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PubMed2000

Detection of susceptibility effects using simultaneous T(2)* and magnetic field mapping.

Tracking susceptibility effects is a convenient way to detect small inclusions in a bulk tissue matrix by MRI. We propose a quantitative assessment of these susceptibility effects by simultaneously mapping T(2)* and magnetic field from the time course of magnitude and phase using a multiple GE sequence at 4.7 T. A high-pass scheme is also introduced to highlight the mesoscopic magnetic field variations due to local susceptibility differences specifically in the magnetic field map. Applying this method to muscle tissue, we demonstrate that connective tissue generates detectable susceptibility effects through concomitant local magnetic field variation and T(2)* shortening.

Adipose Tissue↗
PubMed1975

Field dependence and physical ability.

Field-dependence scores of professional dancers, highly skilled performers in tennis, soccer, cricket and track and field athletics, medium-ability level players in the same four sports and a group of non-game players were measured using a rod and frame test. Results showed that highly skilled tennis players were significantly more field-dependent than top-class track and field athletes and medium-ability level tennis players.

Aptitude↗
PubMedDate not supplied

Selected kinematic characteristics of intercollegiate women triple jumpers.

Eight women triple jump finalists at the 1986 Big Ten Track and Field Championships and 10 women triple jump finalists at the 1986 National Track and Field Competition were filmed during competition. Among selected kinematic characteristics, the following high correlations (r greater than 0.70) were found: the distance of the hop phase correlated highly with the total jump distance; the horizontal position of the center of gravity of the body in relation to the support foot at takeoff correlated highly with the distance of the hop and the jump phases; the horizontal velocity into the step phase correlated highly with the total distance of the jump; the vertical velocity into the hop and step phases correlated highly with the respective phase distance; and there was an inverse correlation between the maximum height of the center of gravity during the flight phase of the step and the total distance. A significant difference was found between men and women triple jumpers in relation to the contribution of the step phase to the total distance of the jump (men, means = 29.5, SD = 1.46; women, means = 26.7, SD = 2.94; P less than 0.05). All remaining relationships among the kinematic variables studied were found to be not significant at P less than 0.05 or were less than r = 0.70. The phase ratios of current women triple jumpers were similar to ratios that have been reported for the novice athlete.

Biomechanical Phenomena↗
PubMed2004

Radiographic changes in the lumbar spine in former elite athletes.

STUDY DESIGN: The authors conducted a retrospective cohort study. OBJECTIVE: The objective of this study was to clarify the occurrence of radiographic changes (vertebral osteophytes, heights of lumbar discs, concavity index) of the lumbar spine in former elite athletes of different track and field disciplines. SUMMARY OF BACKGROUND DATA: The influence of physical activity on occurrence of radiographic changes in the lumbar spine is not well known and seems to be contradictory. The loadings in the different track and field disciplines seem to play an important role in the development of radiographic changes. METHODS: One hundred fifty-nine former male elite track and field athletes were selected for a radiologic study. The heights of lumbar discs, the concavity index, the presence of anterior vertebral osteophytes, a radiographic evaluation according to Kellgren and Lawrence, and the FFbH-R score for the assessment of functional limitations in activities of daily living (ADLs) were determined. The influence of age, body mass index, current physical activity, and training history was also examined. RESULTS: In high jumpers and throwers, the absolute heights of lumbar discs increased from level T12/L1 to a maximum at L4/L5 and decreased again from level L4/L5-L5/S1. In endurance athletes and other jumpers, the absolute heights increased linearly from level T12/L1 to a maximum at L5/S1. The concavity index did not yield any significant differences between athlete categories. Shot putters, discus throwers, and high jumpers showed a significantly higher prevalence of osteophytes after adjustment for possible confounders. According to Kellgren and Lawrence, the highest prevalence of radiographic changes in the lumbar spine is seen in javelin throwers. Significant differences in the assessment of functional limitations in ADLs are not found between the disciplines. CONCLUSION: In throwing disciplines, the lumbar spine is more highly loaded than in jumpers and runners. Despite the observation of evident degenerative changes in some former athletes, there were only minor changes seen in ADLs. Even if body constitution is taken as a preselection factor, athletes in throwing disciplines as well as high jumpers have a higher risk of developing vertebral osteophytes of the lumbar spine.

Adult↗
PubMed1977

Migrating birds respond to Project Seafarer's electromagnetic field.

