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PubMed2003

Physical and physiological factors associated with success in professional alpine skiing.

Scientific data on the physiological profile of world class skiers are sparse. During the last decade the Austria Ski Team was the most successful in the world. It was the objective of this study to describe the physical and physiological characteristics of World Cup (WC) skiers. Twenty female and 28 male members of the Austrian WC Ski Team were examined pre- and post-seasonally from 1997 to 2000. Physical parameters such as age, height, body mass, body mass index, percent body fat and thigh circumference were recorded from each athlete. The physiological variables investigated consisted in the aerobic power and in the muscle strength of the lower limbs. Racing performance was defined by the WC ranking position. The athlete's aerobic performance capacity was assessed by maximal exercise testing on a bicycle ergometer, and the isokinetic muscle strength of the knee extensor and flexor muscles by the use of a computer-interfaced dynamometer. From 1997 to 2000 about half (48 %; n = 106) of all alpine WC racing events (n = 221) were won by the athletes investigated. The typical world class skier is in the mid-twenties (25.2 y [female]; 27.6 y [male]). The mean values for height were 1.66 m (female) vs. 1.81 m (male), for body mass 65.1 kg (female) vs. 87 kg (male) and for the percentage of body fat 24.5 % (female) vs. 15.8 % (male). The maximum power output was 4.3 +/- 0.4 (female ) and 4.7 +/- 0.4 W/kg (male), the corresponding values for VO(2)max were 55 +/- 3.5 (female) and 60 +/- 4.7 ml/kg/min (male). The maximal values for peak torque and work for knee extension amounted to 206 +/- 21 (female) and 334 +/- 43 Nm (male), and 2690 +/- 364 (female) and 4414 +/- 629 J (male), respectively. In both sexes there were neither significant laterality nor dysbalance. The hamstring/quadriceps ratios were between 0.57 - 0.60. Among all physical and physiological variables, only the aerobic power in males was found to be strongly correlated (r = 0.947; p = 0.001 for W (max); r = 0.964; p < 0.001 for VO(2)max) to racing performance. The study proves the practical experience that success in professional alpine skiing is not related to single physiological variables. Two main factors, however, are crucial, i. e. high levels of aerobic power and muscle strength.

Adult↗

PubMed2000

Effect of gender, sex hormones, time variables and physiological urinary pH on apparent CYP2D6 activity as assessed by metabolic ratios of marker substrates.

The effects of gender, time variables, menstrual cycle phases, plasma sex hormone concentrations and physiologic urinary pH on CYP2D6 phenotyping were studied using two widely employed CYP2D6 probe drugs, namely dextromethorphan and metoprolol. Phenotyping on a single occasion of 150 young, healthy, drug-free women and men revealed that the dextromethorphan: dextrorphan metabolic ratio (MR) was significantly lower (P < 0.0001) in 56 female extensive metabolizers (0.008+/-0.021) compared to 86 male extensive metabolizers (0.020 +/-0.040). Urinary pH was a significant predictor of dextromethorphan: dextrorphan MRs in men and women (P < 0.001). Once-a-month phenotyping with dextromethorphan of 12 healthy young men (eight extensive metabolizers and four poor metabolizers) over a 1-year period, as well as every-other-day phenotyping with dextromethorphan of healthy, pre-menopausal women (10 extensive metabolizers and 2 poor metabolizers) during a complete menstrual cycle, did not follow a particular pattern and showed similar intrasubject variability ranging from 24.1% to 74.5% (mean 50.9%) in men and from 20.5% to 96.2% (mean 52.0%) in women, independent of the CYP2D6 phenotype (P = 0.342). Using metoprolol as a probe drug, considerable intrasubject variability (38.6+/- 12.0%) but no correlation between metoprolol: alpha-hydroxymetoprolol MRs and pre-ovulatory, ovulatory and luteal phases (mean +/- SD metoprolol: a-hydroxymetoprolol MRs: 1.086+/- 1.137 pre-ovulatory; 1.159+/-1.158 ovulatory and 1.002+/-1.405 luteal phase; P> 0.9) or 17beta-oestradiol, progesterone or testosterone plasma concentrations was observed. There was a significant inverse relationship between physiologic urinary pH and sequential dextromethorphan: dextrorphan MRs as well as metoprolol: alpha-hydroxymetoprolol MRs in men and women, with metabolic ratios varying up to six-fold with metoprolol and up to 20-fold with dextromethorphan (ANCOVA P < 0.001). We conclude that apparent CYP2D6 activity is highly variable, independent of menstrual cycle phases, sex hormones, time variables or phenotype. Up to 80% of the observed variability can be explained by variations of urinary pH within the physiological range. An apparent phenotype shift as a result of variations in urinary pH may be observed in individuals who have metabolic ratios close to the population antimode.

