A Systematic Review of the Role of Vitamin D on Neuromuscular Remodelling Following Exercise and Injury

Advances in Understanding the Interplay between Dietary Practices, Body Composition, and Sports Performance in Athletes

The dietary practices of athletes play a crucial role in shaping their body composition, influencing sports performance, training adaptations, and overall health. However, despite the widely acknowledged significance of dietary intake in athletic success, there exists a gap in our understanding of the intricate relationships between nutrition, body composition, and performance. Furthermore, emerging evidence suggests that many athletes fail to adopt optimal nutritional practices, which can impede their potential achievements. In response, this Special Issue seeks to gather research papers that delve into athletes' dietary practices and their potential impacts on body composition and sports performance. Additionally, studies focusing on interventions aimed at optimizing dietary habits are encouraged. This paper outlines the key aspects and points that will be developed in the ensuing articles of this Special Issue.

Nutritional Strategies in the Rehabilitation of Musculoskeletal Injuries in Athletes: A Systematic Integrative Review

It is estimated that three to five million sports injuries occur worldwide each year. The highest incidence is reported during competition periods with mainly affectation of the musculoskeletal tissue. For appropriate nutritional management and correct use of nutritional supplements, it is important to individualize based on clinical effects and know the adaptive response during the rehabilitation phase after a sports injury in athletes. Therefore, the aim of this PRISMA in Exercise, Rehabilitation, Sport Medicine and Sports Science PERSiST-based systematic integrative review was to perform an update on nutritional strategies during the rehabilitation phase of musculoskeletal injuries in elite athletes. After searching the following databases: PubMed/Medline, Scopus, PEDro, and Google Scholar, a total of 18 studies met the inclusion criteria (Price Index: 66.6%). The risk of bias assessment for randomized controlled trials was performed using the RoB 2.0 tool while review articles were evaluated using the AMSTAR 2.0 items. Based on the main findings of the selected studies, nutritional strategies that benefit the rehabilitation process in injured athletes include balanced energy intake, and a high-protein and carbohydrate-rich diet. Supportive supervision should be provided to avoid low energy availability. The potential of supplementation with collagen, creatine monohydrate, omega-3 (fish oils), and vitamin D requires further research although the effects are quite promising. It is worth noting the lack of clinical research in injured athletes and the higher number of reviews in the last 10 years. After analyzing the current quantitative and non-quantitative evidence, we encourage researchers to conduct further clinical research studies evaluating doses of the discussed nutrients during the rehabilitation process to confirm findings, but also follow international guidelines at the time to review scientific literature.

Vitamin D Status and Health Outcomes in School Children in Northern Ireland: Year One Results from the D-VinCHI Study

(1) Background: Vitamin D status has never been investigated in children in Northern Ireland (UK). (2) Methods: Children (4-11 years) (n = 47) were recruited from November 2019 to March 2020 onto the cross-sectional study. Anthropometry was assessed. Plasma 25-hydroxyvitamin D (25(OH)D) was analysed. Vitamin D intake, parental knowledge and perceptions, participant habits, physical activity and sedentary behaviour were established via questionnaire. Muscle strength was assessed via isometric grip strength dynamometry and balance via dominant single-leg and tandem stance. Parathyroid hormone, bone turnover markers (OC, CTX and P1NP), glycated haemoglobin and inflammatory markers (CRP, IFN-γ, IL-10, IL-12p70, IL-13, IL-1β, IL-2, IL-4, IL-6, IL-8 and TNF-α) were analysed. (3) Results: Mean (SD) 25(OH)D was 49.17 (17.04) nmol/L (n = 47); 44.7% of the children were vitamin D sufficient (25(OH)D >50 nmol/L), 48.9% were insufficient (25-50 nmol/L) and 6.4% were deficient (<25 nmol/L). 25(OH)D was positively correlated with vitamin D intake (µg/day) (p = 0.012, r = 0.374), spring/summer outdoor hours (p = 0.006, r = 0.402) and dominant grip strength (kg) (p = 0.044, r = 0.317). Vitamin D sufficient participants had higher dietary vitamin D intake (µg/day) (p = 0.021), supplement intake (µg/day) (p = 0.028) and spring/summer outdoor hours (p = 0.015). (4) Conclusion: Over half of the children were vitamin D deficient or insufficient. Wintertime supplementation, the consumption of vitamin D rich foods and spring/summer outdoor activities should be encouraged to minimise the risk of vitamin D inadequacy.

