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Biomedical subjects

J Karlsson

Publications and source records attributed to J Karlsson.

At least 235 records · Page 13Linked to original sources
PubMed1984

Angina pectoris and blood lactate concentration during graded exercise.

Nineteen patients with angina pectoris referred for preoperative evaluation were studied by psychophysical scaling of the chest pain according to Borg and blood lactate determination at rest and during a graded exercise test. The exercise tests consisted of stepwise increments of 10 W every min. Anginal pain, systolic blood pressure, heart rate (HR), and blood lactate concentration were determined at the end of each work load. The exercise test was interrupted at a rated anginal pain level (RAP) of 5-6/9 ("strong"), and this load was referred to as Wmax. The patients were divided into three groups: A with a Wmax less than or equal to 74 W, B 75-124 W, and C greater than or equal to 125 W. At submaximal loads HR was almost identical at the same absolute work load in all three groups. The heart rate at Wmax varied, however, and averaged 98 (A), 118 (B), and 136 (C), respectively. Corresponding peak values for RAP were 3.8, 4.5, and 4.8. Blood lactate at rest ranged from 1.0-1.6 mmol X 1-1 and increased curvilinearly with intensity, which was also the case for RAP. RAP was almost linearly related to blood lactate in all three groups suggesting a causal relationship between these two parameters.

Aged↗
PubMed1984

Comparative study of netilmicin/tinidazole versus netilmicin/clindamycin in the treatment of severe abdominal infections.

The efficacy of netilmicin combined with tinidazole (N + T) or clindamycin (N + C) in the treatment of severe abdominal infections was evaluated in a prospective randomized study with 20 patients in the N + T group and 21 patients in the N + C group. Normally the maintaining dose for netilmicin was 2.25 mg/kg every 12 h, for tinidazole 400 mg every 12 h and for clindamycin 300-600 mg every 6-8 h. The mean duration time of treatment was 8 days in the N + T group and 10 days in the N + C group respectively. In the N + T group 18 patients were cured and in the N + C group 17 patients. Among aerobic bacteria Escherichia coli was most frequently isolated and among anaerobes Bacteroides sp. All aerobic bacteria with 2 exceptions were susceptible to netilmicin and all anaerobic bacteria but 2 to tinidazole or clindamycin. Adequate serum levels were obtained for each antibiotic during therapy. In this study with a small number of patients the combination of netilmicin and tinidazole was as effective as netilmicin and clindamycin.

Adolescent↗
PubMed1984

Unstable fractures of the pelvis treated with a trapezoid compression frame.

Sixteen patients with unstable pelvic fractures were treated by early reduction and fixation of the pelvic ring with a trapezoid compression frame. This provided firm fixation of the fractured pelvis in all but one patient. External fixation afforded relief from pain and greatly facilitated nursing. At follow-up, all the fractures but one had healed in the position secured initially by the frame.

Adolescent↗
PubMed1984

Profiles of cross-country and alpine skiers.

Skiers were profiled in regard to cardiovascular fitness, muscle strength, motor control, coordination, and muscle fiber composition. Skiing injuries were also profiled. The profile is useful in determining the potential for injury and in developing training programs to prevent injuries.

Athletic Injuries↗
PubMed1984

Exaggerated systolic blood pressure response to exercise in a water polo team.

Twenty-three top-level water polo players (WP) were examined for blood pressure (BP) response to graded and continuous cycle ergometry. Testing also included resting muscle biopsy for fiber typing, exercise ECG recording for heart rate (HR), exercise concentrations of blood lactate (LA), measured VO2max, and ratings of perceived exertion (RPE). A control group (C), whose subjects were physically active in endurance sports, but were older and less fit than the experimental subjects, was tested by an identical protocol. The BP response to exercise was significantly higher in the WP group at all comparison criteria including onset of blood lactate accumulation, absolute HR, percent of HRmax, and power loads (including loadless pedaling). To date, we are unaware of other reports on whole groups of sportsmen showing an exaggerated BP response to exercise. While it would appear from previous studies that normotensive individuals showing such a response are at a greater risk of developing hypertension, the significance of this BP response in highly-trained athletes in a specific sport remains unclear.

