Effect of strength training and the practice of Alpine skiing on bone mass density, growth, body composition, and the strength and power of the legs of adolescent skiers

To what extent do somatotype structures affect athletic performance in professional athletes?

BACKGROUND

This study aimed to ascertain the influence of somatotype structures on athletic performance among professional athletes.

METHODS

Twenty-eight professional athletes, comprising 14 handball players and 14 volleyball players, were enlisted as participants for this study. As per the methodology, evaluations encompassing explosive power, strength, flexibility, horizontal jump, agility, sprint, and hand-foot reaction tests were conducted. Following physiological assessments, parameters including body mass index, body fat percentage, and somatotype were computed. The impact of athletes' somatotype structures on their athletic performance was investigated employing linear regression analysis.

RESULTS

The endomorphy value serves as a negative predictor (r2=0.159) for explosive power, whereas the mesomorphy (r2=0.204) and ectomorphy (r2=0.379) values act as positive predictors of explosive power. Ectomorphy value negatively predicts grip strength (r2=0.399) and back strength (r2=0.214), while mesomorphy value positively predicts grip strength (r2=0.233) and back strength (r=0.338; r2=0.114). Mesomorphy value negatively predicts flexibility (r2=0.247), long jump (r2=0.311), sprint (r2=0.256), and reaction (r2=0.133), whereas ectomorphy value positively predicts flexibility (r2=0.225), long jump (r2=0.463), sprint (r2=0.393), and reaction (r2=0.208).

CONCLUSIONS

This study showed a correlation between various somatotype structures and indicators of athletic performance. Within this framework, it can be inferred that mesomorphy and ectomorphy values serve as reliable predictors of athletes' performance. Furthermore, individuals with elevated mesomorphy values may exhibit enhanced strength performance, while those with higher ectomorphy values may demonstrate superior flexibility performance. Hence, when designing training programs aimed at enhancing athletes' performance attributes, it is imperative to account for the influence of body type on such performances.

Nutrition Status of Female Winter Sports Athletes

Eating disorders, especially restrictive eating, are common among female athletes. There are two main types of winter sports: those that are practiced outdoors on snow (-25 to +5 °C and 2500 m), such as alpine skiing and snowboarding, and those that are practiced indoors on ice (5-10 °C at low altitude), such as figure skating and ice hockey. The aim of this research was to identify the nutritional status and potential risk of female athletes practicing winter sports, considering the altitude of training. The sample was composed of 58 women (aged 19.81 years (SD: 12.61)) who were competitors in some winter sports. Anthropometrics and nutritional variables were taken. Statistically significant differences were found between HA and LA groups for all the characteristics except thigh skinfold, and neither group had an energy intake (EI) that matched their total energy expenditure (TEE). Both groups met at least two-thirds of the RDI for all minerals and vitamins except iodine, fluorine, vitamin D, vitamin E, and retinol. This study suggests that female winter sports athletes have insufficient energy, vitamin, and mineral intake, which can be worsened with altitude.

A Classification of Fitness Components in Elite Alpine Skiers: A Cluster Analysis

The current study is an exploratory, secondary data analysis of a selection of physiological and biomechanical fitness components used to assess elite alpine skiers. The present study will provide new knowledge that can be used to aid training prescription and talent identification. A hierarchical cluster analysis was used to identify groups of variables that are crucial for elite alpine skiers and differences based on sex and competition level. The key findings of the study are the patterns that emerged in the generated dendrograms. Physiological and biomechanical fitness components are differentiated in the dendrograms of male and female world-cup-level alpine skiers, but not in non-world-cup athletes. Components related to the aerobic and anaerobic capacity tightly cluster in male athletes at world cup and non-world-cup level, and female world cup athletes. Lower body explosive force production appears to be more critical in male world cup athletes than female world cup athletes. More research is needed into the importance of isometric strength in the lower body. Future research should use larger sample sizes and consider other alpine ski demographics.

Bone and body characteristics of freestyle and nonfreestyle skiers

BACKGROUND

Freestyle skiers must optimize their aerial performance by maintaining the strength and coordination to propel themselves in the air and adapt to landings and take-offs on uneven surfaces. The purpose of this study is to investigate the differences in areal bone mineral density (aBMD) and body composition in freestyle skiers and nonfreestyle skiing controls.

