Anthropological and physiological observations on Tarahumara endurance runners.
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Adolescent↗
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Magnetic resonance imaging of body fat of athletes compared with controls, and the oxidative metabolism of estradiol.
The extent of 2-hydroxylation of estradiol (E2), which yields a non-estrogenic metabolite (2-OHE1), increased significantly with decreasing subcutaneous fat (ScF)/total volume percent (TV%) and total fat (TF)/TV% evaluated by magnetic resonance imaging (MRI) for five athletes during low- and high-intensity training, and four controls. The increase in 2-hydroxylation with decreasing adiposity was associated with anovulation and amenorrhea among the athletes.
Adipose Tissue↗
Asthma in United States olympic athletes who participated in the 1998 olympic winter games.
BACKGROUND: About one of every 5 athletes who participated in the 1996 Summer Olympic Games in Atlanta had a past history of asthma, had symptoms that suggested asthma, or took asthma medications. No previous study has determined the prevalence of asthma in all US athletes who participated in an Olympic Winter Games. OBJECTIVES: We sought to determine how many US athletes who participated in the 1998 Olympic Winter Games had a past history of asthma, had symptoms that suggested asthma, or indicated taking a medication used to treat asthma. METHODS: We evaluated responses to questions that asked about allergic and respiratory diseases in the United States Olympic Committee Medical History Questionnaire that was completed by all 196 athletes who represented the United States at the 1998 Olympic Winter Games in Nagano, Japan. RESULTS: Forty-three (21.9%) of the 196 athletes had a previous diagnosis of asthma, and 36 (18. 4%) recorded use of an asthma medication at some time in the past. Forty-four (22.4%) reported use of an asthma medication, a diagnosis of asthma, or both (our basis for the diagnosis of asthma). Thirty-four (17.4%) of the athletes were currently taking an asthma medication at the time that they completed the questionnaire or indicated that they took these medications on a permanent or semipermanent basis and were considered to have active asthma. Athletes who participated in Nordic combined, cross-country, and short track events had the highest prevalence of having been told that they had asthma or had taken an asthma medication in the past (60.7%) in contrast with only one (2.8%) of the 36 athletes who participated in bobsled, biathlon, luge, and ski jumping. Eighteen (24%) of 75 athletes who participated in alpine, long track, figure skating, snow boarding, and curling had a previous diagnosis of asthma or recorded use of an asthma medication. CONCLUSIONS: We conclude that asthma appeared to have been more common in athletes who participated in the 1998 Winter Games than in athletes who participated in either the 1996 or 1984 Summer Games. Clearly, asthma rates vary widely among sports. This suggests that the environment in which exercise is performed is important in leading to a decrease in the amount of exercise required to trigger asthma and perhaps in causing injury to the airways.
Asthma↗
Bone mineral density and body composition of the United States Olympic women's field hockey team.
OBJECTIVE: To evaluate total bone mineral density (BMD) and body composition (% fat) in world class women field hockey players, members of the 1996 United States Olympic team. METHODS: Whole body BMD (g/cm2) and relative body fatness (% fat) were assessed by dual energy x ray absorptiometry using a Lunar DPX-L unit with software version 1.3z. Body composition was also estimated by hydrostatic weighing and the sum of seven skinfolds. RESULTS: Mean (SD) BMD was 1.253 (0.048) g/cm2 which is 113.2 (4.0)% of age and weight adjusted norms. Estimates of body composition from the three methods were similar (statistically non-significant): 16.1 (4.4)% fat from dual energy x ray absorptiometry, 17.6 (3.2)% from hydrostatic weighing, and 16.9 (2.6)% from the sum of seven skinfolds. Mean fat free mass was approximately 50 kg. CONCLUSIONS: The mean whole body BMD value for members of the 1996 United States Olympic women's field hockey team is one of the highest reported for any women's sports team. Moreover, the mean fat free mass per unit height was quite high and % fat was low. In this group of world class sportswomen, low % fat was not associated with low BMD.
Absorptiometry, Photon↗
Insulin response of women athletes in relation to body fat quantified by magnetic resonance imaging.
