Assessment of vitamin D concentration in non-supplemented professional athletes and healthy adults during the winter months in the UK: implications for skeletal muscle function

The relationship between serum vitamin D, bone mineral density, and injury in collegiate acrobatics and tumbling athletes

Background: Medical staff for indoor aesthetic sports such as acrobatics and tumbling (A&T) is often concerned with athletes' bone mineral density (BMD), serum vitamin D (SvD), and associated injury risks. Aim: To evaluate the relationship between BMD, SvD, and injury among A&T athletes. Methods: 42 (19 tops, 23 bases) female A&T athletes aged 19.6 (±1.17) years participated. Two samples of SvD were taken. Injury and BMD data were provided by support staff. Bivariate and multivariate analysis assessed relationships between and among variables. Results: Participants experienced a decrease in SvD (6.093 ± 10.973). Spine BMD was significantly higher in bases compared to tops (p = 0.039). BMD and SvD did not differ based on injuries sustained. Conclusion: Relationships between SvD, BMD, and injury were not identified. Positional differences in BMD may be related to the demands of each role. Participants possessed low SvD and high BMDs, which may provide useful information for medical staff.

Stay in the Game: Comprehensive Approaches to Decrease the Risk of Sports Injuries

Recurrent sports injuries present complex challenges that extend beyond the playing field, impacting athletes' physical well-being, mental resilience, and financial stability. This review outlines a comprehensive framework designed to prevent and manage these setbacks, empowering athletes to achieve sustained performance and recovery. This multidimensional issue requires an integrative approach encompassing physical rehabilitation, psychological resilience, and nutritional strategies. Physically, injury prevention relies on tailored rehabilitation programs that address athletes' specific injury histories and sport-related demands. Techniques such as biomechanical assessments and neuromuscular training correct faulty movement patterns, while workload monitoring ensures a balance between training and recovery. Strength and conditioning programs have demonstrated success in reducing injury rates and enhancing musculoskeletal resilience. Psychologically, reinjury anxiety and mental disengagement are key barriers to recovery and performance. Interventions such as goal setting, mindfulness, and cognitive restructuring rebuild confidence and foster readiness to return to play. Addressing psychological well-being is as critical as physical health in promoting sustained performance. Nutrition is equally pivotal, with balanced macronutrient intake supporting energy and tissue repair and micronutrients (magnesium, manganese, vitamin D, selenium, zinc, coenzyme Q10, etc.) bolstering bone health. Anti-inflammatory nutrients and proper hydration reduce muscle strain and aid recovery, while personalized dietary strategies meet the specific demands of individual sports. By integrating these physical, psychological, and nutritional dimensions, this framework empowers athletes, coaches, and medical teams to minimize injury recurrence and enhance long-term performance, ensuring athletes remain competitive and resilient in their sporting pursuits.

The relationships of serum vitamin D concentration with linear speed and change of direction performance in soccer players

The aim of the study was to establish whether the level of 25 hydroxyvitamin D (25(OH)D) in serum has an influence on speed (m/s) and change of direction (COD, s) performance. Twenty male soccer players from the top league participated in the study. All subjects were evaluated for the serum concentration of 25(OH)D at the beginning of the preseason. The linear sprint test was performed at 5 m and 30 m, and COD (time and deficit) at the beginning (BPP) and after (APP) 6 weeks of the preparatory period. The results revealed that 20% of soccer players had a significant deficiency of 25(OH)D (<20 ng/mL) and 30% had insufficient 25(OH)D levels (between 20 and 30 ng/mL). Positive correlations were found between the training effect for the ∆COD (BPP-APP) (p = 0.003) and ∆deficit (BPP-APP) (p = 0.039). Significant differences were noticed for the ∆COD (m = 0.60 [s]) and ∆deficit (m = 0.56[s]) in the soccer players whose 25(OH)D concentration was <=30 ng/mL, and for the ∆COD (p = 0.002) and ∆deficit (p = 0.017) in the soccer players whose 25(OH)D concentration was >30 ng/mL. The training effect was significantly higher for the soccer players whose 25(OH)D concentration was above 30 ng/mL. Soccer players with higher 25(OH)D levels achieved superior results in the COD test and demonstrated better deficit outcomes, affirming the positive influence of 25(OH)D on muscle metabolism.

Is Micronutrient Supplementation Helpful in Supporting the Immune System during Prolonged, High-Intensity Physical Training?

It is well known that during prolonged, high-intensity physical training, athletes experience a state of immunosuppression and that balanced nutrition can help maintain immunity. This review summarizes the effects (amplified by virus infection) of high-intensity, long-term exercise on immunity, critically presenting key micronutrients and supplementation strategies that can influence athletes' performance and their immune system. The main conclusion is that micronutrient supplementation with diet could help to protect the immune system from the stress effects induced by intense physical activities. The importance of personalized supplementation has been also recommended.

The Prevalence of Low Vitamin D in Elite Para-Athletes: A Systematic Review

BACKGROUND

Vitamin D insufficiency (25OHD, 50-75 nmolˑl- 1) is a common issue within healthy adults and elite athletes and is associated with decreased musculoskeletal health and performance. However, few studies have identified the prevalence and risk factors associated with vitamin D insufficiency within elite Para-Athletes.

METHODS

An electronic search was completed on the 5th January 2023 and updated on the 21st June 2024, searching Web of Science, PubMed, Scopus, Cochrane Library and EASY (originally OpenGrey). To meet the eligibility criteria, retrieved studies were required to include at least one baseline measure of a vitamin D biomarker from elite Para-Athletes performing at national or international levels and therefore all quantitative study designs could be included. Risk of bias was assessed using the Joanna Briggs Institute Critical Appraisal Checklist (8-item) for analytical cross-sectional studies. Data from the eligible studies was extracted and charted, with a supporting narrative synthesis.

RESULTS

The search strategy retrieved 3083 articles, of which ten studies met the inclusion criteria. In total there were n = 355 Para-Athletes, 69.6% of which comprised of males in the included studies. Across the ten included studies, n = 546 samples were taken from n = 355 Para-Athletes across different seasons and based upon the 25(OH)D insufficiency and deficiency thresholds set by each individual study 43.2% of the samples were considered insufficient and 28.1% deficient. During the winter months vitamin D insufficiency was at its most prevalent at 74.1%, compared to 57.1% in summer of the 25(OH)D samples measured in Para-Athletes. Wheelchair athletes who competed in indoor sports were also more susceptible to low vitamin D.

CONCLUSION

This review has highlighted that vitamin D insufficiency and deficiency is highly prevalent in elite level Para-Athletes, all year, across both summer and winter months. Therefore, this review highlights the need for education, treatment, and preventative measures in elite Para-Athletes throughout the year.

REGISTRATION

The following systematic review was prospectively registered through PROSPERO International prospective register of systematic reviews (PROSPERO registration ID number: CRD42022362149).

Effects of vitamin D3 supplementation on strength of lower and upper extremities in athletes: an updated systematic review and meta-analysis of randomized controlled trials

Background

Coaches and athletes are increasingly interested in understanding athletes' serum vitamin D levels, their impact on strength, physical performance, and athletic outcomes. Previous meta-analyses were reported with limited sample size and no significant overall effect was found. Hence, it is crucial to conduct a thorough and up-to-date systematic examination and meta-analysis to elucidate the potential advantages of supplementing with vitamin D3 in enhancing muscle strength for athletes.

Methods

We performed a thorough investigation, spanning three databases (PubMed, EBSCO, and Cochrane Library), seeking randomized controlled trials (RCTs) in all languages. These trials delved into the influence of vitamin D3 supplementation on the changes of pre- and post-intervention muscle strength in healthy athletes. Our systematic examination and meta-analysis took into account serum 25(OH)D levels exceeding 30 ng/mL as a marker of adequacy.

Results

Ten RCTs, comprising 354 athletes (185 in the vitamin D3 group and 169 in the placebo group), fulfilled the inclusion criteria. During the study, 36 athletes were lost to follow-up, leaving 318 athletes (166 in the vitamin D3 group and 152 in the placebo group) with documented complete results. In comparison with the placebo group, there is a significant increase between the changes of pre- and post-intervention serum 25(OH)D levels among athletes following a period of vitamin D3 supplementation (MD 14.76, 95% CI: 8.74 to 20.77, p < 0.0001). Overall effect of four strength measurements including handgrip, one repetition maximum Bench Press (1-RM BP), vertical jump, and quadriceps contraction was not significantly improved (SMD 0.18, 95% CI: -0.02 to 0.37, p = 0.08), but there was a significant increase in quadriceps contraction (SMD 0.57, 95% CI: 0.04 to 1.11, p = 0.04).

Conclusion

This updated meta-analysis indicates the potential benefits of vitamin D supplementation for enhancing muscle strength in athletes when analyzing its quantitatively synthesized effects. With limited available studies for the quantitative synthesis, it cannot warrant significant overall enhancements in muscle strength when athletes attain adequate serum 25(OH)D levels through supplementation.

A Diagnosis of Vitamin D Deficiency Is Associated With Increased Rates of Primary Patellar Instability and Need for Recurrent Surgical Stabilization

BACKGROUND

Vitamin D has been proven experimentally to affect musculoskeletal health. The purpose of this study was to identify the relationship between vitamin D deficiency and patellar instability.

HYPOTHESIS

Vitamin D deficiency is associated with an increased risk of experiencing primary patellar instability and recurrent patellar dislocation after primary surgical stabilization.

STUDY DESIGN

Retrospective comparative study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A 1:1 matched retrospective study of 328,011 patients diagnosed with vitamin D deficiency was performed using the PearlDiver database. Incidence of primary patellar instability was calculated according to sex and age. Rates of primary patellar instability and surgical stabilization for recurrent dislocation were calculated with sex- and age-specific stratifications. Multivariable logistic regression was used to compare the rates of primary injury and recurrent stabilization while controlling for demographics and medical comorbidities.