HYPOTHESIS

We hypothesized that the unique demands and summation of forces experienced by freestyle athletes would manifest as greater femoral neck aBMD, lower percent body fat, and lower BMI than nonfreestyle skiing controls.

LEVEL OF EVIDENCE

Level 3, Retrospective Cohort Study.

METHODS

18 freestyle skiers (14M 4F, [27.56 ± 5.22 years]) and 15 controls (7M 8F, [26.93 ± 3.54 years]) were measured with dual energy X-ray absorptiometry (DXA) to determine total body composition, hip and lumbar spine aBMD, and bone mineral composition (BMC). Height and weight were measured with an in-office stadiometer and scale. Questionnaires were used to determine physical activity and pertinent medical history. Between-group variations were analyzed with an analysis of variance (ANOVA) and stratified by sex.

RESULTS

Percent body fat, hip and lumbar spine aBMD, BMC, and area were all similar between freeski and nonfreeski athletes (p<0.05 for all). BMI was significantly lower in male freeski athletes (23.97kg/m2, 95% CI [22.75-25.18]) compared to nonfreestyle skiing controls (26.64kg/m2, 95% CI [24.43-28.86]) (p=0.03).

CONCLUSIONS

Freestyle skiers have a lower BMI than nonfreestyle skiers. All skiers in this study has similar percent body fat, aBMD, and BMC. This pilot study supports that there are unique musculoskeletal adaptations based on type of skiing.

CLINICAL RELEVANCE

Skiers endure a variety of intense physical forces yet remain understudied despite high orthopedic injury rates. This study serves to broaden the current sports health literature and explore the physical demands and subsequent physiology of freestyle skiers.

Heel Lift for Skiing to Compensate for Corrected Sagittal Vertical Axis After Spinal Surgery: A Case Report

Lateral lumbar interbody fusion (LLIF) and pedicle subtraction osteotomy are common procedures to correct adult spinal deformities. Little is known about returning postoperatively to a high-performance sport such as skiing after spinal surgery. We report a case of an alpine skier who underwent a LLIF procedure combined with a posterior corrective osteotomy and posterior instrumentation, who had difficulties returning to skiing postoperatively because of new spinal biomechanics. The case report describes the possible consequences of spinal sagittal deformity surgery on postoperative skiing. A 63-year-old man with a complex lumbar spinal surgery history showed severe adjacent segment degenerative spondylolistheses at L1-L2 and at L5-S1. A lateral approach at L1-L2 combined with a posterior corrective osteotomy at L3 and instrumentation from T10 to the pelvis were performed. At his 1-year follow up, he made excellent progress and returned to skiing. However, he reported that skiing did not feel the same, and his center of gravity felt as if it shifted backwards. Consequently, he placed a 2-cm wedge in his ski binding, which improved his skiing experience. Sagittal vertical axis changes after spinal surgery affect the biomechanics of the entire body. After surgery, the body's ligaments, muscles, and fascia adapt to the new body posture. Activities such as skiing, where body posture plays an essential role, are particularly affected by spine surgeries. Surgeons should discuss this issue before spinal surgery with patients, especially if patients are involved in high-intensity sports.

Physical fitness is associated with better technical performance in adolescent alpine ski racers after controlling for practice time: A retrospective regression analysis

In an effort to evaluate the mechanisms underpinning performance in alpine ski racing, researchers have focused on the predictive validity of measures derived from fitness assessments. However, a limitation of this literature is the absence of practice time, since prolonged training may naturally develop specific fitness capacities, making some tests of physical ability less predictive of performance. We examine the relationship between fitness tests, practice, and performance using linear regressions with fitness test data, practice history data, and performance results from adolescent alpine ski racers attending professional development academies in the United States (N = 82). Only aerobic capacity (i.e. 20 m shuttle run) was significantly associated with more practice time. After controlling for practice hours, 5.5-6.5% of variance in ski performance was significantly explained by assessments of lower body power (i.e. standing long jump, triple jump), anaerobic capacity (i.e. 60 s box jump), and upper body strength/endurance (i.e. push-ups). Findings highlight the important role of anaerobic power on alpine ski racing performance, which may be developed outside of regular practice, possibly through weight training or physical maturation. The small variance explained by physical/physiological measures suggests that superior ski performance is likely a product of various skills and characteristics (e.g. technical, tactical, perceptual-cognitive, psychosocial).

