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PubMedDate not supplied

Development of a distance-based interval throwing program for Little League-aged athletes.

We developed a distance-based interval throwing program for Little League-aged athletes (9 to 12 years) to be used in training and rehabilitation. The timing and repetition parameters were developed from data collected during 400 innings of organized baseball during a single season, and short toss distance from Little League rules for field dimensions. There were 1022 boys from organized baseball teams in the four studies. Maximal distance and speed measurements were recorded for 853 boys. We developed a mathematical model from these data to predict maximal throwing distance from maximal throwing speed. This model was then tested on a second sample of 114 players. We compared the predicted distance with the actual maximal throwing distance; the correlation coefficient was 0.92. Forty players aged 9 to 12 participated in a study to assess degradation of speed and distance. The average variability of the speed was small (< 5 mph), but the variability in distance was large (22.4 feet). Fifteen boys then threw the entire throwing program as designed. These results show that healthy young athletes can be expected to be able to throw the predicted value of this practical progressive interval throwing program for Little League-aged athletes. The appropriate program can be assigned from age and known preinjury pitch speed.

Adolescent↗
PubMed2007

Phylogenetic tree information aids supervised learning for predicting protein-protein interaction based on distance matrices.

BACKGROUND: Protein-protein interactions are critical for cellular functions. Recently developed computational approaches for predicting protein-protein interactions utilize co-evolutionary information of the interacting partners, e.g., correlations between distance matrices, where each matrix stores the pairwise distances between a protein and its orthologs from a group of reference genomes. RESULTS: We proposed a novel, simple method to account for some of the intra-matrix correlations in improving the prediction accuracy. Specifically, the phylogenetic species tree of the reference genomes is used as a guide tree for hierarchical clustering of the orthologous proteins. The distances between these clusters, derived from the original pairwise distance matrix using the Neighbor Joining algorithm, form intermediate distance matrices, which are then transformed and concatenated into a super phylogenetic vector. A support vector machine is trained and tested on pairs of proteins, represented as super phylogenetic vectors, whose interactions are known. The performance, measured as ROC score in cross validation experiments, shows significant improvement of our method (ROC score 0.8446) over that of using Pearson correlations (0.6587). CONCLUSION: We have shown that the phylogenetic tree can be used as a guide to extract intra-matrix correlations in the distance matrices of orthologous proteins, where these correlations are represented as intermediate distance matrices of the ancestral orthologous proteins. Both the unsupervised and supervised learning paradigms benefit from the explicit inclusion of these intermediate distance matrices, and particularly so in the latter case, which offers a better balance between sensitivity and specificity in the prediction of protein-protein interactions.

Computational Biology↗
PubMed1996

Distance estimation by foraging honeybees

Honeybees are widely believed to assess feeder distances by the energy spent on foraging flights. However, a critical review of this 'energy hypothesis' reveals many inconsistencies in the experiments from which it was derived. In fact, new evidence shows that the energy hypothesis cannot be correct. Foragers loaded with weights do not overestimate distance, as indicated by their waggle dances performed upon return to the hive. Bees that climb to a feeder on top of a high building (50 m) signal the same distance as hive mates that visit an equidistant feeder at ground level. Foragers visiting a feeder suspended from a balloon at 70 m from their hive underestimate the distance flown dramatically when the balloon lifts the feeder from ground level to 90 m, even though the energy required to reach the feeder increases considerably. Foragers from a hive situated on a high building (50 m) that fly to a feeder on the roof of another high building (34 m) signal a much shorter distance than the actual distance flown. We propose instead an 'optical flow hypothesis': bees use the speed of retinal image motion perceived from the ground to estimate the distance flown. Flight altitude is important for distance estimation by retinal image flow, because objects move faster and farther across the retina when the bee flies closer to the ground. When the forager's flight behavior is considered, the optical flow hypothesis does not conflict with previous findings.

Journal Article↗
PubMed2005

Effect of distance feedback on pacing strategy and perceived exertion during cycling.