Adolescent↗
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↗
PubMed1983

Alpine skiing and acute beta-blockade.

The effect of acute unselective (propranolol) and beta 1-selective (atenolol) beta-adrenoceptor blockade was studied on alpine skiing in six leisure and seven elite skiers. Prior to the skiing tests a short time "all out" cycle ergometer test (Wingate muscle power test) was performed to confirm whether a beta-blocking effect (80 mg propranolol and 100 mg atenolol orally) was present or not. Peak and average power of the Wingate test showed an impairment in the order of 4%--6% (P less than 0.05--0.001). Peak blood lactate was only reduced after propranolol (0.05 greater than P greater than 0.01). During leisure skiing under submaximal exercise conditions peak blood lactate was increased (P less than 0.05) as compared to placebo, but rated perceived exertion (RPE) was unchanged as well as the estimated skiing technique. The elite skiers showed prolonged performance times (P less than 0.05) after beta-blockade and in the case of propranolol also reduced peak and mean blood lactates (P less than 0.05). It is suggested that during intense exercise propranolol reduced lactate formation, which is in line with previous reports. This might impair short time, "explosive" type muscular exercise. If there is a risk factor for injury during beta-blockade and alpine skiing, it might be connected to the impaired performance and metabolism in relation to intense exercise and propranolol treatment.

Adolescent↗
PubMed1983

The effect of lumbar sympathectomy on fiber composition, contractility of skeletal muscle and regulation of central circulation in dogs.

It has been speculated upon that the sympathetic activity might be of significance for fiber composition in skeletal muscle and by similar features indirectly affecting muscle contractility and regulation of circulation. To further study this hypothesis unilateral lumbar sympathectomy from L-2 and down was applied on 5 female dogs. After 14 weeks the gracilis muscle on the sympathectomized and the control side as well were examined for their muscle fiber compositions, endurance capacity and how heart rate and blood pressure responses were affected. Muscle fiber composition decreased to 28% slow twitch fibers as compared to 41% on the control side (p less than 0.01). The relative cross-sectional area of the fast twitch fibers increased simultaneously from 57 (control side) to 71% (p less than 0.05). Endurance performance measured as contraction time at 50% of peak tension decreased from 55 to 29 s (p less than 0.05). On an individual bases including both control and sympathectomized muscles it was found that heart rate increased with percent fast twitch muscle fibers (p less than 0.01) and a tendency was present for a similar relationship between blood pressure and fiber types (p less than 0.1).

Animals↗
PubMed1983

Influence of lactate accumulation of EMG frequency spectrum during repeated concentric contractions.

One hundred and twenty consecutive maximal leg extensions at a constant angular velocity of 1.5 radians . s-1 were performed by nine physical education students. Integrated electromyographic (IEMG) activity and power spectrum density function (PSDF) of the EMG were recorded from m. vastus lateralis, vastus medialis and m. rectus femoris using bipolar surface electrodes. Muscle biopsies were obtained from m. vastus lateralis before and after exercise. Tissue samples were analyzed for muscle fiber type distribution and lactate and glycogen concentration. Muscle force and IEMG decreased in parallel over the exercise period. Thus, the IEMG/force ratio was unchanged. Mean power frequency (MPF) of PSDF of the three nucleus decreased by 10% (p less than 0.001) during the initial 25 contractions with no further decline during the latter part of exercise. The relative contribution of the highest bandwidth (130-500 Hz) of the PSDF decreased (p less than 0.001) between the first and final contractions. Muscle glycogen concentration decreased from 85 +/- 23 to 68 +/- 22 mmol . kg-1 w.w. during the exercise. Muscle and blood lactate concentration averaged 12.1 +/- 8.8 mmol . kg-1 w.w. and 3.8 +/- 0.8 mmol . l-1, respectively. The relative changes in MPF and in the highest bandwidth were correlated with muscle lactate concentration and fiber type distribution: in individuals with a high proportion of fast twitch muscle fibres and/or the greatest lactate accumulation, MPF and high frequency components of EMG PSDF decreased most markedly. Reductions in muscle force and IEMG are suggested to be partly due to a decreased motor neuron firing rate. It is discussed whether lactate or associated metabolic changes are influencing the motor unit action potential through feedback processes.

