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

Non-specific and ski-specific performance development in peri-pubertal cross-country skiers

PURPOSE

To evaluate non-specific and ski-specific performance development in male (M) and female (F) peri-pubertal cross-country skiers and to evaluate their relationship with cross-country skiing (XCS) performance and biological maturation within each age category and sex.

METHODS

Twenty-one and 19 athletes under 14 and 16 years old, respectively (U14 and U16), were tested for biological maturation; non-specific speed, agility, strength, endurance, and balance; ski-specific speed, agility, and endurance. XCS index was considered as average percentage time-gap from the winner in four official races. Sex and age-category effects were verified and a model predicting XCS index was extrapolated for each group.

RESULTS

Performance capacities raised across age categories (p < 0.05) except for non-specific speed, agility, balance, and relative arm strength (p > 0.05). F showed advanced biological maturation and greater balance than M (p < 0.05), while M showed higher performance capacities (p < 0.05). XCS index was not related to biological maturation within each group (p > 0.05); its variance was explained by non-specific speed and ski-specific upper-body endurance in M-U14 (p = 0.014), lower-limb strength and ski-specific agility in M-U16 and F-U14 (both p = 0.001), ski-specific upper-body endurance in F-U16 (p = 0.002).

CONCLUSION

Ski-specific performance capacities still develop during peri-puberty, with peri-pubertal M overperforming with respect to F of comparable performance level. XCS index was not influenced by biological maturation withing each age category, but it was rather explained by specific parameters that commonly undergo the "adolescent spurts", accordingly to the average biological maturation level of M and F athletes of each age category.

Skiing economy and kinematic during a field double poling roller skiing among novice and experienced cross-country skiers

To assess the skiing economy (SE) and kinematics during double poling (DP) roller skiing between two groups of skiers in a field setting. Five experienced and five novice male skiers performed a SEDP test at 16 km∙h-1 on an outdoor athletics track. Gas exchange parameters were measured to determine SEDP. A two-dimensional video was filmed to measure the kinematics variables. Experienced skiers exhibited a 21% lower oxygen cost than novice skiers (p = 0.016) in DP, indicating a strong association between SEDP, cycle length and cycle rate (p < 0.001). Additionally, before the poling phase, experienced skiers manifested significantly greater maximum hip and knee extension angles than novice skiers (p < 0.001). During the poling phase, experienced skiers with a greater pole plant angle (p = 0.001), longer flexion time (p < 0.001) and higher flexion angular velocity in the elbow joint (p < 0.05) demonstrated better SEDP. There was an interaction effect of the one-repetition maximum bench press × group in SEDP (b = - 0.656, SE = 0.097, t = - 6.78, p = 0.001). Therefore, experienced skiers with better SEDP demonstrated more efficient cycles, potentially accomplished using dynamic full-body DP motion to ascertain effective propulsion. Combined upper body strength and ski-specific skill training may enhance SEDP in novice skiers.

From juniors to seniors: changes in training characteristics and aerobic power in 17 world-class cross-country skiers

Purpose: To compare training characteristics and aerobic power (VO2max) between the most successful junior and senior seasons of world-class cross-country (XC) skiers and to identify differences between sexes and among sprint and distance skiers. Methods: Retrospective analysis was conducted on self-reported training and VO2max tests of ten male and seven female world-class XC-skiers, collectively holding 38 Olympic medals. Training was categorized by form (endurance, strength, speed, other) and mode (specific, unspecific) and was divided into low- (LIT), moderate- (MIT), and high-intensity training (HIT). Results: Total training increased by 203 ± 130 h (35% ± 31%, p < .001, large effect) and 78 ± 69 sessions (21% ± 24%, p < .001, very large effect). Junior training volume (658 ± 107 h) did not correlate with senior volume (861 ± 74 h) but correlated negatively with changes in volume (r = -.822, p < .001). No sex differences were observed related to total volume, but distance skiers increased their total volume more than sprint skiers (p = .037, large effect). Endurance training increased by 197 ± 117 h (p < .001; large effect) tied to increased low-intensity training (186 ± 115 h, p < .001; large effect) and moderate-intensity training (13 ± 7 h, p < .001; large effect). Training intensity distribution (% LIT/MIT/HIT) was 91/3/6 in junior and 92/4/4 in senior season. Women demonstrated greater increase of unspecific modes (100 ± 58 vs. 37 ± 44 h, p = .022; large effect) and strength training (25 ± 23 vs. -3 ± 17 h, p = .010, large effect). Men improved absolute (8% ± 5%; p = .009; large effect) and relative VO2max (6% ± 4%; p = .016; large effect) from junior to senior, while women only increased relative VO2max (7% ± 5%, p = .012; large effect). Conclusion: This study provides novel information regarding changes in training characteristics and aerobic power from junior to senior age in world-class XC-skiers. Overall, the enhanced training volume during this transition was primarily driven by increased LIT and MIT and the exceptionally high relative VO2max at junior age further increased in both sexes.