Pleiotropic actions of Vitamin D in composite musculoskeletal trauma

Composite tissue injuries are the result of high energy impacts caused by motor vehicle accidents, gunshot wounds or blasts. These are highly traumatic injuries characterized by wide-spread, penetrating wounds affecting the entire musculoskeletal system, and are generally defined by frank volumetric muscle loss with concomitant segmental bone defects. At the tissue level, the breadth of damage to multiple tissue systems, and potential for infection from penetration, have been shown to lead to an exaggerated, often chronic inflammatory response with subsequent dysregulation of normal musculoskeletal healing mechanisms. Aside from the direct effects of inflammation on myogenesis and osteogenesis, frank muscle loss has been shown to directly impair fracture union and ultimately contribute to failed wound regeneration. Care for these injuries requires extensive surgical intervention and acute care strategies. However, often these interventions do not adequately mitigate inflammation or promote proper musculoskeletal injury repair and force amputation of the limb. Therefore, identification of factors that can promote tissue regeneration and mitigate inflammation could be key to restoring wound healing after composite tissue injury. One such factor that may directly affect both inflammation and tissue regeneration in response to these multi-tissue injuries may be Vitamin D. Beyond traditional roles, the pleiotropic and localized actions of Vitamin D are increasingly being recognized in most aspects of wound healing in complex tissue injuries - e.g., regulation of inflammation, myogenesis, fracture callus mineralization and remodeling. Conversely, pre-existing Vitamin D deficiency leads to musculoskeletal dysfunction, increased fracture risk or fracture non-unions, decreased strength/function and reduced capacity to heal wounds through increased inflammation. This Vitamin D deficient state requires acute supplementation in order to quickly restore circulating levels to an optimal level, thereby facilitating a robust wound healing response. Herein, the purpose of this review is to address the roles and critical functions of Vitamin D throughout the wound healing process. Findings from this review suggest that careful monitoring and/or supplementation of Vitamin D may be critical for wound regeneration in composite tissue injuries.

Effects of a multinutrient-fortified milk drink combined with exercise on functional performance, muscle strength, body composition, inflammation, and oxidative stress in middle-aged women: a 4-month, double-blind, placebo-controlled, randomized trial

BACKGROUND

Multinutrient protein-enriched supplements are promoted to augment the effects of exercise on muscle mass and strength, but their effectiveness in middle-aged women, or whether there are any additional benefits to physical function, remains uncertain.

OBJECTIVES

We aimed to evaluate whether a multinutrient-fortified milk drink (MFMD) could enhance the effects of exercise on functional muscle power (stair climbing) in middle-aged women. Secondary aims were to evaluate the intervention effects on physical function, muscle strength, lean mass (LM), fat mass (FM), bone mineral content (BMC), muscle cross-sectional area (CSA), muscle density, balance, flexibility, aerobic fitness, inflammation, oxidative stress, bone and cartilage turnover, blood pressure, and blood lipids.

METHODS

In this 4-mo, double-blind, placebo-controlled, randomized trial, 244 women (45-65 y) participated in a multimodal resistance-type exercise program 3 d/wk, with random allocation to a twice-daily MFMD containing added protein, vitamin D, calcium, milk fat globule membrane (phospholipids and other bioactives), and other micronutrients (Ex + MFMD, n = 123) or an energy-matched placebo (Ex + placebo, n = 121).

