Vitamin D Supplementation Has No Impact on Cardiorespiratory Fitness, but Improves Inflammatory Status in Vitamin D Deficient Young Men Engaged in Resistance Training.

Data on the effect of vitamin D (Vit-D) supplementation on cardiorespiratory fitness (VO2max) are conflicting. A possible source of discrepancies in the literature is the heterogeneity in baseline Vit-D status among participants in previous studies. The main objectives of the present study were to assess the impact of Vit-D supplementation on VO2max and inflammatory status in Vit-D deficient young healthy men. Participants (n = 39, baseline serum Vit-D level < 50 nmol/L) were quasi-randomly assigned to one of the two groups, which, in a double-blind manner, supplemented their diet daily with either Vit-D (8000 IU; VD) or placebo (PLC) and concomitantly performed a 12-week supervised resistance training program. During the 12-week intervention, serum Vit-D concentrations increased 3.9-fold (p < 0.001) in the VD group while no changes occurred in the PLC group. Baseline VO2max did not differ in the two groups and remained unchanged during the intervention. Serum interleukin-10/tumour necrosis factor alpha ratio increased significantly (30%, p = 0.007; effect size 0.399) in VD but not in PLC group. In conclusion, 12-week Vit-D supplementation increases serum 25(OH)D levels and improves inflammatory status, but has no impact on VO2max in Vit-D deficient young men engaged in resistance training.

Contemporary Nutrition Strategies to Optimize Performance in Distance Runners and Race Walkers.

Distance events in Athletics include cross country, 10,000-m track race, half-marathon and marathon road races, and 20- and 50-km race walking events over different terrain and environmental conditions. Race times for elite performers span ∼26 min to >4 hr, with key factors for success being a high aerobic power, the ability to exercise at a large fraction of this power, and high running/walking economy. Nutrition-related contributors include body mass and anthropometry, capacity to use fuels, particularly carbohydrate (CHO) to produce adenosine triphosphate economically over the duration of the event, and maintenance of reasonable hydration status in the face of sweat losses induced by exercise intensity and the environment. Race nutrition strategies include CHO-rich eating in the hours per days prior to the event to store glycogen in amounts sufficient for event fuel needs, and in some cases, in-race consumption of CHO and fluid to offset event losses. Beneficial CHO intakes range from small amounts, including mouth rinsing, in the case of shorter events to high rates of intake (75-90 g/hr) in the longest races. A personalized and practiced race nutrition plan should balance the benefits of fluid and CHO consumed within practical opportunities, against the time, cost, and risk of gut discomfort. In hot environments, prerace hyperhydration or cooling strategies may provide a small but useful offset to the accrued thermal challenge and fluid deficit. Sports foods (drinks, gels, etc.) may assist in meeting training/race nutrition plans, with caffeine, and, perhaps nitrate being used as evidence-based performance supplements.

Anabolic Adaptations Occur in Conscripts During Basic Military Training Despite High Prevalence of Vitamin D Deficiency and Decrease in Iron Status.

INTRODUCTION: In Estonian Defense Forces that are drawn up on the basis of the conscription model considerable numbers of young men are prematurely discharged from military service for medical reasons, but causes leading to premature dropout of conscripts have not been systematically studied. However, one of the factors involved could be relatively demanding physical training that starts at the beginning of military service in the form of basic military training (BMT). Cumulative training and nontraining stresses experienced by conscripts during BMT may exceed their physiological adaptability and increase the probability of becoming prematurely discharged. Therefore, the primary purpose of this study was to assess physiological responses to 10-week BMT in Estonian conscripts. MATERIALS AND METHODS: The protocol of the study confirmed to the standards set by the Declaration of Helsinki and it was approved by the Research Ethics Committee of the University of Tartu. Mean ± SD age and body mass index of 94 conscripts studied was 20.9 ± 1.7 years and 24.2 ± 3.0 kg · m-2, respectively. Fasting venous blood analysis was performed four times during BMT (October to December) and once 15 weeks after the end of BMT (in March). One-factor (time) repeated measures analysis of variance was used to evaluate the differences within the variables. Statistical significance was set at p < 0.05. Where a significant main effect was observed, Tukey's honesty significant difference post-hoc analysis was used to locate differences between the means. A Pearson product moment coefficient of correlation (r) with α level set at 0.05 was applied to determine the relationship between variables. RESULTS: Significant increases in serum testosterone concentration (60.6%), testosterone to cortisol ratio (61.1%), blood erythrocyte count (4.3%), hemoglobin concentration (3.8%) and hematocrit (2.2%), and decrease in serum ferritin concentration (39.3%) occurred between weeks 1 and 10 during BMT (in all cases p < 0.0001). Fifteen weeks later, these parameters were still at increased or decreased levels, respectively, compared to week 1. The prevalence of vitamin D deficiency (serum 25(OH) D concentration <50 nmol · L-1) increased from 42.6% in week 1 to 80.8% in week 10 and to 91.5% 15 weeks later. Serum 25(OH)D levels did not correlate with testosterone concentrations (r = 0.062, p = 0.552 in Wk-1 and r = -0.079, p = 0.448 in Wk-25). CONCLUSION: These findings suggest that BMT induces anabolic physiological adaptations in conscripts despite vitamin D deficiency and decrease in iron status. However, high prevalence of vitamin D deficiency and decline in iron status may limit physiological adaptations and improvement in physical work capacity to a suboptimal level. Furthermore, as vitamin D influences a variety of functions important for health, deficiency in conscripts should be considered a major concern that needs treatment. An acknowledged limitation of the study is the lack of a control group of conscripts possessing normal vitamin D status and stable serum ferritin levels throughout the study period. Nevertheless, the research design employed enabled to determine two factors that potentially limit physiological adaptability of conscripts to military training loads in ecologically authentic environment.