Kicking Velocity and Effect on Match Performance When using a Smaller, Lighter Ball in Women's Football.

The present study evaluated the effect of a smaller, lighter ball on kicking speed and technical-tactical and physical match performance in high-level adult female footballers. In the laboratory test setting, the peak ball velocity was 6% higher with the new ball (NB) than the standard ball (SB) (26.5±0.5 vs. 25.1±0.5 m·s-1, p<0.05). However, during match-play, no differences were observed in mean heart rate (87±5 vs. 87±5%HRmax; p>0.05), blood lactate (90 min: 4.7±1.7 and 4.0±1.7 mmol·l-1; p>0.05), total distance covered (10.6±0.9 and 10.4±0.8 km; p>0.05), intense running (>16 km/h) (2.08±0.42 and 1.94±0.38 km; p>0.05) and match-induced decrement in Yo-Yo IR1 performance (28 vs. 31%, respectively, p<0.05) using NB compared to SB. Likewise, no difference was observed in the number of short, medium-range or long passes during matches played with the 2 ball types, and there was no difference in passing success rate (NB: 68±1% and SB: 68±1%, p>0.05). In conclusion, high-level adult female footballers had a higher kicking speed when using a smaller, lighter ball, but no differences were observed during match-play with the 2 ball types in respect of technical-tactical and physical match performance. The physical loading was high for the players when playing with both ball types.

Effect of game format on heart rate, activity profile, and player involvement in elite and recreational youth players.

The purpose of this study was to evaluate activity profile, aerobic load, and player involvement in two game formats of recreational and elite youth football for two age groups. A total of 152 youth players participated, with 45 U10 players playing 5v5 and 8v8 games, and 41 U13 players playing 8v8 and 11v11 (20 min) games. Activity profile, heart rate (HR), and technical actions were measured during all games using 10 Hz GPS, video filming, and HR monitors. For U10, no difference was found in total distance covered (1754 ± 237 vs 1771 ± 314 m, P = 0.650, d = 0.06), whereas mean HR (174 ± 10 vs 168 ± 12 bpm, P = 0.001, d = 0.59) and number of technical actions (65.1 ± 24.0 vs 36.9 ± 20.4, P 0.001, d = 1.27) were higher in 5v5 than in 8v8. For U13, lower total distance covered (1821 ± 325 vs 2038 ± 328 m, P < 0.001, d = 0.66) and higher number of technical actions (36.2 ± 14.9 vs 26.9 ± 14.1, P < 0.001, d = 0.64) were observed in 8v8 than in 11v11, with no difference in mean HR (170 ± 10 vs 171 ± 10 bpm, P = 0.679, d = 0.10). In conclusion, HR is high in youth football matches irrespective of the level of play and the game format. Playing with fewer players on smaller pitches results in minor changes to the physical loading but elevates the technical involvement of youth players both at elite level and recreational level.

Cryopreservation of winter-dormant apple buds: I -Variation in recovery with cultivar and winter conditions.

The widely-adopted protocol for the cryopreservation of winter buds of fruit trees, such as Malus and Pyrus, was developed in a region with a continental climate, that provides relatively hard winters with a consequent effect on adaptive plant hardiness. In this study the protocol was evaluated in a typical maritime climate (eastern Denmark) where milder winters can be expected. The survival over two winters was evaluated, looking at variation between seasons and cultivars together with the progressive reduction in survival due to individual steps in the protocol. The study confirms that under such conditions significant variation in survival can be expected and that an extended period of imposed dehydration at -4 degree C is critical for bud survival. The occurrence of freezing events during this treatment suggests that cryodehydration may be involved, as well as evaporative water loss. To optimize the protocol for maritime environments, further investigation into the water status of the explants during cryopreservation is proposed.

The influence of speed of approach and accuracy constraint on the maximal speed of the ball in soccer kicking.

