Search PubMed⌕ Search

Biomedical subjects

J Keul

Publications and source records attributed to J Keul.

At least 91 records · Page 5Linked to original sources

Heart rate deflection related to lactate performance curve and plasma catecholamine response during incremental cycle ergometer exercise.

The correlation between the behaviour of the heart rate/work performance (fc/W) curve and blood lactate ([la]b) and plasma adrenaline/noradrenaline concentrations ([A]/[NA]) during incremental cycle ergometer exercise was investigated. A group of 21 male sports students was divided into two groups: group I, with a clear deflection of the fc/W curve; group II, without or with an inverse deflection of the fc/W curve. The aerobic threshold (Thaer) and the lactate turn point (LTP) were defined. Between Thaer and maximal work performance (Wmax) the behaviour of the fc/W curve as well as the behaviour of [la-]b and [A]. [NA] were described mathematically. The fc, systolic blood pressure (BPs), W, [la-]b, [A] and [NA] at rest, Thaer, LTP, Wmax, after 3 and 6 min of recovery (Re3/Re6) were calculated. A significant difference between the two groups could only be detected for fc at LTP, Re3 and Re6 (P < 0.05). No significant correlation could be found between individual fc/W-behaviour and individual time course of [la-]b, [A] and [NA]. However, a significant correlation was visible between [la-]b/W-behaviour and individual catecholamine response. These results and the fact that the different flattening at the top of the fc/W curve was related to diminished stress-dependent myocardial function led us to the conclusion that it is possible that sympathetic drive is not directly involved in mechanisms of regulation between load dependent fc and myocardial function. In addition, individual fc/W behaviour was independent of BPs and Wmax, or individual conditions of energy supply.

Adult↗

Unaccustomed high mileage compared to intensity training-related neuromuscular excitability in distance runners.

The influence of a 4-week unaccustomed average 103% mileage increase (ITV, increase in training volume; n = 8; average baseline mileage 85.9 km.week-1, final mileage 174.6 km.week-1) on performance and neuromuscular excitability (NME) was tested in experienced distance runners and controlled 1 year later by a 4-week unaccustomed average 152% increase in tempo-pace and interval-runs (ITI, increase in training intensity; n = 9; baseline 9 km.week-1 final 22.7 km.week-1) with an average total mileage of 61.7 km.week-1 (week 1) to 84.7 km.week-1 (week 4). Seven athletes participated in ITV as (week 4). Seven athletes participated in ITV as well as in ITI. During incremental treadmill test performance at a lactate concentration of 2 mmol.1-1 (2 LP) increased, and at 4 mmol.1-1 (4 LP) performance did not change, whereas total running distance (TD) during the incremental test decreased in ITV compared to an increase in 2 LP, 4 LP and TD during ITI which may indicate that there was an ITV-related overtraining. The NME of the reference muscles vastus medialis and rectus femoris deteriorated in ITV (day 28 compared to 0) compared to constant values during ITI, reflecting an ITV-related overload of neuromuscular structures.

Adult↗

Relationship between obesity and concentration and composition of low-density lipoprotein subfractions in normoinsulinemic men.

Obesity, insulin resistance (IR) with hyperinsulinemia, and a dyslipoproteinemia characterized by reduced high-density lipoprotein 2 (HDL2) cholesterol and elevated levels of small, dense low-density lipoprotein (LDL) particles are risk factors for coronary artery disease (CAD). The impact of obesity independent of hyperinsulinemia on the concentration and composition of small, dense LDL subfractions is uncertain. The aim of this study was to investigate the relationship between obesity indices, namely body mass index (BMI), skinfold measurements (SF), and waist to hip ratio (WHR), and LDL-subfraction particle concentration and composition in 200 healthy men without evidence of IR. A precise analysis of the concentration of lipids and apolipoproteins and the composition of very-low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), and two HDL- and six LDL-subfraction particles was obtained using the technique of density-gradient ultracentrifugation. Dividing the individuals according to BMI showed that those with a BMI greater than 27 kg/m2 had significantly lower HDL2 cholesterol and apolipoprotein (apo) A-I and higher VLDL and IDL cholesterol and apo B concentrations than those with a BMI less than 25 kg/m2. Regarding LDL particles, we found that men with a BMI above 25 kg/m2 had significantly more small, dense LDL particles (d 1.044 to 1.063 g/mL) and correspondingly fewer medium, dense LDL particles (d 1.031 to 1.037 g/mL) than leaner men; those with a BMI above 27 kg/m2 had the highest concentration of circulating small, dense LDL particles. These findings were not influenced by fasting insulin concentrations, IR, or WHR.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Serum amino acid concentrations in nine athletes before and after the 1993 Colmar ultra triathlon.