PURPOSE: The aim of this study was to investigate whether providing incorrect distance feedback would alter pacing strategies, perceived exertion, and heart rate during 20-km cycling time trials (TT). METHODS: Well-trained cyclists (N=15) performed a peak power output (PPO) test, familiarization trial, and four 20-km cycling TT during which they were provided with only distance feedback using 1-km distance splits. For the control trial, subjects received accurate feedback at each kilometer split. In the increase trial, they received inaccurate feedback at 0.775 km for the first kilometer split with the distance increasing by 25 m each subsequent split up to 1.25 km in the final kilometer split. For the decrease trial, inaccurate feedback was provided at 1.25 km for the first kilometer split with the distance decreasing by 25 m each subsequent split up to 0.775 km in the final split. For the random trial, distance splits were randomized. RESULTS: No significant differences were found in the finishing times between trials. Pacing strategies were unaltered as suggested by similar power output profiles during all trials. RPE scores were also similar for all trials. However, average heart rate varied significantly between trials (P<0.05). CONCLUSIONS: These results suggest that exercise performance, pacing strategy, and RPE during a 20-km cycling TT are not altered by incorrect distance feedback. The data supported the existence of a pacing strategy that is set before exercise and that is unaffected by external distance feedback.

Adaptation, Physiological↗
PubMed2006

Distance from home when death occurs: a population-based study of Washington State, 1989-2002.

OBJECTIVE: For patients who die in hospitals, the regionalization of tertiary health care services may be increasing the home-to-hospital distance, particularly for younger patients whose care is especially regionalized and for whom access to and use of home hospice services remains limited. The objective of this study was to test the hypotheses that the distance from home at the time of death in a hospital has increased over time and is inversely related to the age of the dying patient. METHODS: A population-based case series was conducted in Washington State of all deaths of state residents from 1989 to 2002. The main outcome measure was driving distance between home residence and location at the time of death. RESULTS: The overall mean distance from home to the hospital where death occurred has increased by 1% annually. Children who died in hospitals were much farther from home than their adult counterparts: the mean distance was 37.4 km for neonates and 50.9 km for children who were aged 1 to 9 years, compared with 19.9 km for adults who were aged 60 to 79 years and 14.0 km for patients who were older than 79 years. Disparities of distance were even greater among patients who were at the 90th percentile for distance (85.6 km for neonates compared with 30.8 for patient who were older than 79 years). CONCLUSIONS: The distance between home residence and the hospital where death occurs is greatest for children and has increased over time. Both of these findings have implications for the design of local and regional pediatric end-of-life supportive care services.

Adolescent↗
PubMed2002

Neural function of the mesencephalic dorsomedial nucleus (DM) on distance call production in Bengalese finches.

In sexually mature Bengalese finches, acoustic structures of distance calls show sexual difference. The dorsomedial nucleus (DM) of intercollicular complex is known as the midbrain vocal center of distance calls. Neural input from the robust nucleus of archistriatum (RA) was observed in the DM of sexually mature males, but not observed in that of sexually mature females. The purpose of this study is to clarify somo more details of physiological function of the neural system in the DM in distance call production. Electrical stimulation to the DM of both sexes induced a call acoustically similar to distance calls, whose duration depended on the number of the pulses/train of electrical stimulation; electrical stimulation in relatively large (or small) numbers of pulses/train induced calls with relatively long (or short) duration, respectively. Multi-unit spikes were recorded from neurons in the DM. The increment of the frequency of recorded spikos was large when the bird vocalized distance calls, and the number of the frequency decreased when the bird vocalized calls whose duration was shorter than that of distance calls. These results suggest that the neural system in the DM controls duration of distance calls in sexually mature males and females. Electrical stimulation to the DM under different pulse frequencies induced calls with different patterns of time-frequency characteristics. The relation between the pulse frequencies and time-frequency characteristics showed sexual difference. The relation between them in RA-lesioned males was similar to that in females. These results suggest that the neural circuit in the DM of sexually mature males is consisted of sexually common neural circuit controlled by the neural input from the RA, and that these sexually different neural system produce sexually different acoustic structures of distance calls.

Animals↗
PubMed1995

Physiological factors associated with middle distance running performance.

