Werner Nachbauer

Effects of arch height of the foot on angular motion of the lower extremities in running.

It has been suggested that a relationship exists between the height of the medial longitudinal arch of the foot and athletic injuries to the lower extremities. However, the functional significance of arch height in relation to injury is not well understood. The purpose of this study was to determine the influence of arch height on kinematic variables of the lower extremities that have been associated with the incidence of injury in running in an attempt to gain some insight into a functional relationship between arch height and injury. The three-dimensional kinematics of the lower extremities were measured during running for 30 subjects using high-speed video cameras. A joint coordinate system was used to calculate the three-dimensional orientation of the ankle joint complex for a single stance phase. Simple, linear regression analyses showed that arch height does not influence either maximal eversion movement or maximal internal leg rotation during running stance. However, assuming that knee pain in running can result from the transfer of foot eversion to internal rotation of the tibia, a functional relationship between arch height and injury may exist in that the transfer of foot eversion to internal leg rotation was found to increase significantly with increasing arch height. A substantial (27%), yet incomplete, amount of the variation in the transfer of movement between subjects was explained by arch height, indicating that there must be factors other than arch height that influence the kinematic coupling at the ankle joint complex. Additionally, the transfer of movement is only one factor of many associated with the etiology of knee pain in running.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of modern ski equipment on the overall injury rate and the pattern of injury location in Alpine skiing.

In this article, the relationship, perhaps interdependence, between sleep-disordered breathing, hypertension, and obesity is discussed. There is strong evidence that sleep-disordered breathing and hypertension are related. On the one hand, the prevalence of hypertension increases with the number of apnea-hypopnea episodes per hour of sleep, whereas on the other hand, treating sleep-disordered breathing reduces hypertension. It has also been shown that this relationship between sleep-disordered breathing and hypertension is stronger in individuals with a high body mass index. Thus, it is concluded that in individuals presenting with hypertension, sleep-disordered breathing, or increased weight, the two other variables must be investigated and treated if present.Objective:To identify whether the introduction of carving skis and related equipment has altered the overall injury rate and/or the pattern of injury location. Design:Comparative case series. Setting:In the winter season of 1997-98, when carving skis began to appear on the ski market, all injured skiers requiring evacuation or medical treatment in 70 Austrian ski areas were recorded. Five years later, when most skiers were using carving skis, ski injury data were collected in a representative sample consisting of 5 ski areas from the first study. Assessment of Risk Factors:Data collection on injured skiers included subject demographics, weather and snow conditions, mechanism of the skiing accident, the type of ski used, injury location, and in the second study, additionally the date of the last ski binding adjustment. Main Outcome Measurements:Frequency of injured body parts. Results:In 1997-98, 1.43 injuries per 1000 skier days were calculated. Out of 17,914 injured alpine skiers, 29.5% of the injured men and 53.0% of the injured women suffered knee injuries. Five years later with the introduction of carving skis, the overall injury rate decreased by 9% but the gender-specific percentages of knee injuries did not change. Female carving skiers not using newly adjusted bindings had a higher risk of knee injury than those with newly adjusted bindings. Conclusion:The maintenance of adequate binding adjustment is especially important for the prevention of knee injuries in female carving skiers.

Aspirin for prophylaxis against headache at high altitudes: randomised, double blind, placebo controlled trial

At altitudes of 3000-5000 m about 20-50% of skiers and mountaineers experience headache, the main symptom of acute mountain sickness.1 Although most mountaineers know that they should avoid climbing great heights too early on and too fast, they may not always act accordingly. The use of drugs to prevent and treat headaches at high altitudes is therefore widespread, aspirin being one of the most commonly taken. We tested the efficacy of aspirin as prophylaxis against headache at high altitudes. Twenty nine volunteers with a history of headache at high altitude were randomly assigned in a double blind fashion to receive placebo (eight men, six women, mean age 38 (SD 12) years) or 320 mg aspirin (nine men, six women, mean age 38 (14) years). After examination at low altitude (600 m), subjects were transported to high altitude (3480 m) …

Effects of arch height of the foot on ground reaction forces in running.

There is a suggested link between running injuries and arch type of the foot. However, a distinct cause and effect relationship has not been established. Feet may be functionally categorized on the basis of arch height. The purpose of this study was to compare selected ground reaction force variables in running for different arch heights. Static height of the medial longitudinal arch was measured using a caliper, arch flattening during running was determined by video analysis, and ground reaction forces during running were recorded from a KISTLER force plate. Thirty-four subjects were divided into three arch height and three arch flattening groups, and single-factor analyses of variance were conducted to compare the groups. Arch height and arch flattening were not found to be significantly related. However, the initial medial force peak in the low arch group occurred significantly later than in the normal and high arch groups, and the anterior force peak in the low flattening group was lower compared with the medium and high flattening groups (P < 0.05). Both arch measurements were ineffective in accounting for the observed variability in the ground reaction forces in running. Specifically, the impact forces did not differ for the different arch height and arch lowering groups.