RESULTS

A total of 216 women (89%) completed the study. After 4 mo, both groups experienced similar 3.6%-4.3% improvements in the primary outcomes of fast-pace 5- and 10-step stair ascent power. In contrast, Ex + MFMD experienced greater improvements in 5-step regular-pace stair descent time [net difference (95% CI): -0.09 s (-0.18, 0.00 s), P = 0.045], countermovement jump height [0.5 cm (0.04, 1.0 cm), P = 0.038], total body LM [0.3 kg (0.04, 0.60 kg), P = 0.020], FM [-0.6 kg (-1.0, -0.2 kg), P = 0.004], BMC [0.4% (0.1%, 0.6%), P = 0.020], muscle CSA [thigh: 1.8% (0.6%, 2.9%), P = 0.003; lower leg: 0.9% (0.3%, 1.6%), P = 0.005], balance eyes closed [3.3 s (1.1, 5.4 s), P = 0.005], 2-min step performance [8 steps (3, 12 steps), P = 0.003], and sit-and-reach flexibility [1.4 cm (0.6, 2.2 cm), P = 0.026]. MFMD did not enhance the effects of exercise on any measures of muscle strength, gait speed, dynamic balance, reaction time, or blood lipids, and there was no effect of either intervention on blood pressure, markers of inflammation, or cartilage turnover. Ex + placebo had a greater improvement in the oxidative stress marker protein carbonyls (P < 0.01).

CONCLUSIONS

In middle-aged women, daily consumption of an MFMD did not enhance the effects of a multimodal exercise program on the primary outcome of stair climbing ascent power, but did elicit greater improvements in multiple secondary outcomes including various other measures of functional performance, LM, muscle size, FM, balance, aerobic capacity, flexibility, and bone metabolism.This trial was registered at www.anzctr.org.au as ACTRN12617000383369.

Efficacy of Vitamin D Supplementation in Physical Performance of Iranian Elite Athletes

Background:

There has been no report of the vitamin D status of the professional athletes from Iran to date. This study was performed to evaluate the efficacy of weekly vitamin D supplementation on athletic performance in Iranian athletes expedited to Asian competition in Taipei, China, 2015.

Methods:

This study was a randomized controlled clinical trial. Seventy subjects were enrolled in the study. The athletes were randomly divided into two groups: vitamin D supplement (D; received 50,000 IU of vitamin D supplement weekly) and control (P, received a placebo weekly). Duration of the study was 8 weeks. Anthropometric, dietary, athletic performance, and biochemical evaluations were performed for all subjects in the beginning and in the end of the intervention period.

Results:

A significant rise in circulating 25(OH)D concentration was observed in D group (17.3 ± 16.9 ng/mL, P < 0.001), whereas in P group, there was a statistically significant decrement (−3.1 ± 8.4 ng/mL, P = 0.040). There were no either within- or between-group significant differences in Ergo jump, vertical jump, and agility tests. In strength leg press tests, both groups showed a significant improvement. However, comparisons of changes revealed that the improvement in D group was significantly higher than in P group (P = 0.034). Moreover, in sprint test (one repetition-Max, 1RM), only D group had a significant within-group improvement (P = 0.030).

Conclusions:

Weekly supplementation with 50,000 IU vitamin D resulted in nearly 17 ng/mL increment in circulating calcidiol. This increase was associated with significant improvement of power leg press and sprint tests in D-supplemented group.

High prevalence of vitamin D insufficiency in professional handball athletes

OBJECTIVES

Vitamin D affects multiple body functions through the regulation of gene expression. In sports medicine, its influence on musculoskeletal health and performance is of particular interest. Vitamin D insufficiency might decrease athletic performance and increase the risk of musculoskeletal injuries. Several studies have demonstrated vitamin D deficiency in professional athletes; however, the prevalence of vitamin D insufficiency in professional handball players is yet unknown.