RESULTS

A total of 656,022 patients were analyzed. The overall 1-year incidence rate of patellar instability in patients with vitamin D deficiency was 82.6 per 100,000 person-years (95% CI, 73.2-92.9), compared with 48.5 (95% CI, 41.4-56.5) in the matched control. Women were significantly more likely to experience primary patellar instability within 1 (adjusted odds ratio [aOR] = 1.45; 95% CI, 1.12-1.88) and 2 years (aOR, 1.31; 95% CI, 1.07-1.59) of hypovitaminosis D diagnosis. Patients aged 10 to 25 years with hypovitaminosis D were at greater risk of requiring recurrent patellar stabilization for both men (aOR, 2.48; 95% CI, 1.06-5.80) and women (aOR, 1.77; 95% CI, 1.04-3.02).

CONCLUSION

Patients diagnosed with vitamin D deficiency experienced higher rates of primary patellar instability and have greater risk of requiring recurrent surgical stabilization for subsequent dislocations.

CLINICAL RELEVANCE

These results suggest that monitoring and proactively treating vitamin D deficiency in the physically active patient may lower the risk of suffering primary patellar instability or recurrence after surgical stabilization.

Dietary Intake of Soccer Players before, during and after an Official Game: Influence of Competition Level and Playing Position

Physical demands in soccer differ according to league level and playing position and may influence nutritional requirements. This study examined the effect of competition level and playing position on dietary intake in male soccer players (SP). Diet was weighed and recorded by 123 SP for 3 days; before, on the day, and the day after an official match. SP in the Super League (SL, n = 33) division reported higher (p < 0.05) average three-day energy (195 ± 36 kJ/kg), carbohydrate (6.0 ± 1.1 g/kg), and protein (2.2 ± 0.5 g/kg) intakes compared to the intakes reported by SP in the 2nd (n = 30) (energy: 159 ± 31 kJ/kg; carbohydrate: 4.6 ± 1.2 g/kg; protein: 1.9 ± 0.4 g/kg), 3rd (n = 30) (energy: 153 ± 34 kJ/kg; carbohydrate: 4.5 ± 1.2 g/kg; protein: 1.7 ± 0.4 g/kg), and 4th (n = 30) (energy: 152 ± 36 kJ/kg; carbohydrate: 4.2 ± 1.2 g/kg; protein: 1.7 ± 0.5 g/kg) national leagues (mean ± SD). Furthermore, when data were analyzed by playing position (pooled data), wide midfielders reported higher (p < 0.05) energy (183 ± 33 kJ/kg), carbohydrate (5.4 ± 1.2 g/kg), and fat (1.5 ± 0.4 g/kg) intakes compared to central defenders (energy: 147 ± 37 kJ/kg; carbohydrate: 4.1 ± 1.1 g/kg; fat: 1.2 ± 0.4 g/kg). The dietary intake of SP may differ according to the playing position and competition level, possibly due to different metabolic demands in training and competition.

Effects of Vitamin D Supplementation in Elite Athletes: A Systematic Review

Background

Deficiency in vitamin D has been shown to increase the risk of injury.

Purpose

To synthesize current placebo-controlled randomized trials investigating the effect of vitamin D supplementation in elite athletes on (1) aerobic capacity; (2) anaerobic measures, such as strength, speed, and anaerobic power; (3) serum biomarkers of inflammation; and (4) bone health.

Study Design

Systematic review; Level of evidence, 1.

Methods

A literature search was conducted on November 30, 2022, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Included were randomized, placebo-controlled studies of longer than 2 weeks on subjects with active participation in organized sport. Excluded were nonrandomized controlled trial study designs, vitamin D administration routes other than oral, studies that did not use vitamin D supplementation as the sole intervention, and studies with nonathletic or military populations.

Results

Out of 2331 initial studies, 14 studies (482 athletes) were included. Of the 3 studies that assessed aerobic capacity, 2 demonstrated significantly greater improvements in maximal oxygen uptake and physical working capacity-170 (P < .05) in supplemented versus nonsupplemented athletes. Measurements of anaerobic power and strength were consistently increased in supplemented groups compared with nonsupplemented groups in 5 out of the 7 studies that assessed this. Of the 6 studies that assessed sprint speed, 4 found no significant difference between supplemented and nonsupplemented groups. Aside from 1 study that found significantly lower interleukin-6 levels in supplemented athletes, measures of other inflammatory cytokines were not affected consistently by supplementation. The 4 studies that assessed markers of bone health were conflicting regarding benefits of supplementation. One study found demonstrated improvements in bone mineral density in response to supplementation (P = .02) compared with control whereas another found no significant difference between supplemented and nonsupplemented groups. However, in 3 other studies, serum biomarkers of bone turnover such as bone-specific alkaline phosphatase, parathyroid hormone, and N-terminal telopeptide appeared to be higher in subjects with lower serum vitamin D levels (P < .05).

Conclusion

Results of this systematic review indicated that the greatest benefit of vitamin D supplementation in elite athletes may be improving aerobic endurance, anaerobic power, and strength. More research is needed to determine the effect of vitamin D supplementation on bone health and injury risk in this population.

Effect of vitamin D3 supplementation in winter on physical performance of university students: a one-month randomized controlled trial

BACKGROUND

There is epidemiological evidence which suggests an association between 25-hydroxyvitamin D [25(OH)D] levels and bone and muscle function; however, it is unclear whether vitamin D supplementation has an added benefit beyond bone health. Here, we investigated the effects of vitamin D3 supplementation (1 month) on physical performance in Chinese university students in winter.

METHODS

One hundred and seventeen eligible subjects with 25(OH)D (19.2 ± 7.8 ng/mL) were randomly assigned to either vitamin D3 supplement (N = 56; 1000 IU/day) or the control (N = 61) group for 1 month. Pre- and post-measurements included: 1) serum levels of 25(OH)D; 2) musculoskeletal and pulmonary function [vertical jump height (VJH) and right handgrip strength (RHS), forced vital capacity (FVC), and forced expiratory volume at 1s (FEV1)]; 3) bone turnover markers [parathyroid hormone (PTH), n-terminal osteocalcin (N-MID), and calcium]; 4) hemoglobin-related parameters [hemoglobin (Hb), hematocrit (HCT), red blood cells (RBC), and red cell distribution width (RDW)]; 5) lipid parameters [total triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C)]; 6) Fatigue-related indicators [serum creatine kinase (CK), lactate dehydrogenase (LDH), and total testosterone (T)]. In addition, aerobic capacity was assessed by measuring maximal oxygen uptake (VO2max) at baseline.

RESULTS

During wintertime, supplementation with 1000 IU/d of vitamin D3 significantly increased serum 25(OH)D levels (from 18.85 ± 7.04 to 26.98 ± 5.88 ng/mL, p < 0.05), accompanied by a decrease of PTH (p < 0.05). However, vitamin D3 supplementation did not significantly impact the physical performance, serum lipid parameters, and bone turnover markers of students. Furthermore, 25(OH)D was found to be positively correlated with VJH and negatively correlated with PTH and TC at the beginning and end of the study (p < 0.05). In addition, the multiple linear regression analysis showed that 25(OH)D combined with athletic, gender, height, weight, Hb, and FVC could account for 84.0% of the VO2max value.

CONCLUSIONS

The study demonstrated that one-month of 1000 IU/d of vitamin D3 supplementation during the winter had beneficial effects on 25(OH)D status and PTH. However, vitamin D3 intervention was not sufficient to improve physical performance. Furthermore, 25(OH)D levels combined with athletic, Hb and FVC could be a predictor of VO2max.

A Diagnosis of Vitamin D Deficiency Is Associated With Increased Rates of Anterior Cruciate Ligament Tears and Reconstruction Failure

PURPOSE

To characterize the association between a diagnosis of hypovitaminosis D and primary anterior cruciate ligament (ACL) tear, primary anterior cruciate ligament reconstruction (ACLR), and revision ACLR in different sex and age cohorts.

METHODS

In this retrospective cohort study of the PearlDiver claims database, records were queried between January 1, 2011, and October 31, 2018 for all patients aged 10 to 59 years who received a diagnosis of hypovitaminosis D. Rates of primary ACL tears, primary reconstruction, and revision reconstruction were calculated for sex- and age-specific cohorts and compared with a control of patients without a diagnosis of hypovitaminosis D. Incidence rates for primary ACL injuries were calculated, and multivariable logistic regression was used to compare rates of ACL injury, primary reconstruction, and revision reconstruction while controlling for age, sex, Charlson Comorbidity Index, and several other comorbidities.

RESULTS

Among the 328,011 patients (mean age 41.9 ± 12.6 years, 65.8% female) included in both the hypovitaminosis D and control cohorts, the incidence of ACL tears was 115.2 per 100,000 person-years (95% confidence interval [CI] 107.2-123.7) compared with 61.0 (95% CI 55.2-67.2) in the demographic- and comorbidity-matched control cohort. The study cohort was significantly more likely to suffer an ACL tear over a 1- (aOR 1.67, 95% CI 1.41-1.99, P < .001) and 2-year (aOR 1.81, 95% CI 1.59-2.06, P < .001) period. This trend remained for both male patients at the 1- (aOR 1.66, 95% CI 1.29-2.14, P < .001) and 2-year (aOR 1.68, 95% CI 1.37-2.06, P < .001) mark and female patients at the 1- (aOR 1.69, 95% CI 1.33-2.14, P < .001) and 2-year (aOR 1.80, 95% CI 1.51-2.14, P < .001) mark. Finally, patients with vitamin D deficiency had a significantly increased likelihood of undergoing a revision ACLR within 2 years of a primary reconstruction (aOR 1.28, 95% CI 1.05-1.55, P = .012).