Administration, Oral↗

PubMed1990

The abdominal trauma index--a critical reassessment and validation.

The Abdominal Trauma Index (ATI) was devised to quantify the risk of complications following abdominal trauma. With scores greater than 25, the risk of postoperative complications became exponential. The purpose of the present study was to determine if: 1) the organ risk factors previously assigned were more statistically valid; and 2) the addition of physiologic variables would enhance the prediction of postinjury intra-abdominal sepsis. Fifteen abdominal organ systems and 17 physiologic variables in 300 consecutive patients were analyzed to determine ability to predict intraabdominal sepsis. There were no significant differences in predictive ability between the old and new organ risk factors. The addition of physiologic factors did not enhance the prediction of intra-abdominal sepsis. This clinical study demonstrates that: 1) the risk of intra-abdominal sepsis increases with increasing ATI score; 2) the previous (1979-initial) organ risk grading concept is statistically valid; 3) six of the 15 organ systems warrant a change in their relative rank order (1989-revision); 4) the addition of demographic, physiologic, and immunologic variables did not significantly improve the prediction of intra-abdominal sepsis.

Abbreviated Injury Scale↗

PubMed1992

Psychological and physiological predictors of lipids in black males.

The association between lipids and both psychological and physiological measures were examined in this study of healthy black males. The results revealed that certain psychological measures, namely, State and Trait Curiosity and Trait Anger, explained a significant proportion of the variance in high-density lipoproteins (HDL), low-density lipoproteins (LDL), and triglycerides. Although psychological factors accounted for a significant proportion of the variance in lipids (29% for HDL, 25% for LDL, 64% for LDL/HDL, 29% for triglyceride), the amount of explained variance was significantly increased by the inclusion of both psychological and physiological variables in the regression equation. However, neither of the psychological variables explained any of the variance for total cholesterol when physiological variables were included in the regression analysis. The overall pattern of the findings suggests that black males who are at increased risk for elevated lipid levels may be identified by their level of mental vigilance, the frequency at which their anger is experienced, and the presence of other traditional risk factors.

Adult↗

PubMed1994

Behavioral states in the fetal baboon.

This study was designed to characterize behavioral states in the fetal baboon. Automated methods were developed and validated to recognize behavioral states based on relationships among three physiologic variables (EEG patterns, eye movements, heart period variability). Data included twelve 16-h records from 3 chronically instrumented fetal baboons at 0.8-0.9 of term. Randomly generated control records were used to differentiate occurrences of state from chance association of the variables. For 41.2 +/- 4.6% (mean +/- S.E.) of the time, the physiologic variables were synchronous and formed cycles of state with a mean duration of 34.4 min. Components of these cycles had mean +/- S.E. durations of 7.2 +/- 0.3 min for state 1FB (the analogue of quiet sleep in the human infant and state 1F in the human fetus), 20.7 +/- 1.2 min for the state 2FB (the analogue of active sleep in the human infant and state 2F in the human fetus), and 3.6 +/- 0.2 min for state transitions. For 24.6 +/- 2.4% of the time, the state variables exhibited coincidental, state-like agreements, that were not part of state cycles. Finally, for 34.3 +/- 2.7% of the time, there was no systematic agreement among the three variables. These data provide convincing evidence that organized behavioral states are present in the fetal baboon as early as 0.8 of term gestation.