Action Potentials↗
PubMed1983

Lactate in human skeletal muscle after 10 and 30 s of supramaximal exercise.

The purpose of this study was to evaluate the extent of anaerobic glycogenolysis, as indicated by intramuscular lactate concentration, after 10 and 30 s of supramaximal exercise and to compare male and female subjects in this regard. Fifteen males and seven females performed two cycle exercise bouts against a resistance which was standardized so that one pedal revolution resulted in 4.90 J work X kg body wt-1. A muscle biopsy was obtained after 10- and 30-s exercise bouts and analyzed for lactate concentration. The lactate concentrations averaged 36 and 61 mmol X kg dry wt-1 after the 10- and 30-s exercise bouts, respectively. The male subjects had higher (P less than 0.005) lactate concentrations and generated higher (P less than 0.001) power outputs for both exercise bouts. When the mean lactate concentrations were statistically adjusted after controlling for between-group variation in power output, no difference was evident between groups for the 10- or the 30-s lactate value. The results are evidence that pronounced lactate accumulation occurs during supramaximal exercise of a 10-s duration, suggesting that glycolysis can occur within this time frame. This is in contrast to the theory that glycolysis does not occur until endogenous phosphagen levels reach some critically low value, not thought to be obtainable within the first 10 s of supramaximal exercise.

Female↗
PubMed1983

Mechanical efficiency of positive work in running at different speeds.

To investigate the possible role of elastic potentiation on mechanical efficiency, three male marathon runners were filmed while running on a treadmill at various steady-state speeds ranging from 7.0-22.0 km X h-1. Kinematic and mechanical energy analyses were performed from the film. Expired air was collected for energy expenditure determination. The analysis disclosed that during contact on the treadmill the knee and ankle joints initially had a phase of negative (flexion) angular velocity, followed by a positive velocity. In the hip joint the stretch-shortening cycle of the extensor muscles occurred primarily during the flight phase. The mean vertical and horizontal forces of the negative and positive phases of the contact period increased linearly with the increase in the running speed. The calculated mechanical efficiency of positive work was high but relatively constant (55.1 +/- 12.7%) across all speeds. The absolute contribution of the extra work, which comes from the stored elastic energy to the positive work, increased with running speed; however, its relative value (0.61 +/- 0.09 J X min-1 X kg-1) remained constant at all measured speeds. It is suggested, therefore, that when the flight phase is included in the mechanical energy calculations, the measured efficiency for the positive work reaches a high but constant value in running at low-to-moderate speeds.

Ankle Joint↗
PubMed1983

Muscle fiber type characteristics of M. deltoideus in wheelchair athletes. Comparison with other trained athletes.

Muscle biopsies were obtained from the midportion of m. deltoideus of seven male wheelchair basketball athletes. High caliber kayak paddlers (n = 8) and wrestlers (n = 8) as well as mountain ranger soldiers (n = 8) served as controls. Histochemical methods were applied to identify fast twitch (FT) and slow twitch (ST) fibers and furthermore assess muscle fiber type distribution and muscle fiber cross-sectional area. The relative percentage of FT fibers averaged (+/-SD) 47 +/- 12% and 52 +/- 9% in wheelchair athletes and soldiers. The value obtained in kayakers was significantly lower (30 +/- 11). Both FT area (p less than 0.01) and mean fiber area (p less than 0.05) were significantly larger in wheelchair athletes as compared with soldiers and kayakers. It is suggested that the involvement in specific physical training was the main cause for hypertrophy of individual muscle fibers observed in m. deltoideus of wheelchair athletes.

