Impact of Vitamin D on Physical Efficiency and Exercise Performance-A Review

Positive Association of Urinary Dimethylarsinic Acid (DMAV) with Serum 25(OH)D in Adults Living in an Area of Water-Borne Arsenicosis in Shanxi, China

Limited studies have demonstrated that inorganic arsenic exposure is positively associated with serum vitamin D levels, although the correlation between urinary arsenic species and serum vitamin D has not been investigated in areas of water-borne arsenicosis. A cross-sectional study of 762 participants was conducted in Wenshui Country, Shanxi Province, a water-borne arsenicosis area. The results showed a positive relationship between urinary arsenic species (inorganic arsenic (iAs), methylarsonic acid (MMAV), dimethylarsinic acid (DMAV) and serum 25(OH)D. Log-binomial regression analysis indicated a 0.4% increase in the risk of vitamin D excess for every 1-unit increment in the Box-Cox transformed urinary DMAV after adjustment for covariates. After stratifying populations by inorganic arsenic methylation metabolic capacity, serum 25(OH)D levels in the populations with iAs% above the median and primary methylation index (PMI) below the median increased by 0.064 ng/mL (95% CI: 0.032 to 0.096) for every one-unit increase in the Box-Cox transformed total arsenic (tAs) levels. Serum 25(OH)D levels increased by 0.592 ng/mL (95% CI: 0.041 to 1.143) for every one-unit rise in the Box-Cox transformed iAs levels in people with skin hyperkeratosis. Overall, our findings support a positive relationship between urinary arsenic species and serum 25(OH)D. It was recommended that those residing in regions with water-borne arsenicosis should take moderate vitamin D supplements to avoid vitamin D poisoning.

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.

Association between Vitamin D and Short-Term Functional Outcomes in Acute Ischemic Stroke

Vitamin D (Vit D) affects musculoskeletal performance and central nervous system neuroprotection. We aimed to investigate the association between serum Vit D levels and short-term functional outcomes in patients with acute ischemic stroke. This study involved patients with acute ischemic stroke confirmed on brain MRI. The National Institutes of Health Stroke Scale (NIHSS) was used to assess initial stroke severity upon admission. We evaluated the functional outcomes using the Berg Balance Scale (BBS), Manual Function Test (MFT), Korean Mini-Mental State Examination (K-MMSE), Korean version of the modified Barthel Index (K-MBI) within three weeks from the onset of stroke, and modified Rankin Scale (mRS) score at discharge. Overall, 192 patients were finally included and divided into three groups: Vit D sufficient (n = 28), insufficient (n = 49), and deficient (n = 115). Multivariate analysis showed that the Vit D deficient group presented with a higher risk of initially severe stroke (p = 0.025) and poor functional outcomes on the BBS (p = 0.048), MFT (p = 0.017), K-MMSE (p = 0.001), K-MBI (p = 0.003), and mRS (p = 0.032) compared to the Vit D sufficient group. Vit D deficiency may be associated with severe initial stroke and poor short-term post-stroke functional outcomes.

Vitamin D Intake and Serum Levels in Pregnant and Postpartum Women

Maternal vitamin D deficiency, which is highly prevalent in pregnant women in Europe, is linked to adverse health effects for both the mother and child. The objective was to assess vitamin D status in pregnant women by evaluating their dietary and supplemental vitamin D intake, serum vitamin D levels, parathyroid hormone levels, and lifestyle factors. This cross-sectional study, with a total of 735 participants (145 pregnant and 590 up to the seventh day postpartum), took place in Latvia. Blood samples, a food frequency questionnaire, and medical documentation were used for data collection. The median serum vitamin D concentration was 34.0 ng/mL, with pregnant women having higher levels (42.9 ng/mL) than postpartum women (31.8 ng/mL). There was no association between vitamin D serum concentration and dietary intake of vitamin D (p > 0.05), whereas there was a significant correlation with use of vitamin D supplements (r = 0.41; p < 0.001 in pregnant women and r = 0.35; p < 0.001 in postpartum women). This study demonstrated that a minority of pregnant women (21.9%) had optimal serum vitamin D concentration (>45 ng/mL), and diet had no significant impact on vitamin D levels. Thus, our proposed recommendation for vitamin D intake during pregnancy was 63 mcg (2500 IU) year-round for optimal levels in pregnant women in Northeastern Europe.

