Female Cross-country Skiers Research Articles

女子クロスカントリースキー選手の滑走速度を高める技術に関する事例研究：フライト局面発生を伴った V2 スケーティング走法に着目して

女子クロスカントリースキー選手の滑走速度を高める技術に関する事例研究：フライト局面発生を伴った V2 スケーティング走法に着目して

Body Composition and Performance

Body composition is well known to be associated with endurance performance among adult skiers; however, the association among adolescent crosscountry and alpine skiers is inadequately explored. The study sample comprised 145 male and female adolescent subjects (aged 15-17 years), including 48 crosscountry skiers, 33 alpine skiers, and 68 control subjects. Body composition (%body fat [BF], %lean mass [LM], bone mineral density [grams per centimeter squared]) was measured with a dual-emission x-ray absorptiometer, and pulse and oxygen uptake was measured at 3 break points during incremental performance tests to determine physical fitness levels. Female crosscountry and alpine skiers were found to have significantly higher %LM (mean difference = 7.7%, p < 0.001) and lower %BF (mean difference = 8.1%, p < 0.001) than did female control subjects. Male crosscountry skiers were found to have lower %BF (mean difference = 3.2%, p < 0.05) and higher %LM (mean difference = 3.3%, p < 0.01) than did male alpine skiers and higher %LM (mean difference = 3.7%, p < 0.05) and %BF (mean difference = 3.2%, p < 0.05) than did controls. This study found strong associations between %LM and the onset of blood lactate accumulation and VO2max weight adjusted thresholds among both genders of the crosscountry skiing cohort (r = 0.47-0.67, p < 0.05) and the female alpine-skiing cohort (r = 0.77-0.79, p < 0.001 for all). This study suggests that body composition is associated with physical performance amongst adolescents.

Sport injuries as the main cause of sport career termination among Finnish top-level athletes

Injuries are common among athletes, and are sometimes so severe that they affect an athlete's career in sport. As studies on sport career termination are few, we conducted a study to investigate the role of injuries as a reason for ending a sport career. The study group consisted of 574 male and female top-level cross-country skiers, swimmers, long-distance runners and soccer players who responded to a retrospective postal questionnaire in 2006. Twenty-seven athletes (4.9%, 27/548) reported ending their sport career because of injury. A follow-up interview was conducted by telephone in 2007 (n=20 volunteered to be interviewed) to confirm sport career termination and the reasons for this. Fifteen of the interviewed athletes terminated and five continued their sport on the same level as earlier. Female athletes (12/15) terminated their sport career more frequently than male athletes (3/15). Athletes who reported terminating their sport career because of injury were on average two and a half years older (24.1 years vs. 21.6 years, P=0.006) than athletes who continued the sport. All the swimmers (n=5) who were interviewed terminated their career because of a shoulder injury. All the soccer players who ended their career (n=4) were female and had a severe knee injury, such as anterior cruciate ligament injury. Most of the athletes who terminated their sport career (70.4%, 19/27) reported that the injury caused them mild or moderate permanent disability. We found that sports injuries play a significant role in terminating a career in sport, and in some sports events injuries may commonly be the main reason for sport career termination. Injury prevention and adequate treatment and rehabilitation of injuries are thus essential to avoid the long-term consequences of severe sport injuries.

Racing Performance and Incremental Double Poling Test on Treadmill in Elite Female Cross-Country Skiers

The national Italian cross-country ski team has been evaluated on the basis of a new double poling cross-country roller skiing incremental test to exhaustion (DP) on a motorized driven treadmill. To verify the capacity of this specific test to predict performance, peak oxygen uptake (VO2peak), oxygen uptake at anaerobic threshold (VO2Th), peak treadmill speed, and treadmill speed at anaerobic threshold (Speak and STh, respectively) were measured during the test and correlated with the level of performance of 10 world class Italian female cross-country skiers. The physiological data obtained were also compared with results of an incremental and maximal test carried out by the same athletes but with the diagonal stride (DS) technique. Peak heart rate (HRpeak), HRTh, and VO2Th were significantly higher during DS than during DP (p < 0.001 for HRpeak and heart rate at anaerobic threshold (HRTh) p < 0.05 for VO2Th), whereas no difference was observed for VO2Thpeak. Speak and VO2peak were significantly correlated to FISI points only during DP (r = -0.88, p < 0.001 and r = -0.77, p < 0.01, respectively). STh and VO2Th during DP and VO2Th during DS were correlated with the level of performance (r = -0.88, p < 0.001; r = -0.63, p < 0.05; and r = -0.65, p < 0.05, respectively). Finally, VO2peak DP/VO2peak DS ratio was also correlated to the performance (r = -0.77, p < 0.01). On the other hand, no peak value achieved during DS was correlated with the level of performance. Based on these physiological results, this incremental DP test to exhaustion appears like a good predictor of elite cross-country skiers' performance.