We report the glucose and insulin response to a 300-min glucose tolerance test among 17 women athletes as compared with 11 normal, nonatheletic controls. Also reported is the relationship of the insulin area under the curve as a function of percentages of total fat (TF), subcutaneous fat, and internal fat of total volume (TV) quantified by magnetic resonance imaging overall and at six regional sites. Athletes had a more sensitive insulin response to the glucose tolerance test as compared with controls. The insulin area under the curve of athletes and controls was significantly (p = 0.05) related to their overall TF/TV%; athletes had significantly less TF/TV% compared with the controls.
Adipose Tissue↗
Snowboard traumatology: an epidemiological study.
In the past 10 years, snowboarding has become a popular winter sport among young people, and the number of accidents has increased proportionately. The incidence of traumas from snowboarding is shown to be 4 to 6 for every 1000 medical examinations, which is similar to that of downhill skiing. However, other important statistical differences exist between the two sports. This study of 106 snowboarding-related injury cases analyzes the epidemiology of these injuries in Italy. Results found that 45.1% of injuries are located in the upper limbs and that significant advantages are obtained with the introduction of guards to protect the upper limbs during descent. Serious ligament injuries to the knee are more rare in snowboarding than in downhill skiing. In both sports, injuries are more common with rigid boots, which lead to a higher incidence of injury to the upper limbs. Finally, a high percentage of injury to beginners was found in this study. Training courses for those who are considering taking up the sport of snowboarding could significantly lower their risk of trauma.
Adolescent↗
Spinal injuries in snowboarders: risk of jumping as an integral part of snowboarding.
BACKGROUND: The purpose of this study was to clarify the occurrence rate and characteristics of spinal injuries caused by snowboarding that were sustained at the Okumino skiing area in Gifu Prefecture, Japan, from 1988 to 2000. METHODS: This study was a retrospective review of 13,490 cases of snowboard- or ski-related injury treated at Sumi Memorial Hospital over this period. RESULTS: A total of 7,188 patients sustained snowboard-related injuries, and 238 of these had spinal injuries caused by snowboarding (3.3%), whereas 6,302 patients sustained ski-related injuries, and 86 of these had spinal injuries caused by skiing (1.4%). Although there were no significant differences in the difficulty of slope, location of vertebral fracture, or spinal cord injury between snowboarders and skiers, the incidence of transverse process fractures was significantly higher in snowboard-related than in skiing-related injury (p < 0.05). In addition, there was a significantly higher incidence of spinal injury among beginner snowboarders than among beginner skiers (p = 0.04). Furthermore, intermediate or expert snowboarders were more likely to be injured because of jumping than beginners (p < 0.001), whereas about 70% of spinal injuries caused by skiing resulted from a simple fall. CONCLUSION: Spinal injuries sustained while snowboarding are increasing considerably in incidence and are characterized as complex injuries. We must educate young snowboarders of the risk of this sport, to prevent these serious injuries.
Adolescent↗
Some factors influencing plasma AST/CK activities in thoroughbred racehorses.
Sixty-six Thoroughbred horses in training (2 or 3 years of age) were studied during one flat racing season, to investigate the relationship between age, sex, time of year, dietary electrolyte imbalances and plasma aspartate aminotransferase/creatine kinase (AST/CK) activities. Management and training variations were minimised. Between February to October, monthly 24 h post exercise samples were collected and analysed for AST and CK activities. Sex and/or age were shown to have a significant effect on the occurrence of high CK (> 100 iu/litre) and AST (> 300 iu/litre) activities. Fillies were more likely to have elevated CK and AST than colts. Two-year-olds tended to have higher AST activities than three-year-olds. Time of year had no significant effect on the number of animals with high or low activities. Fourteen animals had consistently raised plasma AST activities (median > 300 iu/litre). Eight of these raced and seven won at least one race. The average daily intake of calcium, sodium, phosphorus and potassium was determined at each sampling time. In eight of the horses, the fractional electrolyte excretion (FE) of phosphate (PO4) and sodium (Na) was determined monthly. FE values were also determined in three horses which had suffered repeated attacks of the equine rhabdomyolysis syndrome. The FE, PO4 and Na values reflected dietary intake of calcium, phosphorus and sodium respectively. It was not possible to determine any effect of training or a predisposition to equine rhabdomyolysis. No obvious differences were found between the resting thyroxine values of three animals with consistently low AST activities, six of those with consistently raised AST and three animals which had suffered repeated attacks of rhabdomyolysis.