Performance-related physiological changes induced by one year of endurance training in young athletes

Introduction

Although maximal oxygen uptake (VO₂max) is generally recognized as the single best indicator of aerobic fitness in youth, interpretation of this parameter and the extent to which it can be improved by training remain controversial, as does the relative importance of VO₂max for performance in comparison to other factors such as power production. Here, we examined the influence of endurance training on the VO₂max, muscle power and sports-related performance of cross-country skiers attending a school specializing in sports, as well as potential relationships between any changes observed to one another and/or to perceived stress scale (Cohen) and certain blood parameters.

Methods

On two separate occasions, prior to the competition season and separated by one year of endurance training, the 12 participants (5 males, 7 females, 17 ± 1 years) carried out tests for VO₂max on a treadmill, explosive power utilizing countermovement jumps (CMJ) and ski-specific maximal double pole performance (DPP) employing roller skis on a treadmill. Blood levels of ferritin (Fer), vitamin D (VitD) and hemoglobin (Hg) were monitored, and stress assessed with a questionnaire.

Results

DPP improved by 10 ± 8% (P < 0.001), but no other significant changes were observed. There were no significant correlations between the changes in DPP and any other variable.

Discussion

Whereas one year of endurance training improved the cross-country ski-specific performance of young athletes significantly, the increase in their maximal oxygen uptake was minimal. Since DPP was not correlated with VO₂max, jumping power or the levels of certain blood parameters, the improvement observed probably reflected better upper-body performance.

Technique and maximal skiing speed for youth cross-country skiing performance

Introduction

Numerous researches concentrate on examining and preparing high-level male cross-country skiers, with a significant number of tests being conducted on roller skis. However, there is a scarcity of research on the testing and preparation of younger male and female athletes ranging from 10 to 16 years old. The main purpose of this research was to determine if certain cross-country (XC) skiing tests and maturity status are indicators of performance in youth cross-country skiing; to examine any differences in performance between young males and females; and to establish non-invasive diagnostic tools for assessing performance.

Methods

Fifty-eight young XC skiers (36 boys; 12.88 ± 1.19 yrs and 22 girls; 12.79 ± 1.09 yrs) performed specific XC skiing maximal speed tests consisting of short (50 m) flat and uphill distances (30/40 m). Results were correlated with on snow XC skiing performance (P_XC) based on one skating (including an agility parcours) and one classical distance competition.

Results

The key findings of this research were: 1) Age and maturity status were associated to boys'and girls' P_XC; 2) Significant moderate to high correlations between girls' and boys' short duration XC skiing sprint performance 30-50 m (double poling (DP) flat and uphill, free skating, leg skating and V1 uphill skating) and P_XC were revealed; 3) In general, the best prediction for P_XC (Boys and Girls) was found to be the asymmetrical uphill (V1 40 m uphill) sub-technique; and 50 m DP (flat) while Boys' P_XC was determined by V1 skating and girls' performance mainly by 50 m free skating (flat); 4) When using maturity offset as a confounding variable, boys' and girls' P_XC was still highly associated with short duration skiing tests.

