Young Cross-country Skiers Research Articles

Cheese positively affects serum osteocalcin levels, bone turnover markers and bone mineral density in cross-country skiers: a dose-response study

Background: Vitamin K2-rich Jarlsberg Cheese is demonstrated to increase Osteocalcin and bone turnover markers in fertile women. The impact on endurance-trained young cross-country skiers (XCS) with elevated bone turnover remains unclear. Purpose of study was to estimate the optimal daily efficacy dose of Jarlsberg cheese to increase serum Osteocalcin level in young female and male XCS and estimate the Jarlsberg effect on bone turnover markers (BTMs) and bone mineral density (BMD). Methods: In a parallel group study consisting of three design levels, 10 female and 10 male XCS were included, using Response Surface Pathway design. Blood samples were taken at each level for measurements of Osteocalcin, vitamin K2, BTMs and other biochemical parameters. Resting metabolic rate (RMR), BMD, VO2max and muscle strength were measured at start and at the end of the study. Results: The Osteocalcin development with increasing dose of Jarlsberg cheese was almost parallel in both sexes. These variables were reduced significantly from baseline during the first two design levels but increased above baseline by the end of the study. BTMs decreased significantly during the first and second level but increased during the third level. Total and L1-L4 BMD, s-phosphate, s-urea, RMR, muscle strength and Peak VO2 increased significantly while s-calcium and s-magnesium decreased. Conclusions: Estimated OED of Jarlsberg cheese was 73 and 84 g/day for females and male athletes, respectively. The development in OC, BTMs and BMD suggest an antiresorptive and perhaps anabolic effect of Jarlsberg Cheese on bone tissue. VO2 max, RMR and muscular strength development indicated an anabolic situation.

Training journals and the development of an elite sports identity

In this article we investigate whether the practice of writing training journals can shed light on the process whereby young cross-country skiers are transformed from promising talents into serious, committed athletes. By using data from athletes and coaches themselves, we explore how training journals help shape athletes’ outlook on sports, their relationship with their coach, and their personal identity. We focus on the cross-country skiers’ and coaches’ attitudes to planning their training sessions and keeping a journal. Journal writing can be understood as a project of subjectification, whereby the discourses place an athlete in certain positions that then imply particular expectations as to how the athlete will behave. In order to understand the subjectification process, we use what Michael Foucault called the technologies of the self, that is, the discourses and practices that individuals use when working on themselves.

Associations between objective measures of performance-related characteristics and perceived stress in young cross-country skiers during pre-season training

ABSTRACT Monitoring performance-related characteristics of athletes can reveal changes that facilitate training adaptations. Here, we examine the relationships between submaximal running, maximal jump performance (CMJ), concentrations of blood lactate, sleep duration (SD) and latency (SL), and perceived stress (PSS) in junior cross-country skiers during pre-season training. These parameters were monitored in 15 male and 14 females (17 ± 1 years) for the 12-weeks prior to the competition season, and the data was analysed using linear and mixed-effect models. An increase in SD exerted a decrease in both PSS (B = -2.79, p ≤ 0.01) and blood lactate concentrations during submaximal running (B = -0.623, p ≤ 0.05). In addition, there was a negative relationship between SL and CMJ (B = -0.09, p = 0.08). Compared to males, females exhibited higher PSS scores and little or no change in performance-related tests. A significant interaction between time and sex was present in CMJ with males displaying an effect of time on CMJ performance. For all athletes, lower PSS appeared to be associated with longer overnight sleep. Since the females experienced higher levels of stress, monitoring of their PSS might be beneficial. These findings have implications for the preparation of young athletes’ competition season.

W244 Measurement of different salivary biomarkers in young cross-country skiers at rest and following the Bruce protocol exercise test

W244 Measurement of different salivary biomarkers in young cross-country skiers at rest and following the Bruce protocol exercise test

Session Rating of Perceived Exertion Is Different for Similar Intensity and Duration Prescribed Low-Intensity Sessions and Has a Different Effect on Performance in Young Cross-Country Skiers.