Algorithms↗

PubMedDate not supplied

Plasma fibrinogen and ischemic heart disease risk factors.

The association between risk factors for ischemic heart disease and plasma fibrinogen level was analyzed in a cross-sectional population study. All 51-year-old men living in a certain area within the county of Copenhagen were invited; 439 of 542 (81%) participated in the study. Data were collected via questionnaire and at health examinations. The following independent variables were analyzed: social variables, which included social class, marital status, and job strain; psychological and psychosomatic variables, which included abdominal pain, personal and economic problems, self-assessed state of health, and degree of loneliness; behavioral variables, which included smoking, drug consumption, physical activity, use of sugar, and alcohol consumption; and physiological variables, which included high density lipoprotein (HDL) and low density lipoprotein (LDL) cholesterol, physical fitness, fasting glucose level, waist-to-hip ratio, and systolic blood pressure. In the multivariate analyses, the following variables showed an independent positive association with plasma fibrinogen level: one social variable (low social class); two psychological variables (abdominal pain index and personal/economic problems); two behavioral variables (smoking and physical inactivity during leisure time); and three physiological variables (low HDL cholesterol, low physical fitness, and high LDL cholesterol). The strongest independent associations with plasma fibrinogen level were found for smoking, social class, LDL cholesterol, and HDL cholesterol. These analyses suggest that smoking is a major risk factor for an elevated plasma fibrinogen level, but that other factors such as social class, cholesterol level, physical inactivity/physical fitness, and psychological problems also influence plasma fibrinogen level.

Abdominal Pain↗

PubMed1995

Scaling, normalizing, and per ratio standards: an allometric modeling approach.

The practice of scaling or normalizing physiological variables (Y) by dividing the variable by an appropriate body size variable (X) to produce what is known as a "per ratio standard" (Y/ X), has come under strong criticism from various authors. These authors propose an alternative regression standard based on the linear regression of (Y) on (X) as the predictor variable. However, if linear regression is to be used to adjust such physiological measurements (Y), the residual errors should have a constant variance and, in order to carry out parametric tests of significance, be normally distributed. Unfortunately, since neither of these assumptions appear to be satisfied for many physiological variables, e.g., maximum oxygen uptake, peak and mean power, an alternative approach is proposed of using allometric modeling where the concept of a ratio is an integral part of the model form. These allometric models naturally help to overcome the heteroscedasticity and skewness observed with per ratio variables. Furthermore, if per ratio standards are to be incorporated in regression models to predict other dependent variables, the allometric or log-linear model form is shown to be more appropriate than linear models. By using multiple regression, simply by taking logarithms of the dependent variable and entering the logarithmic transformed per ratio variables as separate independent variables, the resulting estimated log-linear multiple-regression model will automatically provide the most appropriate per ratio standard to reflect the dependent variable, based on the proposed allometric model.

Exercise↗

PubMed1996

Circadian variation in sports performance.