Middle distance running involves popular race distances with performance dependent on a number of physiological factors. The physiological characteristics of successful runners are different from those of sprinters and long distance runners. Maximal oxygen uptake (VO2max), running economy and the anaerobic threshold are variables that have been shown to limit performance during long distance running, and rapid velocity and anaerobic variables have been shown to limit performance during sprinting. Success with middle distance running is dependent on an integrative contribution from aerobic and anaerobic variables which allows a runner to maintain a rapid velocity during a race. The relative contributions of the 2 energy systems are functions of distance, intensity and the physiological abilities of the runner. Middle distance runners can be successful with physiological profiles that include a variety of aerobic and anaerobic capabilities, and this characteristic separates them from long distance runners.

Anaerobic Threshold↗
PubMed2003

The impact of resistance training on distance running performance.

Traditionally, distance running performance was thought to be determined by several characteristics, including maximum oxygen consumption (VO(2max)), lactate threshold (LT), and running economy. Improvements in these areas are primarily achieved through endurance training. Recently, however, it has been shown that anaerobic factors may also play an important role in distance running performance. As a result, some researchers have theorised that resistance training may benefit distance runners. Because resistance training is unlikely to elicit an aerobic stimulus of greater than 50% of VO(2max), it is unlikely that resistance training would improve VO(2max) in trained distance runners. However, it appears that VO(2max) is not compromised when resistance training is added to an endurance programme. Similarly, LT is likely not improved as a result of resistance training in trained endurance runners; however, improvements in LT have been observed in untrained individuals as a result of resistance training. Trained distance runners have shown improvements of up to 8% in running economy following a period of resistance training. Even a small improvement in running economy could have a large impact on distance running performance, particularly in longer events, such as marathons or ultra-marathons. The improvement in running economy has been theorised to be a result of improvements in neuromuscular characteristics, including motor unit recruitment and reduced ground contact time. Although largely theoretical at this point, if resistance training is to improve distance running performance, it will likely have the largest impact on anaerobic capacity and/or neuromuscular characteristics. The primary purpose of this review is to consider the impact of resistance training on the factors that are known to impact distance running performance. A second purpose is to consider different modes of resistance exercise to determine if an optimal protocol exists.

Anaerobiosis↗
PubMed2006

Is there an optimal training intensity for enhancing the maximal oxygen uptake of distance runners?: empirical research findings, current opinions, physiological rationale and practical recommendations.

The maximal oxygen uptake (V-dotO(2max)) is considered an important physiological determinant of middle- and long-distance running performance. Little information exists in the scientific literature relating to the most effective training intensity for the enhancement of V-dotO(2max) in well trained distance runners. Training intensities of 40-50% V-dotO(2max) can increase V-dotO(2max) substantially in untrained individuals. The minimum training intensity that elicits the enhancement of V-dotO(2max) is highly dependent on the initial V-dotO(2max), however, and well trained distance runners probably need to train at relative high percentages of V-dotO(2max) to elicit further increments. Some authors have suggested that training at 70-80% V-dotO(2max) is optimal. Many studies have investigated the maximum amount of time runners can maintain 95-100% V-dotO(2max) with the assertion that this intensity is optimal in enhancing V-dotO(2max). Presently, there have been no well controlled training studies to support this premise. Myocardial morphological changes that increase maximal stroke volume, increased capillarisation of skeletal muscle, increased myoglobin concentration, and increased oxidative capacity of type II skeletal muscle fibres are adaptations associated with the enhancement of V-dotO(2max). The strength of stimuli that elicit adaptation is exercise intensity dependent up to V-dotO(2max), indicating that training at or near V-dotO(2max) may be the most effective intensity to enhance V-dotO(2max) in well trained distance runners. Lower training intensities may induce similar adaptation because the physiological stress can be imposed for longer periods. This is probably only true for moderately trained runners, however, because all cardiorespiratory adaptations elicited by submaximal training have probably already been elicited in distance runners competing at a relatively high level.Well trained distance runners have been reported to reach a plateau in V-dotO(2max) enhancement; however, many studies have demonstrated that the V-dotO(2max) of well trained runners can be enhanced when training protocols known to elicit 95-100% V-dotO(2max) are included in their training programmes. This supports the premise that high-intensity training may be effective or even necessary for well trained distance runners to enhance V-dotO(2max). However, the efficacy of optimised protocols for enhancing V-dotO(2max) needs to be established with well controlled studies in which they are compared with protocols involving other training intensities typically used by distance runners to enhance V-dotO(2max).