Pind, R, Purge, P, Mäestu, E, Vahtra, E, Hofmann, P, and Mäestu, J. Session rating of perceived exertion is different for similar intensity and duration prescribed low-intensity sessions and has a different effect on performance in young cross-country skiers. J Strength Cond Res 37(1): 187-193, 2023-The aim of this study was to analyze whether the rating of perceived exertion (RPE) and the resulting internal load (sRPE) could differ among subjects when volume and intensity are matched in young cross-country (XC) skiers. Second, we analyzed whether subjects with a high or low RPE response and sRPE have different adaptation after a 1-week low-intensity high-volume training period. Well-trained national level XC skiers (n = 13) aged 13.4 ± 1.9 years took part in a 1-week training period with double poling performance tested pretraining and after 1-week training. All subjects trained under a similar training program. Rating of perceived exertion was measured after each training session on a 10-point scale, and the total training load was calculated by the sRPE method by multiplying training session's duration and the RPE. Subjects were divided into Glow (n = 6) or Ghigh (n = 7) groups based on median rating of RPE (3.78 ± 1.24) in low-intensity trainings. Total training load in low-intensity trainings was higher in Ghigh compared with Glow (4,010 ± 765 vs. 2,499 ± 193 arbitrary units, respectively), although total training time with (16.3 ± 0.8 hours vs. 16.0 ± 0.6 hours) or without (13.1 ± 0.9 hours vs. 13.3 ± 0.7 hours, p > 0.05, respectively to Glow and Ghigh) high-intensity sessions was not different. No significant differences were found for time spent in different heart rate zones between the 2 groups. Increases in performance were significant for both groups (p< 0.05), while the effect was large in Ghigh (+12.5%; ES = 0.74), and medium in Glow (+10.7%; ES = 0.34). Differences in the internal load and the further quantification of training load for different target intensity sessions could provide important practical information to stimulate expected adaptation in young endurance athletes.

Impact of cardiac remodelling on physical fitness measured by VO2 max in preadolescent and adolescent endurance athletes

Abstract Background Endurance training is associated with both physiological cardiac remodelling and increased maximal oxygen uptake. The relationship between VO2 max and cardiac dimension has not been described in young athletes or in longitudinal studies. Aims This study aims to explore the impact of cardiac remodelling on VO2 max in a cohort of young athletes assessed at age 12, 15 and 18. Methods Seventy-six promising young cross country skiers were examined at age 12 with echocardiography, including 3D and cardiopulmonary exercise test (CPX). Forty-six (61%) participated in the first follow-up at age 15 and 36 (47%) athletes completed the second follow-up at age 18. The impact of left ventricular (LV) mass and LV end-diastolic volume (EDV) on VO2 max at each time point was assessed using mixed model analysis. Correlation coefficients were calculated at each time point. Results There were moderate to very strong correlations between the cardiac parameters and VO2 max at all time points (Figure). In the full model, each improvement in VO2 max of 1000 mL/min at age 15 was associated with an increase in LV mass of 18 g (p&amp;lt;0.001) and an increase in LV EDV of 36 mL (p&amp;lt;0.001), while each improvement in VO2 max of 1000 mL/min at age 18 was associated with an increase in LV mass of 19 g (p&amp;lt;0.001) and LV EDV of 31 mL (p&amp;lt;0.001). Conclusion Physical fitness measured by VO2 max is strongly correlated to LV mass and volume in adolescent athletes, suggesting a strong link between cardiac adaption and VO2 max in young athletes. Figure 1 Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): South-Eastern Norway Health Authority

Talent Development in Young Cross-Country Skiers: Longitudinal Analysis of Anthropometric and Physiological Characteristics.

Introduction: Very little is known about talent development and selection processes in young cross-country skiers.Aim: (1) to analyze the effect of age on anthropometric and physiological parameters in medium-to-high level cross-country skiers during the late teenage period; (2) to describe parameters' trend in selected talents after the late teenage period; (3) to define which characteristics during the late teenage period could discriminate against further talent selection.Method: We found 14 male (M) and nine (F) athletes in our database, identified as talents by regional teams during the late teenage period, who performed the same diagonal-stride roller-skiing incremental test to exhaustion at 17 and 18 years old. Of these, four M and three F teenagers performed four further evaluations, and were selected by the national team. Age effect during the late teenage period was verified on anthropometric and physiological parameters measured at maximal intensity (MAX), first (VT1), and second (VT2) ventilatory thresholds, and 3° and 6° of treadmill incline. An observational analysis allowed to evaluate parameters' trend after the late teenage period in selected athletes, and to determine possible characteristics early discriminating further selection.Results: During the late teenage period, height, weight, and BMI was still raising in M as well as V'O2 at VT2 and 6° of treadmill incline (all P > 0.05). In F, mass-scaled V'O2 MAX increased while heart rate (HR) at MAX and VT2 decreased (all P > 0.05). Since the late teenage period, all selected males showed maximal ventilation volumes, absolute V'O2 at MAX, VT1, and VT2 that were within or above the 75th percentile of their group; the same was found in selected females for mass-scaled V'O2 MAX, VT1, and VT2 time. After the late teenage period, all selected athletes showed an increasing trend for VT2 time, while a decreasing trend for sub-maximal energetic cost, %V'O2 and HR.Discussion: During the late teenage period, males are still completing their maturation process. Since the late teenage period, some physiological parameters seem good indicators to early discriminate for further talents. A progressive increase in skiing efficiency was demonstrated in developing talents of both sexes after the late teenage period.