CONCLUSIONS

This study reports an association between patients previously diagnosed with hypovitaminosis D and significantly increased rates of both index ACL tears (81% increase within 2 years of diagnosis) and revision ACLR (28% within 2 years). These results identify a population with increased odds of injury and provide valuable knowledge as we expand our understanding of the relationship between vitamin D and musculoskeletal health.

LEVEL OF EVIDENCE

Level III, retrospective database study.

Considerations for the Consumption of Vitamin and Mineral Supplements in Athlete Populations

Vitamins and minerals are of fundamental importance to numerous human functions that are essential to optimise athlete performance. Athletes incur a high turnover of key vitamins and minerals and are therefore dependent on sufficient energy intake to replenish nutrient stores. However, many athletes are poor at servicing their energy replenishment needs, especially female athletes, and although a 'food first approach' to meeting nutrient requirements is the primary goal, it may be important for some athletes to consider a vitamin and/or mineral supplement to meet their daily needs. When working to determine if an athlete requires vitamin or mineral supplements, practitioners should use a robust framework to assess the overall energy requirements, current dietary practices and the biological and clinical status of their athletes. Of note, any supplementation plan should account for the various factors that may impact the efficacy of the approach (e.g. athlete sex, the nutrient recommended dietary intake, supplement dose/timing, co-consumption of other foods and any food-drug interactions). Importantly, there are numerous vitamins and minerals of key importance to athletes, each having specific relevance to certain situations (e.g. iron and B vitamins are significant contributors to haematological adaptation, calcium and vitamin D are important to bone health and folate is important in the female athlete); therefore, the appropriate supplement for a given situation should be carefully considered and consumed with the goal to augment an athlete's diet.

Vitamin D deficiency contributes to overtraining syndrome in excessive trained C57BL/6 mice

Overtraining syndrome is a condition resulting from excessive training load associated with inadequate recovery and poor sleep quality, leading to performance decrements and fatigue. Here we hypothesized that vitamin D (VitD) deficiency is a lead factor in the development of the overtraining syndrome. To test this hypothesis, two groups of 60-week-old C57BL/6 mice followed a 16-week excessive eccentric-based overtraining by excessive downhill running with or without dietary VitD depletion (EX and EX-D- groups). Two control groups were trained by uphill running at the same load with or without VitD depletion (CX and CX-D- groups). Handgrip strength decreased throughout the protocol for all groups but the decrease was sharper in EX-D- group (VitD × training, p = 0.0427). At the end of the protocol, the mass of Triceps brachii muscle, which is heavily stressed by eccentric contractions, was reduced in eccentric-trained groups (training effect, p = 0.0107). This atrophy was associated with a lower concentration of the anabolic myokine IL-15 (training effect, p = 0.0314) and a tendency to a higher expression of the atrogene cathepsin-L (training effect, p = 0.0628). VitD depletion led to a 50% decrease of the fractional protein synthesis rate in this muscle (VitD effect, p = 0.0004) as well as decreased FGF21 (VitD effect, p = 0.0351) and increased osteocrin (VitD effect, p = 0.038) concentrations that would lead to metabolic defects. Moreover, the proportion of anti-inflammatory Th2 lymphocytes was significantly decreased by the combination of eccentric training with VitD depletion (vitD × training, p = 0.0249) suggesting a systemic inflammation. Finally, exploratory behavior time of mice was decreased by VitD depletion (VitD effect, p = 0.0146) suggesting a cognitive dysfunction. Our results suggest that VitD deficiency exacerbates the effects of overtraining.

Effects of vitamin D supplementation on maximal strength and power in athletes: a systematic review and meta-analysis of randomized controlled trials

Background

Vitamin D is thought to be a powerful modulator of skeletal muscle physiology. However, available data on the effects of vitamin D supplementation on muscle function in athletes are limited and with mixed results. This meta-analysis therefore, aimed to quantitatively summarize the up-to-date literature assessing the effects of vitamin D supplementation on muscle strength and power in athletes.

Methods

Sport Discus, PubMed, Cochrane Library and Web of Science were searched to identify randomized controlled trials (RCTs) that used one-repetition maximum (1RM) tests to assess maximal strength, and vertical jump to assess muscle power in athletes. The Cochrane Risk of Bias tool was used to evaluate the included RCTs for sources of bias. The standardized mean difference (SMD) was used as the effect size, interpreted together with its 95% confidence intervals (CI). The effect sizes were calculated on the changes from baseline between vitamin D and placebo groups for maximal strength results by upper body and lower body, and for power results.

Results

Eleven RCTs involving 436 athletes were included. The results indicated that if baseline serum 25(OH)D concentration was < 75 nmol/L, the treatment had a small effect on upper body muscle strength [SMD 0.25, 95% CI: (-0.44, 0.95), p = 0.47] and on lower body muscle strength [SMD 0.26, 95% CI: (-0.13, 0.65), p = 0.19]; if the baseline serum 25(OH)D concentration was ≥ 75 nmol/L, the treatment had a trivial effect on muscle power [SMD 0.15, 95% CI: (-0.42, 0.72), p = 0.61].

Discussion

This meta-analysis demonstrated that there is not a statistically significant effect of vitamin D supplementation on improving maximum strength and power, but highlights that further research is required addressing the key limitations in previous studies before definitive conclusions can be made.

Seasonal variations in vitamin D do not change the musculoskeletal health of physically active ambulatory men with cerebral palsy: a longitudinal cross-sectional comparison study

Increased levels of vitamin D in the summer months from natural seasonal variations in sun exposure have been linked to improvements in musculoskeletal health and function in UK populations; however, studies have shown that differences in lifestyles because of disability can inhibit the natural vitamin D increase in these populations. We hypothesized that men with cerebral palsy (CP) will experience smaller increases in 25-hydroxyvitamin D (25(OH)D) from winter to summer and men with CP will not experience any improvements in musculoskeletal health and function during the summer. A longitudinal observational study in 16 ambulant men with CP aged 21.0 ± 1.3 years and 16 healthy, physical activity matched, typically developed controls aged 25.4 ± 2.6 years, completed assessments of serum 25(OH)D and parathyroid hormone during winter and summer. Neuromuscular outcomes included vastus lateralis size, knee extensor strength, 10-m sprint, vertical jumps, and grip strength. Bone ultrasounds were performed to obtain radius and tibia T and Z scores. Men with CP and typically developed controls showed a 70.5% and 85.7% increase in serum 25(OH)D from winter to summer months, respectively. Neither group showed seasonal effect on neuromuscular outcomes muscle strength, size, vertical jump, or tibia and radius T and Z scores. A seasonal interaction effect was seen in the tibia T and Z scores (P < .05). In conclusion, there were similar seasonal increases in 25(OH)D observed in men with CP and typically developed controls, but serum 25(OH)D levels were still considered insufficient to improve bone or neuromuscular outcomes.

Do Adolescent Idiopathic Scoliosis Patients With Vitamin D Deficiency Have Worse Spine Fusion Outcomes?

BACKGROUND

Prior research has shown that patients with adolescent idiopathic scoliosis (AIS) have a higher prevalence of vitamin D deficiency compared with healthy peers. In adult orthopaedic populations, vitamin D deficiency has been shown to be a risk factor for higher reported pain and lower function. We investigated whether there was an association between vitamin D levels and AIS patient-reported outcomes, as measured by the Scoliosis Research Society (SRS-30) questionnaire.

METHODS

This was a single-center, cross-sectional study. Postoperative AIS patients were prospectively recruited during routine follow-up visits, 2 to 10 years after spine fusion. Vitamin D levels were measured by serum 25-hydroxyvitamin D (ng/mL). Patients were categorized based on vitamin D level: deficient (<20 ng/mL), insufficient (20 to 29 ng/mL), or sufficient (≥30 ng/mL). The correlation between vitamin D levels and SRS-30 scores was analyzed using multivariable analysis and pair-wise comparisons using Tukey method.

RESULTS

Eighty-seven AIS patients (83% female) were enrolled who presented at median 3 years (interquartile range: 2 to 5 y; range: 2 to 10 y) after spine fusion. Age at time of surgery was mean 15 (SD±2) years. Major coronal curves were a mean of 57 (SD±8) degrees preoperatively and 18 (SD±7) degrees postoperatively. It was found that 30 (34%) of patients were vitamin D sufficient, 33 (38%) were insufficient, and 24 (28%) were deficient. Although there was no correlation between vitamin D level and Pain, Mental Health, or Satisfaction domains ( P >0.05), vitamin D-deficient patients were found to be younger ( P <0.001) and had lower SRS-30 function ( P =0.002), Self-image ( P <0.001), and total scores ( P =0.003).

CONCLUSIONS

AIS patients with vitamin D deficiency (<20 ng/mL) are more likely to be younger age at time of surgery, and report lower Function, Self-image, and Total SRS-30 scores postoperatively. Further work is needed to determine whether vitamin D supplementation alters curve progression and patient outcomes.

LEVEL OF EVIDENCE

Level II-prognostic study.

Alternations of vitamin D and cognitive function in first-diagnosed and drug-naïve BD patients: Physical activity as a moderator

BACKGROUND

The pathophysiological mechanism of cognitive impairments of bipolar disorder (BD) has not yet been completely revealed. It is well known that Vitamin D and physical activity (PA) are associated with BD. However, specific links between Vitamin D and cognitive deficits in BD are still unclear.

METHOD

The serum levels of vitamin D were measured. The cognitive performances of 102 first-diagnosed and drug-naïve BD patients were evaluated for analysis. The repeatable battery for the assessment of neuropsychological status (RBANS) and the Stroop Color-Word test was used in this study. PA was collected by international physical activity questionnaire.

RESULT

Patients with BD had high levels of serum vitamin D. Furthermore, immediate and delayed memory was negatively associated with vitamin D levels in patients' group. The serum levels of vitamin D in patients with low PA were positively associated with memory. However, increased PA attenuated the protective effect of vitamin D on executive cognition.