Relationship Between Strength, Athletic Performance, and Movement Skill in Adolescent Girls

Sommerfield, LM, Harrison, CB, Whatman, CS, and Maulder, PS. Relationship between strength, athletic performance, and movement skill in adolescent girls. J Strength Cond Res XX(X): 000-000, 2019-Muscular strength in youth has been linked to health and physical benefits, enhanced movement skill, and an active lifestyle in adulthood. However, the relationship between maximum strength, athletic performance, and movement skill in youth females remains unclear. The purpose was to examine the relationship between maximum strength, athletic performance, and movement skill and determine whether differences exist between strong girls (SGs), average girls (AGs), and weak girls (WGs). One hundred four girls (age 14.0 ± 0.6 years, height 162.6 ± 5.9 cm, body mass 57.3 ± 9.7 cm) from a girls' secondary school performed an isometric midthigh pull (IMTP), double- and single-leg (right leg = R, left leg = L) countermovement jump, 10- and 20-m sprints, a drop vertical jump ,and the back squat assessment. Significance was set at p < 0.01 for correlations and p < 0.05 for one-way analysis of variance. Correlations revealed IMTP had significant small to large relationships with all performance variables (r = 0.27-0.62) except right-leg countermovement jump and left-leg countermovement jump height (r = 0.17-0.23). Relative IMTP had significant moderate to large relationships with all performance variables (r = 0.32-0.60). There were significant differences between strength groups for all performance measures. Strong girls had significantly faster sprint times than AGs. In addition, SGs and AGs performed significantly better than WGs in all assessments. The results of this study demonstrate the importance of strength for athletic performance and movement skill in adolescent girls.

A Review of Countermovement and Squat Jump Testing Methods in the Context of Public Health Examination in Adolescence: Reliability and Feasibility of Current Testing Procedures

BACKGROUND

In the context of a public health physical fitness (PF) examination in adolescence, a countermovement jump (CMJ) and a squat jump (SJ) are two vertical jump (VJ) tests widely used to evaluate lower limb muscle strength and power, respectively. The main criticism of both the CMJ and SJ test is the lack of test standardization. Therefore, the objectives of this review are: (a) to gather information about both jumps; (b) to investigate whether it is possible to identify common procedures referred to in the CMJ and SJ technical execution, and (c) to design standard operating procedures (SOPs) to promote CMJ and SJ standardization in an adolescent population aged 12-18 years.

METHODS

The review partially adopted the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statement (PRISMA). Due to growing attention in monitoring physical health through field tests in recent years, articles were collected using the PubMed, Web of Science, and Scopus databases from January 2009 to July 2019. Original articles in which CMJ or SJ were used to assess the muscular strength in adolescents were eligible for further analysis. Articles written in English was imposed as a limit.

RESULTS

A total of 117 studies met the inclusion criteria. The description of the CMJ and SJ test procedures was different within the literature, with discrepancies in the jump technique, number of jumps, and measurement devices used.

CONCLUSIONS

A lack of method standardization for both the CMJ and the SJ test was identified. Based on the literature, SOPs for both VJs were proposed. These are useful in the context of public health PF examination in adolescents, as they facilitate an unbiased comparison of jump performance data between published studies.

Potential Health Benefits From Downhill Skiing

Objectives: Downhill skiing represents one of the most popular winter sports worldwide. Whereas a plethora of studies dealt with the risk of injury and death associated with downhill skiing, data on its favorable health effects are scarce. A more comprehensive overview on such effects might emerge from a multidisciplinary perspective.

Methods: A literature search has been performed to identify original articles on downhill/alpine skiing interventions or questionnaire-based evaluation of skiing effects and the assessment of health effects (cardiorespiratory, neurophysiological, musculoskeletal, psycho-social).