Glide Time Relates to Mediolateral Plantar Pressure Distribution Rather Than Ski Edging in Ski Skating.

The purpose of this study was (i) to assess the differences in relative glide time and both ski edging angle and plantar pressure mediolateral distribution in skiers of different levels and (ii) to further investigate the relationships between the aforementioned variables. Twelve male cross-country skiers (6 national and 6 regional level) skied at 4.2 m s−1 on a 2.5° uphill snow track using the V2 technique. The relative glide time (in percentage of contact time) and mediolateral plantar pressure distribution variables (asymmetry index, ASI) were derived from pressure insole measurements. Ski edging angle variables were calculated from an Inertial Measurement Unit placed on the ski. Minimum, maximum, mean, and range of both ASI and ski edging angle were computed over the gliding phase, giving information about the beginning, end, and throughout the gliding phase. Relative glide time was significantly higher, and minimum and mean ASI were significantly lower in the national- than in the regional-level skiers. Relative glide time was strongly negatively correlated to minimum ASI (i.e., plantar pressure mostly on the foot lateral side at the beginning of gliding phase) and strongly positively correlated to ASI range. These results may reflect a larger body mass transfer above the ski from the beginning of the gliding phase to increase gliding, especially in the national-level skiers. Ski edging angle seems less relevant to discriminate skiers' level of performance. These results have direct consequences on how technique must be taught to young cross-country skiers.

Hypobaric live high-train low does not improve aerobic performance more than live low-train low in cross-country skiers.

Live high-train low (LHTL) using hypobaric hypoxia was previously found to improve sea-level endurance performance in well-trained individuals; however, confirmatory controlled data in athletes are lacking. Here, we test the hypothesis that natural-altitude LHTL improves aerobic performance in cross-country skiers, in conjunction with expansion of total hemoglobin mass (Hbmass , carbon monoxide rebreathing technique) promoted by accelerated erythropoiesis. Following duplicate baseline measurements at sea level over the course of 2weeks, nineteen Norwegian cross-country skiers (three women, sixteen men, age 20±2year, maximal oxygen uptake (VO2 max) 69±5mL/min/kg) were assigned to 26 consecutive nights spent at either low (1035m, control, n=8) or moderate altitude (2207m, daily exposure 16.7±0.5hours, LHTL, n=11). All athletes trained together daily at a common location ranging from 550 to 1500m (21.2% of training time at 550m, 44.2% at 550-800m, 16.6% at 800-1100m, 18.0% at 1100-1500m). Three test sessions at sea level were performed over the first 3weeks after intervention. Despite the demonstration of nocturnal hypoxemia at moderate altitude (pulse oximetry), LHTL had no specific effect on serum erythropoietin, reticulocytes, Hbmass , VO2 max, or 3000-m running performance. Also, LHTL had no specific effect on (a) running economy (VO2 assessed during steady-state submaximal exercise), (b) respiratory capacities or efficiency of the skeletal muscle (biopsy), and (c) diffusing capacity of the lung. This study, showing similar physiological responses and performance improvements in the two groups following intervention, suggests that in young cross-country skiers, improvements in sea-level aerobic performance associated with LHTL may not be due to moderate-altitude acclimatization.

Effects of Fatigue Related to Uphill on Kick Double Pole Kinematics of Young Cross Country Skiers

The purpose of this study was to examine the effect of fatigue due to uphill on the kick double pole technique. Ten young male subjects volunteered to study. Subjects’ cross country sprint times were taken using a kick double pole technique with maximum effort for 1 km in a climbing course with an average slope of 4%. In accordance with these measured times, a separate average speed for each subject was modified, and the subjects were tested on the treadmill at these specified speeds, with the same duration, slope, and technique. Each participant was asked to perform three trials with half an hour between them. Kinematic data were obtained using a three-dimensional motion capture system (Vicon Peak, Oxford, UK). Statistical analysis was performed by separating the variables into 3 separate groups: a) periods of time b) distance data c) joint angles. In conclusion, in kinematic data analyzed according to the fatigue of climb, there was a significant difference between the duration of the poling times, duration of the first cycles with the left leg propulsion and the last cycles, and the duration of the first cycles with the right leg propulsion and left leg propulsion. Significant differences were found in the hip, shoulder, elbow and trunk angles. Significant differences were also found among all the identified distances.