Adult↗
PubMed1982

Muscle glycogen and diet in elite soccer players.

The top players in an elite soccer team volunteered as subjects in a study to determine intramuscular glycogen concentrations after a regular season match, and whether optimal glycogen levels could be re-attained prior to the team's next match. Fifteen players were biopsied in the M. vastus lateralis following a regular season game (Day I). Of these, eight were biopsied 24 h later in the evening of a free day during which no training session was held (Day II), and again 24 h later after a very light training session (Day III). Muscle glycogen concentrations for the eight players averaged (+/- SD) 45.9 +/- 7.9, 68.9 +/- 2.7, and 72.8 +/- 8.3 mmol glucose units x kg-1 wet muscle weight on Day I, Day II, and Day III respectively. Dietary records were analysed during a week of peak, season competition and training. The average daily total energy consumption and total quantity of carbohydrates consumed were less than what is normally consumed by athletes in similar sports. The inability of the players to maintain even normal, resting levels of muscle glycogen is probably related to their dietary practices.

Adult↗
PubMed1982

Decrease of lipoprotein lipase activity in skeletal muscle in man during a short-term carbohydrate-rich dietary regime. With special reference to HDL-cholesterol, apolipoprotein and insulin concentrations.

Seven men took part in a study in which the diet was changed from an ordinary mixed one to a fat-rich diet [greater than 70% energy (E)] for 3 days followed by a carbohydrate-rich diet (greater than 70% E) for 3 days. Blood was drawn and muscle biopsies [for analysis of lipoprotein-lipase (LPL) activity] were taken before the study and at the end of each diet period. Insulin, apolipoprotein (apo) B, A-I and A-II, cholesterol and triglyceride concentrations were determined in serum and the lipids also in the high density lipoproteins (HDL). Serum insulin was higher (p less than 0.01) during the carbohydrate-rich diet than during the fat-rich diet (12.0 +/- 0.9 vs. 7.5 +/- 0.5 microunits/l, mean +/- SEM), as were serum-triglycerides (2.42 +/- 0.27 vs. 0.98 +/- 0.07 mmole/1, p less than 0.001). Muscle LPL activity, on the other hand, was lower (p less than 0.01), 27.3 +/- 6.1 vs. 75.1 +/- 13.2 microunits/g. HDL-cholesterol was 1.22 +/- 0.08 during the carbohydrate-rich diet which was lower (p less than 0.01) than during the fat-rich diet, 1.45 +/- 0.11. The concentration of apo A-I and A-II did not vary significantly. It is suggested that the increased insulin concentrations during a short-term, carbohydrate-rich diet may have a down-regulating effect on muscle LPL activity. Low muscle LPL activity may account for part of the elevation of serum triglycerides. An ineffective hydrolysis of VLDL-triglycerides may contribute to the variation in HDL-cholesterol concentration seen under these circumstances.

Adolescent↗
PubMed1982

Dietary effects on glycogen and lipoprotein lipase activity in skeletal muscle in man.

The influence of short-term adaptation to a fat and protein enriched diet (F + P) and a carbohydrate enriched diet (CHO) on skeletal muscle lipoprotein lipase (LPL) activity and muscle glycogen levels was evaluated in 7 males. Muscle biopsies were taken from the m. vastus lateralis after an uncontrolled, mixed diet (M), after a 3 day F + P) diet preceded by intense exercise, and after a 3 day CHO diet. After the F + P diet glycogen concentration was 55% that of the M diet while LPL activity increased by 21% (n.s.). After the CHO diet glycogen levels increased by 82% and LPL activity decreased by 55% compared to the M diet (p less than 0.01). The changes in LPL after the CHO diet were related to the changes in glycogen concentration (r = 0.98, p less than 0.01). LPL activity in the control situation was directly related to percent slow twitch (ST) muscle fibre type (r = 0.95, p less than 0.01). The results suggest that the uptake of fat from the circulation may be actively regulated by the muscle as a function of intramuscular substrate availability and that this regulation may be related to muscle fibre type composition.

Adolescent↗