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At least 19 recordsLinked to original sources
PubMed1982

[Changes in stress to the knee joint in skiing from a medical viewpoint with special reference to the modern ski shoe and the skiing technic].

The changed skiing-technique with more knee flexion (so called jet-position) has lead to rising pressures in the femoro-patellar joint. The danger of traumatic and arthritic diseases has increased as well. We suggest to avoid extreme anteflexed crural position in the ski-boots (more than 5 degrees). It should be possible to walk and stand in ski-boots without pressure on the knee-joint. This problem is most important in the growing locomotor system.

Humans↗
PubMed1997

Impact of super sidecut skis on the epidemiology of skiing injuries.

Concerns about whether a new type of ski--the super sidecut or carving ski--has the potential to significantly alter the incidence and type of skiing injuries have arisen in the past two years. These skis have become extremely popular during the past ski season. A case control study of skiing injuries done in a serial fashion at a Northern Vermont ski area since 1972 offers the potential to monitor changes in skiing injuries as these skis increase in popularity. Only during the last ski season have a significant number of skiers in our study (approximately 18% of all) utilized these skis. Our data reveals that skiing injuries associated with super sidecut skis occurred at a higher rate than expected in comparison to conventional skis. We also have observed that expert skiers using super sidecut skis apparently have higher than the expected incidence of ski injuries. It is hoped that in another season or two of continued study that stronger statements can be made and that the preliminary trends we have observed can be confirmed or refuted.

Athletic Injuries↗
PubMed2004

Knee angular displacement and extensor muscle activity in telemark skiing and in ski-specific strength exercises.

Much of the training of competitive telemark skiers is performed as dry-land exercises. The specificity of these exercises is important for optimizing the training effect. Our aim here was to study the activation of the knee extensor musculature and knee angular displacement during competitive telemark skiing and during dry-land strength training exercises to determine the specificity of the latter. Specificity was analysed with respect to angular amplitude, angular velocity, muscle action and electromyographic (EMG) activity. Five male telemark skiers of national and international standard volunteered to participate in the study, which consisted of two parts: (1) skiing a telemark ski course and (2) specific dry-land strength training exercises for telemark skiing (telemark jumps and barbell squats). The angular displacement of the right knee joint was recorded with an electrogoniometer. A tape pressure sensor was used to measure pressure between the sole of the foot and the bottom of the right ski boot. Electromyographic activity in the right vastus lateralis was recorded with surface electrodes. The EMG activity recorded during maximum countermovement jumps was used to normalize the EMG activity during telemark skiing, telemark jumps and barbell squats. The results showed that knee angular displacement during telemark skiing and dry-land telemark jumps had four distinct phases: a flexion (F1) and extension (E1) phase during the thrust phase of the outside ski/leg in the turn/jump and a flexion (F2) and extension (E2) phase when the leg was on the inside of the turn/jump. The vastus lateralis muscle was activated during F1 and E1 in the thrust phase during telemark skiing and telemark jumps. The overall net knee angular amplitude was significantly greater (P < 0.05) for telemark jumps than for telemark skiing. Barbell squats showed a knee angular amplitude significantly greater than that in telemark skiing (P < 0.05). The mean knee angular velocity of the F1 and E1 phases during telemark skiing was about 0.47 rad x s(-1); during barbell squats, it was about 1.22 rad x s(-1). The angular velocity during telemark jumps was 2.34 and 1.59 rad x s(-1) in the F1 and E1 phase, respectively. The normalized activation level of the EMG bursts during telemark skiing, telemark jumps and barbell squats was 70-80%. In conclusion, the muscle action and level of activation in the vastus lateralis during the F1 and E1 phases were similar during telemark skiing and dry-land exercises. However, the dry-land exercises showed a larger knee extension and flexion amplitude and angular velocity compared with telemark skiing. It appears that an adjustment of knee angular velocity during barbell squats and an adjustment of knee angle amplitude during both telemark jumps and barbell squats will improve specificity during training.

Adult↗
PubMed1996

Numerical simulation of a turning alpine ski during recreational skiing.