CONCLUSION

It is concluded that the increased levels of vitamin D were observed in the serum of patients with BD. Thus, it is found that more PA is less beneficial to cognition of patients with BD than longer resting.

Nutrition Recommendations for Table Tennis Players-A Narrative Review

Table tennis (TT) is the second most popular racket sport globally and was the sixth most widely played Olympic sport in 2005. It is an indoor racket sport requiring a mixture of power, agility, alertness and fast reactions. Players need to move quickly around a table to receive the ball and produce powerful returns. New rules such as increased ball size and a change in ball material have changed the ball's trajectory, increasing the overall duration and intensity of game play. Scientific research on TT is growing but there has been no systematic review of nutrition for the sport. This review provides nutritional recommendations for TT athletes based on the physiological demands of TT, including energy expenditure during training and competitions, and the main metabolic pathways of TT. Guidelines on the daily intakes of carbohydrate, protein and fat are discussed in addition to hydration strategies. Micronutrients of concern for TT athletes include iron, magnesium and vitamin D and their recommended intakes are also provided. The timing and dose of ergogenic aids that may improve TT performance such as caffeine, creatine, lutein and zeaxanthin and beta-alanine are reviewed. Specific nutritional strategies for intakes leading up to competitions, post training and competition recovery and nutritional strategies for travel are also addressed.

Vitamin D Fortification and Its Effect on Athletes' Physical Improvement: A Mini Review

Poor vitamin D status is a widespread problem regardless of age and sex, emphasizing the necessity of new food sources to improve vitamin D levels. Currently, approximately 60% of dietary vitamin D consumption occurs via fortified foods. Vitamin D insufficiency (50-90%) is widespread according to age and region, despite different levels of sunlight exposure. The food industry must identify more effective strategies to increase normal dietary vitamin D intake and improve overall health. Strategies for vitamin D fortification include bioaddition, wherein a vitamin D-rich food source is added to staple foods during processes. These bioadditive strategies expand the range of vitamin D-containing foods and appeal to different preferences, cultures, and economic statuses. In several countries, vitamin D deficiency places athletes at a high risk of disease susceptibility. Due to low sun exposure, athletes in countries with higher and lower levels of sunlight have similar risks of vitamin D deficiency. In this review, we summarize recent technical advances to promote vitamin D utilization by humans during sports activities and in relation to the normal practices of athletes.

Vitamin D, exercise, and immune health in athletes: A narrative review

Vitamin D exerts important extra-skeletal effects, exhibiting an exquisite immune regulatory ability, affecting both innate and adaptive immune responses through the modulation of immunocyte function and signaling. Remarkably, the immune function of working skeletal muscle, which is fully recognized to behave as a secretory organ with immune capacity, is under the tight control of vitamin D as well. Vitamin D status, meaning hormone sufficiency or insufficiency, can push toward strengthening/stabilization or decline of immune surveillance, with important consequences for health. This aspect is particularly relevant when considering the athletic population: while exercising is, nowadays, the recommended approach to maintain health and counteract inflammatory processes, “too much” exercise, often experienced by athletes, can increase inflammation, decrease immune surveillance, and expose them to a higher risk of diseases. When overexercise intersects with hypovitaminosis D, the overall effects on the immune system might converge into immune depression and higher vulnerability to diseases. This paper aims to provide an overview of how vitamin D shapes human immune responses, acting on the immune system and skeletal muscle cells; some aspects of exercise-related immune modifications are addressed, focusing on athletes. The crossroad where vitamin D and exercise meet can profile whole-body immune response and health.

Dietary Supplement Use of Turkish Footballers: Differences by Sex and Competition Level

This study aimed to evaluate the consumption of dietary supplements (DS) and to determine related topics in Turkish football players of different sexes and competition levels. A total of 117 footballers (79 males and 38 females) completed a specific survey regarding DS consumption in athletes. The type of DS ingested was classified based on the level of scientific evidence by the Australian Institute of Sport (AIS): group A (high level of scientific evidence), group B (DS that could have a positive effect, but require more evidence), group C (evidence is against their use), and group D (prohibited substances). After a Kolmogorov−Smirnov test, a t-test or Mann−Whitney U test was performed for quantitative variables, while Pearson’s chi-square and odds ratio (with the confidence interval) were performed for qualitative variables. Of the sample, 87.2% reported having consumed DS, with a higher consumption rate in males (males: 93.7%, females: 73.7%; p = 0.006; OR = 5.3 [1.7−16.8]) and professional players (professional: 98.2%, non-professional: 77.4%; p < 0.001; OR = 7.9 [1.2−52.3]). Males and professional players consume more sports foods (p < 0.001), performance supplements (p < 0.001), and total group A supplements (p < 0.001) compared to females and non-professionals. In addition, males consume more medical supplements (p = 0.012) and total group C supplements (p < 0.001) than female footballers. The most consumed DS were sports drinks (63.2%), magnesium (52.1%), vitamin C (51.3%), vitamin D (46.2%), caffeine (38.5%), sports bars (37.6%), whey protein (28.2%), meat protein (25.6%), vitamin E (24.8%), and omega-3 fatty acids (24.8%). The supplement consumption was higher in male and professional footballers. According to the AIS classification, there were significant differences in the consumption of sports foods, medical supplements, performance supplements, and the total number of group A and group C supplements according to sex, and there were significant differences in the consumption of sports foods, performance supplements, and the total number of group A supplements according to competition level.

Association between Blood Vitamin D Levels and Regular Physical Activity in Korean Adolescents

This study aimed to investigate the relationship between vitamin D levels and physical activity in adolescents using data from the Korea National Health and Nutrition Survey (KNHANES). The serum vitamin D concentrations were measured between 2008 and 2014 and analyzed. Adolescents aged 13 to 18 years comprised 4527 of the 61,370 participants surveyed. A final dataset including 2811 adolescents was obtained after those with missing data were excluded. Those who did not participate or only participated in 1−3 days of intense physical activity (p < 0.001), moderate physical activity (p = 0.002), and muscular exercise (weight training) (p < 0.001) showed a higher level of vitamin D deficiency than those who performed the same activities 4−7 days per week. Our results showed that most of the adolescents (76%) were vitamin D-deficient, and the risk was higher among high school than middle school students (odds ratio (OR) = 1.70, 95% confidence interval (CI) = 1.40−2.06; p < 0.001) and higher in girls than boys (OR = 1.43, 95% CI = 1.18−1.72; p < 0.001). Reduced participation in physical activity was correlated with vitamin D deficiency. Furthermore, vitamin D deficiency was associated with a lower frequency of participation in all forms of physical activity, and the association increased significantly with an increase in body mass index.

Influences of Vitamin D and Iron Status on Skeletal Muscle Health: A Narrative Review

There is conflicting evidence of the roles vitamin D and iron have in isolation and combined in relation to muscle health. The purpose of this narrative review was to examine the current literature on the roles that vitamin D and iron have on skeletal muscle mass, strength, and function and how these nutrients are associated with skeletal muscle health in specific populations. Secondary purposes include exploring if low vitamin D and iron status are interrelated with skeletal muscle health and chronic inflammation and reviewing the influence of animal-source foods rich in these nutrients on health and performance. PubMed, Scopus, SPORT Discus, EMBAE, MEDLINE, and Google Scholar databases were searched to determine eligible studies. There was a positive effect of vitamin D on muscle mass, particularly in older adults. There was a positive effect of iron on aerobic and anaerobic performance. Studies reported mixed results for both vitamin D and iron on muscle strength and function. While vitamin D and iron deficiency commonly occur in combination, few studies examined effects on skeletal muscle health and inflammation. Isolated nutrients such as iron and vitamin D may have positive outcomes; however, nutrients within food sources may be most effective in improving skeletal muscle health.

The Vitamin D/Vitamin D receptor (VDR) axis in muscle atrophy and sarcopenia

Muscle atrophy and sarcopenia (the term given to the age-related decline in muscle mass and function), influence an individuals risk of falls, frailty, functional decline, and, ultimately, impaired quality of life. Vitamin D deficiency (low serum levels of 25-hydroxyvitamin D (25(OH)D₃)) has been reported to impair muscle strength and increase risk of sarcopenia. The mechanisms that underpin the link between low 25(OH)D₃ and sarcopenia are yet to be fully understood but several lines of evidence have highlighted the importance of both genomic and non-genomic effects of active vitamin D (1,25-dihydroxyvitamin D (1,25(OH)₂D₃)) and its nuclear vitamin D receptor (VDR), in skeletal muscle functioning. Studies in vitro have demonstrated a key role for the vitamin D/VDR axis in regulating biological processes central to sarcopenic muscle atrophy, such as proteolysis, mitochondrial function, cellular senescence, and adiposity. The aim of this review is to provide a mechanistic overview of the proposed mechanisms for the vitamin D/VDR axis in sarcopenic muscle atrophy.

Correlation between the Positive Effect of Vitamin D Supplementation and Physical Performance in Young Male Soccer Players

The aim of this study was to determine whether supplementation with vitamin D during eight weeks of high-intensity training influences muscle power and aerobic performance in young soccer players. A total of 25 athletes were divided into two groups: the supplemented group (GS; n = 12; vitamin D 20,000 IU, twice a week) and the non-supplemented group (GN; n = 13). A set of measurements, including sprint tests, explosive power test, maximal oxygen uptake (VO2max), and serum 25(OH)D concentration, were obtained before (T1) and after (T2) the intervention. A significant group x time interaction was found in the 25(OH)D serum levels (p = 0.002; ES = 0.36, large). A significant improvement in VO2max was found in the TG (p = 0.0004) and the GS (p = 0.031). Moreover, a positive correlation between 25(OH)D and VO2max (R = 0.4192, p = 0.0024) was calculated. The explosive power tests revealed insignificant time interactions in the average 10-jump height and average 10-jump power (p = 0.07, ES = 0.13; p = 0.10, ES = 0.11, respectively). A statistically insignificant trend was observed only in the group-by-time interaction for the sprint of 10 m (p = 0.05; ES = 0.15, large). The present study provides evidence that vitamin D supplementation has a positive but trivial impact on the explosive power and locomotor skills of young soccer players, but could significantly affect their aerobic performance.