Immunologic, Anti-Inflammatory, and Anti-Muscle Damage Profile of Supplemented Vitamin D3 in Healthy Adults on Strenuous Endurance Exercise

Reportedly, strenuous endurance exercise can depress the immune system and induce inflammation and muscle damage. Therefore, this double-blinded, matched-pair study aimed to investigate the impact of vitamin D₃ supplementation on immune response (leukocyte, neutrophil, lymphocyte, CD4⁺, CD8⁺, CD19⁺, and CD56⁺ counts), inflammatory profile (TNF-α and IL-6), muscle damage (CK and LDH levels), as well as aerobic capacity after strenuous endurance exercise in 18 healthy men taking 5000 IU of vitamin D₃ (n = 9) or placebo (n = 9) daily for 4 weeks. Total and differential blood leukocyte counts, levels of cytokines, and muscle damage biomarkers were determined before, immediately after, and 2, 4, and 24 h after exercise. The IL-6, CK, and LDH levels were significantly lower in vitamin D₃ group at 2, 4, and 24 h post exercise (p < 0.05). Maximal and average heart rates during exercise were also significantly lower (p < 0.05). In the vitamin D₃ group, the CD4⁺/CD8⁺ ratio after 4 weeks of supplementation was only significantly lower at post-0 than at baseline and significantly higher at post-2 than at baseline and post-0 (all p < 0.05). Taken together, 5000 IU of daily vitamin D₃ supplementation for 4 weeks exhibited positive effects in terms of increased blood 25(OH)D levels, CD4⁺/CD8⁺ ratio (immune response), and aerobic capacity while inhibiting inflammatory cytokines and CK and LDH (muscle damage) in people performing strenuous endurance exercise.

Does vitamin D affect strength and speed characteristics and testosterone concentration in elite young track and field athletes in the North European summer?

BACKGROUND

Currently there are no data examining the relationship between the serum concentration of vitamin D bio-chemical marker 25(OH)D and strength and speed characteristics in elite young track and field athletes. Moreover, there are currently no data examining the correlation of vitamin D status with testosterone concentration in elite young track and field athletes. In studies involving members of the general population and athletes from other sports, conflicting data have been reported.

MATERIAL AND METHODS

Athletes (n = 68) from both genders took part in this study. Male athletes (n = 23) with mean ± SD age of 18.2 ± 1.9 years and female athletes (n = 45) with mean ± SD age of 17.3 ± 2.6 years participated. All athletes were ranked in the Top-3 in their respective age group and their corresponding results were listed in the Top-20 European records according to https://www.tilastopaja.eu/ in 2021.

RESULTS

The average 25(OH)D concentration was 36.5 ± 10.8 ng/mL and 37.8 ± 14.5 ng/mL in male and female athletes respectively. The prevalence of 25(OH)D deficiency (below 20 ng/ml) in both genders was only 5.8%. In the whole group, only 27.9% of athletes had 25(OH)D concentrations between 20 and 30 ng/ml, while 66.2% of athletes had concentrations above 30 ng/ml. There was no difference in vitamin D status between male and female athletes. There was no statistically significant Kruskal-Wallace test correlation between 25(OH)D concentration and performance in the 20 m and 30 m sprint, counter-movement jump and broad jump. There was no correlation between serum concentrations of 25(OH)D and total testosterone in either male or female athletes.