While downhill snow skiing, recreational alpine skiers enjoy making turning motions with their skis. These motions are mainly induced by skidding, while turning by alpine ski racers is made by carving a trace in the snow. In the present study we treat the turning motions by recreational alpine skiers. This "skidding" turning motion is made possible by centripetal forces acting on the ski and skier dynamic motion systems, with these forces arising due to the skier placing the ski's longitudinal axis at an angle that is inclined away from the velocity vector and edging the ski into the snow. When snow is soft, the edged ski creates a snow impacting force, whereas a snow cutting force occurs when it is hard. Here, we calculate the former force using a three-dimensional water jet analogy, while the latter one using conventional metal cutting theory, after which the corresponding equations of motion for each system are derived and numerically solved. This methodology enables simulating the curvilinear and rotational motion of the ski and skier systems. Resultant simulations quantitatively show for the first time that the resultant radius of curvature of a ski track while downhill skiing is strongly dependent on the location of the ski boot on the ski's longitudinal axis and also on its side-cut (midlength taper).

Biophysical Phenomena↗
PubMed1997

A comparison of the effect of ski sidecut on three-dimensional knee joint kinematics during a ski run.

The popularity of alpine skis with large sidecuts has increased dramatically in the last few years. However, little scientific data exists regarding the effect of these skis on certain human factors. The purpose of this study was to compare three-dimensional knee joint motions during entire ski runs while skiing on two skis with a large difference in sidecut (Elan SCX and Elan RP90). Five, expert male skiers performed three runs on each ski. Three-dimensional knee joint motion was collected throughout each run using a portable, magnetic motion tracking system. Twenty-four turns from each run were analyzed for joint motion characteristics. The results indicated that no statistically significant differences in knee joint range of motion or angular velocities were found to exist between the Elan SCX and Elan RP90 during normal skiing maneuvers. Further research is needed on the effect of ski sidecut on knee joint kinematics while skiing on varied terrain and/or with different skiing styles. In addition, similar studies comparing the effect of ski sidecut on metabolic cost and effect on injury rates are also needed.

Adult↗
PubMed1998

Transcriptional repression by v-Ski and c-Ski mediated by a specific DNA binding site.

The Ski oncoprotein has been shown to bind DNA and activate transcription in conjunction with other cellular factors. Because tumor cells or myogenic cells were used for those studies, it is not clear that those activities of Ski are related to its transforming ability. In this study, we use a nuclear extract of c-ski-transformed cells to identify a specific DNA binding site for Ski with the consensus sequence GTCTAGAC. We demonstrate that both c-Ski and v-Ski in nuclear extracts are components of complexes that bind specifically to this site. By evaluating the features of the sequence that are critical for binding, we show that binding is cooperative. Although Ski cannot bind to this sequence on its own, we use cross-linking with ultraviolet light to show that Ski binds to this site along with several unidentified cellular proteins. Furthermore, we find that Ski represses transcription either through upstream copies of this element or when brought to the promoter by a heterologous DNA binding domain. This is the first demonstration that Ski acts as a repressor rather than an activator and could provide new insights into regulation of gene expression by Ski.

Animals↗
PubMed1989

The v-ski oncogene encodes a truncated set of c-ski coding exons with limited sequence and structural relatedness to v-myc.

The nucleotide sequence of a biologically active v-ski gene from a cloned proviral segment shows that ski is a 1,312-base sequence embedded in the p19 region of the avian leukosis virus gag gene. The v-ski sequence contains a single open translational reading frame that encodes a polypeptide with a molecular mass of 49,000 daltons. The predicted amino acid sequence includes nuclear localization motifs that have been identified in other nuclear oncoproteins. It also contains a proline-rich region and a set of cysteine and histidine residues that could constitute a metal-binding domain. Two regions of the amino acid sequences of v-ski and v-myc are related, and the two proteins exhibit similar distributions of hydrophobic and hydrophilic amino acids. Cloned segments of the chicken c-ski proto-oncogene totaling 65 kilobases have been analyzed, and regions related to v-ski have been sequenced. The results indicate that v-ski is derived from at least five coding exons of c-ski, that it is correctly spliced, and that it is missing c-ski coding sequences at both its 5' and 3' ends. The c-ski and avian leukosis virus sequences that overlap the 5' virus/v-ski junction in Sloan-Kettering virus contain an 18-of-20-base sequence match that presumably played a role in the transduction of ski by facilitating virus/c-ski recombination.