Adaptation, Physiological↗
PubMed1999

Changes in basketball shooting patterns as a function of distance.

The effect of distance on the accuracy and movement form in basketball shooting was examined using a dynamic systems approach. Five male and five female young adults (M = 26 yr.) with no basketball experience beyond regular physical education shot a basketball 20 times at each of eight distances from 5 to 40 ft. (Natural condition). Also, they pretended to shoot the ball 5 times at each of the eight distances, for a total of 200 shots each (Pretend condition). In the Natural condition, shooting accuracy significantly decreased as shooting distance increased. Across both conditions and across four body components (feet position, hand position, trunk rotation, and jump height), the participants shifted from one movement pattern to another 86.3% of the time as shooting distance increased. The distances at which the transitions occurred were significantly shorter in the Natural than the Pretend condition for the feet and hand components but not the trunk and jump-height components. These results indicated that shooting a basketball at increasing distances can be portrayed as a dynamic system characterized by abrupt changes in at least four body components at critical distances.

Adolescent↗
PubMed2006

Morphometry of the intercommissural distances and other structures of the aortic valve of bovine heart.

The morphometry of the intercommissural distances and their relation with other structures of the aortic valve of bovine heart was carried out. A total of 32 apparently healthy bovine hearts of indigenous cattle of both sexes (50% male and 50% female), 2-4 years of age, weighing 500 to 800 gms were used in this study. The external intercommissural distances were higher in all cusps of the valve compared to the internal intercommissural distances. The internal intercommissural distance was larger in the RC sinus in case of male animals followed by that of the LC and NC sinus. The mean external intercommissural distances were 34.67+/-3.40, 34.40+/-3.64 and 34.97+/-4.37 mm and the internal intercommissural distances were 21.60+/-4.21, 21.20+/-4.70 and 20.67+/-4.06 mm for LC, RC and NC respectively. Analyzing the internal intercommissural distance, value in the LC sinus was higher followed by the RC and the NC but this variation was non-significant. In regard to the position of the coronary ostia, there were two coronary ostia, the right coronary ostium present in the RC sinus and the left coronary ostium in the LC sinus respectively and the right coronary ostium was supracommissural in position in bovine heart. Data about the morphometrical analysis of intercommissural distances and the position of the coronary ostia of the aortic valve facilitate the knowledge of manufacturing bovine tissue valve as well as those might be involved in valve replacement in human.

Animals↗
PubMed2000

Long-distance seed dispersal in plant populations.

Long-distance seed dispersal influences many key aspects of the biology of plants, including spread of invasive species, metapopulation dynamics, and diversity and dynamics in plant communities. However, because long-distance seed dispersal is inherently hard to measure, there are few data sets that characterize the tails of seed dispersal curves. This paper is structured around two lines of argument. First, we argue that long-distance seed dispersal is of critical importance and, hence, that we must collect better data from the tails of seed dispersal curves. To make the case for the importance of long-distance seed dispersal, we review existing data and models of long-distance seed dispersal, focusing on situations in which seeds that travel long distances have a critical impact (colonization of islands, Holocene migrations, response to global change, metapopulation biology). Second, we argue that genetic methods provide a broadly applicable way to monitor long-distance seed dispersal; to place this argument in context, we review genetic estimates of plant migration rates. At present, several promising genetic approaches for estimating long-distance seed dispersal are under active development, including assignment methods, likelihood methods, genealogical methods, and genealogical/demographic methods. We close the paper by discussing important but as yet largely unexplored areas for future research.

Journal Article↗
PubMed2000

Changes in cellular proliferation rate of lymphocytes after long-distance flights as a possible risk for patients with HIV-infection.