CONCLUSION

In elite young track and field athletes who permanently live and train in an area above 50° north latitude, the prevalence of vitamin D deficiency in the summer months was much lower than in previously published studies examining an athletic population, that may be related to the training process. In this specific group of athletes, no correlation was found between serum 25 (OH) D concentration and strength and speed characteristics or total testosterone concentration.

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.

Severe deficiency of vitamin D has no negative effect on physical performance during military training

BACKGROUND

Decreased physical fitness and inferior physical performance are potentially life-threatening risk factors in a combat situation. To examine the effect of vitamin D on physical performance, a prospective study of young men conscripts in the Estonian Army was designed. The hypothesis of the study was that severe deficiency of vitamin D has a negative effect on physical performance.

METHODS

All conscripts (N.=410) entering 10-month military service in July 2015 at the Kuperjanov Battalion were asked to participate. Initially, a total of 98 conscripts volunteered to participate. A prospective longitudinal study with a 10-month follow-up period was performed. The Army Physical Fitness Test (APFT) was performed three times, and hand grip strength, and blood serum values of 25(OH)D, parathyroid hormone (PTH) and calcium (Ca) were measured four times.

RESULTS

A significant decrease in the levels of 25(OH)D compared with baseline values were found, with a lowest mean value of 31.9 nmol/L in March 2016 (P<0.001). No significant differences were found in serum Ca levels. In March 2016, PTH was significantly higher in the severe deficiency group (<25 nmol/L of 25(OH)D) (P=0.02). No significant differences were found in terms of the APFT or hand grip strength between conscripts with severe deficiency of 25(OH)D or values >25 nmol/L. The main finding of the present study was that severe 25(OH)D deficiency was common among male conscripts during the winter season but had no negative effect on physical performance in terms of the APFT test and hand grip strength test.

CONCLUSIONS

Severe vitamin D deficiency during the winter season is common but has no negative effect on physical performance in young, physically active men in military service.

Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial

PURPOSE

Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency.

METHODS

Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m²) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D₃ (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups.

RESULTS

Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.5 ± 14.7 nmol/L; treatment: 43.4 ± 18.4 nmol/L; P < 0.001) and reduced stair climb times (placebo: 0.3 ± 1.0 s; treatment: - 0.2 ± 1.0 s; P = 0.046). From 12 to 24 weeks, vitamin D supplementation combined with exercise decreased waist circumference (placebo: 1.3 ± 7.3 cm; treatment: - 3.0 ± 6.1 cm; P = 0.02) and waist-to-hip ratio (placebo: 0.01 ± 0.05; treatment: - 0.03 ± 0.05; P = 0.01) relative to placebo. Vitamin D supplementation, with or without exercise, had no effect on other physical function, body composition or metabolic health outcomes.

CONCLUSION

Vitamin D supplementation had no effect on most physical function, body composition or metabolic health parameters when taken alone, or during exercise, in overweight or obese older adults with vitamin D deficiency. Vitamin D-related improvements in stair climb times and waist circumference suggest that future trials should explore the effects of vitamin D on muscle power, and its effects on body composition when combined with exercise, in populations with moderate or severe vitamin D deficiency.

Vitamin D Supplementation and Its Impact on Different Types of Bone Fractures

Vitamin D helps to balance the levels of calcium and phosphorus to maintain proper bone structure. It is also involved in essential biological roles and displays a wide spectrum of potential benefits in the human body. Since there are many types of fractures that occur at specific ages and due to different circumstances, the influence of vitamin D on the frequency of a particular fracture may differ. Thus, the authors investigated the possible preventive effect of vitamin D on the risks of vertebral fractures, hip fractures, stress fractures and pediatric fractures. Additional aspects of vitamin D, especially on recuperation after injures and its impact on the severity of particular fractures, were also discussed. It was suggested that vitamin D supplementation may contribute to a reduction in hip fracture risk due to reduced bone turnover, decreased frequency of falls and improved muscle function. Furthermore, vitamin D appears to lower the risk of stress fractures in athletes and military recruits. Due to a nonunified protocol design, presented investigations show inconsistencies between vitamin D supplementation and a decreased risk of vertebral fractures. However, a vitamin D preventive effect on pediatric fractures seems to be implausible.