Results and Discussion: A total of 21 original articles dealing with potentially favorable health effects resulting from downhill skiing were included in this review. Results indicate that downhill skiing, especially when performed on a regular basis, may contribute to healthy aging by its association with a healthier life style including higher levels of physical activity. Several other mechanisms suggest further favorable health effects of downhill skiing in response to specific challenges and adaptations in the musculo-skeletal and postural control systems, to exposures to cold temperatures and intermittent hypoxia, and/or emotional and social benefits from outdoor recreation. However, reliable data corroborating these mechanisms is scarce.

Aerobic Variables for Prediction of Alpine Skiing Performance - A Novel Approach

The aim of this study was to investigate the predictive power of aerobic test results and anthropometric variables on FIS-ranking of junior elite alpine skiers. Results from twenty-three male and female adolescent elite alpine skiers from two seasons were included in the multivariate statistical models. Physical work capacity was determined by V̇O2peak, blood lactate concentration ([HLa]b), and heart rate (HR) during ergometer cycling. Anthropometric variables were body stature, body weight and calculated BMI. No significant correlation between competitive performance and aerobic work capacity or anthropometric data was observed neither in male nor female adolescent skiers. Pre-season physical tests and anthropometric data could therefore not predict end-season FIS-ranking. The best regression (R2) and prediction (Q2) models of FIS slalom (SL) and giant slalom (GS) rank reached R2=0.51 to 0.86, Q2=−0.73 to 0.18, indicating no valid models. This study could not establish V̇O2peak and other included variables as predictors of competitive performance. When combining results from commonly used tests for alpine skiers, and applying multivariate statistical models, investigated tests seems of limited used for athletes, coaches, and ski federations. Performance-specific pre-season tests must be developed and validated for prediction of performance and guidance of exercise training.

No difference in prevalence of spine and hip pain in young Elite skiers

PURPOSE

To investigate the prevalence between back and hip pain in young Elite skiers.

METHODS

Sample group (n = 102), consisted of young Elite skiers (n = 75) and age-matched non-athletes (n = 27), all completed a three-part back and hip pain questionnaire, Oswestry Disability Index and EuroQoL to evaluate general health, activity level, back and hip pain prevalence.

RESULTS

No significant differences were shown for lifetime prevalence of back pain in the skiers (50%) compared with controls (44%) (n.s.). Duration of back pain for the skiers showed (30%) > 1 year, whilst (46%) > 5 years. A significant difference was shown with increased Visual Analogue Scale back pain levels for skiers 5.3 (SD 3.1) compared with controls 2.4 (SD 1.9, p = 0.025). No significant differences were shown for lifetime prevalence of hip pain in skiers (21%) compared with controls (8%) (n.s.).

CONCLUSION

Young Elite skiers are shown not to have increased lifetime prevalence for back and hip pain compared with a non-athletic control group.

LEVEL OF EVIDENCE

II.

National Strength and Conditioning Association Position Statement on Long-Term Athletic Development

There has recently been a growing interest in long-term athletic development for youth. Because of their unique physical, psychological, and social differences, children and adolescents should engage in appropriately prescribed exercise programs that promote physical development to prevent injury and enhance fitness behaviors that can be retained later in life. Irrespective of whether a child is involved in organized sport or engages in recreational physical activity, there remains a need to adopt a structured, logical, and evidence-based approach to the long-term development of athleticism. This is of particular importance considering the alarmingly high number of youth who fail to meet global physical activity recommendations and consequently present with negative health profiles. However, appropriate exercise prescription is also crucial for those young athletes who are physically underprepared and at risk of overuse injury because of high volumes of competition and an absence of preparatory conditioning. Whether the child accumulates insufficient or excessive amounts of exercise, or falls somewhere between these opposing ends of the spectrum, it is generally accepted that the young bodies of modern day youth are often ill-prepared to tolerate the rigors of sports or physical activity. All youth should engage in regular physical activity and thus should be viewed as "athletes" and afforded the opportunity to enhance athleticism in an individualized, holistic, and child-centered manner. Because of emerging interest in long-term athletic development, an authorship team was tasked on behalf of the National Strength and Conditioning Association (NSCA) to critically synthesize existing literature and current practices within the field and to compose a relevant position statement. This document was subsequently reviewed and formally ratified by the NSCA Board of Directors. A list of 10 pillars of successful long-term athletic development are presented, which summarize the key recommendations detailed within the position statement. With these pillars in place, it is believed that the NSCA can (a) help foster a more unified and holistic approach to long-term athletic development, (b) promote the benefits of a lifetime of healthy physical activity, and

