000 m events (64% and 1186% respectively, P less than 0.05). Changes in plasma creatine kinase activity showed no correlation with changes in plasma concentration of either hypoxanthine or uric acid for the 5000 m and 42,000 m events (r = 0.00-0.45, P greater than 0.05).

Adenosine Triphosphate↗
PubMed1991

The effect of different blood sampling sites and analyses on the relationship between exercise intensity and 4.0 mmol.l-1 blood lactate concentration.

The aim of the study was to examine whether the difference in lactate concentration in different blood fractions is of practical importance when using blood lactate as a test variable of aerobic endurance capacity. Ten male firefighters performed submaximally graded exercise on a cycle ergometer for 20-25 min. Venous and capillary blood samples were taken every 5 min for determination of haematocrit and lactate concentrations in plasma, venous and capillary blood. At the same time, expired air was collected in Douglas bags for determination of the oxygen consumption. A lactate concentration of 4.0 mmol.l-1 was used as the reference value to compare the oxygen consumption and exercise intensity when different types of blood specimen and sampling sites were used for lactate analysis. At this concentration the exercise intensity was 17% lower (P less than 0.01) when plasma lactate was compared to venous blood lactate, and 12% lower (P less than 0.05) when capillary blood lactate was used. Similar discrepancies were seen in oxygen consumption. The results illustrated the importance of standardizing sampling and handling of blood specimens for lactate determination to enable direct comparisons to be made among results obtained in different studies.

Adult↗