The kicking skill of the individual player is of great importance in soccer, and two parameters can be identified as being important in soccer kicking--achieving high speed of the ball and accuracy of performance. The purpose of the current study was to examine the influence of different speeds of approach on the maximal speed of the ball when kicking a stationary ball, and to examine the influence of accuracy of performance on the maximal speed of the ball relevant to a penalty kick. Seven male soccer players kicked for maximal speed of the ball (I) with a self-selected angle and speed of approach, (II) with accuracy demand placed on the subjects, (III) with a straight-line approach of different velocities ranging from 0 m/s to maximal running speed. The maximal speed of the ball was between 28.60 and 34.48 m/s. An accuracy constraint caused the speed of the ball to decline to 85%. With a straight-line approach, the maximal speed of the ball was between 25.64 and 32.26 m/s. When the subjects approached the ball at speeds other than the self-selected speed of approach, the speed of the ball declined, indicating a subject-specific optimal speed of approach.

The biomechanics of kicking in soccer: a review.

Kicking is the defining action of soccer, so it is appropriate to review the scientific work that provides a basis of our understanding of this skill. The focus of this review is biomechanical in nature and builds on and extends previous reviews and overviews. While much is known about the biomechanics of the kicking leg, there are several other aspects of the kick that have been the subject of recent exploration. Researchers have widened their interest to consider the kick beginning from the way a player approaches the ball to the end of ball flight, the point that determines the success of the kick. This interest has encapsulated characteristics of overall technique and the influences of the upper body, support leg and pelvis on the kicking action, foot-ball impact and the influences of footwear and soccer balls, ball launch characteristics and corresponding flight of the ball. This review evaluates these and attempts to provide direction for future research.

Increase in spinal stability obtained at levels of intra-abdominal pressure and back muscle activity realistic to work situations.

In this study, sudden load was applied to the trunk and situations with alternating low levels of intra-abdominal pressure (IAP) realistic to work situations were compared. The aim was to see if IAP and the small increases in co-contraction of back muscles that follow are capable of increasing the stiffness of the lumbar spine. Nine subjects participated in ten sudden load situations during which they were asked to hold a box and conduct a percentage of maximal IAP. The hip was fixed and the load was applied horizontally on the trunk. EMG, IAP, and movement of the trunk were measured. It was found that IAP of a size likely to appear in work situations, and the concomitant increase in muscle co-activation increased the spine stiffness. This increase in stiffness decreased the movement caused by the sudden load. These results show that both abdominal- and back muscles may have an important role in stabilising the spine, and in decreasing movements caused by sudden loads likely to appear in numerous work

EMG activity of the iliopsoas muscle and leg kinetics during the soccer place kick.

The purpose of the study was to develop a method to record intramuscular electromyogram (EMG) from the iliopsoas muscle and to relate this activity to the kinetics during the soccer place kick. Seven skilled soccer players performed 3 maximal velocity place kicks. The kicks were filmed with a high-speed camera (400 Hz) and EMG recordings were obtained from 5 muscles of the kicking leg, including wire electrodes inserted into the m. iliopsoas. The EMG signals were compared to the kinetics of the kicking leg, which were calculated from the digitised film. The results showed hardly any torque reversal about the hip joint before impact. Angular deceleration of the thigh segment did not increase the angular velocity of the shank (work -3.57 to 0.0%). M. iliopsoas was active during the entire kicking motion (average EMG 65.1-100.9%), even in the period when the thigh was decelerating. Wire electrodes can successfully be applied to EMG recordings of fast unloaded movements.

Analysis of functional domain organization in DNA topoisomerase II from humans and Saccharomyces cerevisiae.