Radar tracking of individual migrating birds flying over a large alternating-current antenna system showed that the birds turned or changed altitude more frequently when the antenna system was operating than when it was not. These results suggest that birds sense low-intensity alternating-current electromagnetic fields during nocturnal migratory flight.

Animals↗
PubMed1998

Eye tracking abnormalities in schizophrenia: evidence for dysfunction in the frontal eye fields.

BACKGROUND: Eye tracking deficits are robust abnormalities in schizophrenia, but the neurobiological disturbance underlying these deficits is not known. METHODS: To clarify the pathophysiology of eye tracking disturbances in schizophrenia, we tested 12 first-episode treatment-naive schizophrenic patients and 10 matched healthy individuals on foveofugal and foveopetal step-ramp pursuit tasks. RESULTS: On foveopetal tasks, the initiation of pursuit eye movements was delayed in schizophrenic patients, and their steady-state pursuit gain was reduced particularly at slower target speeds (8 and 16 deg/sec). In foveofugal step-ramp tasks, their primary catch-up saccades were normal in latency and accuracy, but their postsaccadic pursuit in the first 100 msec after the primary catch-up saccade was significantly reduced even relative to their slow steady-state pursuit, especially during and immediately after an acute episode of illness. CONCLUSIONS: These observations indicate that motion-sensitive areas in posterior temporal cortex provide sufficiently intact information about moving targets to guide accurate catch-up saccades, but that the sensory processing of motion information is not being used effectively for pursuit eye movements. Low-gain pursuit after the early stage of pursuit initiation suggests that the use of extraretinal signals about target motion (e.g., anticipatory prediction) only partially compensates for this deficit. The pattern of low-gain pursuit, impaired pursuit initiation, and intact processing of motion information for catch-up saccades but not pursuit eye movements, was consistent in the schizophrenic patients tested at five time points over a 2-year follow-up period, and implicates the frontal eye fields or their efferent or afferent pathways in the pathophysiology of eye tracking abnormalities in schizophrenia.

Adult↗
PubMedDate not supplied

Age differences in growth and physical abilities in trained and untrained girls 10-17 years of age.

The purpose of the present study was to assess the age differences in growth characteristics and physical abilities of physically active adolescent girls and to compare them to corresponding data for girls nonactive in sport. The cross-sectional study was carried out on 643 Estonian girls, 10-17 years of age, who were regularly training track and field, and 902 nonactive girls. The organized physical activity of the studied girls consisted of lessons in the school curriculum (2 x 45 minutes per week) for both groups and special track and field training for the first group. Height, weight, and the body mass index (BMI) were used to characterize growth status. Physical ability was assessed with the 30-m dash, standing long jump, medicine ball throw (2 kg), standing quintuplet jump, isometric strength of back extensor muscles, and 1-minute ergocycling at the highest possible rate. Girls active in track and field were taller in all the age groups (P < 0.05-0.001) and lighter except at 17 years, when they were heavier (P > 0.05), but the differences at 12 and 13 years were not significant. BMI was also significantly lower in active girls (P < 0.05-0.001) in all age groups, except at 17 (P > 0.05). The actively training girls had higher physical abilities at all ages from 10-17. The annual differences in performance scores were significant (P < 0.05-0.001) up to 15 years except for the standing long jump. Differences in mean scores of most motor abilities were minimal or reduced significantly at 13-14 years in nonactive girls, but were significant in active girls.

Adolescent↗
PubMed1998

Sickle cell trait in Ivory Coast athletic throw and jump champions, 1956-1995.

In order to assess the performance of subjects with sickle cell trait (SCT) during brief and explosive exercise involving mainly alactic anaerobic metabolism, the percentage of athletes with SCT was determined in Ivory Coast track and field throw and jump champions, both men and women, for the period 1956-1995. Thirty-four (27.8%) sickle cell trait carriers (SCTC) were identified among the 122 national champions that we were able to contact. These 34 SCTC had won 78 national titles (24.5%) and established 37 national records (43.5%), distributed among the throw and jump events. These percentages were significantly higher than the prevalence of SCT in the general Ivory Coast population (12.0%). The women's high jump and men's shot put events had the highest percentages of SCTC record holders (90.9% and 87.5%, respectively). Moreover, the two top national record holders and title winners, one man and one woman, were SCTC athletes, and their hemoglobin S percentage (HbS: 39.1% and 39.4%, respectively) and mean corpuscular volume (MCV) excluded an associated alpha-thalassemia. We conclude that the significantly higher percentage of SCTCs among Ivory Coast track and field champions, as compared to the percentage in the general population suggests that SCT may be a determinant factor for success in brief and explosive track and field events involving mainly alactic anaerobic metabolism.