METHODS

The study was planned as a prospective, non-interventional study. We examined 70 male elite handball athletes (first league) in a pre-competition medical assessment in July. Age, height, weight, body mass index, 25-OH vitamin D, calcium, and parathyroid hormone were evaluated, and a sun exposure score was calculated. Players were then divided into two groups of vitamin D levels: insufficient (<30 ng/mL) and sufficient (≥30 ng/mL).

RESULTS

The mean 25-OH vitamin D level of the 70 players was 33.5 ± 10.9 ng/mL (median 32.2, IQR 26.5-38.9 ng/mL). Thirty-nine (55.7%) had sufficient and 31 (44.3%) insufficient levels. Athletes with sufficient vitamin D levels had significantly lower parathyroid hormone levels than athletes with insufficiency (24.9 ± 12.1 vs. 33.5 ± 15.1 ng/mL, p = 0.02). All other parameters evaluated demonstrated no significant difference between the two groups.

CONCLUSION

Vitamin D insufficiency is a common finding in professional handball athletes even in summer, which might negatively affect physical performance. Furthermore, it might lead to an increased risk of musculoskeletal injuries and infections. This should be evaluated in further studies.

Serum 25-hydroxyvitamin D levels and incident falls in older women

Three hundred eighty-seven home-dwelling older women were divided into quartiles based on mean serum 25-hydroxyvitamin D (S-25(OH)D) levels. The rates of falls and fallers were about 40% lower in the highest S-25(OH)D quartile compared to the lowest despite no differences in physical functioning, suggesting that S-25(OH)D levels may modulate individual fall risk.

INTRODUCTION

Vitamin D supplementation of 800 IU did not reduce falls in our previous 2-year vitamin D and exercise RCT in 70-80 year old women. Given large individual variation in individual responses, we assessed here effects of S-25(OH)D levels on fall incidence.

METHODS

Irrespective of original group allocation, data from 387 women were explored in quartiles by mean S-25(OH)D levels over 6-24 months; means (SD) were 59.3 (7.2), 74.5 (3.3), 85.7 (3.5), and 105.3 (10.9) nmol/L. Falls were recorded monthly with diaries. Physical functioning and bone density were assessed annually. Negative binomial regression was used to assess incidence rate ratios (IRRs) for falls and Cox-regression to assess hazard ratios (HR) for fallers. Generalized linear models were used to test between-quartile differences in physical functioning and bone density with the lowest quartile as reference.

RESULTS

There were 37% fewer falls in the highest quartile, while the two middle quartiles did not differ from reference. The respective IRRs (95% CI) for falls were 0.63 (0.44 to 0.90), 0.78 (0.55 to 1.10), and 0.87 (0.62 to 1.22), indicating lower falls incidence with increasing mean S-25(OH)D levels. There were 42% fewer fallers (HR 0.58; 040 to 0.83) in the highest quartile compared to reference. Physical functioning did not differ between quartiles.

CONCLUSIONS

Falls and faller rates were about 40% lower in the highest S-25(OH)D quartile despite similar physical functioning in all quartiles. Prevalent S-25(OH)D levels may influence individual fall risk. Individual responses to vitamin D treatment should be considered in falls prevention.

Effects of activated vitamin D, alfacalcidol, and low-intensity aerobic exercise on osteopenia and muscle atrophy in type 2 diabetes mellitus model rats