Evolution of Determinant Factors of Repeated Sprint Ability

The aim of this study was to investigate the changes in the relationships between repeated sprint ability (RSA) and anthropometric measures as well as fitness qualities in soccer players. Twenty-one professional soccer players performed several anthropometric and physical tests including countermovement vertical jumps (CMJs), a straight-line 30 m sprint (T30), an RSA test (6 x 20 + 20 m with 20 s recovery), a progressive isoinertial loading test in a full squat, a Yo-Yo Intermittent Recovery Test Level-1 (YYIRT-1) and a 20 m shuttle run test (20mSRT). The mean (RSAmean), the fastest (RSAbest), each single sprint time, and the percentage in a sprint decrease (%Dec) in the RSA test were calculated. RSAbest correlated significantly with RSAmean (r = .82) and with all single sprints (p < 0.05), showing a downward trend as the number of sprints performed increased. No significant relationship was observed between the %Dec and RSA performance. CMJs and the T30 also showed a correlation with RSA performance, whereas lower limb strength did not show any relationship with RSA performance. RSAmean showed significant (p < 0.05) relationships with body mass (r = .44), adiposity (r = .59) and the YYIRT-1 (r = -.62), increasing as the number of repeated sprints increased. The 20mSRT showed minimal relationships with RSA performance. In conclusion, maximal sprint capacity seems to be relevant for the RSA performance, mainly in the first sprints. However, high intermittent endurance capacity and low adiposity might help enhance the RSA performance when increasing the number of repeated sprints.

Back pain and MRI changes in the thoraco-lumbar spine of young elite Mogul skiers

Athletes have a higher prevalence of LBP and spinal abnormalities on Magnetic Resonance Imaging (MRI) compared to non-athletes. The objective of this study was to investigate the amount of spinal MRI abnormalities and the lifetime prevalence of low back pain (LBP) in 16 young elite Mogul skiers compared to 28 non-athletes in the corresponding age in a cross-sectional design. LBP was assessed by a questionnaire consisting of a part regarding previous or present back pain, the Oswestry disability index, and the EuroQol questionnaire. MRI examinations from Th5 to sacrum were conducted to evaluate spinal pathologies. The Mogul skiers had significantly more MRI abnormalities (like disc degeneration) in mean (7.25 vs 3.78, P < 0.023) compared to the controls. No significant difference was seen regarding the lifetime LBP prevalence between the groups (50% vs 42%, P = 0.555). No correlation could be found between disc degeneration and back pain in this study. Young elite Mogul skiers, compared to an age-matched control group of non-athletes, have an increased risk of developing spinal abnormalities potentially due to the different high loads that they are subjected to in their sport. Future relationship between the MRI abnormalities and LBP cannot be verified by this study design.

There is no need to avoid resistance training (weight lifting) until physeal closure

The physis, or growth plate, is relatively weaker than the surrounding bone; as a result, individuals with immature skeletons are at risk for growth plate injury from forces that would not harm an adult. Based on the knowledge that immature growth plates are weaker than adult growth plates, it is not known with certainty whether or not adolescents can participate safely in resistance training programs. Because medical literature does not definitively answer if it is safe for adolescents to pursue strength-training programs, we previously surveyed 500 experts in sports medicine to determine whether they agreed with the statement "resistance training ('weight lifting') should be avoided until physeal closure." Overall, respondents answered that "this statement is very likely false." In this article, we interpret the experts' survey responses by reviewing the basic and clinical sciences implicit in the question, as well as the literature regarding adolescent outcomes. Although the avoidance of resistance training by adolescents is theoretically appealing, we found that the data indicate properly supervised weight programs are not associated with increased risk of acute injury. However, the literature offers no insight about the long-term implications of weight lifting on growth plates. In sum, the expert consensus from our survey that strength training is safe for individuals with immature skeletons is consistent with data from medical literature.