Blood Lactate Response To Maximal Exercise In Master Cross-country Skiers

PURPOSE To examine the blood lactate responses to maximal exercise in the laboratory and on the snow across a competitive racing season in masters level male and female cross-country skiers. METHODS Twelve competitive cross-country skiers, six women (45.3 ± 3.6 yrs) and six men (50.8 ± 1.6 yrs) were studied at the start of their competitive season (December) and at the end of the racing season (March and April). Diet was controlled the morning of testing and activity levels were kept to a minimum the day prior to testing. Blood lactate, heart rate (HR) and oxygen consumption (VO2) responses to maximal graded exercise testing were examined using a treadmill protocol in the laboratory. Within 2 weeks of each laboratory test, blood lactate and heart rate responses were determined during skate skiing at different paces on the snow. Summary of RESULTS While there were gender differences in height, weight and body composition, these variables did not change significantly during the season. However, there were significant differences in heart rates at 2, 3 and 4 mMol/L of lactate between tests in the laboratory compared to tests on the snow during the early part of the season. The HR on the snow was lower at the same level of lactate on the snow in the early part of the season compared to both laboratory tests and to the test on the snow late in the season. At the end of the competitive season there were no changes in the lactate-heart rate profiles between the 2 laboratory tests, but there were significant changes between the 2 field tests. As the season progressed, the values on the snow became closer to the values in the laboratory. Women had lower heart rates at each level of lactate in all the tests, but had a similar change to the men over the racing season. There were significant improvements in VO2peak in the women only (53.6 ± 0.26 ml/kg/min vs. 55.9 ± 0.92 ml/kg/min) over the 4-month racing season. CONCLUSIONS 1) Testing in the laboratory at the start of the competitive season had a different lactate vs. HR response than testing on the snow 2) as the season progressed the lactate vs. HR response on the snow more closely matched the response in the laboratory. 3) Women had different lactate vs. heart rate responses compared to men.

THE EFFECTS OF TRAINING ON UPPER BODY POWER IN FEMALE CROSS-COUNTRY SKIERS

A distinguishing feature of elite cross-country (xc) skiers is their superlative upper body power (UBP). Race points/rankings are highly correlated to UBP, thus it appears that UBP training is an integral component to the success of xc ski racers. Recently, roller board training was shown to be superior for improving UBP when compared to circuit-type resistance training, free-weight training, and specificstrength training. However, a recent innovation in UBP training has been the introduction of the wind machine, and this has gained wide usage by xc skiers. PURPOSE To determine if wind machine training is as effective as roller board training in increasing upper body power in female cross-country skiers. METHODS Forty-four female xc skiers, age 23–59 years, were matched on initial absolute maximal UBP, measured in watts (w), and placed into one of two experimental groups (roller board or wind machine). All subjects underwent eight weeks of progressive UBP training. RESULTS While both groups improved significantly pre-post (p < .05) in mean absolute maximal UBP, t-tests indicated that there was no significant difference (p > .05) between the two groups' improvements. Roller Board: Pre 74.5+30.9, Post 95.9+29.8 w, Wind Machine: Pre 74.5+33.5, Post 99.3+34.3 w. CONCLUSION The wind machine was as effective at enhancing absolute UBP as the roller board. Future research should focus on determining the ideal UBP training program, which may involve combining the use of the wind machine, roller board, and various core and body resistance exercises. Supported in part by OSU H&HP Student Research Grant.

Physiological predictors of performance in cross-country skiing from treadmill tests in male and female subjects.