The amino acid imbalance hypothesis should explain the fatigue originating in the brain during sustained exercise or over-training as a branched-chain (BCAA)/aromatic amino acids (AAA) imbalance with increased brain tryptophan uptake and 5-hydroxytryptamine synthesis. The serum amino acid profile was determined in 9 ultra-triathletes before and after completing the 1993 Colmar ultra-triathlon to additionally analyse the extent of this amino acid imbalance during such an extreme prolonged contest lasting more than 23 hours. The summed serum concentration of 25 amino acids decreased by 18% from 3962 +/- 846 to 3255 +/- 694 umol.l-1 likely reflecting a catabolic state of the organism with a decrease in 18 individual amino acids by 9-56%, an increase in cystine (+38%), methionine (+24%), tyrosine (+10%), phenylalanine (+12%), free tryptophan (+74%), and constant glutamine, leucine and total tryptophan levels. Since plasma volume increased by approximately 7.6% with a 3.3 kg body mass decrease in the athletes during the ultra triathlon, a decrease in intra-cellular water with an extra-cellular fluid increase is hypothesized. This decrease in cellular hydration state is seen as a protein-catabolic signal.

Adult↗

[Assessment and evaluation of leisure activity of participants in heart rehabilitation groups].

A self-administered questionnaire was used to assess leisure-time physical activity (LTPA) of patients participating in cardiac rehabilitation groups (CHD: n = 144, 115 male, 29 female) and an age-matched control group (CG: n = 100, 76 male, 24 female). The mean times spent on LTPA per week were 12.2 h (CHD) and 13.3 h (CG); this difference was due to the fact that participants of the cardiac rehabilitation groups were less engaged (1 h) in sports activities (12% contribution to LTPA versus 19.5%). The results show that most of the CHD patients organized in the groups achieved LTPA levels and energy turnover rates which are thought to have beneficial effects on the course of the atherosclerotic coronary disease. Participants who did not reach the critical energy turnover threshold should be paid particular attention with regard to their educational, as well as their medical needs.

Adult↗

Sports and nutrition--an out-patient program for adipose children (long-term experience).

Sports activity (3 times per week), nutritional changes and modification of behavior are the basic tenets of an outpatient program run for 9- to 12-year-old adipose children since 1987. The following goals are to be attained: increase in physical performance capacity and body awareness, long-lasting change in eating habits, weight loss to under 20% overweight compared to the age-normal (height/normal weight), and understanding of the permanence of body weight problems. Individual nutritional consultation is offered in addition to the initial examination consisting of physical examination, skin fat-fold measurement, blood chemical parameters, spiroergometry and a detailed consultation with parents and children. The eating habits of the children are recorded in a dietary history (3-day dietary protocol, questionnaire) and discussed in individual meetings with the parents and children. Moreover, the nutritional program includes regular nutritional consultations and parents' meetings every month. Cooking instructions for children and parents provide practical knowledge of food preparation to preserve nutrients in an energy-reduced, tasty diet, as well as theoretical basics of nutrition. The control examinations show individual weight loss or stability and improvement in blood lipid parameters. Awareness and controlled nutritional habits were learned especially by the children of parents who, for their part, tried to tailor their nutrition to be better balanced, more nutritional and more need-oriented. Children who maintain the learned nutritional habits after completion of the outpatient program, and who remain active in sports, show long-lasting constant weight. Prevention must begin in childhood. Intensive nutritional support combined with an appropriate sports program should be offered as a preventive measure.

Ambulatory Care↗

Echocardiographic findings in endurance athletes with hypertrophic non-obstructive cardiomyopathy (HNCM) compared to non-athletes with HNCM and to physiological hypertrophy (athlete's heart).