Aging↗
Estrogen 2-hydroxylase oxidation and menstrual function among elite oarswomen.
We monitored the estrogen metabolism and menstrual function of two groups of elite oarswomen as they progressed from a phase of low intensity training (phase I), to high intensity training (phase II), and back to low intensity training (phase III). Each phase lasted 3 months. The two groups of oarswomen included five oarswomen (group A) who experienced no menstrual dysfunction during the training year, even during the phase of high intensity training, and five oarswomen (group B) who experienced normal menses during phases of low intensity training but disrupted menses during the phase of high intensity training. Four nonathletic controls were also studied. Menstrual function was monitored throughout the training year by assay for pregnanediol glucuronide in overnight 12-h urine samples collected twice weekly. Repeated measures of the extent of estradiol metabolized by 2-hydroxylase oxidation, total body water, and nutrient intake of group A and B oarswomen were made at the three phases of the training year; the extent of estradiol metabolized by 2-hydroxylase oxidation was evaluated by radiometric analysis; total body water was measured by deuterium oxide dilution and bioimpedance analysis; and nutrient intake was evaluated by food frequency questionnaire. The group B oarswomen were found to metabolize a significantly greater fraction of administered [2-3H]estradiol by 2-hydroxylase oxidation than group A oarswomen (chi 2(1) = 6.57; P = 0.01). The extent of estradiol metabolized by 2-hydroxylase oxidation among group A oarswomen did not differ from that among nonathletic controls. The extent of 2-hydroxylase activity did not change significantly with the intensity of training among either group A or group B oarswomen. Oarswomen in groups A and B lost body weight and became leaner during the phase of high intensity training (phase II). Group A and B oarswomen did not differ in the degree of weight loss or in relative fatness during phase II. Over all subjects, the extent of estradiol metabolized by 2-hydroxylase oxidation was positively correlated with the extent of leanness. These data suggest that elevated estradiol 2-hydroxylase oxidation among elite oarswomen is associated with the occurrence of menstrual disturbances during phases of high intensity training and increased relative leanness.
Adult↗
The downside of snowboarding. Common injuries in novices and those seeking 'hospital air'.
Depending on where you live, you may never have treated a snowboarding injury. However, some of your patients (or maybe your own children) may return from a vacation in the Rockies sporting a snowboarding injury and needing immediate treatment or follow-up care. How familiar are you with the injury patterns specific to this increasingly popular sport? Read on for an introduction to the world of snowboarding and helpful guidelines on how to recognize and treat common snowboarding injuries.
Adolescent↗
Magnetic resonance imaging of overall and regional body fat, estrogen metabolism, and ovulation of athletes compared to controls.
The association of menstrual dysfunction of athletes with changes in body composition has been controversial, because most estimations of body fatness have been indirect. Using magnetic resonance imaging, we quantified the sc and internal fat over a specific volume from the fifth thoracic vertebra to femoral fat in the upper thigh and at 4 other anatomical landmarks of 17 athletes (13 oarswomen and 4 runners) compared to that in 11 nonathletic controls. The magnetic resonance imaging data were also analyzed for the athletes and controls in relation to ovulatory status, which was determined by assay of urinary pregnanediol glucuronide, and in relation to the extent of 2-hydroxylation of estradiol to a nonpotent metabolite, 2-hydroxyestrone, which was evaluated by radiometric analysis. We found that 1) the relative and absolute body fat values of the athletes were significantly less (P < 0.05) than those of the controls overall and at each of the six regional sites, although the body weights of the rowers were significantly heavier than those of the controls, and the runners did not differ from the controls; 2) the ratio of sc fat to internal fat was 80%:20% among both athletes and controls, even though the athletes had significantly less fat; 3) the extent of estradiol 2-hydroxylation was significantly (P = 0.005) inversely related to total fat as a percentage of the total volume and to sc fat as a percentage of the total volume (P = 0.004) overall and at each of the regional fat depots; 4) athletes with menstrual disorders had significantly decreased sc and internal fat overall and at all regional sites compared to controls; and 5) a subgroup of ovulatory rowers had an apparent increase or lack of decrease in internal fat at the level of vertebrae lumbar 4, sacral 1, and sacral 4, compared to controls, whereas their sc fat was decreased at these sites compared to that in controls. Changes in regional fat deposits of both sc and internal fat may be involved in the menstrual dysfunction of the athletes in addition to their decreased overall fatness. The body weight and body mass index of well trained athletes can be a misleading index of body composition.