Amino Acid Sequence↗
PubMed1997

[Carving in comparison with ski technique of the skiing athlete (competitive skier) and the leisure and comfort level skier].

In skiing there is principally no difference between the operating mechanism of a ski-racer and a skier who masters the technic of carving. Both try to ski with as less sliding as possible. The pressure distribution on the ski in a curve is very important. Near the end of the curve the pressure on the edge of the ski must be increased through various methods, on the one hand to avoid sliding and on the other hand to prepare the next curve correctly. In mastering the necessary mechanism of movements, the carving with the more wasted skis will be easier, because it is not necessary to put as much pressure on the last section of the ski, as it is necessary with the original skies to have the same result. Therefore even the holiday-skier has the possibility with carving-skis to master the ski-technic of the ski-racer and to have the pleasure of carving instead of sliding.

Acceleration↗
PubMed2003

Biomechanical aspects of new techniques in alpine skiing and ski-jumping.

There have been considerable changes in equipment design and movement patterns in the past few years both in alpine skiing and ski-jumping. These developments have been matched by methods of analysing movements in field conditions. They have yielded new insights into the skills of these specific winter sports. Analytical techniques have included electromyography, kinetic and kinematic methods and computer simulations. Our aim here is to review biomechanical research in alpine skiing and ski-jumping. We present in detail the techniques currently used in alpine skiing (carving technique) and ski-jumping (V-technique), primarily using data from the authors' own research. Finally, we present a summary of the most important results in biomechanical research both in alpine skiing and ski-jumping. This includes an analysis of specific conditions in alpine skiing (type of turn, terrain, snow, speed, etc.) and the effects of equipment, materials and individual-specific abilities on performance, safety and joint loading in ski-jumping.

Biomechanical Phenomena↗
PubMed1996

Ski injuries in Scotland. A review of statistics from Cairngorm ski area winter 1993/94.

Scottish skiing is a growth industry-nearly all acute ski injuries in Aviemore are managed initially by local general practitioners. This study set out to examine the nature and incidence of ski injuries in one Scottish ski resort, and to calculate the additional workload generated for the health centre, ambulance service and local hospital. During the study period, the winter ski season of 1993-94, a prospective study was made of the 486 acute ski injuries presenting to Aviemore Health Centre. Despite frequently poor weather conditions, the season's injury rate for Cairngorm was 2.43 per 1000 skier days which compares favourably with statistics from other ski centres world-wide. The anatomical pattern of injuries for both downhill skiing and snowboarding was similar to that of other countries. Knee injuries constituted nearly one third of all cases. 8% of injuries involved the ski lift machinery. 31% of casualties underwent radiographic examination, 17% needed hospital referral and 7% required admission to hospital. The management of acute ski injuries can be performed effectively in the primary care setting. It has significant benefits in rural areas by rationalising the use of ambulance and hospital services.

Acute Disease↗
PubMed1997

Trans-regulation of myogenin promoter/enhancer activity by c-ski during skeletal-muscle differentiation: the C-terminus of the c-Ski protein is essential for transcriptional regulatory activity in myotubes.

c-ski gene product is a nuclear protein with myogenesis-promoting and transforming activities. We have analysed the effects of c-ski transfection on the promoter/enhancer activity of the upstream region of the myogenin gene during in vitro myogenesis using CAT reporter assay. When co-transfected with c-ski into myogenic C2C12 cells, promoter/enhancer activity was efficiently suppressed in proliferating cells, but the myogenesis-induced increase in activity was potentiated approximately ten times more (150-fold in the ski-transfected cells) than the ordinary increase (12-fold in the mock) 48 h after induction of differentiation. In non-myogenic 10T1/2 cells, c-ski transfection caused persistent suppression of promoter/enhancer activity in both proliferating and growth-arrested (i.e. myogenesis-inducing) conditions. Thus the ski-dependent potentiation of myogenin gene transcriptional activity appears to be specific for myogenesis. The C-terminal region (amino acids 595-663) of the c-Ski protein was essential for the potentiating activity in myotubes. Other members of the ski-gene family, snoN and snoA, were ineffective in transactivation, possibly because of the defect in the corresponding C-terminal region. c-Ski protein underwent a mobility shift on SDS/PAGE after in vitro myogenesis which may explain the conversion of the activity from suppressive in myoblasts to potentiating in myotubes. Deletion analysis of the upstream region of the myogenin gene revealed that a responsive element to c-ski in myotubes is located at a distinct site upstream of the basal promoter/enhancer region.