In order to study which parameter that best corresponds to performance during cross-country skiing, seven male and nine female cross-country skiers were tested with treadmill tests. Parameters measured or computed by metabolic gas measurements were the anaerobic threshold (AT), threshold of decompensated metabolic acidosis (TDMA), the exercise intensity where the Respiratory exchange ratio reaches 1.0 (R = 1) and peak oxygen (O2) uptake (VO2peak). Onset of blood lactate accumulation (OBLA, 4 mmol.l-1 blood lactate) was also measured. The various parameters were measured in percentage of maximal heart rate, percentage of peak O2 uptake, VO2 ml.kg-1.min-1, VO2 ml.min-1.kg-2/3 and VO2 l.min-1. Results from four large competitions were also collected to rank the subjects. With correlation analysis, it was revealed that in male subjects a high OBLA was associated with good ranking results (r = (-0.829) - (-0.964); P < 0.05-0.001). In female subjects, the best association with competition results was found for R = 1 (r = (-0.715) - (-0.810); P < 0.05). Concerning VO2 measurements, for male subjects the unit l.min-1 is suggested to be used and for female subjects either the units l.min-1, ml.min-1.kg-2/3, or ml.kg-1.min-1 could be used when predicting performance in cross-country skiing. In conclusion, treadmill tests can be used for the prediction of performance in cross-country skiing. Further, various parameters from treadmill tests in men and women are best used as predictors of performance in cross-country skiing.

Predicting performance in ski and swim championships: effectiveness of mood, perceived exertion, and dispositional optimism.

Two studies were performed with young athletes to investigate the utility of three psychological tests regarding the prediction of sport performance: the Profile of Mood States. Ratings of Perceived Exertion, and Dispositional Optimism. In Study 1, young male and female cross-country skiers and ski-marksmen in final preparation for the Junior National Swedish Championships were tested. Measured 5 wk. before both competitions, the higher the optimism (LOT), the better performance. In Study 2, which tested young swimmers in preparation for the Senior National Swedish Championships, competitors who had the highest scores on optimism performed less well during the competitions. The results are interpreted to indicate that optimism presents an important factor for predicting achievement in sports.

Atrioventricular plane displacement in female endurance athletes.

A novel hypothesis for increased ventricular pumping describes the heart as a displacement pump, in which atrioventricular plane displacement (AVPD) is an important mechanism. The hypothesis predicts that AVPD increases at high heart rates. The aim of the present study was to determine whether AVPD increases during exercise at high heart rates. A secondary aim was to study the left ventricular function and dimensions in endurance-trained young female athletes. Eight female cross-country skiers (18.5 +/- 0.9 yr, 169.3 +/- 2.9 cm, 55.7 +/- 4.2 kg, and 64.8 +/- 3.7 mL x kg(-1) x min(-1) in maximal oxygen uptake) were compared with seven sedentary female controls (18.0 +/- 0.6 yr, 175.0 +/- 2.5 cm, 71.1 +/- 4.1 kg, and 42.8 +/- 3.0 mL x kg(-1) x min(-1) in maximal oxygen uptake). Cardiac anatomy and function were assessed by echocardiography. Whereas left ventricular ejection fraction (LVEF) increased in both groups, AVPD fell significantly during exercise. AVPD did not correlate with LVEF, and there were no differences in AVPD between groups either at rest or during exercise. Cardiac output index (mL x lean body mass(-0.67)) and stroke volume index (mL x lean body mass(-1)) were higher in the trained group. The trained group had a larger left ventricular mass, and left ventricular internal dimensions, scaled to lean body mass. This first study to examine AVPD at rest and during exercise in endurance-trained athletes did not indicate that AVPD is an important mechanism of increased cardiac pumping during exercise. Endurance-trained female athletes have larger left ventricular dimensions and increased function as compared with sedentary subjects.

Hard training for 5 mo increases Na(+)-K+ pump concentration in skeletal muscle of cross-country skiers.

To study how training affects the Na(+)-K+ pump concentration, 11 male and 9 female elite junior cross-country skiers trained 12-15 h/wk at 60-70% (moderate-intensity group) or 80-90% (high-intensity group) of their maximal O2 uptake for 5 mo. Muscle biopsies taken from the vastus lateralis muscle before and after the training period were analyzed for Na(+)-K+ pump concentration by the [3H]ouabain-binding technique. Before training, the concentration was 343 +/- 11 nmol/kg wet muscle mass (mean +/- SE) for the men and 281 +/- 14 nmol/kg for the women (18% less than for the men, P = 0.003). The Na(+)-K+ pump concentration rose by 49 +/- 11 nmol/kg (16%, P < 0.001) for all subjects pooled during the training period, and there was no difference between the two training groups (P = 0.3) or the sexes (P = 0.5) in this increase. The Na(+)-K+ pump concentration correlated with the maximal O2 uptake (r = 0.6, P = 0.003), with the performance during a 20-min treadmill run (r = 0.6, P = 0.003), and to the rank of the subjects' performance as cross-country skiers (Spearman's rank correlation coefficient = 0.76, P < 0.001). These data could mean that for elite cross-country skiers the performance is related to the Na(+)-K+ pump concentration. However, other studies have shown an equally high pump concentration for far less fit subjects, suggesting that the pump concentration may not be a limiting factor.