Adipose Tissue↗
[Analysis of accidental deaths in mountain tourism and sport according to statistics from the Republic of Kabardino-Balkariia].
Lethal cases in mountain tourism and sports in the Republic of Kabardino-Balkaria were studied for 1978-1995. A total of 152 accidental deaths were analysed. Most of the victims were males under 30 years of age. The greatest number of the accidents took place on Monday, in July and August. Many amateur visitors from abroad were among the victims. The main cause of death in the mountains of Kabardino-Balkaria for the 18 years studied was multitrauma of the body (69.7%). Hypothermia and obturation asphyxia with snow and compression asphyxia due to snowbreak account for 11.8 and 13.2% deaths, respectively; lightning killed 4%. Combination of high mountain hypoxia with exacerbated chronic somatic disease or hypothermia caused death in 1% victims. The authors propose how to improve forensic-medical expert examination of accidental death and safety in the mountains.
Accidents↗
Mechanical constraints on Nordic ski performance.
Skiers, coaches, and sports scientists must work within mechanical constraints to improve performance. If Nordic skiing is to be improved by mechanical means, it will be achieved by affecting one or more of the major constraints: gravity, mass, friction, aerodynamic or hydrodynamic lift and drag, and centripetal force. For example, the skier who assumes a tucked position, drafts a competitor, and wears a drag-reducing hood and body suit is reducing aerodynamic constraints. Sliding friction may also be reduced by using specially prepared skis and by selecting skis appropriate for the snow characteristics of the race course. Skin friction hydrodynamic drag may also be affected by ski selection and by special base preparations. Gravity and mass constraints are diminished by using lightweight components, by carrying them in the least costly way, and by minimizing swing weight. The toppling effect of centripetal forces is addressed by leaning into turns. All of these examples address mechanical constraints in a way that reduces physical power requirements, and thus decrease the metabolic power required to ski at a given speed, as well as increasing the maximal speed attainable.
Biomechanical Phenomena↗
Case study of training, fitness, and nourishment of a dog driver during the Iditarod 1049-mile dogsled race.
The purpose of the present case study was threefold: (a) to estimate intake and expenditure of a dog driver (musher) while participating in the Iditarod, (b) to determine the hydration status of the musher at the completion of the event, and (c) to evaluate training related changes in aerobic capacity and body composition of a long-distance dog sled driver in preparation for and following completion of a 1049-mile (1692-km) sled dog race. Actual energy intake during the Iditarod Sled Dog Race was estimated at 8,921 kilojoules (kJ) per day. Nutrient intake expressed as percentage kJ of total energy (14%, 44% and 42% for protein, carbohydrates, and fat, respectively). Weight loss of .72 kg of body weight indicated an energy deficit of 1819 kJ per day during the race. Total energy needs per day were calculated to be 10,740 kJ/day. An increase in hematocrit and hemoglobin during the race may indicate dehydration during the event. There was an improvement in aerobic fitness during on-snow training as determined by ventilatory threshold and VO2peak data. Fat-free mass was maintained during training (46.4 kg), with a concomitant decrease in fat (2.4 kg). Fat-free mass was also maintained during the 12-day race.
Alaska↗
["Warm-up!" Prevention of skiing accidents. A preventive campaign by the Swiss Accident Insurance Organization].