Animals↗
PubMed1995

Treadmill roller ski test predicts biathlon roller ski race results of elite U.S. biathlon women.

This study evaluated ski-specific laboratory testing and the relationship of test parameters to biathlon race performance. Since the ski skating technique used exclusively during biathlon racing requires a large upper body contribution, treadmill roller ski test parameters may provide relevant information for ski-specific training and ski performance. Seven top U.S. female biathlon skiers performed lactate threshold and VO2 peak tests running (TR) and roller skiing (skating technique, RS) on a motor driven treadmill. In addition, a constant workload (14 km.h(-1), 6% grade) roller ski test to exhaustion at race pace (ET) on a motor driven treadmill, and a short-term double pole power test (DP) were also performed. Results indicate that lactate threshold VO2 and HR were significantly lower during RS than TR, DP power (w.kg(-1)) was related to RS VO2 peak (r = 0.90), but not to TR parameters. ET time to exhaustion was related to gross efficiency during ET (r = -0.86), RS VO2 peak (r = 0.80) and DP HR (% peak HR, r = 0.80). These results suggest that ski-specific laboratory testing provides better insight to ski performance than treadmill run testing.

Adult↗
PubMed2003

Direct interaction of Ski with either Smad3 or Smad4 is necessary and sufficient for Ski-mediated repression of transforming growth factor-beta signaling.

The oncoprotein Ski represses transforming growth factor (TGF)-beta signaling in an N-CoR-independent manner. However, the molecular mechanism(s) underlying this event has not been elucidated. Here, we identify an additional domain in Ski that mediates interaction with Smad3 which is important for this repression. This domain is distinct from the previously reported N-terminal Smad3 binding domain in Ski. Individual alanine substitution of several residues in the domain significantly affected Ski-Smad3 interaction. Furthermore, combined mutations within this domain, together with those in the previously identified Smad3 binding domain, can completely abolish the interaction of Ski with Smad3, while mutation in each domain alone retained partial interaction. By introducing those mutations that abolish direct interaction with Smad3 or Smad4 individually, or in combination, we show that interaction of Ski with either Smad3 or Smad4 is sufficient for Ski-mediated repression of TGF-beta signaling. Furthermore our results clearly demonstrate that Ski does not disrupt Smad3-Smad4 heteromer formation, and recruitment of Ski to the Smad3/4 complex through binding to either Smad3 or Smad4 is both necessary and sufficient for repression.

Amino Acid Sequence↗
PubMed1989

Isolation of human cDNA clones of ski and the ski-related gene, sno.

cDNA clones of ski and the ski-related gene, sno, were obtained by screening human cDNA libraries. The predicted open reading frame of h-ski could encode a protein of 728 amino acid residues. The h-ski protein is highly homologous with the v-ski protein. The overall homology between h-ski and v-ski is 91% at the amino acid level. DNA sequencing analysis revealed two types of cDNA clones from the sno (ski-related novel gene) gene, possibly due to alternative splicing. The first type, named snoN (non Alu-containing), encoded a protein of 684 amino acid residues. The second type, named snoA (Alu-containing), encoded a protein of 415 amino acid residues. The first 366 amino acid residues of snoN and snoA are the same, but subsequent amino acids show divergence. Several transcripts of h-ski (6.0, 4.7, 3.8, 3.0, 2.1 and 1.8 kb) were detected. The mRNAs of h-sno were 6.2, 4.4 and 3.2kb.

Amino Acid Sequence↗
PubMed2000

Upper limb in injuries in dry ski slope skiing--a continuing problem.