Chronobiology is the science concerned with investigations of time-dependent changes in physiological variables. Circadian rhythms refer to variations that recur every 24 hours. Many physiological circadian rhythms at rest are endogenously controlled, and persist when an individual is isolated from environmental fluctuations. Unlike physiological variables, human performance cannot be monitored continuously in order to describe circadian rhythmicity. Experimental studies of the effect of circadian rhythms on performance need to be carefully designed in order to control for serial fatigue effects and to minimise disturbances in sleep. The detection of rhythmicity in performance variables is also highly influenced by the degree of test-retest repeatability of the measuring equipment. The majority of components of sports performance, e.g. flexibility, muscle strength, short term high power output, vary with time of day in a sinusoidal manner and peak in the early evening close to the daily maximum in body temperature. Psychological tests of short term memory, heart rate-based tests of physical fitness, and prolonged submaximal exercise performance carried out in hot conditions show peak times in the morning. Heart rate-based tests of work capacity appear to peak in the morning because the heart rate responses to exercise are minimal at this time of day. Post-lunch declines are evident with performance variables such as muscle strength, especially if measured frequently enough and sequentially within a 24-hour period to cause fatigue in individuals. More research work is needed to ascertain whether performance in tasks demanding fine motor control varies with time of day. Metabolic and respiratory rhythms are flattened when exercise becomes strenuous whilst the body temperature rhythm persists during maximal exercise. Higher work-rates are selected spontaneously in the early evening. At present, it is not known whether time of day influences the responses of a set training regimen (one in which the training stimulus does not vary with time of day) for endurance, strength, or the learning of motor skills. The normal circadian rhythms can be desynchronised following a flight across several time zones or a transfer to nocturnal work shifts. Although athletes show all the symptoms of 'jet lag' (increased fatigue, disturbed sleep and circadian rhythms), more research work is needed to identify the effects of transmeridian travel on the actual performances of elite sports competitors. Such investigations would need to be chronobiological, i.e. monitor performance at several times on several post-flight days, and take into account direction of travel, time of day of competition and the various performance components involved in a particular sport. Shiftwork interferes with participation in competitive sport, although there may be greater opportunities for shiftworkers to train in the hours of daylight for individual sports such as cycling and swimming. Studies should be conducted to ascertain whether shiftwork-mediated rhythm disturbances affect sports performance. Individual differences in performance rhythms are small but significant. Circadian rhythms are larger in amplitude in physically fit individuals than sedentary individuals. Athletes over 50 years of age tend to be higher in 'morningness', habitually scheduling relatively more training in the morning and selecting relatively higher work-rates during exercise compared with young athletes. These differences should be recognised by practitioners concerned with organising the habitual regimens of athletes.

Circadian Rhythm↗

PubMed1993

Handshaking, personality, and psychopathology in psychiatric patients, a reliability and correlational study.

A study of 29 psychiatric inpatients was performed to investigate the relation of handshaking variables (anatomical and physiological variables) with demographic data, personality traits, psychosocial functioning, and clinical diagnoses. Two psychologists rated patients' handshaking independently of each other according to four variables on an ordinal scale of five steps. The interrater reliability was satisfactory. Analysis showed that the handshaking procedure may in fact give some information about the personality make-up of the patients, most clearly through the relationship between low temperature and humidity of the palmar skin and social introversion, depression, and tendency towards symptom enhancement mainly in women. The handshaking procedure did not seem informative about psychosocial functioning and clinical diagnoses.

Adult↗

PubMed1990

Hyperventilation and panic attacks.

The role of hyperventilation in the aetiology of panic attacks is still unclear. This paper briefly reviews the role of hyperventilation and abnormal respiration to panic attacks and examines the experimental evidence. Evidence has been found that physiological variables such as paCO2 and pH are involved in the aetiology of panic attacks and panic disorder but the extent and the nature of the involvement of cognitive variables is undetermined. Based on current evidence, there is a need to integrate cognitive variables with the physiological framework proposed by the hyperventilation theory. Until clear experimental evidence is produced about the relationships between cognitive and physiological factors, the applicability of hyperventilation in the aetiology and treatment of panic attacks remains in question.

Agoraphobia↗

PubMed1975

The assessment of near vision.

There are many variables in the physiology of near vision, the end-point criteria, the types available, and the measurements made. I have suggested a hard criterion of the smallest print at the nearest distance. This controls the physiological variables and provides repeatable data for the evaluation of vision, accommodation, and binocular function.

Accommodation, Ocular↗

PubMed1977

[Fibrinogen level in clinically healthy horses].

Various sets of horses were examined in view of the necessity of widening the range of biochemical substances for diagnostic purposes in the field of veterinary medicine. The aim of the investigations was to obtain basic information on fibrinogen level and its variability. The average value stated was 280 mg% s = 89, sx = 12, V% = 32). The fibrinogen level in horses of the pronounced oxidation type was lower than in those with reduced metabolism, the difference being connected with the speed of sedimentation of erythrocytes. Repeated examination of a part of the set of horses (n = 10) on three different days within one week under the same conditions, showed a nonsignificant difference in the variability of the investigated horses (F = 0.901); neither did the coefficient of repeatability (rop = 0.11) reach the level of the testing criterion. The results indicate variability, with normal physiological condition of the animal, in the fibrinogen level. The physiological variability in fibrinogen level can also be explained in connection with other protein fractions.

