Physical capacity, not skeletal maturity, distinguishes competitive levels in male Norwegian U14 soccer players.

The main aim of the present study was to compare skeletal maturity level and physical capacities between male Norwegian soccer players playing at elite, sub-elite and non-elite level. Secondary, we aimed to investigate the association between skeletal maturity level and physical capacities. One hundred and two U14 soccer players (12.8-14.5 years old) recruited from four local clubs, and a regional team were tested for bone age and physical capacities. Bone age was estimated with x-ray of their left hand and used to indicate maturation of the skeleton. Players went through a comprehensive test battery to assess their physical capacities. Between-groups analysis revealed no difference in chronological age, skeletal maturity level, leg strength, body weight, or stature. However, elite players were superior to sub-elite and non-elite players on important functional characteristics as intermittent-endurance capacity (running distance: 1664 m ± 367 vs 1197 m ± 338 vs 693 m ± 235) and running speed (fastest 10 m split time: 1.27 seconds ± 0.06 vs 1.33 seconds ± 0.10 vs 1.39 seconds ± 0.11), in addition to maximal oxygen uptake ( V ˙ O 2 m a x ), standing long jump, and upper body strength (P < .05 for all comparisons). Medium-to-large correlations were found between skeletal maturity level and peak force (r = 695, P < .01), power (r = 684, P < .01), sprint (r = -.471, P<.001), and jump performance (r = .359, P < .01), but no correlation with upper body strength, V ˙ O 2 m a x , or intermittent-endurance capacity. These findings imply that skeletal maturity level does not bias the selection of players, although well-developed physical capacity clearly distinguishes competitive levels. The superior physical performance of the highest-ranked players seems related to an appropriate training environment.

Immediate effects of blood donation on physical and cognitive performance-A randomized controlled double-blinded trial.

BACKGROUND: The success of implementing damage control resuscitation principles pre-hospital has been at the expense of several logistic burdens including the requirements for resupply, and the question of donor safety during the development of whole blood programs. Previous studies have reported effects on physical performance after blood donation; however, none have investigated the effects of blood donation on cognitive performance. METHOD: We describe a prospective double-blinded, randomized, controlled study comprised of a battery of tests: three cognitive tests, and VO2max testing on a cycle ergometer. Testing was performed 7 days before blinded donation (baseline day), immediately after donation (Day 0), and 7 days (Day 7) after donation. The inclusion criteria included being active blood donors at the Haukeland University Hospital blood bank, where eligibility requirements were met on the testing days, and providing informed consent. Participants were randomized to either the experimental (n = 26) or control group (n = 31). Control group participants underwent a 'mock donation" in which a phlebotomy needle was placed but blood was not withdrawn. RESULTS: In the experimental group, mean ± SEM VO2max declined 6% from 41.35 ± 1.7 mLO2/(min·kg) at baseline to 39.0 ± 1.6 mLO2/(min·kg) on Day 0 and increased to 40.51 ± 1.5 mLO2/(min·kg) on Day 7. Comparable values in the control group were 42.1 ± 1.8 mLO2/(min·kg) at baseline, 41.6 ± 1.8 mLO2/(min·kg)) on Day 1 (1% decline from baseline), and 41.8 ± 1.8 mLO2/(min·kg) on Day 7.Comparing scores of all three cognitive tests on Day 0 and Day 7 showed no significant differences (p > 0.05). CONCLUSION: Our main findings are that executive cognitive and physical performances were well maintained after whole blood donation in healthy blood donors. The findings inform postdonation guidance on when donors may be required to return to duty. LEVEL OF EVIDENCE: Randomized, controlled, double-blinded prospective trial study, level 1.

Steroid receptor antagonist mifepristone inhibits the anti-inflammatory effects of photoradiation.

OBJECTIVE: We designed an animal pleurisy study to assess if the anti-inflammatory effect of photoradiation could be affected by concomitant use of the cortisol antagonist mifepristone. BACKGROUND DATA: Although interactions between photoradiation and pharmacological agents are largely unknown, parallel use of steroids and photoradiation is common in the treatment of inflammatory disorders such as arthritis and tendinitis. METHODS: Forty BALB/c male mice were randomly divided in five groups. Inflammation was induced by carrageenan administered by intrathoracic injections. Four groups received carrageenan, and one control group received injections of sterile saline solution. At 1, 2, and 3 h after injections, photoradiation irradiation was performed with a dose of 7.5 J/cm(2). Two of the carrageenan-injected groups were pre-treated with orally administered mifepristone. RESULTS: Total leukocyte cell counts revealed that in carrageenan-induced pleurisy, photoradiation significantly reduced the number of leukocyte cells (p < 0.0001, mean 34.5 [95% CI: 32.8-36.2] versus 87.7 [95% CI: 81.0-94.4]), and that the effect of photoradiation could be totally blocked by adding the cortisol antagonist mifepristone (p < 0.0001, mean 34.5 [95% CI: 32.1-36.9] versus 82.9 [95%CI: 70.5-95.3]). CONCLUSION: The steroid receptor antagonist mifepristone significantly inhibited the anti-inflammatory effect of photoradiation. Commonly used glucocorticoids are also known to down-regulate steroid receptors, and further clinical studies are necessary to elucidate how this interaction may decrease the effect size of photoradiation over time. For this reason, we also suggest that, until further clinical data can be provided, clinical photoradiation trials should exclude patients who have received steroid therapy within 6 months before recruitment.