The aim of this study was to assess how common injuries to the upper limbs are from dry ski slope skiing, to document the pattern of injury to the upper limbs from dry ski slope skiing and to discuss preventative measures. Skier's experience was also determined. The study was carried out on 174 patients attending the accident and emergency department over a period of 3 years who had sustained injuries from dry ski slope skiing. Prospective registration was used to collect the data. Sixty-seven per cent of the patients had received instructions prior to skiing. Upper limb injuries outnumbered lower limb injuries by a ratio of 7.9 to 1. Thumb injuries outnumbered other injuries in the upper limb. The mechanism of injury was due to a fall in 94.2% of patients. It is concluded that the lattice network on dry ski slopes significantly contributes to the platform of injuries to the upper limbs, and ways in which the lattice network may be improved are recommended.

Accidental Falls↗
PubMed2003

Deaths associated with snow skiing in Colorado 1980-1981 to 2000-2001 ski seasons.

OBJECTIVES: To investigate the trend and injury patterns of deaths associated with snow skiing in Colorado between 1980 and 2001. METHODS: Death certificates were searched electronically and reviewed manually. Total skier ticket sales were used to calculate death rates. Types of injuries and characteristics of those who died were investigated. RESULTS: A total of 274 skier deaths occurred between 1980 and 2001 in Colorado. Death rates ranged from 0.53 to 1.88 per million skier visits. The majority of deaths were among males (>81%). Ages ranged from 7 to 77 years with an average of 32 years. The greatest number of deaths associated with downhill skiing (76 deaths) occurred between 10:00 a.m. and 2:00 p.m. while the greatest number of deaths associated with cross-country skiing happened between 2:00 and 6:00 p.m. About 65% of deaths associated with downhill skiing (133 cases) died of traumatic injuries resulting from collisions. CONCLUSIONS: A slight increase in the rate of ski-related deaths was observed. The role of collisions in ski-related deaths warrants further investigation to reduce the risk of this activity for all skiers. Further work is needed to determine the efficacy of helmet use to reduce the risk of head injuries in the skiing population.

Accidental Falls↗
PubMed2002

Helmet availability at skiing and snowboarding rental shops. a survey of Colorado ski resort rental practices.

BACKGROUND: Many studies have determined that head injuries are serious and potentially life threatening in skiers and snowboarders. Helmets have proven to be effective in reducing the risk of head and brain injury in blunt trauma from bicycling, climbing, skiing, and snowboarding. The objective of this study was to evaluate the availability, cost, and prevelance of helmet rental to skiers and snowboarders at Colorado ski resorts. METHODS: A survey of rental shops based at Colorado ski areas was conducted during the 1998-1999 ski season. Surveys were mailed to 27 Colorado ski areas. The establishments surveyed were skiing/snowboarding rental shops owned, operated, or both by the resorts based at respective mountains. RESULTS: Nineteen of 26 responding Colorado ski resorts rented helmets, and helmet rental has been increasing in popularity. However, helmets were not considered as part of the standard rental package by any of the resorts, and only one resort offered a discount on helmet rental with a package. While 2% to 38% of skiers/snowboarders rented equipment, less than 1% to 8.6% of renters rented helmets. Subjectively, helmet rental was encouraged mostly for children. CONCLUSIONS: The data acquired should represent a reasonable picture of current helmet rental practices at Colorado ski areas. While helmet use is increasing, it has not yet become generally accepted.

Adolescent↗
PubMed1988

Ski-flying: related catecholamine excretion compared with cross-country skiing.

We examined the catecholamine excretion and its performance-diagnostic relevance in athletes of the German National Team during ski-flying and cross-country skiing. Five athletes were examined during the 1986 World Championship ski-flying competition and eight athletes during a 24-km cross-country qualification test. There is little doubt that the special competitive conditions have considerable influence on the usefulness of these data. We decided to publish the results anyway since the results may expand our knowledge about the performance-diagnostic relevance of catecholamine excretion under competitive conditions. During cross-country skiing, the average noradrenaline elimination (1166 pmol.min-1) was about 150% higher and the average adrenaline elimination (243 pmol.min-1) about 30% lower than during ski-flying. The noradrenaline-adrenaline ratio was about 4.8 in cross-country skiing and 1.3-1.5 in ski-flying. Catecholamine excretion does, as expected, therefore permit differentiation of the various strains on the organism. The impression with respect to performance-diagnostic relevance arises that successful athletes show a more stable and lower excretion of noradrenaline under competitive conditions. This can only be a preliminary statement; it should serve to stimulate discussion and further investigations of the problem.

Catecholamines↗