Elastic resistance training is more effective than vitamin D3 supplementation in reducing oxidative stress and strengthen antioxidant enzymes in healthy men

OBJECTIVE

Today, reducing oxidative stress and improving the antioxidant system with antioxidant supplements along with exercise training has received a lot of attention. Vitamin D plays a very important role in general health and reducing oxidative stress. The aim of this study was to examine the effect of vitamin D3 supplements during elastic-band resistance training (EBT) on oxidative stress and antioxidant indices in healthy men.

METHODS

Forty healthy men (Serum: 20 ≤ 25 (OH) D ≤ 25 ng/mL) voluntarily participated in the current study and randomly were assigned to EBT-vitamin D3 (ED, n = 10), EBT-placebo (EP, n = 10), vitamin D3 (VD, n = 10), and control (Con, n = 10). EBT was performed three times per week on non-consecutive days for eight weeks, in seven exercises. The subjects in the ED, VD, and EP consumed 50,000 IU vitamin D3 or placebo once every 2 weeks. Ten ccs blood samples were collected before and after exercise training and the total antioxidant capacity (TAC), superoxide dismutase (SOD), glutathione peroxidase (GPX), and creatine kinase (CK) activities were measured in the plasma. Malondialdehyde (MDA), as the lipid peroxidation index, and 25(OH) D were measured in the plasma.

RESULTS

We found that there was a significant difference between ED with VD (p = 0.011) and Con (p = 0.022) for MDA. A significant difference was also seen for SOD in ED with VD (p = 0.024) and Con (p = 0.038) and TAC in ED with VD (p = 0.020) and Con (p = 0.030), and GPX in ED with VD (p = 0.040) and Con (p = 0.010). While there were no significant differences between ED and EP in all mentioned variables (p > 0.05).

CONCLUSION

Finally, it can be said that elastic resistance training improved antioxidant defence. However, vitamin D3 supplementation during resistance elastic training has no synergistic effect on attenuating oxidative stress indices.

Vitamin D levels on sports injuries in outdoor and indoor athletes: a cross-sectional study

OBJECTIVE

Having vitamin D levels within normal limits is important for bone and muscle health and its deficiency may increase the risk of injury. The aim of this cross-sectional study was to investigate whether vitamin D levels are different in indoor and outdoor athletes and its levels increase the risk of injury.

MATERIAL AND METHODS

Serum vitamin D levels were measured in Caucasian adolescent athletes, who admitted to the sports medicine polyclinic due to a routine health check or injury. The study was carried out at 38°26' north latitude in İzmir between June and September 2019. After the physical examination of the injured athletes, the diagnoses were made accompanied by the findings obtained by imaging methods in cases of necessity.

RESULTS

A total of 256 athletes, including swimmers (n = 87), basketball players (n = 104), and football (n = 65) players aged 13.2 (± 2.2) years, were investigated. The average serum vitamin D (25(OH)D) level in athletes was 29.2 (±10.0) ng/mL (6.0-66.0 ng/mL). Forty-six of all athletes (18%) had vitamin D deficiency, with a mean value of 15.7 (±4.0) ng/mL, and 93 of them (36.3%) had vitamin D deficiency with a mean value of 25.2 (±2.4) ng/mL. While vitamin D levels were significantly higher in football players (32 ng/mL) than in other athletes (p < 0.05), it was similar in basketball players (27 ng/mL) and swimmers (26 ng/mL) (p > 0.05). Vitamin D levels (26 ng/mL) of the injured athletes were significantly lower than those of the non-injured athletes (30 ng/mL) (p = 0.001). Bone injuries were significantly related to Vitamin D levels (p < 0.001) but not with muscle injuries (p > 0.05).

CONCLUSION

Frequency of vitamin D deficiency and insufficiency is higher in indoor athletes andis especially associated with risk of bone injuries . In order to examine the effect of vitamin D level on bone mineral density, comprehensive prospective studies are required.

Supplementation and Performance for Wheelchair Athletes: A Systematic Review

This systematic review aimed to identify nutritional interventions and supplements that improve the performance for wheelchair athletes. Intervention trials involving high-performance wheelchair athletes were analyzed, including those that comprised a nutritional intervention, defined as any intervention related to food, beverages, and supplementation aiming at evaluating the performance of wheelchair athletes. Of the included studies, four evaluated caffeine supplementation, of which one also evaluated sodium citrate supplementation; two studies evaluated vitamin D supplementation; one study assessed creatine monohydrate supplementation; and one assessed carbohydrate supplementation. Most studies were conducted on athletes with spinal cord injury. Athletes who consumed caffeine exhibited an improvement in performance, but this finding is not strong enough to become a recommendation.

Resting Metabolic Rate in Women with Endocrine and Osteoporotic Disorders in Relation to Nutritional Status, Diet and 25(OH)D Concentration

There are speculations that vitamin D may be an important regulator of the energy metabolism. The aim of this study was to evaluate the influence of serum 25(OH)D concentration and nutritional status on the resting metabolic rate. The study group consisted of 223 women with endocrine and/or osteoporotic disorders. The control group consisted of 108 women, clinically healthy. The total 25(OH)D concentration level was measured with an assay using chemiluminescent immunoassay technology. Indirect calorimetry was applied to assess the resting metabolic rate. The mean resting metabolic rate was significantly lower in the group of women with metabolic disorders than in the control group. A correlation was found between serum 25(OH)D levels in healthy subjects and the resting metabolic rate. Significantly higher resting metabolic rate was found in women with normal serum 25(OH)D levels in comparison to subjects with deficient vitamin D levels. The control group demonstrated a relationship between body fat tissue and fat-free body mass and the resting metabolic rate. Both 25(OH)D concentration and body composition were factors influencing the resting metabolic rate in the group of healthy subjects. More research is needed to clarify the relationship between vitamin D status and metabolic rate in individuals with endocrine and osteoporotic disorders.

Evaluation of a Vitamin D Screening and Treatment Protocol Using a Seasonal Calculator in Athletes

ABSTRACT

Vitamin D is important in musculoskeletal health, and low serum vitamin D concentration is common in athletes. This study implemented a vitamin D screening and supplementation protocol in a cohort of National Collegiate Athletic Association Division I athletes using summer 25-hydroxyvitamin D concentration and a seasonal variation calculator to achieve sufficient vitamin D concentration year-round. After implementation of the Vitamin D Protocol, there was a nonsignificant difference in athletes with sufficient winter vitamin D concentrations (72.6%) compared with summer vitamin D concentrations (66.1%) (P = 0.40). The Seasonal Variation Calculator predicted winter vitamin D concentrations (8 ± 18 ng·mL-1) higher than actual winter vitamin D concentrations (P < 0.01). While most athletes (78%) believed vitamin D was important for athletic performance, athlete compliance to the Vitamin D Protocol was inconsistent. In the future, adjustment of vitamin D screening and supplementation protocols may help athletes achieve sufficient vitamin D status year-round.

Effects of Vitamin D in Post-Exercise Muscle Recovery. A Systematic Review and Meta-Analysis

Vitamin D is a key micronutrient modulating function and health in skeletal muscle. Therefore, we sought to systematically review the role of vitamin D in muscle recovery. A search in different databases (PubMed/MEDLINE, WOS, Google Scholar, and Scopus) was carried out following PRISMA^® and PICOS. The search period was from inception to April 2020. Changes in post-exercise muscle damage were quantified comparing experimental group vs. placebo in each study by using number of participants, standardized mean difference (SMD), and standard error of the SMD. Hedges’s g was used to calculate the SMDs for each study group and biased by the inverse of variance that allows calculating an overall effect and the 95% confidence interval (CI). The net vitamin D supplementation effect was calculated by subtracting the placebo SMD from SMD of the experimental group. The DerSimonian and Laird method was used as a random effect model, taking into account that the effect of vitamin D on muscular damage may vary according to the dose administered and additional moderators. Six studies were selected. In conclusion, regarding circulating levels of muscle biomarkers and additional limitations of the studies, it cannot be concluded that vitamin D supplementation exerts an effect in post-exercise muscle recovery. Likely, the anti-inflammatory action of vitamin D is quicker than the recovery of tissue structure and function. This aspect is pending verification in future research.

Vitamin D Awareness and Intake in Collegiate Athletes

ABSTRACT

Leitch, BA, Wilson, PB, Ufholz, KE, Roemmich, JN, Orysiak, J, Walch, TJ, Short, SE, and Fitzgerald, JS. Vitamin D awareness and intake in collegiate athletes. J Strength Cond Res 35(10): 2742-2748, 2021-Poor vitamin D status is a risk factor for negative health and performance outcomes in athletes, but little is known about how athletes' awareness and beliefs about vitamin D affect their consumption of vitamin D. This observational study investigated awareness of vitamin D for health and performance among collegiate athletes and evaluated the association of vitamin D awareness with its dietary intake. Fifty-two female and 29 male Division I collegiate athletes completed an online vitamin D awareness and dietary intake questionnaire between November 1, 2015, and January 30, 2016. Median intake of vitamin D was 330 International Units (IU), which is below the recommended daily allowance (RDA) of 600 IU, but was greater in male athletes (693 IU) than female athletes (263 IU, p < 0.01). The RDA for vitamin D was met by 62% of men and 30% of women. Athletes responded that vitamin D "probably" or "definitely" will play a role in their health (88.9%) and athletic performance (71.6%). However, only 23.4 and 28.4% of athletes reported concern for their vitamin D levels or believed that they were at risk for deficiency, respectively. Results showed small-to-moderate, positive correlations (r = 0.28-0.495, p < 0.05) between aspects of vitamin D awareness and vitamin D intake, particularly with supplemental forms of vitamin D. Given the lack of awareness concerning risk of vitamin D deficiency, and the links between aspects of vitamin D awareness and vitamin D intake, nutritional education programs designed to increase vitamin D awareness in athletes may be an effective strategy to reduce deficiency.

