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Biomedical subjects

N Bachl

Publications and source records attributed to N Bachl.

At least 19 recordsLinked to original sources
PubMed2006

Performance characteristics according to playing position in elite soccer.

The paper provides a large-scale study into the motion characteristics of top class soccer players, during match play, according to playing position. Three hundred top-class outfield soccer players were monitored during 20 Spanish Premier League and 10 Champions League games using a computerized match analysis system (Amisco Pro, Nice, France). Total distance covered in five selected categories of intensity, and the mean percentage of playing time spent in each activity were analyzed according to playing position. Midfield players covered a significantly greater total distance (p < 0.0001) than the groups of defenders and forwards did. Analyzing the different work rates showed significant differences (p < 0.5 - 0.0001) between the different playing positions. There were no significant differences between halves in the total distance covered, or in distances covered at submaximal and maximal intensities. However, significantly more distance was covered in the first half compared to the second in medium intensities (11.1 - 19 km/h). The current findings provide a detailed description of the demands placed on elite soccer players, according to their positional role at different work intensities, which may be helpful in the development of individualized training programs.

Humans↗
PubMed2006

Oral magnesium therapy, exercise heart rate, exercise tolerance, and myocardial function in coronary artery disease patients.

BACKGROUND: Previous studies have demonstrated that in patients with coronary artery disease (CAD) upward deflection of the heart rate (HR) performance curve can be observed and that this upward deflection and the degree of the deflection are correlated with a diminished stress dependent left ventricular function. Magnesium supplementation improves endothelial function, exercise tolerance, and exercise induced chest pain in patients with CAD. PURPOSE: We studied the effects of oral magnesium therapy on exercise dependent HR as related to exercise tolerance and resting myocardial function in patients with CAD. METHODS: In a double blind controlled trial, 53 male patients with stable CAD were randomised to either oral magnesium 15 mmol twice daily (n = 28, age 61+/-9 years, height 171+/-7 cm, body weight 79+/-10 kg, previous myocardial infarction, n = 7) or placebo (n = 25, age 58+/-10 years, height 172+/-6 cm, body weight 79+/-10 kg, previous myocardial infarction, n = 6) for 6 months. Maximal oxygen uptake (VO2max), the degree and direction of the deflection of the HR performance curve described as factor k<0 (upward deflection), and the left ventricular ejection fraction (LVEF) were the outcomes measured. RESULTS: Magnesium therapy for 6 months significantly increased intracellular magnesium levels (32.7+/-2.5 v 35.6+/-2.1 mEq/l, p<0.001) compared to placebo (33.1+/-3.1.9 v 33.8+/-2.0 mEq/l, NS), VO2max (28.3+/-6.2 v 30.6+/-7.1 ml/kg/min, p<0.001; 29.3+/-5.4 v 29.6+/-5.2 ml/kg/min, NS), factor k (-0.298+/-0.242 v -0.208+/-0.260, p<0.05; -0.269+/-0.336 v -0.272+/-0.335, NS), and LVEF (58+/-11 v 67+/-10%, p<0.001; 55+/-11 v 54+/-12%, NS). CONCLUSION: The present study supports the intake of oral magnesium and its favourable effects on exercise tolerance and left ventricular function during rest and exercise in stable CAD patients.

Administration, Oral↗
PubMed2005

Responses of N-terminal pro-brain natriuretic peptide (NT-proBNP) and cardiac troponin I (cTnI) to competitive endurance exercise in recreational athletes.

The present study was designed to investigate whether the stress of a half-marathon race can induce myocardial cell injury or left ventricular dysfunction in moderately trained runners of both gender, as assessed by post-race plasma concentrations of biochemical cardiac-specific markers and by quantitative echocardiographic measurements. We examined 12 male (mean+/-SD); age: 42.8+/-7.3 yr; height: 177.6+/-7.4 cm; body mass: 75.6+/-9.4 kg; BMI: 24.1+/-1.8 and 13 female (mean+/-SD); age: 39.0+/-6.5 yr; height: 164.6+/-6.2 cm; body mass: 58.4+/-9.8 kg; BMI: 21.5+/-3.4 recreational runners, who completed a half-marathon race. Blood samples were collected from each subject before the half-marathon race as well as 20 min and 2 h post-race and cardiac troponin I (cTnI) and N-terminal pro-brain natriuretic peptide (NT-proBNP) were measured. Quantitative echocardiographic analyses of wall dimensions and ejection fraction were also obtained from 14 of 25 subjects within 1 wk after the race. Both blood markers showed significant changes (p<0.05-0.001) over the time course of the three blood draws. A significant percentage of laboratory analytes analyzed in this study were outside the reference ranges and fulfilled conventional criteria for cardiac muscle damage. However, echocardiography within one week following the competition did not show any evidence that running a half-marathon competition damages the myocardium. Strenuous endurance exercise in middle-aged recreational runners induces a significant elevation of biochemical cardiac-specific markers, which may reflect transient subclinical myocardial damage, but can also reflect a physiological reparative or adaptive process.