Diabetes mellitus causes secondary osteoporosis and muscle atrophy. The ability of alfacalcidol (ALF) and exercise (Exe) to inhibit osteoporosis and muscle atrophy in type 2 diabetes mellitus (T2DM) model rats was examined. Twenty-week-old Otsuka Long-Evans Tokushima Fatty rats were randomized to ALF (orally 0.1 μg/kg/day), Exe (treadmill exercise at 10 m/min, 60 min/day, 5 days/week), Comb (ALF and Exe), and Cont (T2DM control treated with vehicle and no exercise) groups (n = 8–10 per group). Sedentary Long-Evans Tokushima Otsuka rats were used as a non-hyperphagic control. After treatment for 2 or 6 weeks, blood glucose (BG) levels, cross-sectional area (CSA) of tibialis anterior muscle fibers, femoral bone mineral density (BMD), and relative quantities of muscle anabolic markers (Pax7, MyoD, and myogenin) and catabolic markers (Atrogin-1, MuRF1, and REDD1) of the soleus muscle assessed by real-time polymerase chain reaction assays were measured. Exe and Comb treatments for 6 weeks decreased BG levels compared with those of the Cont group. ALF, Exe, and Comb treatments for 2 and 6 weeks recovered the CSA compared with that of the Cont group. ALF and Comb treatments for 6 weeks increased femoral BMDs compared with those of the Cont group. After 2 weeks of treatment, Comb treatment increased MyoD expression and decreased MuRF1 expression. ALF or Exe monotherapy significantly decreased Atrogin-1 or MuRF1 expression after 2 weeks of treatment, respectively. After 6 weeks of treatment, ALF and Comb treatments decreased Atrogin-1 and REDD1. These results demonstrate that a combination of ALF and Exe improved CSA from the early phase of treatment by stimulating skeletal muscle differentiation and suppressing muscle catabolic genes. Improvements in BG, BMD, and CSA were observed as long-term effects of the combination therapy. Continued suppression of muscle catabolic genes was observed as a background to these effects.

Association Between Preoperative Vitamin D Status and Short-Term Physical Performance after Total Hip Arthroplasty: A Prospective Study

BACKGROUND

Insufficient serum vitamin D concentrations (50-75 nmol/L) are prevalent in 40-65% of patients who require total hip arthroplasty (THA). This could impair physical recovery after surgery. This study investigated the association between preoperative vitamin D status and physical performance after THA. Additionally, postoperative changes in vitamin D concentrations were measured.

METHODS

We included 87 patients scheduled for elective THA and aged ≥65 years. Three groups were recruited: patients classified as vitamin D deficient (< 50 nmol/L, n = 23), insufficient (50-75 nmol/L, n = 32), or sufficient (> 75 nmol/L, n = 32). Serum 25-hydroxyvitamin D3 (25[OH]D3) concentration and physical performance were measured perioperatively. Linear mixed models were used to examine differences between groups.

RESULTS

Change in physical performance over time was not affected by preoperative vitamin D status. In contrast, for physical activity, both vitamin D (p = 0.021) and time (p < 0.001) effect was seen: from 80.2 ± 25.8 to 58.1 ± 17.8 min/day in the deficient group, 143.7 ± 19.8 to 92.9 ± 11.5 min/day in the insufficient group, and 108.1 ± 20.9 to 62.3 ± 12.9 min/day in the sufficient group. The Chair Stand Test, Timed Up and Go test, and 10-Meter Walking Test also improved significantly over time, but independent of vitamin D status. An increase in 25(OH)D3 concentration 6 weeks postoperatively was correlated with improved hip function (Pearson's r = -0.471, p = 0.018). Overall, serum 25(OH)D3 declined with 32% one day after surgery (p < 0.001), to nearly return to baseline values 6 weeks later in all groups.

CONCLUSION

Vitamin D status did not appear to affect physical recovery after THA. The drop in vitamin D after surgery deserves further investigation, but could possibly be explained by hemodilution.

Higher dietary intake of vitamin D may influence total cholesterol and carbohydrate profile independent of body composition in men with Chronic Spinal Cord Injury

STUDY DESIGN

A case-control design.

OBJECTIVES

To determine the effects of dietary vitamin D intake on insulin sensitivity (Si), glucose effectiveness (Sg), and lipid profile in individuals with spinal cord injury (SCI).