Animals↗

PubMedDate not supplied

Heart rate and blood pressure chronomes during and after pregnancy.

Whereas conventional time-unspecified single measurements of blood pressure and heart rate may mislead, influenced as they are, among other factors, by the individual's emotional state, position, diet and external stimuli generally, the chronobiologic evaluation of predictable variability in these physiologic variables assesses early cardiovascular disease risk in pregnancy by (a) the use of fully ambulatory devices and (b) the proper processing of the time series thus obtained. We have used this approach to quantify changes in 24-h synchronized circadian characteristics of cardiovascular variables in two consecutive pregnancies of a clinically healthy woman. The results were then compared with those obtained from data sampled after the second pregnancy. Blood pressure and heart rate were automatically monitored, at 1-h intervals, each time for at least 48 consecutive hours, and for a total of 76 days of monitoring in each pregnancy. Circadian parameters of those circulatory variables were computed for each 48-h profile of measurements by the least-squares fit of a 24-h cosine curve. Regression analysis of parameters thus obtained revealed patterns of variation of circadian rhythm-adjusted means and amplitudes with gestational age. In both pregnancies, the predictable variability of the circadian rhythm-adjusted mean of blood pressure can be approximated by a second-order polynomial model on gestational age: a steady linear decrease in systolic, mean arterial and diastolic blood pressures up to the 22nd week of pregnancy is followed by an increase up to the day of delivery. This pattern of variation is not found for data similarly sampled during non-pregnancy on the same woman. This longitudinal study confirms and extends to ambulatory everyday life conditions the predictable pregnancy-associated variability in blood pressure and heart rate and also allows the establishment of prediction and confidence limits for cardiovascular parameters in a healthy pregnancy.

Animals↗

PubMed2000

Physiological correlates of bilateral symmetry in humans.

Departures from perfect bilateral symmetry are thought to mirror an organism's ability to maintain developmental homeostasis. There is evidence showing that symmetry is negatively correlated with evolutionary and physical fitness. The purpose of this study was to determine the relationship between symmetry and health-related physiological characteristics in males and females. Forty-six male and female subjects participated in this study. Both facial and anthropometric traits were investigated for deviations from perfect bilateral symmetry. After measurements were made the subjects were tested on a range of physiological variables. There was no pattern of consistent significant correlations between fluctuating asymmetry and the physiological variables across all traits, and poor inter-correlations between the fluctuating asymmetries measured at different sites. The study failed to confirm the hypothesis that symmetric individuals were physiologically fitter when compared to their asymmetric counterparts.

Adaptation, Physiological↗

PubMed2005

An evaluation of a vibro-tactile display prototype for physiological monitoring.

Visual displays and auditory alarms are used to convey information on physiological variables in an operating room. However, the exponential growth in the number of physiological variables and the high probability of false alarms has amplified demands on the clinician's attention. We have extended existing tactile technology to improve situational awareness and produce a practical clinical advisory device. A vibro-tactile display, using two vibrating motors applied to the volar surface of the forearm, was compared to an auditory alarm in a simulated clinical environment. Compared with auditory alarms, the vibro-tactile alarm was as easy to learn and had a better identification rate when used alone or combined with the auditory alarm. Most users preferred the vibro-tactile alarm although the prototype caused some discomfort. Furthermore, a combined vibro-tactile and auditory alarm had reduced accuracy when compared with the vibro-tactile alarm alone. The vibro-tactile modality shows considerable promise for clinical practice but will require further clinical testing and refinement, especially with regard to user comfort.

Anesthesiology↗

PubMed2004

Which laboratory variable is related with time trial performance time in the Tour de France?