In 1991, 762,800 leisure time accidents were recorded in Switzerland. 33% of the accidents occurred in the course of a sporting activity with the majority happening while playing football. Skiing accidents came second. Although the recession reduced the number of accidents, skiing accidents were on the increase. The number of all other leisure time accidents including football accidents (the largest group) declined, as did occupational accidents. In terms of medicine, insurance and the economy, the significance of more than 54,000 skiing accidents each year is enormous. SUVA, the Swiss National Accident Insurance Organization is launching a comprehensive campaign to prevent skiing accidents. Among the many methods of prevention possible, such as physical preparation prior to the skiing season, safe equipment, correct skiing technique, consideration for other slope users and adaptation to the snow conditions, etc., this campaign focuses on the avoidance of a cold start. The campaign, which is planned to last several years and will cover the whole of Switzerland, aims to propagate the warm up before setting off downhill. The concept and development of this large-scale, professionally-run SUVA preventive campaign are described.
Athletic Injuries↗
Water versus carbohydrate-electrolyte ingestion before and during a 15-km run in the heat.
Twelve highly trained male runners ran 15 km at self-selected pace on a treadmill in warm conditions to demonstrate differences in physiological responses, fluid preferences, and performance when ingesting sports drinks or plain water before and during exercise. One hour prior to the start of running, an equal volume (1,000 ml) of either water or a 6% or an 8% carbohydrate-electrolyte (CE) drink was ingested. Blood glucose was significantly higher 30 min following ingestion of 6% and 8% CE compared to water, significantly lower at 60 min postingestion with both sports drinks than with water, but similar after 7.5 km of the run for all beverages. During the first 13.4 km, oxygen uptake and run times were not different between trials; however, the final 1.6-km performance run was faster with both CE drinks compared to water. Despite a lower preexercise blood glucose, CE consumption prior to and during exercise significantly improved performance in last 1.6 km of a 15-km run compared to water.
Adult↗
Cross-country skiing injuries and biomechanics.
Cross-country skiing exercises most of the joints, muscles and tendons in the body giving the skier an all around workout. This, in combination with a low incidence of injury, makes cross-country skiing an ideal recreational and competitive sport. The new skating techniques developed during the last decade have resulted in greater velocity. The maximum speed during the diagonal stride technique is 6 m/sec compared to 8 to 9 m/sec when skating and double poling. Top-level skiers today use strong and ultra light skis of fiberglass and graphite. The ski weight is less than 500g. Today's skating technique does not require any waxing and only the cambered portion of the ski is waxed when performing the diagonal stride. The preparation of the ski course has improved with the development of special track machines. This allows top-level skiers to reach 60 to 80 km/h on downhill slopes, which has resulted in an increased risk of injury. Because cross-country skiing takes place wherever snow is available, it is difficult to establish accurate injury rates in comparison to alpine skiing which is performed on very specialised terrain at ski areas. Studies estimate the cross-country ski injury rate in Sweden to be around 0.2 to 0.5 per thousand skier days. A prospective study of cross-country ski injuries conducted in Vermont revealed an injury rate of 0.72 per thousand skier days. 75% of the injuries sustained by members of the Swedish national cross-country ski team during 1983 and 1984 were overuse injuries while 25% resulted from trauma. The most common overuse injuries included medial-tibial stress syndrome, Achilles tendon problems and lower back pain. Most common among traumatic injuries were ankle ligament sprains and fractures, muscle ruptures, and knee ligament sprains. Shoulder dislocation, acromioclavicular separation and rotator cuff tears are not infrequent in cross-country skiing. Injuries to the ulnar collateral ligament of the metacarpal phalangeal joint of the thumb (Stener's lesion) is the most common ski injury involving the upper extremity. Cross-country skiers 16 to 21 years of age complained more frequently of mild lower back pain than similarly aged non-skiers. This may result from repetitive hyperextension motions during the kick phase and the recurring spinal flexion and extension during the double poling phase. Repeated slipping on hard and icy tracks infrequently produce partial tears or microtrauma in the muscle tendinous units of the groin.(ABSTRACT TRUNCATED AT 400 WORDS)
Adolescent↗
[Snow board accidents. Multicenter Swiss snow board study 1992/93 with the cooperation of the bfu].
Snowboarding has become increasingly popular in recent years. A prospective multicenter study was therefore performed during the winter 1992/93. 345 injuries were analysed and compared with 305 healthy snowboarders on the slopes. Preliminary results show predominantly injuries of the upper extremity comparative to those suffered from alpine skiing. Protection of the hand and wrist is recommended as well as an instruction for a special technique for falling as measurements for accident prevention.
Adolescent↗