Clinical and nutritional management of very-low-calorie ketogenic diet (VLCKD) in patients with psoriasis and obesity: a practical guide for the nutritionist

Psoriasis is an immune-mediated inflammatory skin disease associated with multiple comorbidities. Considered one of the most common inflammatory skin diseases among the general population, it not only affects the skin, but also negatively impacts other organs and joints. In addition, psoriasis has been associated with several chronic cardio-metabolic diseases such as obesity, which would seem to be (i) a risk factor for the onset of psoriasis and (ii) a worsening factor of the severity of the disease. Weight loss appears to improve severity in overweight patients. Recently proposed as an obesity management nutritional strategy, the very-low-calorie ketogenic diet (VLCKD) has demonstrated significant effects in reducing inflammatory processes. In the current review, we describe the evidence available on psoriasis and VLCKD, and provide a practical guide to the prescription of VLCKD in the different phases, evaluation and management of possible adverse events, and the importance of physical activity as a lifestyle modification to reduce psoriasis and associated comorbidities. Randomized control trials are, however, necessary to determine the most effective VLCKD protocol for patients with obesity and psoriasis, optimal protocol duration, composition of micronutrients and macronutrients, choice of special supplements, and management of carbohydrate reintroduction.

Changes of 25(OH)D Concentration, Bone Resorption Markers and Physical Performance as an Effect of Sun Exposure, Supplementation of Vitamin D and Lockdown among Young Soccer Players during a One-Year Training Season

The main purpose of this research was to demonstrate the changes in 25(OH)D concentration, bone resorption markers, and physical fitness along the one-year training season in young soccer players. A total of 24 young soccer players (age: 17.2 ± 1.16 years, mass: 70.2 ± 5.84, height: 179.1 ± 4.26 cm) were tested at four different time points across one year (T1—September 2019; T2—December 2019; T3—May 2020; T4—August 2020). After T2 (during COVID-19 lockdown), players were divided into a supplemented (GS) group and a placebo group (GP). Variables such as 25(OH)D, calcium (Ca), phosphorus (P), parathyroid hormone (PTH), aerobic capacity, speed, and explosive power were measured. Analyses performed for all participants indicated significant changes in all selected blood markers and running speed. The highest values in 25(OH)D were noted during summertime in T1 and T4. After individuals were split into two groups, a two-factorial ANOVA demonstrated a significant time interaction for 25(OH)D, Ca, P, PTH, 30 m sprint, and counter-movement jump. Significant time x group effect was calculated for aerobic capacity. This study confirmed that 25(OH)D concentration varies between four seasons, with the greatest decreases in the low sunlight periods. Vitamin D supplementation did not cause a preventive and long-lasting effect of increasing the 25(OH)D concentration in the young soccer players.

Population Genetic Polymorphism of Skeletal Muscle Strength Related Genes in Five Ethnic Minorities in North China

Musculoskeletal performance is a complex trait influenced by environmental and genetic factors, and it has different manifestations in different populations. Heilongjiang province, located in northern China, is a multi-ethnic region with human cultures dating back to the Paleolithic Age. The Daur, Hezhen, Ewenki, Mongolian and Manchu ethnic groups in Heilongjiang province may have strong physical fitness to a certain extent. Based on the genetic characteristics of significant correlation between some important genes and skeletal muscle function, this study selected 23 SNPs of skeletal muscle strength-related genes and analyzed the distribution of these loci and genetic diversity in the five ethnic groups. Use Haploview (version 4.1) software to calculate the chi-square and the Hardy-Weinberg equilibrium to assess the difference between the two ethnic groups. Use R (version 4.0.2) software to perform principal component analysis of different ethnic groups. Use MEGA (version 7.0) software to construct the phylogenetic tree of different ethnic groups. Use POPGENE (version 1.32) software to calculate the heterozygosity and the F_ST values of 23 SNPs. Use Arlequin (version 3.5.2.2) software to analyze molecular variance (AMOVA) among 31 populations. The results showed that there was haplotype diversity of VDR, angiotensin-converting enzyme, ACTN3, EPO and IGF1 genes in the five ethnic groups, and there were genetic differences in the distribution of these genes in the five ethnic groups. Among them, the average gene heterozygosity (AVE_HET) of the 23 SNPs in the five populations was 0.398. The F_ST values of the 23 SNPs among the five ethnic groups varied from 0.0011 to 0.0137. According to the principal component analysis, the genetic distance of Daur, Mongolian and Ewenki is relatively close. According to the phylogenetic tree, the five ethnic groups are clustered together with the Asian population. These data will enrich existing genetic information of ethnic minorities.