Adult↗
PubMed1995

Saccades to large coloured targets stepping in open fields.

Subjects tracked a 2.3 deg target that stepped 5 deg, in a randomly chosen direction, each time it was foveated. Targets were coloured patches that were fairly close to white; in some cases precise matches ensured equiluminosity with the background. Viewing conditions provided good colour rendering and neutral colour adaptation. Pale colours were surprisingly well tracked. Multiple regressions showed that the colour and spatial characteristics of the target are important determinants of a primary saccade's latency. Significant factors included target size, achromatic contrast, tritanopic purity difference, and chromatic saturation. Colour-normal subjects always responded more slowly to yellow or blue targets which a deuteranomalous subject tracked quite well. Severely blurring the target had a consistent minor effect.

Adult↗
PubMed1980

Force-, power-, and elasticity-velocity relationships in walking, running, and jumping.

Ground reaction forces and mechanical power were investigated when the subjects walked normally, while they were racing or running at four speeds, and when they performed the running long jump take-off. In addition, the apparent spring constants of the support leg in eccentric and concentric phases were investigated at the four running speeds, during the running long jump take-off, and in the triple jump. Six club level track and field athletes, four national level long jumpers, and six national level triple jumpers took part in the study. Cinematographic technique and a mathematical model of hopping (Alexander and Vernon 1975) were employed in the analysis. Force and power values were found to vary in the following order (from highest to lowest): long jump take-off, maximal running speed, submaximal running (80, 60, and 40% of maximum speed), racing gait, and normal gait. The data disclosed that the measured parameters had the highest values in the long jump take-off performed by the long jump athletes. Their peak values were: resultant ground reaction force 3270 +/- 74 N and mechanical power 160.1 +/- 10.5 J x kg-1 x s-1. For the track and field athletes the values were 2010 +/- 80 N and 126.0 +/0 12.6 J x kg-1 x s-1. The apparent spring constant values of the support leg in the national level jumper group were in eccentric phase 30.54 +/- 8.38 N x mm-1 x kg-1 and in concentric phase 0.129 +/- 0.012 N x mm-1 x kg-1. In the track and field athletes the values were 13.97 +/- 1.01 N x mm-1 x kg-1 and 0.093 +/- 0.003 N x mm-1 x kg-1, respectively. In general, the increase in force and mechanical power output was related to the value of the apparent spring constant of the support leg in the eccentric phase. The spring constant in the eccentric phase increased with the velocity of motion in running, the long jump take-off and the triple jump. This suggests that it may be possible to use this parameter as a measure of mechanical performance, as it may reflect the combined elasticity of muscles, tendons, and bones.

Biomechanical Phenomena↗
PubMed1990

Does Swedish amateur boxing lead to chronic brain damage? 3. A retrospective clinical neurophysiological study.

The aim of the present study was to investigate possible chronic brain damage due to Swedish amateur boxing. Forty seven former amateur boxers, 22 with many (HM = high-matched) and 25 with few matches (LM = low-matched) during their career were examined and compared with two control groups of 25 soccer players and 25 track and field athletes in the same age-range. No severe EEG abnormality was found. There was a somewhat higher incidence of slight or moderate EEG deviations among HM-(32%, 7/22) and LM-(36%, 9/25) boxers than among soccer players (20%, 5/25) and track and field athletes (12%, 3/25). Brain electric activity mapping (BEAM), brainstem auditory evoked potential (BAEP) and auditory evoked P 300 potential (P 300) did not differ significantly between the groups. No neurophysiological variable was correlated to the number of bouts, number of lost fights or length of boxing career. Thus, no signs of serious chronic brain damage was found among the amateur boxers or the soccer players and the track and field athletes. However, it cannot be excluded that the EEG differences between the groups may be a sign of slight brain dysfunction in some of the amateur boxers.

Adult↗
PubMed2002

Acoustic tracking of a freely drifting sonobuoy field.