The functional domain structure of human DNA topoisomerase IIalpha and Saccharomyces cerevisiae DNA topoisomerase II was studied by investigating the abilities of insertion and deletion mutant enzymes to support mitotic growth and catalyze transitions in DNA topology in vitro. Alignment of the human topoisomerase IIalpha and S. cerevisiae topoisomerase II sequences defined 13 conserved regions separated by less conserved or differently spaced sequences. The spatial tolerance of the spacer regions was addressed by insertion of linkers. The importance of the conserved regions was assessed through deletion of individual domains. We found that the exact spacing between most of the conserved domains is noncritical, as insertions in the spacer regions were tolerated with no influence on complementation ability. All conserved domains, however, are essential for sustained mitotic growth of S. cerevisiae and for enzymatic activity in vitro. A series of topoisomerase II carboxy-terminal truncations were investigated with respect to the ability to support viability, cellular localization, and enzymatic properties. The analysis showed that the divergent carboxy-terminal region of human topoisomerase IIalpha is dispensable for catalytic activity but contains elements that specifically locate the protein to the nucleus.

[Femoro-crural reconstruction in Denmark 1983-1987]. / Femoro-krurale rekonstruktioner i Danmark 1983-1987.

From 1983 to 1987, 293 femoro-crural bypasses were performed in eight centers for vascular surgery in Denmark. The activity increased in the period from 15 to 135 bypasses per year. The increase took place particularly 1986, when the in situ saphenous vein bypass was introduced in Denmark. A total of 203 bypasses were performed at the University Hospital of Copenhagen, Rigshospitalet: 108 in situ bypasses, 51 bypasses with arterial protheses and 44 bypasses using reversed vein. The cumulated graft patency after one year was 76% for the in situ bypasses, 26% for the bypasses with arterial protheses and 32% for reversed vein. The cumulated limb survivals after one year were 90%, 66% and 63%, respectively.

[Arteriovenous shunts used in hemodialysis. A retrospective study of the results in 86 patients treated during a 5-year period]. / Arteriovenøse shunter til haemodialysebrug. En retrospektiv opgørelse af resultater hos 86 patienter behandlet over en periode på 5 år.

During a period of five years, 104 arterio-venous fistulas and 14 PTFE-grafts were used in the construction of vascular access for long term hemodialysis in 86 patients with end-stage renal disease. The overall cumulative patency rate is 71% at one year, 64% at two years and 47% at five years. Sex and age cannot be shown to influence the patency rates. The vascular access sites in patients with chronic glomerulonephritis have significantly higher patency rates than the vascular access sites in patients with chronic pyelonephritis. We are unable to show any difference in the patency rates of vascular access sites salvaged by revision compared with patency rate of the remaining access sites. The following conclusions are drawn: 1) In the majority of patients undergoing the first vascular access operations, an arterio-venous fistula is the procedure of choice. 2) Advanced age does not itself contraindicate the construction of an arterio-venous fistula. 3) Reoperation should be considered, if dialysis is no longer possible.

Evaluating rms spot radii by ray tracing.

The computation of rms spot radii from ray trace calculations is investigated in relation to the number of rays to be traced to achieve a prescribed accuracy. It is shown that the usual simple averaging formulas will only have as limits for infinitely many rays the correct center of mass and gyration radius if a square ray grid point distribution is used throughout the limiting process. For other ray distributions the ray trace data are given weight according to the local grid point density. Using the simple averaging formulas deviations in computed image radii of 15-20% may be encountered due solely to variations in grid point distributions. A computing method is suggested using a fourth-order quadrature formula giving 1% accuracy with ~20 rays and 0.01% accuracy with ~40-50 rays.

Optical aberration functions: derivatives with respect to axial distances for symmetrical systems.

Simplified formulas are presented for the computation of derivatives of the optical aberration functions S,T,V,W, and K with respect to the axial surface distances for symmetrical optical systems. The formulas are well-suited for implementation in computer programs for automatic computation of optical aberration coefficients.

Optical aberration functions: chromatic aberrations and derivatives with respect to refractive indices for symmetrical systems.

Formulas are presented for the computation of derivatives of the optical aberration functions S, T, V, W, and K with respect to the relative refractive indices, leading to the chromatic aberrations, for symmetrical optical systems. The formulas are suitable for use in computer programs for automatic computation of optical aberration coefficients.