An Association between Bioavailable 25-Hydroxyvitamin D and Bone Mineral Density in a Diverse Cohort of Collegiate Athletes

INTRODUCTION

Although vitamin D is intimately involved in bone metabolism, the relationship between vitamin D status, as measured by serum total 25-hydroxyvitamin D [25(OH)D] concentration, and bone mineral density (BMD) is weak, particularly in non-White populations. Measurement of bioavailable 25(OH)D has been suggested as a better indicator of vitamin D status than total 25(OH)D concentration. To date, the bioavailable 25(OH)D biomarker has been explored minimally in athletic populations. The purpose of this study was to investigate the relationship between total and bioavailable 25(OH)D concentrations and BMD in collegiate athletes.

METHODS

NCAA Division 1 basketball and swimming athletes served as study participants (n = 53; 28 females, 25 males; 28 basketball players, 25 swimmers). All participants completed dual energy x-ray absorptiometry (DXA) scans for analysis of BMD, blood draws for vitamin D measures, and diet/lifestyle questionnaires.

RESULTS

Overall, total 25(OH)D was 80.0 + 13.9 nmol/L and bioavailable 25(OH)D was 6.0 ± 1.9 nmol/L. There was strong disagreement between total 25(OH)D and bioavailable 25(OH)D concentrations (κ = -0.299; r = -0.129) (p = 0.100); 53% of total participants and 77% of Black participants were classified differently (low vs. normal vitamin D status) based on total and bioavailable 25(OH)D criteria. Black participants had significantly lower total 25(OH)D and higher bioavailable 25(OH)D concentrations than White participants (59.5 vs. 102.5 nmol/L and 7.9 vs. 5.4 nmol/L, respectively) (p < 0.001). Total 25(OH)D and total BMD were not correlated, but bioavailable 25(OH)D and total BMD demonstrated a positive correlation (r = 0.618, p < 0.01).

CONCLUSIONS

These results suggest that bioavailable 25(OH)D concentration may be a better clinical measure of vitamin D status than total 25(OH)D in collegiate athletes as related to BMD, particularly in Black athletes. Further research on the utility of the bioavailable 25(OH)D biomarker in athletes is needed.

The interaction of aging with serum 25(OH)D and 1,25(OH)2 D status on muscle strength

BACKGROUND

To investigate the combination relationship of age with serum 25-hydroxyvitamin D (25(OH) D) and 1,25-(OH)2D3 levels on muscle strength.

METHODS

We performed a cross-sectional study on 270 subjects containing 115 men and 155 women. Serum concentration of 25(OH) D and 1,25-(OH)2D3 were assessed. Hand grip strength (HGS) was measured using a digital dynamometer.

RESULTS

There was no significant difference in mean of HGS among tertiles of 25(OH)D (P = .350) and 1,25(OH)₂ D (P = .467) before and after controlling for potential confounding factors. A significant difference in HGS was found between age categories in both crude (P < .001) and adjusted models (P = .018), where mean grip strength increased in the three first age categories, but decreased in the last group (48-69 years old). There was also a significant interaction between age and 25(OH) D (P = .049) and 1,25-(OH)2D3 (P = .047) on HGS, in which the combination effect increased the mean of muscle strength up to middle age after adjusting for confounders.