This paper develops an acoustic inversion algorithm to track a field of freely drifting sonobuoys using travel-time measurements from a series of nonsimultaneous impulsive sources deployed around the field. In this scenario, the time interval between sources can be sufficiently long that significant independent movement of the individual sonobuoys occurs. In addition, the source transmission instants are unknown, and the source positions and initial sonobuoy positions are known only approximately. The formulation developed here solves for the track of each sonobuoy (parametrized by the sonobuoy positions at the time of each source transmission), allowing arbitrary, independent sonobuoy motion between transmissions, as well as for the source positions and transmission instants. This leads to a strongly underdetermined inverse problem. However, regularized inversion provides meaningful solutions by incorporating a priori information consisting of prior estimates (with uncertainties) for the source positions and initial sonobuoy positions, and a physical model for preferred sonobuoy motion. Several models for sonobuoy motion are evaluated, with the best results obtained by minimizing the second spatial derivative of the tracks to obtain the minimum-curvature or smoothest track, subject to fitting the acoustic data to a statistically appropriate level.

Journal Article↗
PubMed2001

Measurements of the high energy neutron component of cosmic radiation fields in aircraft using etched track dosemeters.

Measurements of the complex cosmic radiation field in aircraft at altitude are made with a passive survey meter comprising routine-use thermoluminescent detectors and etched track detectors. The energy dependence of response of the etched track detectors used to determine the neutron component has been characterized, partly, up to a neutron energy of 180 MeV. The neutron detectors are routinely calibrated in the CERN/EC Reference Field. The 15% determination level for total dose equivalent is 100 microSv. The evidence is that the passive survey meter provides a reliable determination of route dose.

Aircraft↗
PubMed1991

[Treadmill versus field trial. Movement analysis and pressure distribution in the athletic shoe].

Our current knowledge on interactions between runner and runningshoe is mainly based on treadmill measurements. In order to reveal stress load and adaptation on playing surfaces it was necessary to develop a combined measuring device out of 3-D video motion analysis and portable pressure measurement system. By means of a motor driven cart moving parallel to the subject with comparable position of cameras to the treadmill test it was possible to set up an identical trial for track and field. 12 subjects (male, age 24-32, size 9) were tested at a speed of 2.8 m/s. The varying conditions were treadmill and grass and two different constructed running shoes. 200 cycles and over 1000 steps were analyzed. The quantitative analysis of 37 parameters describing the contact phase was performed using the wilcoxon test for paired samples.-A qualitative comparison of running styles was introduced by using angle-angle-diagrams (knee and ankle by 3-D data) similar to those first described for 2-D by P.R. Cavanagh in 1973. It showed a huge interindividual variability under same conditions. Comparing the angle-angle-diagrams for the four different running conditions it was possible to classify them into three characteristic groups: non-adaptors, surface-adaptors and shoe-adaptors. Comparing track and field to treadmill measurements significant differences were found for the knee at impact: On treadmill the initial knee angle was 4.6 degrees more extended at a 13% higher angle velocity and a 30% higher angle deceleration (sig. p less than 0.05). A 7.3% higher impulse was found on grass at a 5.9% higher step length. No difference in maximum pressure was found. These results show that adaptation is performed mainly by the knee. Changing the motion pattern the knee seems to be capable of homogenizing the different stress loads to the foot. Comparing the running shoes significant differences were found in the motion of the ankle: a controversial behaviour was found to be on treadmill and grass. The pressure data revealed significant differences for the treadmill test to be in the heel area, for grass in the arch area. This points to an--up to now--unknown importance of the arch on unplain surfaces that are obviously influenced by the construction of the shoe and are not accessible by treadmill tests. The described different behaviour of shoes in treadmill and track and field tests points out the reduced validity of single treadmill tests.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1991

Tracking with a restricted field of view: performance and eye-head coordination aspects.

Vision through a restricted field of view (RFOV) is becoming increasingly common in aviation with the use of helmet mounted displays. Our first experiment investigated the influence of a narrow (20 degrees) binocular RFOV on performance during head-free visuo-manual tracking of a wide range (+/- 85 degrees) horizontally moving target. Second, the effects of two levels of RFOV (20 degrees, 70 degrees) on a similar tracking task presented with various eccentricities were compared to full field of view (FOV). Eye and head movement around the yaw axis were recorded and analyzed versus head-free visual pursuit alone. Tracking performance appeared moderately impaired when RFOV was set to 20 degrees, but did not improve with a 70 degrees field. Discomfort due to unusually large head movements was ruled out as a causal factor. Visuo-manual tracking apparently implies a need for head stability. RFOV degrades this basic requirement which, in turn, could explain performance impairment. Analysis of eye-head coordination characteristics following FOV task conditions supports this hypothesis.

Adult↗
PubMed1998

Contrasting plasma free amino acid patterns in elite athletes: association with fatigue and infection.