Adult↗
PubMed2001

A physiological profile of tennis match play.

PURPOSE: The aim of this investigation was to examine physiological demands of single match play in tennis. METHODS: 20 players performed 10 matches of 50 min. Respiratory gas exchange measures (RGEM) and heart rates (HR) were measured using two portable systems. Lactate concentration was determined after each game. The average oxygen uptake (VO2) of 270 games was 29.1 +/- 5.6 mL.kg-1.min-1 (51.1 +/- 10.9% of VO2max). Average VO2 for a game ranged from 10.4 to 47.8 mL.kg-1.min-1 (20.4 and 86.8% of VO2max). Average lactate concentration (LA) was 2.07 +/- 0.9 mmol.L-1 (ranging from 0.7 to 5.2 mmol.L-1). Furthermore, we monitored the duration of rallies (DR), the effective playing time (EPT), and the stroke frequency (SF). The average values of 270 games were DR: 6.4 +/- 4.1 s, EPT: 29.3 +/- 12.1%, SF: 42.6 +/- 9.6 shots.min-1. RESULTS: Multiple regression revealed that the DR was the most promising variable for the determination of VO2 in match play (r = 0.54). The body surface area (BSA) and EPT were also entered into the calculation model. In games of two defensive players, VO2 was significantly higher than in games with at least one offensive player. CONCLUSION: Our results suggest that energy demands of tennis matches are significantly influenced by DR. The highest average VO2 of a game of 47.8 mL.kg-1.min-1 may be regarded as a guide to assess endurance capacity required to sustain high-intensity periods of tennis matches compared with average VO2 of 29.1 mL.kg-1.min-1 for the 270 games. Our results suggest that proper conditioning is advisable especially for players who prefer to play from the baseline.

Adult↗
PubMed2001

[Amount and intensity of physical exercise in primary prevention].

Numerous epidemiological studies have demonstrated an inverse relation between physical activity and physical "fitness" on one hand and premature death and the risk of chronic disease on the other hand. However, most of these studies showed crucial methodological and statistical differences, a fact which caused a lack of consensus of dose and intensity of physical activities for "health benefits". The optimal amount of physical activity to decrease mortality is in literature stated to range between 1,000 and 3,500 motoric kcal per week. Only a few data exist concerning the optimal intensity of preventive physical activities. There is some indication that only "vigorous" but not "non-vigorous" physical activities are associated with decreased mortality. Previous investigations suggest that a "threshold-intensity" (e.g. of at least 6 MET of "conditioning physical activity") is needed to produce an adequate preventive effect. On the other hand it has been documented, that "physical fitness" (endurance capacity) is a decisive factor for a decreased mortality. Therefore it may be assumed, that physical activities are only efficient for health benefits, if they also result in increased physical fitness. Following from this assumption the quality and quantity of training in primary prevention has to be adjusted to the individual requirements (performance, age, gender, health) of men.

Age Factors↗
PubMed2000

Comparison of laboratory and "on-court" endurance testing in tennis.