Manipulation of Dietary Intake on Changes in Circulating Testosterone Concentrations

Elevations in the circulating concentration of androgens are thought to have a positive effect on the anabolic processes leading to improved athletic performance. Anabolic-androgenic steroids have often been used by competitive athletes to augment this effect. Although there has been concerted effort on examining how manipulating training variables (e.g., intensity and volume of training) can influence the androgen response to exercise, there has been much less effort directed at understanding how changes in both macronutrient and micronutrient intake can impact the androgen response. Thus, the focus of this review is to examine the effect that manipulating energy and nutrient intake has on circulating concentrations of testosterone and what the potential mechanism is governing these changes.

Associations of Vitamin D Levels with Physical Fitness and Motor Performance; A Cross-Sectional Study in Youth Soccer Players from Southern Croatia

Simple Summary

Vitamin D is a fat-soluble prohormone crucial for bone mineralization, muscle contractility, and neurological conductivity. It is theorized that Vitamin D plays an important role in sport performances, especially in young athletes. In this study we examined the associations of levels of 25-hydroxyvitamin D (25(OH)D) with physical fitness and motor-performance achievements in youth soccer players from Southern Croatia. Participants were tested on physical fitness, motor performance and vitamin D at the end of the winter period, when levels of vitamin D are known to be lowest due to low exposure to sunlight. Results showed that deficiency of 25(OH)D was widespread among youth soccer players living in Southern Croatia. Low 25(OH)D levels were associated with lower results in fitness tests (i.e., tests of energetic capacities), but there was no correlation between 25(OH)D levels and the results in motor performance tests (i.e., skill tests). Our results support the theory of the association between vitamin D and energetic capacities of athletes, but there is no evidence on association between vitamin D and skill-based capacities.

Abstract

Vitamin D level is known to be a factor potentially influencing physical fitness, but few studies have examined this phenomenon among youth athletes. We aimed to evaluate the associations of vitamin D levels (as measured by 25-hydroxyvitamin D concentrations—25(OH)D) with various physical fitness and motor performance tests in youth football (soccer) players. This cross-sectional study included a total of 52 youth soccer players (15.98 ± 2.26 years old) from Southern Croatia. The participants were evaluated at the end of the winter period and data were collected of anthropometric measures (body mass and body height), vitamin D status (25(OH)D levels), physical fitness tests (sprints of 10 and 20 m, 20 yards test, the countermovement jump, the reactive strength index (RSI)) and motor performance tests (the soccer-specific CODS, the soccer-specific agility, and static balance). Among the studied players, 54% had 25(OH)D insufficiency/deficiency, showing a lack of 25(OH)D is widespread even in youth athletes living at a southern latitude. The 25(OH)D level was correlated with sprint 20 m, 20 yards tests, and RSI, showing a greater role of 25(OH)D in physical fitness tests where energetic capacity is essential than in sport-related motor performance tests where skills are crucial. Our results support the idea that vitamin D can play a determinant role in physical fitness tests with a clear physiological component, but is not crucial in motor performance tests related to specific sports where skills are a key component. Future studies should investigate the effects of vitamin D supplementation on the performance in physical fitness and motor performance tests among youth athletes.

Nutrition for Older Athletes: Focus on Sex-Differences

Regular physical exercise and a healthy diet are major determinants of a healthy lifespan. Although aging is associated with declining endurance performance and muscle function, these components can favorably be modified by regular physical activity and especially by exercise training at all ages in both sexes. In addition, age-related changes in body composition and metabolism, which affect even highly trained masters athletes, can in part be compensated for by higher exercise metabolic efficiency in active individuals. Accordingly, masters athletes are often considered as a role model for healthy aging and their physical capacities are an impressive example of what is possible in aging individuals. In the present review, we first discuss physiological changes, performance and trainability of older athletes with a focus on sex differences. Second, we describe the most important hormonal alterations occurring during aging pertaining regulation of appetite, glucose homeostasis and energy expenditure and the modulatory role of exercise training. The third part highlights nutritional aspects that may support health and physical performance for older athletes. Key nutrition-related concerns include the need for adequate energy and protein intake for preventing low bone and muscle mass and a higher demand for specific nutrients (e.g., vitamin D and probiotics) that may reduce the infection burden in masters athletes. Fourth, we present important research findings on the association between exercise, nutrition and the microbiota, which represents a rapidly developing field in sports nutrition.

Vitamin D Status in Spanish Elite Team Sport Players

Low vitamin D is usual; however, data are limited for elite team players. The aim was to investigate the vitamin D levels in Football Club Barcelona (FCB) first division players of six sport modalities. Ninety-five elite male players (27.3 ± 4.6 y) belonging to FCB provided data for vitamin D throughout a season. In this study, 25(OH)D was measured in serum by chemiluminescent immunoassay. Outdoor/indoor training and supplementation were also considered. Total mean 25(OH)D concentrations were 91.9 ± 23.1 nmol/L in all players, with higher mean levels among supplemented players (94.7 ± 24.3 nmol/L). Around 25% of the team players were below optimal levels (<75 nmol/L), but none were below 50 nmol/L. Caucasian, supplemented football and handball players had the highest mean vitamin D concentrations over the whole year, whereas basketball players (indoor training) had the lowest ones. The highest rate of vitamin D insufficiency was found in spring (40%). A positive significant effect was observed for the interaction between indoor/outdoor training and supplementation with 25(OH)D concentrations (p < 0.05). Those team players training outdoors with supplementation had higher total vitamin D concentrations than those with indoors training and/or supplementation. A positive interaction of outdoor training with supplementation exists to determine 25(OH)D concentrations in team players.

Seasonal Changes in 25(OH)D Concentration in Young Soccer Players-Implication for Bone Resorption Markers and Physical Performance

Searching for potential relations between changes in 25(OH)D concentration and in physical fitness is an interesting scientific topic. Thus, the main purpose of this study was to investigate the changes in serum concentrations of 25(OH)D in young football players in conjunction with indicators determining bone resorption and physical fitness. A total of 35 young soccer players were tested during the autumn competition period. Biochemical analysis of blood, aerobic capacity, running speed and power tests (Wingate test, squat jump, counter movement jump) were carried out at the beginning and at the end of the competition period. Significant decrements in concentration of 25(OH)D from 33.9 ± 5.87 to 23.7 ± 5.58 ng/mL were noted after the analyzed competition period. There were no significant changes in aerobic capacity along the competition period. Significant improvements were observed in 10 m sprint, 30 m sprint (p < 0.001), maximal power (p = 0.011) and total work capacity (p = 0.024). We found that the effect of changes in the players' physical fitness does not occur in relation to 25 OH(D) concentration but occurs when these changes are analyzed as a function of the duration of the observation period. Changes in physical fitness of soccer players are determined by other factors then 25(OH)D concentration.

Age-Related Skeletal Muscle Dysfunction Is Aggravated by Obesity: An Investigation of Contractile Function, Implications and Treatment

Obesity is a global epidemic and coupled with the unprecedented growth of the world's older adult population, a growing number of individuals are both old and obese. Whilst both ageing and obesity are associated with an increased prevalence of chronic health conditions and a substantial economic burden, evidence suggests that the coincident effects exacerbate negative health outcomes. A significant contributor to such detrimental effects may be the reduction in the contractile performance of skeletal muscle, given that poor muscle function is related to chronic disease, poor quality of life and all-cause mortality. Whilst the effects of ageing and obesity independently on skeletal muscle function have been investigated, the combined effects are yet to be thoroughly explored. Given the importance of skeletal muscle to whole-body health and physical function, the present study sought to provide a review of the literature to: (1) summarise the effect of obesity on the age-induced reduction in skeletal muscle contractile function; (2) understand whether obesity effects on skeletal muscle are similar in young and old muscle; (3) consider the consequences of these changes to whole-body functional performance; (4) outline important future work along with the potential for targeted intervention strategies to mitigate potential detrimental effects.

[Musculoskeletal laboratory diagnostics in competitive sport]

Hintergrund

Die labordiagnostische Untersuchung stellt eine wichtige Möglichkeit zur Beurteilung und Optimierung der Leistungs- und Regenerationsfähigkeit professioneller Athleten dar. Ferner ist sie für die Prävention, Diagnostik und Rehabilitation von Verletzungen und Überbelastungen von Bedeutung.

Fragestellung

Ziel dieser Arbeit ist die Darstellung muskuloskelettaler laborchemischer Parameter, die relevante Erkenntnisse für die medizinische Betreuung von Leistungssportlern liefern.

Material und Methoden

Literaturrecherche und narratives Review.

Ergebnisse

Die Bestimmung des Vitamin-D-, Calcium- und Knochenstoffwechsels stellt die laborchemische Basisdiagnostik im Rahmen der Beurteilung des Skelettstatus mit zusätzlichem präventivem Nutzen bezüglich muskuloskelettaler Verletzungen dar. Ferner können muskuläre Serummarker, z. B. Laktatdehydrogenase (LDH), Kreatinkinase (CK), Myoglobin und Aspartat-Aminotransferase (ASAT), helfen, eine metabolische Adaptation an das physische Training festzustellen und Aussagen über die muskuläre Arbeitslast und mögliche Schädigungen zu gewinnen. Die Energieverfügbarkeit kann durch eine entsprechende Bilanzierung sowie die laborchemische Bestimmung der Makro- und Mikronährstoffe eingeschätzt und optimiert werden.