Optical aberration coefficients: FORTRAN subroutines for symmetrical systems.

FORTRAN computer subroutines for the automatic computation of the optical aberration functions S, T, V, W, and K to the 15th order for rotationally symmetric systems are presented. The routines may be conveniently extended toward higher orders.

Optical aberration functions: computation of caustic surfaces and illuminance in symmetrical systems.

The use of automatically computed aberration functions for an exact determination of the geometric illuminance and caustic surfaces is demonstrated. Numerical results for two optical systems studied using aberration coefficients to the thirteenth order are presented.

Automatic computation of optical focal surfaces.

The use of automatically computed aberration coefficients of arbitrary order for an exact determination of the surface of best focus of a symmetrical system, by minimizing the gyration radius of the spot diagram, is demonstrated. For the two optical systems studied, a Schmidt camera and a Ritchey-Chrétien telescope, the results from the exact model are found to be significantly different from the paraxial approximation predictions.

Automatic computation of optical aberration coefficients.

A method based on ray tracing equations is presented facilitating the computation of polynomial functions that predict the x and y intercepts, direction tangents, and optical path length of an arbitrary skew ray on a defocused image surface. The optical systems considered may contain surfaces of general nonrotationally symmetric figure and orientation, refracting as well as reflecting, including plane diffraction gratings. The classical aberration coefficient equations are a subset of these polynomials. The method can, without hard programming work, be extended to arbitrarily high orders.

Effect of althesin anesthesia on blood loss during therapeutic abortion. A comparison with local and thiopental anesthesia.

During recent years, the use of steroid anesthesia has rapidly increased. In our hospital, a number of surgical procedures have been performed under Althesin anesthesia, and in some cases the peroperative bleeding seemed to be rather profuse. Blood loss was studied in 90 healthy women in the first trimester of pregnancy undergoing therapeutic abortion using different types of anesthesia. The patients were divided into three equal groups according to the duration of pregnancy. In each group, 10 patients underwent operation under local anesthesia, 10 under thiopental anesthesia and 10 under Althesin. In all three groups, blood loss was the smallest when local anesthesia was used (Fig 1). Amounting to only one third to one half of that occurring under thiopental anesthesia. Under thiopental anesthesia the blood loss gradually increased with increasing gestational age with moderate variations. Alternatively, in this investigation, Althesin anesthesia was characterized by pronounced blood loss, particularly in the ninth and tenth weeks of pregnancy, and in some cases by rather profuse bleeding. We find that Althesin anesthesia should be used for gynecological surgery only in departments which are equipped to control profuse bleeding and possible cardiovascular complications.

PIP: During recent years, the use of steroid anesthesia has rapidly increased. A number of surgical procedures have been performed under Althesin anesthesia, and in some cases the peroperative bleeding seemed to be rather profuse. Blood loss was studied in 90 healthy nulliparous women, ages 15-39 years, in the 1st trimester of pregnancy, undergoing therapeutic abortion with different types of anesthesia. The patients were divided into 3 equal groups of 10 persons according to duration of pregnancy. Group 1 patients underwent surgery under local anesthesia, group 2 under thiopental anesthesia, and group 3 under Althesin. Blood loss in all 3 groups was smallest when local anesthesia was used (only 1/3 - 1/2 of that occurring under thiopental anesthesia). With thiopental anesthesia, the blood loss gradually increased with increasing gestational age with only moderate variations. Alternatively, in this investigation, Althesin anesthesia was characterized by pronounced blood loss, particularly in group 2 (p 0.05) and particularly in weeks 9-10 of pregnancy. Althesin was also associated with a wide range in blood loss, especially in group 2 (40-300 ml). The occurrence of profuse hemorrhage, seen in those administered Althesin, may be hazardous to those with cardiovascular difficulty. Thus it should be used for gynecological surgery only in departments equipped to control profuse bleeding and possible cardiovascular complications.