Treadmill testing (TT) commonly used in endurance testing is often not sport-specific. Therefore a field test (FT) for tennis players was developed. The purpose was 1) to compare metabolic and cardiorespiratory response between TT and FT and 2) to assess tennis stroke ratings during FT. In both tests ventilatory variables (VO2, VE, VT, Bf, VE x VO2(-1)), heart rate (HR), and lactate (LA) were measured. For both tests an "individual anaerobic threshold" (IAT) was calculated. The comparison of TT and FT yielded significant differences in cardiorespiratory and metabolic response. LA and VE were significantly higher in TT compared to FT at VO2 of 35, 40, and 45 ml x kg(-1) x min(-1). There were statistical differences between IAT resulting from both tests (TT vs. FT): HR (165+/-16, 175+/-11, p<0.001), VO2 (44.4+/-4.3, 47.8+/-4.8, p<0.05), LA (3.1+/-0.5, 2.5+/-0.4, p < 0.001), VE (97.0+/-15.6, 89.1+/-14.9, p < 0.05), VT (2.66+/-0.34, 2.34+/-0.47, p<0.05), VE/VO2 (27.9+/-3.9, 23.9+/-2.9, p<0.01). High correlation was found between stroke ratings and the national ranking of the players. We concluded that 1) metabolic, ventilatory, and cardiorespiratory demands of TT vs. FT were (semi)sport-specific and significantly different and 2) that the stroke rating in our study was a good predictor for tournament performance (r = 0.94). This type of stroke rating can be implemented in a FT.

Adult↗
PubMed2000

Change in left atrial and ventricular dimensions during and immediately after exercise.

PURPOSE: The aim of this study was to evaluate differences in the left atrial (LAD), total ventricular end-diastolic (TEDD), end-systolic diameters (TESD), and left ventricular shortening fraction (SF) compared with heart rate (HR) and systolic blood pressure (SBP) during exercise and recovery. METHODS: Healthy young male (N = 15) and female (N = 16) subjects performed an incremental cycle ergometer test in upright position, and three phases of energy supply were defined by means of blood lactate concentration (LA) and respiratory gas exchange variables (I: aerobic; II: aerobic-anaerobic transition; III: anaerobic). Subjects were required to rest their arms on a steering bar and to lean their upper body forward; two dimensional (2-D) echocardiograms were obtained over the left parasternal area at rest (R), at the end of each phase, immediately within 15 s post, and 6 min after exercise (6 min). By using VINGMED's "Anatomical M-Mode," it was possible to extract M-Mode Sweeps from stored 2-D-Loops and perform the M-Mode measurement. RESULTS: In contrast to the significant decrease in TEDD and TESD from III to 15 s up to resting values and the significant increase in SF from III to 15 s, the moderate decrease in HR immediately post exercise (15 s) was not significant. The SBP showed a significantly decrease from III to 15 s; in contrast to TEDD, TESD, and SF, the values at 15 s were comparable with the values at II. For LAD, significant increase during exercise and a decrease during recovery were observed. Sex-specific differences of changes in measured variables could not be found. CONCLUSION: We concluded that post exercise measurement of left ventricular and atrial dimensions or SF were not valid to describe heart function at maximal exercise although immediately post exercise HR was near maximal level.

Adult↗
PubMed1999

Measurement of maximal power output in isokinetic and non-isokinetic cycling. A comparison of two methods.

The main goal of the study was to compare maximal power output and power output at different pedalling frequencies obtained during isokinetic all-out tests with maximal power output obtained during a single all-out sprint (against the same braking force for every subject). Sixty healthy male subjects participated in the study. The ergometer system used in this study has three operating modes: the isokinetic mode (maintaining pedal crank velocity constant at a present level), a revolution dependent mode and a revolution independent mode. In all three operating modes the effective forces are monitored by means of strain gauge. All subjects performed a single all-out sprint against a braking force of 20 Newton and an all-out isokinetic cycling test consisting of ten 10 s bouts of maximal cycling at speeds ranging from 50 rpm to 140 rpm. In both tests, irrespective of which test mode was used, the mean power for a complete crank revolution showed parabolic relationships to crank velocity. For the isokinetic test, the subjects showed a peak power (IsoWpeak) of 15.3+/-1.7 W/kg corresponding to an optimal velocity of 115+/-8.6 rpm. For the force-velocity test NonisoWpeak (the highest power obtained at any time during the test) was 14.4+/-1.9 W/kg and was achieved at a pedalling rate of 127+/-14 rpm. IsoWpeak was significantly higher than NonisoWpeak (p<0.001) but there were no significant differences between NonisoWpeak and IsoWmax (maximal mean power for each full crank revolution) for the revolutions from 90 rpm to 140 rpm. Though, NonisoWpeak and IsoWpeak are significantly different, there was a strong relationship between NonisoWpeak and IsoWpeak (r = 0.7158, p<0.001). There was also a strong relationship between NonisoWpeak and IsoWmax for the revolutions from 50 rpm to 120 rpm (p<0.001) and at 130 rpm (p<0.01).