Schlussfolgerungen

Die labordiagnostische Untersuchung besitzt in der Betreuung von Athleten eine sportartenübergreifende klinische Relevanz. Sie dient der Erreichung einer höchstmöglichen Leistungsfähigkeit sowie optimalen Prävention von Knochen- und Muskelverletzungen, wobei sämtliche Mangelzustände (z. B. Vitamin D) ausgeglichen werden sollten. Durch eine Periodisierung der laborchemischen Untersuchungen, mit zumindest zwei Labordiagnostiken im Jahr, und Aufstellung individueller Variabilitäts- und Referenzbereiche kann ferner eine bessere Beurteilbarkeit erreicht werden.

[Vitamin D Deficiency in Sports]

Vitamin D Deficiency in Sports Abstract. A deficiency in vitamin D is very common in the general population as well as in athletes. The aim of this overview is to assess the level of knowledge about the importance of vitamin D for athletes. A deficiency in vitamin D is present in up to 90 % of athletes. Risk groups are young athletes, female athletes, athletes with a limitation such as paraplegia, vegetarians, athletes with a resorption disorder such as celiac disease, athletes training and competing indoors (e.g. ice hockey, basketball, boxing, rhythmic gymnastics), and older athletes. Dark skin pigmentation, the use of sunscreen, the time of day of the training (early morning, late evening) and the geographical location influence the risk for a deficiency in vitamin D. Exposure to the sun and a balanced diet are often not enough to prevent a vitamin D deficiency.

The mechanisms of skeletal muscle atrophy in response to transient knockdown of the vitamin D receptor in vivo

KEY POINTS

Reduced vitamin D receptor (VDR) expression prompts skeletal muscle atrophy. Atrophy occurs through catabolic processes, namely the induction of autophagy, while anabolism remains unchanged. In response to VDR-knockdown mitochondrial function and related gene-set expression is impaired. In vitro VDR knockdown induces myogenic dysregulation occurring through impaired differentiation. These results highlight the autonomous role the VDR has within skeletal muscle mass regulation.

ABSTRACT

Vitamin D deficiency is estimated to affect ∼40% of the world's population and has been associated with impaired muscle maintenance. Vitamin D exerts its actions through the vitamin D receptor (VDR), the expression of which was recently confirmed in skeletal muscle, and its down-regulation is linked to reduced muscle mass and functional decline. To identify potential mechanisms underlying muscle atrophy, we studied the impact of VDR knockdown (KD) on mature skeletal muscle in vivo, and myogenic regulation in vitro in C2C12 cells. Male Wistar rats underwent in vivo electrotransfer (IVE) to knock down the VDR in hind-limb tibialis anterior (TA) muscle for 10 days. Comprehensive metabolic and physiological analysis was undertaken to define the influence loss of the VDR on muscle fibre composition, protein synthesis, anabolic and catabolic signalling, mitochondrial phenotype and gene expression. Finally, in vitro lentiviral transfection was used to induce sustained VDR-KD in C2C12 cells to analyse myogenic regulation. Muscle VDR-KD elicited atrophy through a reduction in total protein content, resulting in lower myofibre area. Activation of autophagic processes was observed, with no effect upon muscle protein synthesis or anabolic signalling. Furthermore, RNA-sequencing analysis identified systematic down-regulation of multiple mitochondrial respiration-related protein and genesets. Finally, in vitro VDR-knockdown impaired myogenesis (cell cycling, differentiation and myotube formation). Together, these data indicate a fundamental regulatory role of the VDR in the regulation of myogenesis and muscle mass, whereby it acts to maintain muscle mitochondrial function and limit autophagy.

Performance and Health Decrements Associated With Relative Energy Deficiency in Sport for Division I Women Athletes During a Collegiate Cross-Country Season: A Case Series

The purpose of this case series was to evaluate the presence of low Energy Availability (EA) and its impact on components of Relative Energy Deficiency in Sport (RED-S) in a population of female collegiate runners. Seven female NCAA Division I athletes (age: 22.3 ± 1.5 yrs; height: 169.7 ± 5.7 cm; weight: 58.3 ± 4.1 kg) were tracked from August until February, covering the beginning (Pre XC), end (Post XC) of their competitive cross country season, and beginning of the following track season (Pre Track). The athletes were assessed for female athlete triad (Triad) risk, energy availability, body composition, resting metabolic rate (RMR), nutritional intake, and blood markers (including vitamin D, ferritin, and triiodothyronine (T3)). From Pre XC to Post XC there were no significant differences in body mass, fat free mass or body fat percentage. At Pre XC, mean EA was 31.6 ± 13.3 kcal/kg FFM∙d^-1. From Post XC to Pre Track, there was a significant increase in body mass (59.1 ± 5.1 to 60.6 ± 5.7 kg, p<0.001,d=0.27). From Post XC to Pre Track, there was a significant increase in RMR (1466 ± 123.6 to 1614.6 ± 89.1 kcal·d^-1, p<0.001,d=2.6). For 25(OH) vitamin D, there was a significant reduction from Pre XC to Post XC (44.1 ± 10.6 vs 39.5 ± 12.2 ng·mL^-1, p=0.047,d=-0.4), and a significant increase from Post XC to Pre Track (39.5 ± 12.2 vs. 48.1 ± 10.4 ng·mL^-1, p=0.014,d=0.75). For ferritin, there was a trend towards a decrease from Pre XC to Post XC (24.2 ± 13.2 vs. 15.7 ± 8.8 ng·mL^-1, p=0.07, d=-0.75), as well as a trend toward an increase from Post XC to Pre Track (15.7 ± 8.8 vs. 34.1 ± 18.0 ng·mL^-1, p=0.08, d=1.3). No differences in T3 were observed across time points. Average Triad risk score was 2.3 ± 1.4. Notably, 5 of 7 athletes met criteria for moderate risk. Despite many athletes meeting criteria for low EA and having elevated Triad risk assessment scores, most were able to maintain body mass and RMR. One athlete suffered severe performance decline and a reduced RMR. Surprisingly, she was the only athlete above the recommended value for ferritin. Following increased nutritional intake and reduced training volume, her performance and RMR recovered. Changes in body mass and body composition were not indicative of the presence of other concerns associated with RED-S. This exploratory work serves as a guide for future, larger studies for tracking athletes, using RMR and nutritional biomarkers to assess RED-S.

Prevalence of Vitamin D Insufficiency and Deficiency in Young, Female Patients With Lower Extremity Musculoskeletal Complaints

BACKGROUND

Low levels of vitamin D have well-known impacts on bone health, but vitamin D also has a more global role throughout many tissues, including skeletal muscle. The high prevalence of hypovitaminosis D and the vast physiological features of vitamin D have led researchers to examine the influence of vitamin D on physical performance and injury. Because of the critical role of vitamin D in maintaining musculoskeletal health and function, a high rate of hypovitaminosis D among female patients with a variety of musculoskeletal issues could be of high clinical relevance.

HYPOTHESIS

There is a high prevalence of low vitamin D in female patients with both acute and overuse sports-related issues of both soft tissue and bone.

STUDY DESIGN

Prospective cohort study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Female patients, aged 16 to 40 years, presenting with lower extremity injury diagnosed within the past 4 weeks, no use of multivitamin or vitamin D supplement, and no history of malabsorption syndrome met the inclusion criteria. Vitamin D levels were assessed and categorized as normal (≥32 ng/mL) and low, which includes insufficient (20.01-31.9 ng/mL) and deficient (≤20 ng/mL).

RESULTS

Of the 105 patients enrolled, 65.7% had low vitamin D. Within the low vitamin D cohort, 40.6% were deficient and 59.4% were insufficient. Injuries were grouped into overuse or acute with 74 overuse injuries and 31 acute injuries, exhibiting low vitamin D prevalence of 60.8% and 77.4%, respectively. Patients with ligamentous/cartilaginous injuries exhibited the highest percentage of low vitamin D (76.5%), followed by those with patellofemoral-related complaints (71.0%), muscle/tendon injuries (54.6%), and bone stress injuries (45.5%). In univariable analysis, older age, non-White race, less physical activity, less high-intensity interval training days, less endurance training days, and more rest days showed an association with low vitamin D, but none showed an independent association in multivariable analysis.

CONCLUSION

The prevalence of low vitamin D in female patients with various musculoskeletal complaints was high. Clinicians should evaluate for low vitamin D in both acute and overuse injuries.

CLINICAL RELEVANCE

In addition to screening, this study suggests that clinicians should evaluate for low vitamin D levels beyond bone stress injuries in the setting of acute and overuse injuries.

Is it reasonable to ignore vitamin D status for musculoskeletal health?

Severe vitamin D deficiency—25-hydroxyvitamin D (25OHD) concentrations below around 25–30 nmol/L—may lead to growth plate disorganization and mineralization abnormalities in children (rickets) and mineralization defects throughout the skeleton (osteomalacia) and proximal muscle weakness. Both problems are reversed with vitamin D treatment. Apart from this musculoskeletal dysfunction at very low vitamin D levels, there is apparent inconsistency in the available data about whether concentrations of 25OHD below around 50 nmol/L cause muscle function impairment and increase the risk of fracture. This narrative review provides evidence to support the contention that improving vitamin D status, up to around 50 nmol/L, plays a small causal role in optimizing bone and muscle function as well as reducing overall mortality.