OBJECTIVES: Several studies showed that long-distance flights can influence cellular immunity. This might be due to a cortisol- and catecholamin- induced change in immunity with an impairment of T-lymphocyte dependent cellular immunity and an enhancement of B-lymphocyte dependent humoral immunity. Similar results can be found in patients with HIV. It is also known that progress of this disease and affection of T-helper-cells by the virus are induced by stimulation of the immune system, a phenomenon that also occurs during long distance flights. Therefore, a possible interaction between long-distance flights and the progression of HIV-infection should be discussed. METHODS: Cell cultures of 22 subjects after long-distance flights with and without rapid time zone shifts and of 16 patients with HIV (stage 2 3) were investigated. Mononuclear blood cells were stimulated with different lectins in culture and proliferation was measured by incorporation of bromodesoxyuridine. Moreover, all cultures were titrated with chromate concentrations between 0 to 700 ng/ml to measure the tolerance of the cells against chromate (VI) in vitro as a marker of the functional efficiency of the cellular part of the immune system. Maximal proliferation rate and tolerance against chromate were compared in both groups. RESULTS: After long distance flights tolerance against chromate decreased significantly during the first 24 h after flight. After 48 h levels were similar to those 1 week after flights. The decrease was similar to the results found in the stage 2 group of HIV-patients, but by far less to the decrease in stage 3 patients. Maximal proliferation rate dropped significantly during the second day after arrival compared to 1-week control values. CONCLUSION: Changes in the cellular immune system in healthy subjects after long-distance flights have been similar to the results of patients with stage 2 of HIV-infection. Mechanisms of changes in both groups are comparable in influencing T-cell-induced immunity. This could point to an additive effect on cellular immunity of HIV-patients by long distance-flights. Rosen neopterin concentrations and increases of apoptotic T-cells in both groups support this assumption. Therefore, further studies are urgently needed to investigate the interactions between HIV-infection and long-distance flights.

Adolescent↗
PubMed2003

The interutricular distance determined from external landmarks.

Knowledge of the exact distance between the utricles is important in new vestibular tests, such as the unilateral centrifugation (UC) test for the unilateral examination of the utricles. During this test, subjects are rotated at constant velocity and simultaneously laterally displaced along an interaural axis so that one labyrinth becomes aligned with the axis of rotation. When the axis of rotation crosses precisely through one labyrinth, only the opposite labyrinth is stimulated. To achieve this setup, precise knowledge of the interutricular distance is needed. The purpose of this study is to investigate the correlation between the interutricular distance (IUD), measured on T2-weighted magnetic resonance images, and specific external measures of head dimensions such as distance nasion-inion, intermastoid distance (IMD), distances between the temporomandibular joints and between the lateral margins of the orbits. Data have been collected in a series of 50 subjects (25 men and 25 women). On MR images we found a mean IUD of 7.22 cm (SD = 0.42 cm). There was a strong correlation between the IUD measured on MR images and the intermastoid distance. A linear combination of the IMD, nasion-inion distance and height of the subjects could predict the IUD very satisfactory (R = 0.85, adjusted R2=0.723). We also determined a measure of eccentricity of the vestibular labyrinths. The 95% prediction interval for the asymmetry appeared to be less than 4.3%.

Adolescent↗
PubMed2003

Insertion distance of neonatal intercostal catheters using a 10 French Argyle trocar thoracic catheter.

OBJECTIVE: We believed that intercostal catheters were often inserted too far into the thoracic cavity in neonatal patients. The aim of this study was to determine the average distance from the catheter tip to the midline, of intercostal catheters inserted in our neonatal unit and the incidence of catheters that were inserted too far into the thoracic cavity. METHODS: During a two year period we examined the chest X-rays of all infants who had an intercostal catheter inserted using an Argyle 10 French trocar thoracic catheter for drainage of a pneumothorax. For each initial chest X-ray following the insertion of the intercostal catheter we measured the horizontal distance in mm from catheter tip to the midline. The tip to midline distance was zero if the tip was at the midline and negative if it crossed the midline. To standardise the tip to midline distance for different size infants we measured the distance in 'inter-vertebral' units. RESULTS: During the two year period, 13 of 24 intercostal catheters (54%) crossed the midline (i.e. were inserted too far). The mean (+/- SD) tip to midline distance was -1.29 (+/- 13.9) mm with a range varying between -40 to 34 mm with a calculated 'inter-vertebral' units mean (+/- SD) tip to midline distance of -0.32 (+/- 1.9) range -4.6 to 4.0. CONCLUSIONS: Fifty four percent of the intercostal catheters inserted in our unit were inserted too far. As the distance markings on the Argyle intercostal catheters are marked from the last side-hole rather than from the tip of the catheter, Argyle intercostal catheters may be inadvertently inserted two centimetres further than they should be.