Adult↗
PubMed1999

The heart rate turn point reliability and methodological aspects.

PURPOSE: The aim of the study was to test protocol variations on the heart rate performance curve (HRPC) and the heart rate turn point (HRTP) according to Conconi et al. (1996). Respiratory gas exchange variables were used to define three phases of energy supply (I, II, III). METHODS: Eighteen healthy young male subjects performed 4 tests (T1-T4). T1: initial speed of 6 km x h(-1) followed by increments of 0.6 km x h(-1) every 60 s. Subjects were than randomized for the next three tests. T2: initial speed 5.6 km x h(-1) followed by increments of 0.2 km x h(-1) every 20 s; T3: similar to T2, in the second half of phase III acceleration (S) was increased. T4: like T2, at the beginning of phase III, S was increased. No differences were found in the degree of the deflection of the HRPC expressed as factor kHR between T1 (0.228 +/- 0.225) and T2 (0.248 +/- 0.231) but a significant increase was found in T3 (0.533 +/- 0.248) and T4 (0.770 +/- 0.258). RESULTS: The modifications of the protocol (T3 and T4) systematically influenced the deflection of the HRPC, but kHR was highly reproducible in all tests. Eleven subjects showed degrees of deflection in the HRPC in all tests. There were no significant differences for S, HR, and VO2 at the HRTP. An HRTP was not found in seven subjects in neither T1 or T2; however, in T3 and T4, these seven subjects showed a deflection of HRPC resulting from the protocol. The HRTP was found to be dependent on the start of the acceleration in phase III. In cases with a linear time course in the HRPC in T1 and T2, in T3 an HRTP was found at 15.6 km x h(-1) and in T4 at 13.6 km x h(-1) , respectively. CONCLUSION: The Conconi test protocol with an accelerated increase in S in the final phase of the test has a major influence on the occurrence of the HRTP in cases of near linear HRPC.

Adolescent↗
PubMed1998

Parasympathetic receptor blockade and the heart rate performance curve.

Parasympathetic receptor blockade and the heart rate performance curve. Med. Sci Sports Sci., Vol. 30. No. 2, pp. 229-233, 1998. The aim of the present study was to investigate the influence of parasympathetic receptor blockade on the heart rate performance curve (HRPC). Twenty healthy male subjects performed a first cycle ergometer test (F), showing a HRPC deflection of varying degree and direction. Subjects then in random order performed two additional cycle ergometer tests, one with atropine (A) and the other with placebo (P). Two lactate turn points (LTP1, and LTP2) were determined by means of linear regression turn point analysis. The degree and direction of the deflection of the HRPC was calculated mathematically as factor kHR (kHR>0 = downsloping of HPRC; kHR<0 = upsloping of HRPC). In comparison with that in F and P, HR in A was significantly higher at rest, LTP1, LTP2, and during recovery, but not at Power(max). An upsloping deflection of the HRPC was seen in only five cases in F and P, whereas in A 10 cases were observed (P < 0.05). In A, kHR was significantly lower than in F and P. A significant correlation for kHR was found among F, P, and A. Independent from parasympathetic receptor blockade and the HR at Power(max), the HR at LTP2 was lower in cases with negative kHR (upsloping). In A as well as in P a significant correlation was observed between kHR and HR at LTP2. The individual time course of HRPC is reproducible and may be independent of parasympathetic activity.

Adult↗
PubMed1998

The heart rate performance curve and left ventricular function during exercise in patients after myocardial infarction.