Hypertrophic non-obstructive cardiomyopathy (HNCM) is one of the most frequent causes of sudden cardiac death in young athletes. Since the clinical findings in HNCM patients may be inconspicuous and the ECG changes found in endurance athletes may be similar to those of HNCM patients, echocardiography, as a non-invasive procedure, seems to take on an important role in differential diagnostics. To prove this hypothesis, conventional echocardiographic parameters were compared in three groups with confirmed diagnosis: Group I: HNCM (n = 9) without sports activity; Group II: HNCM (n = 9) with regular, intensive endurance training (3-5 hours/week). The diagnosis was invasively confirmed in both groups. Group III: healthy subjects (n = 9) with physiological hypertrophy and regular endurance training (3-6 hours/week). In the presence of HNCM, endurance sports activity appears to offset the reduction in the left ventricle and enlargement of the left atrium. The wall thickness of the septum and posterior wall do not differ in the two HNCM groups, but show a significant difference to the healthy athletes. The enddiastolic diameter, the absolute septum and posterior wall thickness and the ratio of septum+posterior wall/enddiastolic diameter can be taken as the most important differential diagnostic criterium in physiological hypertrophy, but not the ratio between septum/posterior wall. It is concluded that conventional echocardiographic examination can be considered a valuable non-invasive method for differentiating HNCM from athlete's heart, even in patients with HNCM who participate in endurance sports. However, a reliable diagnosis may not be possible in individual cases.

Adolescent↗

Dietary, serum and urine ascorbic acid status in male athletes.

The ascorbic acid (AA)-status of 14 marathon runners, 12 soccer players, 9 wrestlers, 9 basketball players and 16 controls was determined. A 7-day food weighed record was kept to quantify the AA-intake. In addition, the AA-serum concentrations and urinary ascorbate excretion were measured. The AA-intake of all 44 athletes (median, 26th-75th percentile) was 180.7 (188-239) mg/d, the serum concentration 70.6 (65.7-80.2 mumol/l) and the urine ascorbate excretion 1531 (391-2934) mumol/g creatine. No significant differences could be observed between the various sport groups, or between the sport groups and controls with respect to absolute (mg/d) and relative (mg/g body weight) AA-intake, serum and urine concentrations. Only a few of the athletes had AA-intake below the RDA or serum- or urine levels smaller than the decision limit. The absolute AA-intake (n = 44) from the 7-day record (r = 0.49, p < 0.0009) and the AA-intake on the last day (1-day) prior to urine collection (r = 0.90, p < 0.0000) correlate moderately/strongly with the urinary excretion. Between AA-intake (7-day) and serum concentration there is a correlation of r = 0.59, p < 0.0000. The AA-status of highly trained athletes does not differ significantly from the control group in spite of intensive daily training. Thus, AA-supplementation beyond the normal daily intake does not appear necessary.

Adult↗

Assessment of vitamin B6 status of strength and speedpower athletes.

OBJECTIVE: The investigation was designed to obtain information concerning the vitamin B6 status in high-performance athletes. SUBJECTS: Fifty-seven strength and speedpower athletes were available for examination. METHODS: Vitamin B6 status was determined by a 7-day weighed food record, enzyme activity (alpha-EGOT) measurement, whole blood concentrations (Saccharomyces carlsbergenisis and 4-pyridoxinic acid (4-PA) excretion (high-pressure liquid chromatography). RESULTS: The absolute vitamin B6 intake in > 30% of the athletes was below the German recommended dietary allowance (GRDA) and, in relation to the protein intake (GRDA 0.20 mg vitamin B6/g protein), > 60% of the athletes had values below the GRDA. More than 90% of the athletes did not attain the reference value (0.88 nmol/mL) for untrained individuals in vitamin B6 whole blood concentration, and only a few athletes (< 5%) had alpha-EGOT values above the reference value of alpha-EGOT > 1.50). The 4-PA excretion was below the reference value of > 2.73 mumol/g creatinine in 18% of all athletes examined. CONCLUSIONS: Vitamin B6 status can be quantified using the weighed food record, microbiological whole blood determination, and 4-PA excretion; however, limits of the individual methods must be taken into account. Vitamin B6 supply of the athletes still cannot be definitively assessed because there are no generally valid reference values.