AIM: There is little information on the plasma free amino acid patterns of elite athletes against which fatigue and nutrition can be considered. Therefore the aim was to include analysis of this pattern in the medical screening of elite athletes during both especially intense and light training periods. METHODS: Plasma amino acid analysis was undertaken in three situations. (1) A medical screening service was offered to elite athletes during an intense training period before the 1992 Olympics. Screening included a blood haematological/biochemical profile and a microbial screen in athletes who presented with infection. The athletes were divided into three groups who differed in training fatigue and were considered separately. Group A (21 track and field athletes) had no lasting fatigue; group B (12 judo competitors) reported heavy fatigue at night but recovered overnight to continue training; group C (18 track and field athletes, one rower) had chronic fatigue and had been unable to train normally for at least several weeks. (2) Athletes from each group were further screened during a post-Olympic light training period. (3) Athletes who still had low amino acid levels during the light training period were reanalysed after three weeks of additional protein intake. RESULTS: (1) The pre-Olympics amino acid patterns were as follows. Group A had a normal amino acid pattern (glutamine 554 (25.2) micromol/l, histidine 79 (6.1) micromol/l, total amino acids 2839 (92.1) micromol/l); all results are means (SEM). By comparison, both groups B and C had decreased plasma glutamine (average 33%; p<0.001) with, especially in group B, decreased histidine, glucogenic, ketogenic, and branched chain amino acids (p<0.05 to p<0.001). None in group A, one in group B, but ten athletes in group C presented with infection: all 11 athletes had plasma glutamine levels of less than 450 micromol/l. No intergroup differences in haematological or other blood biochemical parameters, apart from a lower plasma creatine kinase activity in group C than in group B (p<0.05) and a low neutrophil to lymphocyte ratio in the athletes with viral infections (1.2 (0.17)), were found. (2) During post-Olympic light training, group A showed no significant amino acid changes. In contrast, group B recovered normal amino acid levels (glutamine 528 (41.4) micromol/l, histidine 76 (5.3) micromol/l, and total amino acids 2772 (165) micromol/l) (p<0.05 to p<0.001) to give a pattern comparable with that of group A, whereas, in group C, valine and threonine had increased (p<0.05), but glutamine (441 (24.5) micromol/l) and histidine (58 (5.3) micromol/l) remained low. Thus none in group A, two in group B, but ten (53%) in group C still had plasma glutamine levels below 450 micromol/l, including eight of the 11 athletes who had presented with infection. (3) With the additional protein intake, virtually all persisting low glutamine levels increased to above 500 micromol/l. Plasma glutamine rose to 592 (35.1) micromol/l and histidine to 86 (6.0) micromol/l. Total amino acids increased to 2761 (128) micromol/l (p<0.05 to p<0.001) and the amino acid pattern normalised. Six of the ten athletes on this protein intake returned to increased training within the three weeks. CONCLUSION: Analysis of these results provided contrasting plasma amino acid patterns: (a) a normal pattern in those without lasting fatigue; (b) marked but temporary changes in those with acute fatigue; (c) a persistent decrease in plasma amino acids, mainly glutamine, in those with chronic fatigue and infection, for which an inadequate protein intake appeared to be a factor.

Amino Acids↗
PubMed1995

An outbreak of measles at an international sporting event with airborne transmission in a domed stadium.

An outbreak of measles occurred in conjunction with the International Special Olympics Games in the Minneapolis-St. Paul metropolitan area during July 1991. Sixteen outbreak-associated cases of measles were reported among US residents from seven states, with 9 additional cases resulting from subsequent transmission. The primary case was a track and field athlete from Argentina. Transmission occurred in three settings: the opening ceremonies in a domed stadium, track and field events, and first aid stations. Eight secondary cases had their only potential exposure at the opening ceremonies; 2 of these cases were unrelated spectators sitting in the same section of the upper deck > 30.5 m above the athlete's entrance. These findings demonstrate that the risk of indigenous measles transmission associated with international events in the United States must be considered, even in areas without recent measles activity. Moreover, the dynamic airborne transmission of measles illustrates the potential for transmission in the absence of a recognized exposure.

Adolescent↗
PubMed1965

CHEST CONTOUR. A COMPARISON OF AMERICAN AND RUSSIAN TRACK STARS.

Measurement of the chests and other physical features of United States and Soviet Russian track and field stars showed the Americans broader chested, taller, lighter in weight and about two and a half years younger. Comparison of the measurements of the American group with those made on the 1940 and 1949 N.C.A.A. track and field stars in a previous study indicated that the Americans are developing relatively broader, flatter chests and are growing taller.

Anthropometry↗