Discussion

In conclusion, the use of simple, non-invasive XC skiing sprint tests for evaluating P_XC can be beneficial for ski clubs, specialized schools, or skiing federations in identifying and training young talented skiers. Further, this result demonstrates that skiing abilities such as short duration maximal speed and the proper use of different sub-techniques at high speeds during XC skiing is an important performance prerequisite.

Anthropometrical and Physiological Determinants of Laboratory and on-Snow Performance in Competitive Adolescent Cross-Country Skiers

Purpose: To explore the anthropometrical and physiological determinants of laboratory and on-snow performance in competitive adolescent cross-country skiers.

Methods: Fifty-two adolescent (25 girls) (14.8 ± 0.6 years) skiers performed an uphill treadmill rollerski session using the G2 ski skating technique. Gross efficiency (GE) was calculated from a submaximal work bout (∼84% of peak oxygen uptake; V̇O_2peak) while V̇O_2peak, accumulated oxygen deficit (ΣO_2def) and laboratory performance were determined from a 3-min time trial (TT_3min) before upper- and lower-body maximum strength were tested. Pearson’s product moment correlations and multiple regression analysis explored the relationship with anthropometrical and physiological determinations of laboratory and on-snow performance in sprint (∼1 km, ∼2.5–3 min) and distance races (5–7.5 km, ∼12–20 min) from the national championship for this age-group.

Results: A large correlation was found between on-snow sprint and distance performance (boys r = 0.61, girls r = 0.76, both p < 0.01) and for on-snow distance performance with TT _3min (r = 0.51 to 0.56, p < 0.05). V̇O_2peak, ΣO_2def and GE explained ∼80% of variations in performance in the TT_3min, but substantial lower on-snow skiing performance (∼20–30%). For the TT_3min performance, V̇O_2peak showed a very large and large correlation for boys and girls (r = 0.76 and 0.65 respectively, both p < 0.01), ΣO_2def showed a large correlation for boys and girls (r = 0.53 and 0.55 respectively, both p < 0.01) and age showed a large correlation for boys (r = 0.56, p < 0.01), with no significant correlation for girls (r = -0.19). For on-snow distance performance, V̇O_2peak showed a large correlation for boys (r = 0.53, p < 0.01) and girls (r = 0.50, p < 0.05). For on-snow sprint performance, upper-body strength (r = 0.55, both sexes p < 0.01) and body mass index (BMI) showed a large correlation for boys (r = 0.53, p < 0.01) and girls (r = 0.51, p < 0.05).

Conclusion: V̇O_2peak is an important determinant for overall XC skiing performance in competitive male and female adolescent skiers. However, upper-body strength and BMI correlate the most with sprint performance. While laboratory performance can to a large extent be explained by physiological factors, on-snow-performance for adolescents is based more on multivariate factors (tactics, equipment’s, technique, racecourse etc.), implying the need for a holistic approach to understanding the sport-specific demands in such age-groups.

Observational vs coaching feedback on non-dominant whole-body motor skill performance - application to technique training

We studied the effect of peer- and self-observational feedback versus coaching feedback during technique training on performance in competitive adolescent cross-country skiers. Fifty-four skiers (14.3 ± 0.6 years) were divided into a control group and three intervention groups (dyad practice, video, or coaching feedback), which practiced in the asymmetrical uphill sub-technique G2 on one side (non-dominant side), but not the other (dominant side) for 6 × 30 min over a 5 weeks period, on roller skis outdoors. High-speed performance and skiing economy were assessed on a roller ski treadmill before and after the intervention, and a questionnaire was answered post-intervention. The video feedback (p = .025, d = .65) and coaching feedback (p = .007, d = .89) groups improved high-speed performance during the intervention and an ANCOVA showed a tendency for different change scores between interventions (F_3,49  = 2.5, p = .068, η p 2  = .134), with a difference between the coaching feedback and dyad practice (p = .05). No change was seen in skiing economy in any group. Coaching feedback ranked higher on enjoyment compared with dyad practice (p < .001) and led to higher self-perception of improved technique compared with the control group (p = .038). Overall, feedback from a competent coach seems better than observation for improving performance in young athletes, although self-observation through video with attentional cues seems a promising tool for increasing individual feedback when coaching large groups.