Aspartate Aminotransferases↗

Lipid peroxidation and antioxidative vitamins under extreme endurance stress.

The aim of this study was to examine whether extreme endurance stress of trained athletes can influence lipid peroxidation and muscle enzymes. A randomized and placebo-controlled study was carried out on 24 trained long-distance runners who were substituted with alpha-tocopherol (400 I.U. d-1) and ascorbic acid (200 mg d-1) during 4.5 weeks prior to a marathon race. The serum concentrations of retinol, ascorbic acid, beta-carotene, alpha-tocopherol, malondialdehyde (TBARS) and uric acid as well as glutathione peroxidase (GSH Px) and catalase were measured 4.5 weeks before (A), immediately before (B), immediately after (C) and 24 h after (D) the course. After competition (C) TBARS serum concentrations of the athletes (n = 22) decreased in both groups (P < 0.0001). The ascorbic acid serum concentration increased significantly in the supplemented group from (A) to (B) (P < 0.01), from (B) to (C) (P < 0.001) and in the placebo group a significant increase from (B) to (C) (P < 0.01) was observed. The alpha-tocopherol serum concentration increased significantly in the supplemented group from (A) to (B) (P < 0.001) and from (B) to (C) (P < 0.05). The enzymes glutathione peroxidase (GSH Px) and catalase measured in erythrocytes as well as the serum selenium levels did not show significant differences at any time. A significant increase of CK concentration was observed from (C) to (D) in the supplemented group (P < 0.01) and in the placebo group (P < 0.001). The increase of CK serum concentration is remarkably lower in the supplemented group compared with the placebo group (P < 0.01). It is concluded that endurance training coupled with antioxidant vitamin supplementation reduces blood CK increase under exercise stress.

Adult↗

Acute changes in vitamin B6 status in endurance athletes before and after a marathon.

The vitamin B6 status of 13 endurance athletes was determined by whole blood B6 (microbiological) and urine 4-pyridoxic acid (4-PA) (HPLC), serum vitamin B6 (pyridoxal, pyridoxol, pyridoxamine) (HPLC), and erythrocyte alpha-EGOT measurements with the aid of 7-day records. In addition, blood and serum samples and urine were collected before (Time A), directly after (Time B), and 2 hr after a marathon race (Time C). The total energy intake was 12,303 +/- 3,464 kJ/day (34% fat, 48% carbohydrates, 14% protein). The vitamin B6 intake, serum concentrations, alpha-EGOT value, and 4-PA excretion were higher than the reference values at Time A. Only the vitamin B6 whole blood levels were below the normal level at Time A. The vitamin B6 status of the athletes corresponded essentially to reference values obtained for untrained individuals. There was a mean loss of about 1 mg vitamin B6 as a result of the marathon race. Vitamin B6 supplementation does not appear necessary if a balanced diet is consumed.

Adult↗

alpha-Tocopherol supplementation in racing cyclists during extreme endurance training.

This study was undertaken to evaluate the effects of 5 months of alpha-tocopherol supplementation on physical performance during aerobic exercise training in 30 top-class cyclists. Antioxidative effects of supplementation were also studied. Plasma alpha-tocopherol concentration increased significantly in the vitamin E-supplemented group, whereas the placebo group showed a trend toward decrease. Physical performance did not improve in the alpha-tocopherol-supplemented group compared to the placebo group. Heart rates were also not significantly different. Lactate concentrations at the aerobic threshold and the anaerobic threshold were identical. Thus, there was no performance improvement in the alpha-tocopherol-supplemented group. However there was a significant reduction in CK in serum of the E-supplemented group. A trend toward decrease in GOT, GPT, and LDH was observed with alpha-tocopherol supplementation. Moreover, significantly reduced malondialdehyde serum levels were measured in the E-supplemented group. The findings indicate a protective effect of alpha-tocopherol supplementation against oxidative stress induced by strenuous exercise.

Adult↗

Physical activity and lipoprotein lipid disorders.

