Vitamin D Status and its Relation to Exercise Performance and Iron Status in Young Ice Hockey Players

Objectives The aim was to examine the association between serum vitamin D concentration and isometric strength of various muscle groups, vertical jump performance, and repeated sprint ability in young ice hockey players. The secondary aim was to determine the association between vitamin D deficiency and indices of iron status. Methods Fifty male ice hockey players (17.2±0.9 years) participated in this cross-sectional study. Exercise performance was evaluated using isometric strength measures of upper and lower extremities, vertical jump performance and repeated sprint ability (RSA). Blood samples were collected for the determination of serum 25-hydroxyvitamin D (25(OH)D) and multiple indicies of iron status. Results The mean serum 25(OH)D concentration was 30.4 ng-ml-1 and ranged from 12.5 to 91.4 ng-ml-1. Eleven participants (22%) had vitamin D deficiency and 20 athletes (40%) had vitamin D insufficiency. Serum 25(OH)D concentration was not positively correlated with isometric muscle strength, vertical jump performance, or RSA after adjusting for age, training experience, fat mass, fat free mass and height. Serum 25(OH)D concentration was not associated with indices of iron status. Conclusion Vitamin D insufficiency is highly prevalent in ice hockey players, but 25(OH)D concentration but it is not associated with exercise performance or indices of iron status

The aerodynamic assessment of tandem cyclists in preparation for the 2021 Paralympic Games: A case study

Reducing the level of aerodynamic drag (CdA) via use of a wind tunnel will ultimately improve a competitive cyclists performance. Whilst this tool is widely considered a ‘gold standard’, previous studies have centred on single riders or scale models to evaluate aerodynamic drag. No study to date has assessed the precision of wind tunnel testing with the additional perceived complexity of a tandem bicycle with a pair of competitive paracyclists. The first part of this investigation evaluated the use of a wind tunnel in the assessment of tandem paracyclists. A male and female team of paracyclists riding tandem versions of either a time trial track bicycle or a road/time trial bicycle undertook a series of measurement intervals in a wind tunnel. Three different combinations of these riders and bicycles obtained a Coefficient of Variation of their mean CdA of 1.8%–2.6%. The second part of this investigation acted as a case study by implementing a range of aerodynamic interventions to potentially reduce the male team’s CdA. For example, progressive efforts reduced a team’s CdA from the baseline of 0.338 m2 to ultimately 0.321 m2 predominately by lowering both tandem riders heads Whilst tandem cyclist performance enhancement has recieved scant attention in the past, this case study only highlights the value of doing so in the future. </jats:p

Validity of Performance Assessment Methods in Elite Paracanoeists

The problem of valid and reliable research methods in paralympic sports seems of great significance, thus the aim of this study was to evaluate the validity of the Wingate test (WAnT) in assessment of anaerobic performance in elite paracanoeists competing in 200 m races. Seven paralympic athletes (32.6 ± 7.76 years), medal winners and finalists of the Paralympic Games, World and European Championships, as well as World Cups were examined. The evaluations were conducted during a competition which was held at the paralympic distance of 200 m, and included the WAnT for upper limbs and the anaerobic threshold test (ATT). Correlations of selected indices of mechanical work and power in the WAnT, as well as anaerobic threshold (AT) power, with the time recorded during the competition were used to determine indices which affected paracanoeing performance. The results indicated strong negative correlations with time achieved in the competition between peak power and total work in the WAnT, and AT power (R = -0.796 p = 0.032; R = -0.882 p = 0.009; R = -0.900 p &lt; 0.001, respectively). The research confirmed the validity of the WAnT for the upper limbs to assess the performance level of paracanoeists. It may be concluded that the WAnT and ATT may be used for monitoring performance during the paralympic 200 m race.</jats:p

Repeated Sprint Ability Demands in U16 to U19 Highly Trained Handball Players Concerning Playing Position