CONCLUSIONS

Serum 25(OH)D and 1,25(OH)₂ D were not related to muscle strength. However, age, and combination of age with both 25(OH)D and 1,25(OH)₂ D, significantly resulted in improving in muscle strength up to middle age.

In vitro Effects of Biologically Active Vitamin D on Myogenesis: A Systematic Review

Vitamin D (VD) deficiency is associated with muscle weakness. A reduction in the incidence of falls in the elderly following VD supplementation and identification of the VD receptor within muscle cells suggests a direct effect of VD on muscle, but little is known about the underlying mechanisms. Here we systematically searched the literature to identify effects of active VD [1,25(OH)2D3] on skeletal muscle myogenesis in vitro, with no restriction on year of publication. Eligibility was assessed by strict inclusion/exclusion criteria and agreed by two independent investigators. Twelve relevant pa-pers were identified using four different cell types (C2C12, primary mouse satellite cells, primary chick myoblasts, and primary human myoblasts) and a range of myogenic markers (myoD, myogenin, creatine kinase, myosin heavy chain, and myotube size). A clear inhibitory effect of 1,25(OH)2D3 on proliferation was reported, while the effects on the different stages of differentiation were less consistent probably due to variation in cell type, time points and doses of 1,25(OH)2D3 used. However, myotube size was consistently increased by 1,25(OH)2D3. Overall, the evidence suggests that 1,25(OH)2D3 inhibits proliferation and promotes differentiation of myoblasts, but future studies should use time courses to gain a clearer understanding.

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.

Movement as a Positive Modulator of Aging

The aging of human populations, including those in Europe, is an indisputable fact. The challenge for the future is not simply prolonging human life at any cost or by any means but rather extending self-sufficiency and quality of life. Even in the most advanced societies, the eternal questions remain. Who will take care of the older generations? Will adult children’s own circumstances be sufficient to support family members as they age? For a range of complex reasons, including socioeconomic conditions, adult children are often unable or unwilling to assume responsibility for the care of older family members. For this reason, it is imperative that aging adults maintain their independence and self-care for as long as possible. Movement is an important part of self-sufficiency. Moreover, movement has been shown to improve patients’ clinical status. At a time when the coronavirus pandemic is disrupting the world, older people are among the most vulnerable. Our paper explores current knowledge and offers insights into the significant benefits of movement for the elderly, including improved immunity. We discuss the biochemical processes of aging and the counteractive effects of exercise and endogenous substances, such as vitamin D.

Vitamin D Sources, Metabolism, and Deficiency: Available Compounds and Guidelines for Its Treatment

Studies on vitamin/hormone D deficiency have received a vast amount of attention in recent years, particularly concerning recommendations, guidelines, and treatments. Moreover, vitamin D’s role as a hormone has been confirmed in various enzymatic, metabolic, physiological, and pathophysiological processes related to many organs and systems in the human body. This growing interest is mostly due to the evidence that modest-to-severe vitamin D deficiency is widely prevalent around the world. There is broad agreement that optimal vitamin D status is necessary for bones, muscles, and one’s general health, as well as for the efficacy of antiresorptive and anabolic bone-forming treatments. Food supplementation with vitamin D, or the use of vitamin D supplements, are current strategies to improve vitamin D levels and treat deficiency. This article reviews consolidated and emerging concepts about vitamin D/hormone D metabolism, food sources, deficiency, as well as the different vitamin D supplements available, and current recommendations on the proper use of these compounds.

[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.

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.

Vitamin D status and supplementation impacts on skeletal muscle function: comparisons between young athletes and older adults

PURPOSE OF REVIEW

The present narrative review analyzes emerging research implicating vitamin D status and supplementation with skeletal muscle homeostasis and functions in two distinct segments of the adult population: young athletes and older adults.