PURPOSE: The aim of the study was to investigate the heart rate turn point (HRTP) in the time course of the heart rate performance curve (HRPC) in patients after myocardial infarction, and the relationship between the HRTP, the left ventricular function, and the second lactate turn point (LTP2). METHODS: We studied the degree and the direction of the HRPC and the left ventricular ejection fraction (LVEF) in 49 male patients 57 +/- 8 d after their first posterior wall infarction (MI). An incremental cycle ergometer test was performed and three phases of energy supply were defined (I: aerobic; II: aerobic-anaerobic transition; III: anaerobic) via blood lactate LA concentration. HRTP and LVEF-turn points (LVEFTP) were assessed by linear turn point analysis. The degree and direction of the deflection of HRPC were described as factor k (k > 0.1: downward deflection; -0.1 < k < 0.1: linear time curse; k < -0.1: upward deflection). The LVEF was determined by RNA. The difference between Pmax and LTP2 was calculated for LVEF (delta LVEF). RESULTS: An HRTP could be found in 44 and a LVEFTP in 47 cases. The HRTP occurred at 85 +/- 17 Watt (W), which correlated (r = 0.95; P < 0.001) with the LTP2 (84 +/- 17 W) and the LVEFTP (84 +/- 17 W, r = 0.93; P < 0.001). From LTP2 to Pmax a significant decrease in LVEF was found. There was a correlation between the percentage of HRmax at the HRTP and k (r = 0.70), as well as delta LVEF (r = 0.56). CONCLUSIONS: To prevent myocardial overloading, it seems to be useful to determine the HRTP, which indicate the workload where LVEF decreases.

Anaerobic Threshold↗
PubMed1995

Metabolic and cardiorespiratory reactions in tennis-players in laboratory testing and under sport-specific conditions.

Metabolic and cardiorespiratory reactions were investigated during a sport-specific incremental field test (FT) for tennis and compared with a treadmill step test (TT) in a group of 13 trained male tennis players. In both the FT and the TT lactate acid (La), heart rate and oxygen uptake (VO2) were measured. VO2 was determined using a portable telemetric system (K2, Cosmed, Italy). Aerobic- (AT) and anaerobic threshold (ANT) at a blood lactate concentration of 2 mmol/l and at 4 mmol/l respectively was indicated to characterize the endurance capacity of the athletes. In both FT and TT, minimum value of lactate equivalent (LE(min)), measured in every exercise test, was also registered. At AT and ANT values for HR (AT: p < 0.001; ANT: p < 0.001) and VO2 (AT: p < 0.001; ANT: p < 0.001) were significantly higher in FT than in TT at submaximal loads. At LE(min) only higher values for HR (p < 0.05) were registered in FT. In contrast to maximum range significantly higher values for VO2 (p < 0.001) could be seen in TT (there were no significant differences for HR). Comparing maximum lactate (La(max)) subjects reached a higher lactate (p < 0.05) in TT. A particular aim of our investigation was to characterize the individual cardiopulmonal and metabolic adaptation of tennis players, considering sport-specific criteria. As a result, differences in cardiorespiratory and metabolic adaptations could be determined between laboratory TT and FT. This finding seems to point to the fact that, using field testing in addition to laboratory exercise testing, makes a better judgement of aerobic and anaerobic endurance under sport-specific conditions possible. Furthermore, it was important for us to put data, determined in the field test into practice, using the given pattern of the field test as an element of training. This kind of training has the advantage of combining an individually intensity-controlled specific endurance training for tennis with a training of technical skills.

Adult↗
PubMed1994

The constant velocity translatoric dynamo ergometer. A new approach to investigate neuromuscular, metabolic, and cardiovascular parameters.

The goal of this study was to investigate with the new dynamo ergometer the forces produced within a defined range of motion at a constant velocity during concentric translatoric work as well as to investigate fatigue based on neuromuscular and metabolic parameters. We examined 11 male sports students with the "Motomir" device with the subjects in a sitting position. The test consisted of four times 1 min of concentric leg work with 1-min rest phases in between. The subjects were asked to do maximum effort push movements with one leg and maximum effort pull movements with the other leg. The translatoric form of movement did not reveal any significant differences in strength between the left and right legs. The strength of the extensors was significantly higher than that of the flexors during all exercise stages (p < 0.001). A significant decrease in strength was established for extensor muscles and no significant decrease for the flexor muscles. The quotient of flexor/extensor was 0.43 +/- 0.07 in the first exercise stage and increased in every stage till the fourth. There was a correlation (p < 0.001) between the difference in lactate of the first and fourth exercise stages and the percentage of force decrease from the 1st to the 4th min. The electric activity of the vastus medialis, vastus lateralis, and gastrocnemius muscles decreased from the first to the fourth exercise stage. This decrease was however not significant. The translatoric constant velocity dynamo ergometer allows both diagnosis and training at varying angles and varying speeds while avoiding unphysiological maximum loads.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[Principles of muscle efficiency in weightlessness].