METHODS

20 male, paraplegic (T3-L1) with chronic (> one year) motor complete SCI (AIS A or B) were recruited. Three-day dietary records were analyzed for dietary vitamin D (calciferol), and participants were assigned to one of two groups, a high vitamin D intake group and a low vitamin D intake group based on the mid-point of vitamin D frequency distribution. Individuals in both groups were matched based on age, weight, time since injury and level of injury. Sg, Si and lipid profiles were measured of the two groups.

RESULTS

The high vitamin D group had an average intake of 5.33 ± 4.14 mcg compared to low vitamin D group, 0.74 ± 0.24 mcg. None of the 20 participants met the recommended guidelines for daily vitamin D intake. The higher vitamin D group had a significantly lower (P = 0.035) total cholesterol (148.00 ± 14.12 mg/dl) than the lower vitamin D group (171.80 ± 36.22 mg/dl). Vitamin D adjusted to total dietary intake was positively correlated to improvement in Si and Sg (P<0.05).

CONCLUSION

The findings suggest that persons with SCI consume much less than the recommended guidelines for daily vitamin D intake. However, a higher dietary intake of vitamin D may influence total cholesterol and carbohydrate profile as demonstrated by a significant decrease in total cholesterol and improvement in glucose homeostasis independent of body composition changes after SCI.

A role for nutritional intervention in addressing the aging neuromuscular junction

The purpose of this review is to discuss the structural and physiological changes that underlie age-related neuromuscular dysfunction and to summarize current evidence on the potential role of nutritional interventions on neuromuscular dysfunction-associated pathways. Age-related neuromuscular deficits are known to coincide with distinct changes in the central and peripheral nervous system, in the neuromuscular system, and systemically. Although many features contribute to the age-related decline in neuromuscular function, a comprehensive understanding of their integration and temporal relationship is needed. Nonetheless, many nutrients and ingredients show promise in modulating neuromuscular output by counteracting the age-related changes that coincide with neuromuscular dysfunction. In particular, dietary supplements, such as vitamin D, omega-3 fatty acids, β-hydroxy-β-methylbutyrate, creatine, and dietary phospholipids, demonstrate potential in ameliorating age-related neuromuscular dysfunction. However, current evidence seldom directly assesses neuromuscular outcomes and is not always in the context of aging. Additional clinical research studies are needed to confirm the benefits of dietary supplements on neuromuscular function, as well as to define the appropriate population, dosage, and duration for intervention.

A 2-Year Follow-Up After a 2-Year RCT with Vitamin D and Exercise: Effects on Falls, Injurious Falls and Physical Functioning Among Older Women

Background

Both exercise and vitamin D are recommended means to prevent falls among older adults, but their combined effects on fall-induced injuries are scarcely studied.

Methods

A 2-year follow-up of a previous 2-year randomized controlled trial with vitamin D and exercise (Ex) of 409 older home-dwelling women using a factorial 2 × 2 design (D⁻Ex⁻, D⁺Ex⁻, D⁻Ex⁺, D⁺Ex⁺). Besides monthly fall diaries, femoral neck bone mineral density (fn-BMD), and physical functioning were assessed at 1 and 2 years after the intervention.

Results

After the intervention, S-25OHD concentrations declined to baseline levels in both supplement groups. The groups did not differ for change in fn-BMD or physical functioning, except for leg extensor muscle strength, which remained about 10% greater in the exercise groups compared with the reference group (D⁻Ex⁻). There were no between-group differences in the rate of all falls, but medically attended injurious falls reduced in D⁺Ex⁻ and D⁻Ex⁺ groups compared with D⁻Ex⁻. However, all former treatment groups had less medically attended injured fallers, HRs (95% CI) being 0.62 (0.39–1.00) for D⁺Ex⁻, 0.46 (0.28–0.76) for D⁻Ex⁺, and 0.55 (0.34–0.88) for D⁺Ex⁺, compared with D⁻Ex⁻.

Conclusions

Exercise-induced benefits in physical functioning partly remained 2 years after cessation of supervised training. Although there was no difference in the rate of all falls, former exercise groups continued to have lower rate of medically attended injured fallers compared with referents even 2 years after the intervention. Vitamin D without exercise was associated with less injurious falls with no difference in physical functioning.