The aim of the study was to determine anaerobic capacity and characterize changes in repeated sprint ability (RSA) within youth elite handball players. For this study, 142 male athletes (17.1 &plusmn; 0.9 years) were recruited from a handball sports high school and performed the RSA test on a cycle ergometer, including five 6 s all-out efforts separated by 24 s passive breaks. Maximal (Pmax) and mean (Pmean) power, highest (Wmax), and total work (Wtot) as well as power (Pdec) and work (Wdec) decrement were measured. Significant differences in RSA were noted in relation to age (greater values of Pmax, Pmean, Wtot, Wdec, and Pdec in U19 than U17 as well as greater values of Pmax, Wtot, Wmax, Wdec, and Pdec in U19 than U16 (p &lt; 0.05)) and playing position (wing players had greater Wtot than pivot, 269 vs. 243 (J/kg) (p &lt; 0.05), and wing players differed significantly in absolute and relative power from athletes of other positions). RSA depends on playing position and age in groups of youth handball players and the RSA test can be helpful in the selection of athletes for a playing position. The article introduces normative values for elite youth handball players, empowering coaches in the evaluation of anaerobic abilities and selection

Repeated Sprint Ability Demands in U16 to U19 Highly Trained Handball Players Concerning Playing Position

The aim of the study was to determine anaerobic capacity and characterize changes in repeated sprint ability (RSA) within youth elite handball players. For this study, 142 male athletes (17.1 ± 0.9 years) were recruited from a handball sports high school and performed the RSA test on a cycle ergometer, including five 6 s all-out efforts separated by 24 s passive breaks. Maximal (Pmax) and mean (Pmean) power, highest (Wmax), and total work (Wtot) as well as power (Pdec) and work (Wdec) decrement were measured. Significant differences in RSA were noted in relation to age (greater values of Pmax, Pmean, Wtot, Wdec, and Pdec in U19 than U17 as well as greater values of Pmax, Wtot, Wmax, Wdec, and Pdec in U19 than U16 (p &lt; 0.05)) and playing position (wing players had greater Wtot than pivot, 269 vs. 243 (J/kg) (p &lt; 0.05), and wing players differed significantly in absolute and relative power from athletes of other positions). RSA depends on playing position and age in groups of youth handball players and the RSA test can be helpful in the selection of athletes for a playing position. The article introduces normative values for elite youth handball players, empowering coaches in the evaluation of anaerobic abilities and selection.</jats:p

Vitamin D and Cortisol as Moderators of the Relationship Between Testosterone and Exercise Performance in Adolescent Male Athletes

Purpose: Reported associations between vitamin 25(OH)D and exercise performance are equivocal, perhaps due to complex interplay with cortisol and testosterone. In this study, the authors investigated serum 25(OH)D and cortisol as moderators of the testosterone relationship with exercise performance in adolescent male athletes. Methods: A total of 88 ice hockey players were assessed for serum 25(OH)D, cortisol, testosterone, body composition, and exercise performance, based on countermovement jump power and muscle torque. The authors tested independent relationships, before examining complex interactions via moderated regression analyses. Results: Most athletes (62.5%) exhibited a suboptimal (20-30 ng·mL−1) serum 25(OH)D concentration, whereas 9.1% of athletes were deficient (−1). Serum 25(OH)D was not related to performance when controlling for testing year, age, and fat mass. Further modeling revealed a significant hormonal interaction. Specifically, in low-25(OH)D subjects, testosterone predicted countermovement jump power at a high (β = 7.10, effect size = .43, P β = −3.32, effect size = −.20, P = .09), cortisol concentration. Conclusions: Serum 25(OH)D was a poor predictor of exercise performance, but it did moderate (with cortisol) the testosterone link to muscle power. Notably, this relationship emerged among individuals with a 25(OH)D concentration (~22 ng·mL−1) approaching the deficiency cutoff. Viewing 25(OH)D as a moderating, rather than dose responsive, variable could help explain equivocal cross-sectional associations

Usefulness of Portable Device to Establish Differences in Muscle Oxygenation Between the Wingate Test and Graded Exercise Test: Effect of Gender on Anaerobic and Aerobic Capacity in Speed Skaters

