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

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 < 0.05)) and playing position (wing players had greater Wtot than pivot, 269 vs. 243 (J/kg) (p < 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

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

Systemic Lactate Elevation Induced by Tobacco Smoking during Rest and Exercise Is Not Associated with Nicotine

Lactate is a metabolite produced during anaerobic glycolysis for ATP resynthesis, which accumulates during hypoxia and muscle contraction. Tobacco smoking significantly increases blood lactate. Here we conducted a counter-balanced crossover study to examine whether this effect is associated with inhaling nicotine or burned carbon particles. Fifteen male smokers (aged 23 to 26 years) were randomized into 3 inhalation conditions: tobacco smoking, nicotine vaping, and nicotine-free vaping, conducted two days apart. An electronic thermal evaporator (e-cigarette) was used for vaping. We have observed an increased blood lactate (+62%, main effect: p < 0.01) and a decreased blood glucose (−12%, main effect: p < 0.05) during thermal air inhalations regardless of the content delivered. Exercise-induced lactate accumulation and shuttle run performance were similar for the 3 inhalation conditions. Tobacco smoking slightly increased the resting heart rate above the two vaping conditions (p < 0.05), implicating the role of burned carbon particles on sympathetic stimulation, independent of nicotine and thermal air. The exercise response in the heart rate was similar for the 3 conditions. The results of the study suggest that acute hypoxia was induced by breathing thermal air. This may explain the reciprocal increases in lactate and decreases in glucose. The impaired lung function in oxygen delivery of tobacco smoking is unrelated to nicotine

Vitamin D status and its relation to exercise performance and iron status in young ice hockey players

<div><p>Objectives</p><p>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.</p><p>Methods</p><p>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.</p><p>Results</p><p>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.</p><p>Conclusion</p><p>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.</p></div

Pearson’s and partial correlations between exercise performance and (log of) 25(OH)D concentration (n = 50).

<p>Pearson’s and partial correlations between exercise performance and (log of) 25(OH)D concentration (n = 50).</p

Correlations between indices of iron status and (log of) 25(OH)D concentration (n = 50).

<p>Correlations between indices of iron status and (log of) 25(OH)D concentration (n = 50).</p

Descriptive characteristics for all ice hockey players (n = 50).

<p>Descriptive characteristics for all ice hockey players (n = 50).</p

Pearson’s and partial correlations between exercise performance and Iron concentration (n = 50).

<p>Pearson’s and partial correlations between exercise performance and Iron concentration (n = 50).</p