Factors associated with self-reported risk-taking behaviour on ski slopes

Background In recent years, discussions have arisen about the potential influence of wearing a ski helmet on an increasing level of risk taking and higher speeds on ski slopes. Objective To evaluate factors associated with selfreported risk-taking behaviour in recreational skiers and snowboarders. Methods Speeds of skiers and snowboarders were measured with a radar speed gun and sex, age, nationality, height, weight and helmet use, used type of gear, self-estimated skill level and self-estimated fitness level were recorded. In addition, participants were asked if they considered themselves as cautious or risk-taking skier or snowboarder. Results In total, 453 skiers (39.6 (14.8) years) and 74 snowboarders (26.4 (9.6) years) have been interviewed. A stepwise forward logistic regression model revealed five independent factors for a risk-taking behaviour on slopes. Adjusted OR and their 95% CI showed that risk takers were <40 years (OR 2.4, 95% CI 1.51 to 3.80), had a higher skill level (OR 2.1, 95% CI 1.25 to 3.50), were more likely males (OR 2.0, 95% CI 1.22 to 3.26), had a lower body mass index (22.8 vs 24.2) and skied with higher speeds (on average 53 vs 45 km/h) compared to cautious skiers. Conclusion Risk-taking behaviour on ski slopes is associated with younger age, higher skiing ability, male sex, lower body mass index and on average higher speeds. Helmet use is not associated with riskier behaviour on slopes. In addition, helmet use has to be recommended because helmet use reduces the risk of head injuries among skiers and snowboarders.

Consequences of 6 weeks of strength training on red cell O2 transport and iron status.

SummaryEffects of endurance training on OZ transport and on iron status are well documented in the literature. Only a few data are available concerning the consequences of strenuous anaerobic muscular exercise on red cell function. This study was performed to test the influence of strength training alone on parameters of red cell O2 transport and iron status. Twelve healthy untrained males participated in a strength-training pro gramme of 2-h sessions four times a week lasting 6 weeks. After 6 weeks a small but significant reduction of haemoglobin (Hb; − 5.4 g·l−1) was found (p<0.05). Mean red cell volume did not change, but a pronounced decrease of mean cell Hb concentration (from 329.2g·l−1, SE 2.5 to 309.8g·l−1, SE 1.2;p<0.001) and mean corpuscular Hb (from 29.6 pg, SE 0.4 to 27.7 pg, SE 0.3;p<0.01) was observed. Serum ferritin decreased significantly by 35% (p<0.01); transferrin, serum iron and iron saturation of transferrin were unaltered. Serum haptoglobin concentration was diminished significantly by 30.5% (p<0.01). The reticulocyte count had already increased after 3 weeks of training (p<0.05) and remained elevated during the following weeks. Strength training had no significant influence on the O2 partial pressure at which Hb under standard conditions was 50% saturated, red cell 2,3-diphospho glycerate and ATP concentration as well as on erythrocytic glutamate-oxalacetate transaminase activity. The data demonstrate that mechanical stress of red cells due to the activation of large muscle masses led to increased intravascular haemolysis, accompanied by a slightly elevated erythropoiesis, which had no detectable influence on Hb-O2 affinity. Training caused an initial depletion of body iron stores (prelatent iron deficiency). Although Hb had decreased by the end of the training phase a true “sports anaemia” could not be detected.

Are oral contraceptive use and menstrual cycle phase related to anterior cruciate ligament injury risk in female recreational skiers

Oral contraceptive use and menstrual cycle phase are suggested to influence the risk of anterior cruciate ligament (ACL) injuries in female athletes. However, only few data are available for recreational sports. Therefore, female recreational skiers with a non-contact ACL injury and age-matched controls completed a self-reported questionnaire relating to menstrual history, oral contraceptive use and previous knee injuries. Menstrual history data were used to group subjects into either preovulatory or postovulatory phases of menstrual cycle. Our findings suggest that oral contraceptive use did not show any protective effect against ACL injuries nor did self-reported previous knee injuries show any association with ACL injury rate in recreational alpine skiing. Analysis of menstrual history data revealed that recreational skiers in the preovulatory phase were significantly more likely to sustain an ACL injury than were skiers in the postovulatory phase.

Benefits of training at moderate altitude versus sea level training in amateur runners

AbstractAfter more than 25 years of research on altitude training (AT) there is no consensus regarding either the training programme at altitude or the effects of AT on performance at sea level. Based on a review of the research work on AT, we investigated combined base training and interval training at moderate altitude and compared immediate and delayed effects on sea level performance with those following similar sea level training (SLT). The altitude group (AG, 10 male amateur runners) trained at 2315 m (natural altitude) and the sea level group (SLG, 12 male amateur runners) at 187 m. Both groups performed 7 days of base training (running on a trail) lasting between 60 and 90 min a day and 5 days of interval training (speed and hill runs) for between 10 and 45 min a day. Incremental exercise tests were performed 1 week before (t1), 3 days after (t2) and 16 days after (t3) the 12-day main training period. Within AG, exercise performance improved fromt1 tot2 by 8% (P<0.05) and fromt2 tot3 by 8% (P<0.05). Maximum oxygen uptake (

ACL Injury Mechanisms and Related Factors in Male and Female Carving Skiers: A Retrospective Study

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