Working muscle plays a central role in the control of lipid metabolism. Increased physical activity induces a number of positive changes in the metabolism of lipoproteins: serum triglycerides are lowered by the increased lipolytic activity and the production of native high density lipoprotein (HDL) particles is increased. The increased lecithin: cholesterol acyltransferase activity leads to an increased production of HDL2, which in addition is catabolised more slowly due to a decreased activity of hepatic lipase. The 3 effects explain the increased HDL levels of endurance trained individuals. These effects have been demonstrated in cross-sectional as well as longitudinal studies by different groups, and can be induced by training, independent of changes in bodyweight. The influence of endurance activity on the quality and quantity of low density lipoprotein (LDL) particles is a further reason for the antiatherogenic potential of increased physical activity. It has been shown by several groups that small dense LDL particles represent a particular risk factor for atherosclerosis. Recent studies presented strong evidence that LDL level and composition can be influenced favorably by physical activity. In addition to the direct influence of physical activity on lipids and lipoproteins, physical exercise may improve the disturbances of haemorheological factors, particularly those associated with hypertriglyceridaemia. In conclusion, there is increased evidence that physical activity is able to favourably influence all 3 components of the atherogenic lipoprotein phenotype: the HDL concentration increases, the concentration of small dense LDL decreases, and serum triglycerides are reduced.

Apolipoproteins↗

Assessment of vitamin B2 status in performance athletes of various types of sports.

To determine the vitamin B2 supply, 62 athletes in various types of sports and 16 non-athletes were examined, using a weighed food record (7-day), alpha-EGR determination, microbiological blood, and HPLC urinary measurements. If the guidelines of 1.5 or 1.7 mg/day vitamin B2 or 0.6 mg/4,184 kJ (GRDA) are defined for adequate status, all sports groups (M +/- SEM) are above this level. The vitamin B2 blood concentrations show a range (mean) from 303-372 nmol/liter, which indicates that more than 90% of the athletes are above the reference value of 327 nmol/liter (mean). There is a correlation of r = 0.49 between the vitamin B2 intake (mean over 7 days) and the vitamin B2 blood level. Determination of vitamin B2 blood concentration is characterized by good precision (C.V. +/- 3.2%) and recovery (95.7%). The enzyme activation measurement (alpha-EGR) shows that all of the athletes are below the alpha-EGR reference value of < 1.50 (good supply). No significant correlations could be determined between alpha-EGR and vitamin B2 intake, blood concentrations, and urinary excretion. The measurement also shows high precision (C.V. 1.7%). The Vitamin B2 excretion in urine (mumol/g Cr.) was higher than the reference values for non-athletes in more than 90% of the athletes. There is a correlation of r = 0.89 between the vitamin B2 intake on the last day (Day 7) of the food record and the riboflavin excretion, and between vitamin B2 in blood and urinary excretion of r = 0.52. The C.V. of vitamin B2 urinary measurement using HPLC is 2.5%, with recovery of 98.2%. Combined measurement of vitamin B2 intake, blood concentration, and urine excretion appears to be a suitable procedure for determining the vitamin B2 status. Most of the performance athletes were sufficiently supplied with vitamin B2, compared to the reference values for non-athletes.

Adolescent↗

[Energy and nutritional intake in young weight lifters before and after nutritional counseling].

A well-balanced diet is an essential component for the development and maintenance of physical performance. Several studies on the dietary status of power athletes have shown, that there are still problems to realize the nutritional recommendations. The purpose of the present study was to analyse the energy- and nutrient intake of 11 young weight lifters aged 14 to 17 years before and after an intensive nutritional counselling (NC). Dietary status was evaluated by 7-day-protocols filled out by the young athletes 4 weeks before and 4 weeks after the NC. Before the NC the athletes (x: age 15, height 174 cm, weight 69.5 kg, BMI 22.2 kg/m2) had a mean energy intake of 179.7 kJ/kg body weight (11.2 MJ/day). The energy percentage of carbohydrate:fat:protein was 48:37:15. The protein consumption was 1.6 g/kg of body weight and the fluid intake was 1.7 l/day. The athletes did not meet the recommendation for niacin, folic acid, vitamin E, magnesium, calcium, iodine and zinc. After the NC the athletes had a significant higher energy percentage of carbohydrate and lower energy percentage of fat. In addition a significantly higher intake of fluid, dietary fiber, vitamins and minerals was observed. This study revealed that the young weight lifters without NC fall short of nutritional recommendations. With the intensive nutritional counselling an improvement of the nutrient intake could be reached. Additional nutritional counselling for the athletes and an intensive teamwork with the coach and parents of the athletes seem necessary to develop and stabilize a good nutritional behavior.