The subjective assessment of training load in the training process of young skiers

The aim was to investigate how the 10-point intensity scale can be used in characterizing training intensities in young skiers and whether perceptions of training intensity of coach and athlete are related. 13 young crosscountry skiers, aged 14–17 participated. During the 17-day training camp their training data and the subjective intensity perceptions of the coaches and athletes were recorded. Based on the time-in-zone method the subjects trained 71.8% in zone1, 27.1% in zone2 and 2.1% in zone3. According to subjective assessment, 74.1% of trainings were done in zone1, 19.0 in zone2 and 8.0% in zone3. There were no significant differences between intensity distributions between zone1, but according to subjective scale, subjects trained significantly less in zone2 and significantly more in zone3. Subjective assessments of coach and athletes indicated the highest correlations (p<0.05) between zone2 (r=0.80) and interval trainings (r=0.71) and were lower for basic (r=0.25) and recovery trainings (r=0.35). In conclusion, 10-pt scale to describe training intensities is a practical method for young athlete training zone distribution assessment.

Young elite cross-country skiers and low back pain—A 5-year study

Objectives To evaluate possible changes in spinal curvature over a period of 5 years of an elite cross-country skiing squad, and to study whether there are any differences in this respect between individuals who report low back pain and those how do not. Participants Fifteen young cross-country skiers (M age=13.6±0.9) participated voluntarily throughout the entire study period. Main outcome measures Debrunner's kyphometer was used for measuring the difference between thoracic kyphosis and lumbar lordosis of the spine. All subjects also answered a questionnaire including questions about ski-related low back pain, the amount of ski training, and participation in other sports. Results The results at the end of the 5-year period comprise data from 15 skiers (M age=18.5±0.9 years). The relationship between thoracic kyphosis and lumbar lordosis increased from 3.5° to 13.1°, respectively ( p = 0.0001 ). Of the 15 elite cross-country skiers, seven reported low back pain at the 5-year examination. At the 5-year follow-up, skiers with low back pain showed significantly higher relationship between thoracic kyphosis and lumbar lordosis than did those skiers without low back pain, 18.2° and 10.5°, respectively ( p = 0.035 ). Of the eight elite cross-country skiers without low back pain, seven were also involved in other sports ( p = 0.005 ). Conclusions Based on these findings, our advice is that adolescent cross-country skiers also should participate in other physical activities besides cross-country skiing.

UPPER BODY POWER COMPARISONS BETWEEN GROUPS OF CROSS - COUNTRY SKIERS AND RUNNERS.

922 The purpose of this study was to evaluate the relationship between upper body power and cross country ski skating race velocity (RV) in a cross sectional representation of cross country skiers and compare body mass adjusted maximal upper body power (UBP/kg) of cross country skiers with that of distance runners. 158 high school and adult cross country ski racers and 37 high school cross country runners were tested on a Street Arm Ergometer for UBP using a ramped maximal UBP test simulating a double poling motion. A strong relationship (r =.845) between UBP/kg and RV in skiers was determined. High school skiers were separated into slow and fast groups based on reported RV. A difference (p<.001) in both UBP/kg and RV was found between slow and fast groups in both male and female high school skiers. Although there were sex-related differences (p<.01) in UBP/kg, when participants were grouped by UBP/kg there was no sex by upper body power interaction. These results indicate that UBP/kg is an effective partial predictor of success independent of sex. The cross country runners were evaluated to provide a comparison group. Average UBP/kg for the cross country runners was 46% of the average for the cross country skiers. On a sex grouped basis, the runners were able to generate only about 35% of the average UBP/kg of the fast high school or adult skiers and about 75% of the slow high school skiers. With UBP contributing substantially to performance in cross country ski racing, combined with the importance of the adolescent period of years for the development of strength, it is recommended that young cross country skiers focus a significant portion of their training on the development of that fitness factor.