Depending on the time spent in a space station, weightlessness causes varying changes to various organs and regulatory mechanisms of the human organism, among them the structures of the active and passive locomotor system. Experience has shown that regular physical activity using varying forms of training is necessary to keep astronauts and cosmonauts healthy, efficient and fit for work and to prepare them for a safe return to terrestrial conditions. One of the main tasks of physical activity is therefore to counteract the changes in the neuromuscular function, muscle strength, endurance and fatigability under conditions of weightlessness. So far, the diagnostics of these changes was limited to dynamometric measurements before and after space flights as no dynamometric method had been devised which was precise enough under conditions of weightlessness. The development and the introduction of the dynamoergometer Motomir is described against the background of previous results obtained by dynamometric, ergometric, morphometric, biochemical, histochemical and neuromuscular examinations before and after missions of varying duration under conditions of weightlessness. This device was used for the first valid and reproducible examinations of muscle strength and endurance aboard the space station Mir during the Austro-Russian space mission Austromir. The results of the examinations with this speed-controlled dynamometer and training device obtained during a short-term flight of 10 days and a long-term flight of 6 months are described and compared to previous results in the literature. Based on the existing training devices, training methods and training plans and the results of the Motomir Study, plans for devices and methodologies for future long-term space flights of up to 3 years' duration will be discussed. Finally, the possible use of a speed-controlled dynamometer and training device for rehabilitation on earth after injuries, surgery and immobilization of the active and passive locomotor system as well as in the bed-rest syndrome is being presented.

Animals↗
PubMed1992

Decreased nocturnal catecholamine excretion: parameter for an overtraining syndrome in athletes?

The effectiveness of high performance training should be examined at short intervals in order to recognize overtraining promptly. Field or laboratory tests can usually not be performed with such frequency. Easy-to-measure biological, training-relevant parameters are being sought to use in their place. Since the importance of the sympathetic nervous system for adaptation of stress and the relationship between physical training and the activity of the sympathetic nervous system are well accepted, and since an impairment of the sympathetic nervous system is assumed in an overtraining syndrome, we examined the relevance of nocturnal "basal" urinary excretion of free catecholamines with respect to its practical application: 1. during a pilot study (training of road and track cyclists before the 1988 Olympic Games in Seoul), 2. through a 4-week prospective, experimental study in 1989 and 1990 (middle- and long-distance runners), 3. during the competitive season and winter break of a soccer team between August 1990 and April 1991. The following hypothesis was made: An overtraining or exhaustion syndrome in athletes may usually be accompanied by at least a 50% decrease in basal dopamine, noradrenaline and adrenaline excretion. When training is effective or the athletes are not exhausted, the decrease of the excretion rate--with the exception of dopamine--is more likely to be lower (noradrenaline, adrenaline). Generalization of these results requires further expansion of the experimental basis.

Adult↗
PubMed1992

Catecholamine excretion and heart rate as factors of psychophysical stress in table tennis.

Table tennis, like tennis, squash and badminton, is a racket sport. All these sports have in common a rapid succession of mostly short-term maximal or submaximal efforts and short recovery phases. The goal of this paper is to investigate the psychophysical stress in table tennis by means of the stress hormones epinephrine and norepinephrine. The catecholamines were determined from urine samples. 16 Austrian top-level table tennis players were examined. There were 8 female and 8 male players in this group. The catecholamine excretion at rest (R), training (TR), practice competition (PC), competition (C) and treadmill ergometry (TE) are indicated in ng/min of collecting time. When the group is divided according to sex, we find marked differences in the catecholamine release. While the epinephrine excretion during and after training and practice competition is basically the same, it is lower during and after treadmill ergometry and higher after competition. The same result was found with respect to norepinephrine excretion. The ratio between norepinephrine and epinephrine was 4:1 at rest and during and after treadmill ergometry, 6:1 during and after training, 5:1 during and after the practice competition and 2:1 during and after the competition. The investigation showed that a table tennis competition puts high stress on the player. The mental component should therefore receive much more importance in order to keep the stress low.

Adolescent↗