The aim of this study was to compare the oxygenation response in the vastus lateralis muscle (SmO2) in two types of tests: supramaximal and maximal. Furthermore, gender differences in SmO2 response to test exercise were assessed and the usefulness of muscle oxygenation measurements in the assessment of anaerobic and aerobic capacity was determined. The Wingate test (WAnT) and the graded exercise test (GXT) to exhaustion were performed on a cycle ergometer to examine 13 female and 14 male speed skaters from the junior and U23 national teams. During both tests, SmO2 of the vastus lateralis muscle was recorded by near-infrared spectroscopy at baseline (at rest or post warm-up), at exercise, and during recovery. The most significant SmO2 indices (differences between baseline and post-exercise indices and half time for SmO2 to reach the maximal post-exercise value) were not significantly different between the tests. Gender was also not a differentiating factor in muscle oxygenation regardless of test type. In the GXT test, half time required for SmO2 to reach the maximal value correlated negatively with VO2max and test duration, thus confirming the usefulness of SmO2 measurements in the assessment of the aerobic capacity of speed skaters. In contrast, the WAnT test showed no significant correlations between exercise indices and muscle oxygenation indices. From the standpoint of the assessment of anaerobic capacity, SmO2 measurements showed little diagnostic value.</jats:p

Balance Level and Fundamental Motor Skills of Youth with Visual Impairments: Pilot Study

Background: Visual impairment significantly affects balance and motor skills in children, often leading to postural instability and locomotor difficulties, thereby affecting lifestyle and general health. The aim of this study was to assess balance level and fundamental motor skills in the locomotion of youth with regard to their level of visual impairment. Methods: The pilot study included 25 physically active young people with visual impairments, divided into three groups (B1, B2, B3) based on the severity of impairment. Balance was assessed using the AMTI AccuSway platform, both with eyes open and eyes closed. Locomotor skills were evaluated using the TGMD-3. Statistical analysis involved Kruskal&ndash;Wallis, ANOVA, and correlation tests. Results: Significant differences in balance were found between the B1 and B2 groups, with poorer balance in individuals with more severe visual impairments, particularly in static conditions. No significant differences in locomotor skills were observed between groups. However, girls performed better in balance tests, particularly with eyes closed. A positive correlation was found between balance and locomotor skills in the B2 and B3 groups. Conclusions: Visual impairment negatively impacts balance, particularly in individuals with more severe impairments. However, no significant differences were found in locomotor skills between the groups. Regular physical activity supports motor development. Targeted interventions are necessary to improve balance and locomotor skills, especially in children with more severe visual impairments

Vitamin D and Cortisol as Moderators of the Relationship Between Testosterone and Exercise Performance in Adolescent Male Athletes

Purpose: Reported associations between vitamin 25(OH)D and exercise performance are equivocal, perhaps due to complex interplay with cortisol and testosterone. In this study, the authors investigated serum 25(OH)D and cortisol as moderators of the testosterone relationship with exercise performance in adolescent male athletes. Methods: A total of 88 ice hockey players were assessed for serum 25(OH)D, cortisol, testosterone, body composition, and exercise performance, based on countermovement jump power and muscle torque. The authors tested independent relationships, before examining complex interactions via moderated regression analyses. Results: Most athletes (62.5%) exhibited a suboptimal (20–30 ng·mL−1) serum 25(OH)D concentration, whereas 9.1% of athletes were deficient (&lt;20 ng·mL−1). Serum 25(OH)D was not related to performance when controlling for testing year, age, and fat mass. Further modeling revealed a significant hormonal interaction. Specifically, in low-25(OH)D subjects, testosterone predicted countermovement jump power at a high (β = 7.10, effect size = .43, P &lt; .01), but not low (β = −3.32, effect size = −.20, P = .09), cortisol concentration. Conclusions: Serum 25(OH)D was a poor predictor of exercise performance, but it did moderate (with cortisol) the testosterone link to muscle power. Notably, this relationship emerged among individuals with a 25(OH)D concentration (∼22 ng·mL−1) approaching the deficiency cutoff. Viewing 25(OH)D as a moderating, rather than dose responsive, variable could help explain equivocal cross-sectional associations.</jats:p