High proportion of type I fibres in thigh muscle of young dancers.

A previous study showed that adult female dancers have a high percentage of type I fibres in vastus lateralis, similar to that of endurance-trained female runners or female cross-country skiers. It is not known if dancers already at an early age are characterized by a high percentage of type I fibres or develop a high percentage of type I fibres as a consequence of dance training. Furthermore, the muscle fibre composition of male dancers has not previously been studied. Therefore the aim of the study was to analyse skeletal muscle fibre characteristics in 10-year-old and 20-year-old dancers of both sexes. Age-matched boys and girls whose physical activity was average for their age groups served as controls. Muscle biopsies for histochemical analysis were obtained from vastus lateralis using the percutaneous needle technique. The major finding of the present study was that the vastus lateralis of young dancers of both sexes had a higher percentage of type I fibres than that of controls. Moreover, the higher type I percentage was seen not only in 20 year olds, but also in 10 year olds, who had begun their dance training at a professional level only a few weeks earlier. No significant difference in this respect was found between female and male dancers. In conclusion, the muscle fibre type composition in young dancers of both sexes differs from that of the average individual of the same age and is characterized by a high percentage of type I fibres.

Effect of kinematic variables on performance in women during a cross-country ski race.

The purpose of this study was to investigate the relationship of uphill cycle velocity, cycle length, and cycle rate in top U.S. female skiers during a multiple lap cross-country ski skating race. Eighteen female cross-country skiers served as subjects at the United States Women's 10-km Freestyle 1995 National Championships. The course consisted of two laps of the same 5-km loop. The selected filming section was an 11-12% uphill grade approximately 400 m long located at the 2.5- and 7.5-km mark. The video sector was approximately 12 m long at the conclusion of the climb. During the climb, the skating technique used by all skiers was the V-1. The results demonstrated that cycle length is positively related to cycle velocity during uphill ski skating and ultimately translates to faster race times by female cross-country ski racers. Lap 2 cycle velocity and cycle length demonstrated the strongest relationship to lap time and total race time. Moreover, cycle rate was not related to cycle velocity or lap race times and was not different between successful and less successful skiers. The slower climbing velocity noted during the latter half of the 10-km race was a consequence of a decreased cycle length and not cycle rate. This suggests that the degree of physical conditioning could be a factor in the ability to maintain cycle length and thus uphill cycle velocity.

Influence of lifetime cross-country skiing on plasma lipids and lipoproteins

Low concentrations of total and LDL cholesterol are associated with minimal risk of atherosclerosis. Aerobic exercise has been similarly associated with a low risk of heart disease. The literature is inconclusive as to whether there is an association between total and LDL cholesterol and exercise. Further, previous work has, almost exclusively, examined male runners. Therefore, we examined 176 male and female cross-country skiers, participating in the National Master's Championships, for body composition, dietary habits, exercise habits, and serum lipid levels. Our results show markedly low concentrations of serum LDL cholesterol and total cholesterol, as well as the expected high concentrations of HDL cholesterol and low concentrations of triglycerides, in these lean skiers. Their diets contained 30% fat, and they exercised 9 h weekly. Although it is difficult to separate the effects of diet, leanness, and exercise on the lipid profile, it is apparent that the lifestyle led by these people is associated with a lipid profile that confers an extremely low risk of atherosclerotic disease.

Anaerobic threshold, skeletal muscle enzymes and fiber composition in young female cross-country skiers.

Anaerobic threshold (AT) and maximum oxygen uptake (max VO2) were determined in 15 young female cross-country skiers, aged 15--20 years, during incremental bycycle ergometer exercise. Succinate dehydrogenase (SDH), malate dehydrogenase (MDH), citrate synthase (CS) and lactate dehydrogenase (LDH) were analyzed biochemically and percentage of slow twitch fibres (%ST fibres, myosin adenosine triphosphatase staining) histochemically in muscle samples obtained from m. vastus lateralis. Max VO2 correlated significantly with anaerobic threshold in ml x kg-1 x min-1 (mlAT) but when AT was expressed in percent of max VO2 (%AT) the correlation was insignificant. Significant correlations were found between %AT and SDH (r = 0.63) and between mlAT and CS (r = 0.58). Max VO2 showed no significant correlations with the enzymes studied or %ST fibres. The results of the study seem to support the hypothesis that anaerobic threshold is related to oxidative capacity of muscle.