The effect of combined resistance exercise training and vitamin D3 supplementation on musculoskeletal health and function in older adults: a systematic review and meta-analysis

OBJECTIVES

In older adults, there is a blunted responsiveness to resistance training and reduced muscle hypertrophy compared with younger adults. There is evidence that both exercise training and vitamin D supplementation may benefit musculoskeletal health in older adults, and it is plausible that in combination their effects may be additive. The aim of this systematic review was to evaluate the effectiveness of combined resistance exercise training and vitamin D₃ supplementation on musculoskeletal health in older adults.

DATA SOURCES

A comprehensive search of electronic databases, including Science Direct, Medline, PubMed, Google Scholar and Cochrane Central Register of Controlled Trials (Cochrane CENTRAL accessed by Wiley Science) was conducted. Eligible studies were randomised controlled trials including men and women (aged ≥65 years or mean age ≥65 years); enlisting resistance exercise training and vitamin D₃ supplementation; including outcomes of muscle strength, function, muscle power, body composition, serum vitamin D/calcium status or quality of life comparing results with a control group. The review was informed by a preregistered protocol (http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42015020157).

RESULTS

Seven studies including a total of 792 participants were identified. Studies were categorised into two groups; group 1 compared vitamin D₃ supplementation and exercise training versus exercise alone (describing the additive effect of vitamin D₃ supplementation when combined with resistance exercise training) and group 2 compared vitamin D₃ supplementation and exercise training versus vitamin D₃ supplementation alone (describing the additive effect of resistance exercise training when combined with vitamin D₃ supplementation).Meta-analyses for group 1 found muscle strength of the lower limb to be significantly improved within the intervention group (0.98, 95% CI 0.73 to 1.24, p<0.001); all other outcomes showed small but non-significant positive effects for the intervention group. The short physical performance battery (SPPB), timed up and go (TUG), muscle strength of the lower limb and femoral neck bone mineral density showed significantly greater improvements in the intervention group for group 2 comparisons.

CONCLUSIONS

This review provides tentative support for the additive effect of resistance exercise and vitamin D₃ supplementation for the improvement of muscle strength in older adults. For other functional variables, such as SPPB and TUG, no additional benefit beyond exercise was shown. Further evidence is required to draw firm conclusions or make explicit recommendations regarding combined exercise and vitamin D₃ supplementation.

Vitamin D in amyotrophic lateral sclerosis

Vitamin D supplementation has been proposed as a potential treatment to delay amyotrophic lateral sclerosis (ALS) progression. The aims of this study were to compare retrospectively vitamin D blood levels in ALS patients with those in healthy subjects; to correlate vitamin D blood levels with clinical functions in patients; and to evaluate whether administration of vitamin D could modify the clinical progression of the disease. Vitamin D blood levels were evaluated in 57ALS patients and in 57 healthy subjects. In the ALS patients the following clinical variables were evaluated every 3 months: Medical Research Council scale (MRC) score; revised ALS functional rating scale (ALSFRS-R) score; forced vital capacity (FVC). Twentyfour patients were treated with high doses of cholecalciferol. No significant differences were found between the vitamin D blood levels in the ALS patients (18.8 ± 12.2) and the healthy subjects (20.7 ± 10.1). The vitamin D levels in the ALS patientsdid not correlate with recorded clinical parameters. No clinical differences in terms of ALSFRS-R, MRC or FVC were found between the treated and the untreated patients over time. In ALS, as in other chronic neurological diseases, levels of vitamin D in blood appeared reduced, but no difference was found between the levels in ALS patients and in healthy subjects. Oral vitamin D supplementation in ALS patients was not associated with better prognosis in comparison with untreated ALS patients. Further prospective controlled studies are needed to clarify the effect of vitamin D on the progression of ALS disease.