CHANGES IN UPPER BODY ECONOMY OF YOUNG CROSS COUNTRY SKIERS 974

The purpose of this research is to look at changes in economy of double poling technique by upper body ˙VO2 measurements of young cross country skiers following four months of summer training including upper body aerobic and power training. Upper body ˙VO2 was measured during a simulated double poling ˙VO2peak test for cross country skiers using a Freestyle® arm ergometer from Ergometrx. 10 young cross country biathlon skiers, 5 male (15±1.37 years) and 5 female skiers(16.7±5 years) all members of a national development program with running ˙VO2max values of 68.3±3.6ml·kg-1·min-1 and 57.1±2.7 ml·kg-1·min-1 respectively, performed a one minute stage ˙VO2peak test. Stage increments were set to 10% of individual max arm power determined during pretesting. Economy data were analyzed for those stages completed by all subjects (40 - 90 watts). The followingtable shows the changes in ˙VO2 (pre to post training) at each 10 watt increment. Analysis found no difference between the sexes when looking at pre and post ˙VO2 values at each stage. The average post-training reduction in ˙VO2 over the range of 40-90 watts for the young athletes was -2.39±.48 ml·kg-1·min-1. In addition, this group of young athletes improved their max arm power an average of 35.8±4.4 watts and 15±5.63 watts for males and females respectively though upper body˙VO2peak did not change for either sex. Improvements in submaximal arm work in developing cross country athletes seems to be due, in part, to an improvement in economy.

Prevalence of asthma in young cross-country skiers in central Scandinavia: differences between Norway and Sweden

An increased prevalence of asthma in cross-country skiers has been reported previously. This study was conducted in order to evaluate the prevalence of asthma among young, elite cross-country skiers in Trøndelag, Norway and Jämtland, Sweden. These two regions in central Scandinavia have different climates during the winter season, with a coastal type in Trøndelag while Jämtland is characterized by a colder, drier, inland type of climate. The study population consisted of 171 skiers (118 from Norway, 53 from Sweden). The investigation included an asthma questionnaire, spirometry and methacholine provocation testing. The prevalence of self-reported asthma-related symptoms was 46% in Norway and 51% in Sweden. The prevalence of bronchial hyper-responsiveness (BHR) was significantly different between the two regions. In Norway, 14% of the skiers were hyper-responsive to methacholine compared to 43% in Sweden ( P < 0·001). Moreover, the estimated prevalence of clinically diagnosed asthma was 12% in Norway and 42% in Sweden ( P < 0·001). The self-reported frequency of respiratory allergy was higher in Sweden (32%) than in Norway (11%). However, on an individual basis, self-reported allergy did not predict occurrence of asthma or BHR. In conclusion, there is a high prevalence of BHR and asthma among young, elite cross-country skiers in central Scandinavia, especially in Sweden. Cross-country skiing may be a risk factor for the development of asthma. Longitudinal studies of cross-country skiers, and studies to acquire further knowledge of the mechanisms involved in the development of asthma are indicated.

Evaluation of young cross-country skiers by running and roller-skiing tests

Summary This study was unidertaken to compare hormonal and bioenergetic responses between treadmill running and roller-skiing in eight young cross-country skiers ( ± = 13.6 ± 0.5 yrs), during two progressive and maximal tests. At the end of the first running test on treadmill, peak values of heart rate and blood lactate concentration averaged 202.6 ± 10.3 bpm and 9.71 ± 2.23 mmol·L −1 respectively; maximal oxygen uptake was determined by Douglas bag method and reached 61.1 ± 9.5 mL·kg −1 ·min −1 . The graded and maximal roller-skiing test was performed 1 or 2 weeks later. It took place on a flat road and the speed was increased every two minutes until exhaustion; the skiers had to use the diagonal stride technique. At the end of this test, peak heart rate (194.9 ± 7.7 bpm), and peak blood lactate concentrations (5.29 ± 2.05 mmol·L −1 ), were significantly lower than at the end of treadmill test ( P s P s P s

Evaluation of young cross-country skiers

Evaluation of young cross-country skiers

Radiological Findings in the Lumbar Spine of 39 Young Cross-Country Skiers with Low Back Pain

The lumbar spines of 39 active young cross-country skiers suffering from long lasting or frequently remitting low back pain (LBP) were examined by a new radiological method. Plain radiographs in lateral and anteroposterior views were taken. The spinal curves, anomalies, and possible degenerative changes were investigated. The radiological method chosen proved to be suitable for imaging the lumbar spine. There were various radiologically detectable abnormalities in the spine. The most common findings were functional scoliosis (in 49%) and different spinal anomalies (in 23%). The mean lumbar lordosis was 69 degrees (70 degrees in males and 64 degrees in females). The effect of abnormal lumbar posture on LBP should be further studied. None of the numerous radiological findings had an effect on therapy in these skiers.