Adolescent↗

[Physical activity and eating behavior: strategies for improving the serum lipid profile of children and adolescents].

Coronary risk factors such as obesity, dyslipoproteinaemia and low physical fitness are often prevalent in childhood. In contrast, regular physical activity and healthy nutrition have been shown to be effective in primary and secondary prevention of coronary artery disease. An increment in physical activity with concomitant weight loss has a profound influence on peripheral lipoprotein metabolism and has shown to improve the atherogenic lipoprotein profile. As risk factors often track from childhood into adulthood it seems inevitable to prevent or diminish risk factors as early as possible. Therefore, intervention programmes for prevention of coronary artery disease have to be conducted in childhood. Experience from an own intervention programme of obese children has shown that the combination of intensive dietary and physical education improves physical fitness, body composition as well as lipid metabolism. Whether short-term benefits will continue into adulthood and reduce coronary artery disease in midlife will have to be shown. Nonetheless, it seems out of question that children showing risk factors such as obesity or hypercholesterolaemia will benefit from early intervention programmes when changing dietary and exercise behaviours.

Adolescent↗

[Pantothenic acid levels in blood of athletes at rest and after aerobic exercise].

Ninety-six high-performance athletes of various disciplines were available for this investigation. All athletes had many years of training and competition experience. The pantothenic acid contents in the blood were determined by means of microbiological measurements. In addition to the pantothenic acid level at rest, measurements were made resp. physical exertion in 14 marathon runners and nine body builders. Blood was collected for determination of pantothenic acid before (a), after (b) and 2 h after exercise. Compared to the reference values for untrained persons (1.34 +/- 0.13 nmol/mL), the marathon runners with 0.76 (0.31-0.94) nmol/mL and soccer players with 1.19 (0.37-2.64) nmol/mL were below the reference values. According to relative frequencies, more than 30% of all athletes were below the lower limit (< 1.20 nmol/mL). The values in body builders/racing cyclists differed significantly from those in marathon racers (p < 0.001), which is presumably due to unallowed supplementation. During exercise, there was a significant increase in the pantothenic acid level in marathon runners (p < 0.01).

Adult↗

Influence of 6-week, 6 days per week, training on pituitary function in recreational athletes.

The influence on pituitary function of 6 weeks of training on 6 days a week was examined in six recreational athletes. Endurance training on a bicycle ergometer for 31-33 min was performed on 4 days each week at 90-96% (weeks 1-3) and 89-92% (weeks 4-6) of the 4 mmol lactate thresholds determined on day 0 and day 21, respectively, with interval training of 3-5 x 3-5 min in addition on 2 days a week at 117-127% and 115-110%, respectively. Determination of the serum hormone levels and a combined pituitary function test (200 micrograms thyrotropin releasing hormone (TRH), 100 micrograms gonadotrophin-releasing hormone (GnRH), 100 micrograms corticotrophin releasing hormone (CRH), 50 micrograms growth hormone releasing hormone (GHRH)) were made before training, after 6 weeks of training and after another 3 weeks of recovery. Training increased performance at 2 mmol lactate by 25%, at 4 mmol by 12%, and maximum performance by approximately 12%. The releasing hormone-stimulable prolactin, thyroid stimulating hormone (TSH) and somatotrophic hormone (STH) synthesis-secretion capacity remained unchanged, the adrenocorticotrophic hormone (ACTH) was increased after training. Cortisol release was reduced, follicle-stimulating hormone (FSH)-synthesis-secretion capacity was increased after training, and the luteinizing hormone (LH)-synthesis-secretion capacity reduced. This had no influence on base or exercise-induced serum hormone levels (cortisol, aldosterone, insulin, prolactin, FSH, LH, TSH, ACTH, ADH and STH), which showed no dependence on training, except for free testosterone which showed a decreasing trend (P < 0.10) of 19-25% and post-exercise ACTH which showed an increasing trend of 33% (P < 0.10). Conditioning (cortisol sensitivity and ACTH response) or adaptation (FSH and LH responses) to changed testosterone serum levels and altered spermatogenesis is discussed.

Adrenocorticotropic Hormone↗