Vitamin D, sport and health: a still unresolved clinical issue

Vitamin D metabolites have a pleiotropic role in human physiology, both in static and dynamic conditions, and a lot of vitamin D-related biological effects could influence physical and sport performances in athletes. Probably due to different factors (e.g., drugs, doping, nutrition, ultraviolet B radiation exposure), in athletes a very high prevalence of vitamin D inadequacy (i.e., deficiency or insufficiency) has been observed. Vitamin D inadequacy in athletes could be associated with specific health risks and to alterations of functional capacities, potentially influencing the fine adjustment of physical performances during training and sport competitions. When risk factors for vitamin D inadequacy exist, a preventive vitamin D supplementation is indicated, and if a vitamin D inadequacy is diagnosed, its supplementation is recommended. Unfortunately, on these issues many concerns remain unresolved. Indeed, it is not clear if athletes should be classified as a special population at increased risk for vitamin D inadequacy; moreover, in comparison to the non-athletic population, it is still not clear if athletes should have different reference ranges and different optimal target levels for serum vitamin D, if they have additional health risks, and if they need different type of supplementations (doses) for prevention and/or replacement therapy. Moreover, in athletes also the abuse of vitamin D supplements for ergogenic purposes raise different ethical and safety concerns. In this review, the main physio-pathological, functional and clinical issues that relate vitamin D to the world of athletes are described.

Overexpression of the vitamin D receptor (VDR) induces skeletal muscle hypertrophy

OBJECTIVE

The Vitamin D receptor (VDR) has been positively associated with skeletal muscle mass, function and regeneration. Mechanistic studies have focused on the loss of the receptor, with in vivo whole-body knockout models demonstrating reduced myofibre size and function and impaired muscle development. To understand the mechanistic role upregulation of the VDR elicits in muscle mass/health, we studied the impact of VDR over-expression (OE) in vivo before exploring the importance of VDR expression upon muscle hypertrophy in humans.

METHODS

Wistar rats underwent in vivo electrotransfer (IVE) to overexpress the VDR in the Tibialis anterior (TA) muscle for 10 days, before comprehensive physiological and metabolic profiling to characterise the influence of VDR-OE on muscle protein synthesis (MPS), anabolic signalling and satellite cell activity. Stable isotope tracer (D2O) techniques were used to assess sub-fraction protein synthesis, alongside RNA-Seq analysis. Finally, human participants underwent 20 wks of resistance exercise training, with body composition and transcriptomic analysis.

RESULTS

Muscle VDR-OE yielded total protein and RNA accretion, manifesting in increased myofibre area, i.e., hypertrophy. The observed increases in MPS were associated with enhanced anabolic signalling, reflecting translational efficiency (e.g., mammalian target of rapamycin (mTOR-signalling), with no effects upon protein breakdown markers being observed. Additionally, RNA-Seq illustrated marked extracellular matrix (ECM) remodelling, while satellite cell content, markers of proliferation and associated cell-cycled related gene-sets were upregulated. Finally, induction of VDR mRNA correlated with muscle hypertrophy in humans following long-term resistance exercise type training.

CONCLUSION

VDR-OE stimulates muscle hypertrophy ostensibly via heightened protein synthesis, translational efficiency, ribosomal expansion and upregulation of ECM remodelling-related gene-sets. Furthermore, VDR expression is a robust marker of the hypertrophic response to resistance exercise in humans. The VDR is a viable target of muscle maintenance through testable Vitamin D molecules, as active molecules and analogues.

Assessing the impact of a mushroom-derived food ingredient on vitamin D levels in healthy volunteers

BACKGROUND

Prevalence of vitamin D insufficiency/deficiency has been noted in athletic populations, although less is known about recreationally active individuals. Biofortification of natural food sources (e.g. UV radiated mushrooms) may support vitamin D status and is therefore of current scientific and commercial interest. The aim of this study was to assess the impact of a mushroom-derived food ingredient on vitamin D status in recreationally active, healthy volunteers.

METHODS

Twenty-eight participants were randomly assigned to either: 25 μg (1000 IU) encapsulated natural mushroom-derived vitamin D₂; matched-dose encapsulated vitamin D₃ or placebo (PL) for 12 weeks. Venous blood samples were collected at baseline, week 6 and 12 for analysis of serum 25(OH)D₂ and 25(OH)D₃ using liquid chromatography mass spectrometry. Habitual dietary intake and activity were monitored across the intervention.

RESULTS

Vitamin D status (25(OH)D_TOTAL) was significantly increased with vitamin D₃ supplementation from 46.1 ± 5.3 nmol·L^- 1 to 88.0 ± 8.6 nmol·L^- 1 (p < 0.0001) across the intervention, coupled with an expected rise in 25(OH)D₃ concentrations from 38.8 ± 5.2 nmol·L^- 1 to 82.0 ± 7.9 nmol·L^- 1 (p < 0.0001). In contrast, D₂ supplementation increased 25(OH)D₂ by + 347% (7.0 ± 1.1 nmol·L^- 1 to 31.4 ± 2.1 nmol·L^- 1, p < 0.0001), but resulted in a - 42% reduction in 25(OH)D₃ by week 6 (p = 0.001). A net + 14% increase in 25(OH)D_TOTAL was established with D₂ supplementation by week 12 (p > 0.05), which was not statistically different to D₃. Vitamin D status was maintained with PL, following an initial - 15% reduction by week 6 (p ≤ 0.046 compared to both supplement groups).

CONCLUSIONS

The use of a UV radiated mushroom food ingredient was effective in maintaining 25(OH)D_TOTAL in healthy, recreationally active volunteers. This may offer an adjunct strategy in supporting vitamin D intake. However, consistent with the literature, the use of vitamin D₃ supplementation likely offers benefits when acute elevation in vitamin D status is warranted.

The effect of vitamin D supplementation on the muscle damage after eccentric exercise in young men: a randomized, control trial

Background

Vitamin D contributes to the optimal functioning of muscles. This study was designed to determine the modulating effect of vitamin D supplementation on the degree of muscle cell damage caused by eccentric exercise in young men.

Methods

60 male volunteers (20–24 years old) taking part in this study were divided in two groups - with suboptimal (S) and optimal (O;) 25(OH)D plasma levels. These groups were randomly subdivided into groups with vitamin D supplementation (experimental: SE and OE) and controls (SC and OC). Before the supplementation (Test I) and after 3 months (Test II), participants were subjected to two rounds of eccentric exercise tests on a declined treadmill (running speed corresponded 60% VO2peak determined in each subject in incremental exercise test). During each test, blood samples used for determination of 25(OH)D, Il-1β, myoglobin (Mb) levels and CK, LDH activity were taken at three timepoints: before the test, 1 h and 24 h after it ended.

After distribution normality testing (Saphiro-Wilk test), statistical analyses were performed. Non-parametric: Kruskal-Wallis test and the Wilcoxon test were applied, and the Dunn-Bonferroni test as a post-hoc test.

Results

In all groups, after 3 months, higher concentrations of 25(OH)D were indicated (SE p = 0.005; SC p = 0.018; OE p = 0.018; OC p = 0.028). SE and SC groups showed higher baseline concentrations of Il-1β and significantly higher concentrations of this interleukin after 1 h compared to groups with an optimal 25(OH)D level. After supplementation, the SE group reacted with a similar jump in concentration of Il-1β as the OC and OE groups. The change after 1 h after exercise in Test II was significantly different from that from Test I (p = 0.047) in SE group. Lower Mb concentrations indicated 1 h after exercise in Test II for SC and SE groups were indicated. CK activity did not differentiate the studied groups. Plasma calcium and phosphate disorders were also not indicated.

Conclusions

The study has shown that vitamin D doses determined from the plasma concentration of 25(OH)D of individuals to match their specific needs can significantly reduce muscle cell damage induced by eccentric exercise.

UEFA expert group statement on nutrition in elite football. Current evidence to inform practical recommendations and guide future research

Football is a global game which is constantly evolving, showing substantial increases in physical and technical demands. Nutrition plays a valuable integrated role in optimising performance of elite players during training and match-play, and maintaining their overall health throughout the season. An evidence-based approach to nutrition emphasising, a 'food first' philosophy (ie, food over supplements), is fundamental to ensure effective player support. This requires relevant scientific evidence to be applied according to the constraints of what is practical and feasible in the football setting. The science underpinning sports nutrition is evolving fast, and practitioners must be alert to new developments. In response to these developments, the Union of European Football Associations (UEFA) has gathered experts in applied sports nutrition research as well as practitioners working with elite football clubs and national associations/federations to issue an expert statement on a range of topics relevant to elite football nutrition: (1) match day nutrition, (2) training day nutrition, (3) body composition, (4) stressful environments and travel, (5) cultural diversity and dietary considerations, (6) dietary supplements, (7) rehabilitation, (8) referees and (9) junior high-level players. The expert group provide a narrative synthesis of the scientific background relating to these topics based on their knowledge and experience of the scientific research literature, as well as practical experience of applying knowledge within an elite sports setting. Our intention is to provide readers with content to help drive their own practical recommendations. In addition, to provide guidance to applied researchers where to focus future efforts.

Vitamin D Supplementation Does Not Impact Resting Metabolic Rate, Body Composition and Strength in Vitamin D Sufficient Physically Active Adults

Supplementation with the most efficient form of Vitamin D (VitD3) results in improvements in energy metabolism, muscle mass and strength in VitD deficient individuals. Whether similar outcomes occur in VitD sufficient individuals' remains to be elucidated. The aim of this study is to determine the effect of VitD3 supplementation on resting metabolic rate (RMR), body composition and strength in VitD sufficient physically active young adults. Participants completed pre-supplementation testing before being matched for sunlight exposure and randomly allocated in a counterbalanced manner to the VitD3 or placebo group. Following 12 weeks of 50 IU/kg body-mass VitD3 supplementation, participants repeated the pre-supplementation testing. Thirty-one adults completed the study (19 females and 12 males; mean ± standard deviation (SD); age = 26.6 ± 4.9 years; BMI = 24.2 ± 4.1 kg·m²). The VitD group increased serum total 25(OH)D by 30 nmol/L while the placebo group decreased total serum concentration by 21 nmol/L, reaching 123 (51) and 53 (42.2) nmol/L, respectively. There were no significant changes in muscle strength or power, resting metabolic rate and body composition over the 12-week period. Physically active young adults that are VitD sufficient have demonstrated that no additional physiological effects of achieving supraphysiological serum total 25(OH)D concentrations after VitD3 supplementation.