OBJECTIVE: To investigate the relationship between several physiological variables that can be easily obtained during cycle ergometer gradual testing (for example, peak power output (W(peak)), Vo(2max), or ventilatory threshold (VT)) and actual (>50 km) time trials (TT) time performance during the Tour de France. METHODS: We collected data in professional cyclists from the first TT of the 1998 Tour de France (TT1, 58 km distance; n = 6 cyclists) and the first (TT2, 56.5 km; n = 5) and second TT of the 1999 Tour de France (TT3, 57 km; n = 5). RESULTS: A negative relationship was found between power output (W) at VT (VT(Watt)) and TT final time (s) in TT1 (r = -0.864; p = 0.026; standard error of estimate (SEE) of 73 s; and 95% confidence limits (95% CL) -0.98; -0.18), TT2 (r = -0.77; p = 0.27; SEE of 139 s; and 95% CL -0.98; 0.35), and TT3 (r = -0.923; p = 0.025; SEE of 94 s; and 95% CL -1.00; -0.22). CONCLUSIONS: Actual performance in long TT during the Tour de France (>50 km distance, performed after at least 1-2 weeks of continuous competition), in which some cumulative fatigue inevitably occurs, is related, at least in part, to the power output that elicits the VT. No other routine physiological variable (for example, Vo(2max) or W(peak)) is related to performance in this type of event.

Adult↗

PubMedDate not supplied

Circulatory responses to acute asphyxia are not affected by the glutamate antagonist lubeluzole in fetal sheep near term.

OBJECTIVE: Asphyxia is one of the main causes of perinatal brain damage that can result in psychomotor deficits during later development. Recently lubeluzole, a new glutamate antagonist, was shown to improve clinical outcome considerably without any safety concerns in adults who had acute ischemic stroke. However, our preliminary experiments showed transient alterations in heart rate as well as arterial hypertension after intravenous application of this compound in fetal sheep. The aim of the present study was to examine in detail whether lubeluzole affects circulatory responses to acute asphyxia in fetal sheep near term. METHODS: Eleven fetal sheep were chronically instrumented at a mean gestational age of 133 +/- 2 days (term is at 147 days). The fetuses in the study group (n = 6) received three bolus injections of lubeluzole at 30-minute intervals (3 x 0.11 mg/kg estimated body weight), and five controls received solvent. Organ blood flows and physiologic variables were measured before, during, and after arrest of uterine blood flow for 2 minutes (ie, at 0, 1, 2, 3, 4, and 30 minutes). RESULTS: Before asphyxia, distribution of combined ventricular output and physiologic variables in fetuses from the control group were in the normal range for chronically prepared fetal sheep near term. During acute asphyxia there was a redistribution of cardiac output toward the central organs accompanied by pronounced bradycardia and progressive increase in arterial blood pressure. There were nearly no differences between groups in the time course of physiologic and cardiovascular variables measured before, during, and after acute intrauterine asphyxia. CONCLUSION: Lubeluzole did not affect circulatory responses to acute asphyxia in fetal sheep near term.

Animals↗

PubMed1976

[The time-course of alcohol induced changes in self-rating-scales of mood (author's transl)].

Alcohol was administered in a dose of 0.77 g per kg bodyweight to 16 healthy male subjects in a cross-over-design. A study was made of a number of psychological and physiological variables to determine the modifications that accompany the alcohol-induced changes in the orienting response to an auditory stimulus. Five determinations were made at intervals following a dose of alcohol and five in a control session when no alcohol was given. The results obtained for the psychological variables (self-ratings of the intensity of intoxication and the degree of being startled by the first stimulus; and self-assessment of mood) show alcohol to have stimulant as well as depressant effects. Some of the variables show stimulant effects, mainly at the beginning of the absorption phase, whereas other variables show depressant effects, both in the absorption phase and the postabsorption phase. Changes in physiological variables (such as parameters of electrodermal activity and of the heart rate response) support these findings. The simultaneous presence of both stimulant and depressant effects is pointed out as well as the difficulties in describing these findings in terms of a unidimensional model of activation.

Adult↗