Journal Article↗
PubMed1996

[The effect of blood AST, ALT and lactate after short and middle distance exercise training].

Twenty-four nursing college students aged 16 and 17 years were selected as research subjects and divided into two groups. Group A comprised 12 individuals who were trained for short distance running (5km/day) over a four-week period, while group B was trained for middle distance running (7km/day) during the same period. Blood AST (aspartate aminotransferase), ALT (alanine aminotransferase) and lactate were performed at rest (before training) and after exercise every week. After both short and middle distance exercise training, the lactate values after 1-3 week(s) training period were persistently higher than those before training and the differences between then are significant. However, the lactate value after 4 weeks training period is lower than that after the third week training. There are significant differences between the AST values after 1-4 week(s) training period and those before exercise in short distance exercise training. There are no significant differences between the AST values after training and those before exercise in middle distance exercise training. The ALT values after 1-4 week(s) training period were lower than those before exercise in short and middle distance exercise training. In conclusion, after 4 weeks training, the lactate and AST values can't reduce to those before training in middle distance exercise training, and the lactate value in short distance exercise training is the same as former. Further investigation is needed.

Adolescent↗
PubMed1997

A measure of DNA sequence dissimilarity based on Mahalanobis distance between frequencies of words.

A number of algorithms exist for searching genetic databases for biologically significant similarities in DNA sequences. Past research has shown that word-based search tools are computationally efficient and can find similarities or dissimilarities invisible to other algorithms like FASTA. We characterize a family of word-based dissimilarity measures that define distance between two sequences by simultaneously comparing the frequencies of all subsequences of n adjacent letters (i.e., n-words) in the two sequences. Applications to real data demonstrate that currently used word-based methods that rely on Euclidean distance can be significantly improved by using Mahalanobis distance, which accounts for both variances and covariances between frequencies of n-words. Furthermore, in those cases where Mahalanobis distance may be too difficult to compute, using standardized Euclidean distance, which only corrects for the variances of frequencies of n-words, still gives better performance than the Euclidean distance. Also, a simple way of combining distances obtained at different n-words is considered. The goal is to obtain a single measure of dissimilarity between two DNA sequences. The performance ranking of the preceding three distances still holds for their combined counterparts. All results obtained in this paper are applicable to amino acid sequences with minor modifications.

Algorithms↗
PubMed2000

Distance estimation in the visual and visuomotor systems.

Previous work has demonstrated that monocular vision affects the kinematics of skilled visually guided reaching movements in humans. In these experiments, prior to movement onset, subjects appeared to be underestimating the distance of objects (and as a consequence, their size) under monocular viewing relative to their reaches made under binocular control. The present series of experiments was conducted to assess whether this underestimation was a consequence of a purely visual distance underestimation under monocular viewing or whether it was due to some implicit inaccuracy in calibrating the reach by a visuomotor system normally under binocular control. In a purely perceptual task, a group of subjects made similar explicit distance estimations of the objects used in the prehension task under monocular and binocular viewing conditions, with no time constraints. A second group of subjects made these explicit distance estimations with only 500-ms views of the objects. No differences were found between monocular and binocular viewing in either of these explicit distance-estimation tasks. The limited-views subjects also performed a visually guided reaching task under monocular and binocular conditions and showed the previously demonstrated monocular underestimation (in that their monocular grasping movements showed lower peak velocities and smaller grip apertures). A distance underestimation of 4.1 cm in the monocular condition was computed by taking the y intercepts of the monocular and binocular peak velocity functions and dividing them by a common slope that minimised the sum of squares error. This distance underestimation was then used to predict the corresponding underestimation of size that should have been observed in the monocular reaches--a value closely approximating the observed value of 0.61 cm. Taken together, these results suggest that the monocular underestimation in the prehension task is not a consequence of a purely perceptual bias but rather it is visuomotor in nature--a monocular input to a system that normally calibrates motor output on the basis of binocular vision.

Adult↗