RECENT FINDINGS

Vitamin D deficiency compromises multiple indices of muscle function in young athletes and older adults. A variety of vitamin D3 (cholecalciferol) supplementation regimens may transition young athletes and older adults from deficient or inadequate to adequate vitamin D status. Vitamin D supplementation, used to treat a vitamin D deficiency, but not necessarily an inadequacy, promotes muscle anabolism in older adults. For both young athletes and older adults, vitamin D supplementation, which transitions them from inadequate to adequate vitamin D status, may not beneficially affect measures of muscle strength and power, or physical performance. Also, when vitamin D status is adequate, vitamin D supplementation to further increase serum 25(OH)D concentrations does not seem to confer additional benefits to muscle strength and power and physical performance.

SUMMARY

The impacts of vitamin D status and supplementation on skeletal muscle homeostasis and functions seem comparable in young athletes who strive to maximize physical performance and older adults who seek to attenuate muscle mass and physical performance declines.

Influence of Sunlight and Oral D3 Supplementation on Serum 25(OH)D Concentration and Exercise Performance in Elite Soccer Players

The aim of this study was to evaluate the influence of natural sun exposure and six weeks of a high dose of vitamin D supplementation on vitamin D, testosterone and cortisol serum concentrations as well as speed, power and VO_2max in professional soccer players. Materials: The study was conducted from January to September. At the beginning of the study, 33 professional soccer players were enrolled; however, only 28 subjects (height 181.5 cm; body mass 77.81 ± 8.8 kg; body fat 12.38% ± 2.4% and muscle mass 40.27 ± 5.3 kg) completed the study. The research consisted of three stages. The first one, lasting 10 days, was conducted in January during a training camp in the south part of Cyprus at a latitude of 34 33°, where participants experienced natural sun exposure; it was called a winter sun exposure (WSE) period. The second stage, which was a supplementation period (SP), lasted 6 weeks, during which all subjects were randomly assigned either to an experimental group—EG (n = 15)—or a placebo group—PG (n = 13)—and were administered 6000 IU/d cholecalciferol or a placebo, respectively. The third stage took place in September, after summertime (summer sun exposure—SSE). The data of the 25(OH)D, free and total testosterone (fT, tT), cortisol as well as 5 and 30 m sprint tests (STs), power of the left leg (PLL) and VO_2max were evaluated before and after the WSE period, the SP and SSE. Results: In January, the baseline value of vitamin D in 12 subjects was ≤20 ng/mL, and 14 of them had levels between 20–30 ng/mL and 2 individuals >30 ng/mL. After the WSE period, significant changes in 25(OH)D, fT, tT and cortisol concentration, as well as in the 5 m ST, were observed. After the SP, in the EG, significant changes were found in 25(OH)D, fT, tT and the 5 m ST. Furthermore, a positive correlation between the concentration of 25(OH) fT and tT was observed. After SSE, 2 out of 28 players had <20 ng/mL 25(OH)D, 12 of them had 25(OH)D between 20 and 30 ng/mL and 14 of them had 25(OH)D between 30 and 50 ng/mL. Significant differences in 25(OH)D, fT, tT concentration and the 5 m ST performance were observed following SSE compared with the WSE period. Conclusion: Due to the serum level of 25(OH)D demonstrated by most participants at the beginning of the study and after summertime, all-year-round supplementation with high doses of vitamin D seems to be a reasonable solution to enhance high 25(OH)D concentration in blood and physical performance. In the middle of the winter, almost half of the soccer players were serum deficient of 25(OH)D. After ten days of sun exposure and 6 weeks of vitamin D supplementation, the concentration of 25(OH)D significantly increased, as did testosterone and results in the 5 m sprint test also improved. Therefore, athletes should be constantly monitored for serum levels of 25(OH)D throughout the year and should be supplemented if deficiencies or insufficient amounts of this vitamin occur.