A randomized study on the effect of vitamin D₃ supplementation on skeletal muscle morphology and vitamin D receptor concentration in older women. A randomized, controlled trial of vitamin D supplementation upon musculoskeletal health in postmenarchal females. The effects of whole-body vibration training and vitamin D supplementation on muscle strength, muscle mass, and bone density in institutionalized elderly women: a 6-month randomized, controlled trial. The effect of vitamin D2 supplementation on muscle strength in early postmenopausal women: a randomized, double-blind, placebo-controlled trial Vitamin D3 supplementation using an oral spray solution resolves deficiency but has no effect on VO2 max in Gaelic footballers: results from a randomised, double-blind, placebo-controlled trial Influence of vitamin D mushroom powder supplementation on exercise-induced muscle damage in vitamin D insufficient high school athletes Vitamin D2 Supplementation Amplifies Eccentric Exercise-Induced Muscle Damage in NASCAR Pit Crew Athletes The effects of vitamin D3 supplementation on serum total 25[OH]D concentration and physical performance: a randomised dose–response study Effects of Vitamin D3 Supplementation on Muscle Strength, Mass, and Physical Performance in Women with Vitamin D Insufficiency: A Randomized Placebo-Controlled Trial A randomized controlled trial of the effects of vitamin D on muscle strength and mobility in older women with vitamin D insufficiency. Effect of vitamin D supplementation alone on muscle function in postmenopausal women: a randomized, double-blind, placebo-controlled clinical trial Vitamin D supplementation during rehabilitation in COPD: a secondary analysis of a randomized trial The influence of winter vitamin D supplementation on muscle function and injury occurrence in elite ballet dancers: a controlled study. The impact of vitamin D3 supplementation on muscle function among HIV-infected children and young adults: a randomized controlled trial Treatment of Vitamin D Deficiency Increases Lower Limb Muscle Strength in Institutionalized Older People Independently of Regular Physical Activity: A Randomized Double-Blind Controlled Trial Low-Dose Vitamin D Prevents Muscular Atrophy and Reduces Falls and Hip Fractures in Women after Stroke: A Randomized Controlled Trial Vitamin D supplementation improves neuromuscular function in older people who fall.
CONTEXT Studies examining whether vitamin D supplementation increases muscle mass or muscle-specific vitamin D receptor ( VDR ) concentration are lacking . OBJECTIVE Our objective was to determine whether vitamin D₃ 4000 IU/d alters muscle fiber cross-sectional area ( FCSA ) and intramyonuclear VDR concentration over 4 months . DESIGN AND SETTING This was a r and omized , double-blind , placebo-controlled study in a single center . PARTICIPANTS Participants were 21 mobility-limited women ( aged ≥ 65 years ) with serum 25-hydroxyvitamin D ( 25OHD ) levels of 22.5 to 60 nmol/L. MAIN OUTCOME MEASURES Baseline and 4-month FCSA and intramyonuclear VDR were measured from vastus lateralis muscle cross-sections probed for muscle fiber type ( I/IIa/IIx ) and VDR using immunofluorescence . RESULTS At baseline , mean ( ±SD ) age was 78 ± 5 years ; body mass index was 27 ± 5 kg/m² , 25OHD was 46.3 ± 9.5 nmol/L , and  a short physical performance battery score was 7.95 ± 1.57 out of 12 . At 4 months , 25OHD level was 52.5 ± 17.1 ( placebo ) vs 80.0 ± 11.5 nmol/L ( vitamin D [ VD ] ; P < .01 ) , and change in 25OHD level was strongly associated with percent change in intramyonuclear VDR concentration-independent of group ( r = 0.87 , P < .001 ) . By treatment group , percent change in intramyonuclear VDR concentration was 7.8 % ± 18.2 % ( placebo ) vs 29.7 % ± 11.7 % ( VD ; P = .03 ) with a more pronounced group difference in type II vs I fibers . Percent change in total ( type I/II ) FCSA was -7.4 % ± 18.9 % ( placebo ) vs 10.6 % ± 20.0 % ( VD ; P = .048 ) . CONCLUSION Vitamin D₃ supplementation  increased intramyonuclear VDR concentration by 30 % and increased muscle fiber size by 10 % in older , mobility-limited , vitamin D-insufficient women . Further work is needed to determine whether the observed effect of vitamin D on fiber size is mediated by the VDR and to identify which signaling pathways are involved CONTEXT There has been a resurgence of vitamin D deficiency rickets throughout the developed world , with infants and adolescents being primarily affected . Adolescence is a crucial period for muscle and bone mineral accumulation . OBJECTIVE The aim was to determine the effect of vitamin D supplementation on the adolescent musculoskeletal system . DESIGN AND SETTING We conducted a community-based , double-blind , r and omized controlled trial in a secondary school . PARTICIPANTS Postmenarchal 12- to 14-yr-old females participated in the trial . Ninety-nine were screened , 73 were included in r and omized controlled trial , and 69 completed the trial . There were no adverse events . INTERVENTION Four doses of 150,000 IU vitamin D(2 ) ( ergocalciferol ) were given over 1 yr . MAIN OUTCOME MEASURES Dual-energy x-ray absorptiometry , peripheral quantitative computed tomography , and jumping mechanography were used . RESULTS At follow-up , 25-hydroxyvitamin D [ 25(OH)D ] status was 56.0 ± 8.9 nmol/liter in the intervention group and 15.8 ± 6.6 nmol/liter in controls . There were no effects of supplementation on bone ; however , for muscle function , efficiency of movement improved in the vitamin D-treated group . There was an interaction between baseline 25(OH)D concentration and response to vitamin D supplementation for muscle jump velocity . CONCLUSIONS Despite improvements in 25(OH)D status , treatment with vitamin D(2 ) was not shown to increase mineral accretion , bone geometry or strength , muscle force , or power . There were greater increases in jump velocity in girls with the lowest baseline 25(OH)D concentrations . Lack of effect of intervention after the period of peak mineral and muscle mass accretion suggests that earlier action is required Sarcopenia and osteoporosis represent a growing public health problem . We studied the potential benefit of whole-body vibration ( WBV ) training given a conventional or a high dose of daily vitamin D supplementation in improving strength , muscle mass , and bone density in postmenopausal women . In a 2 × 2 factorial- design trial , 113 institutionalized elderly females aged over 70 years ( mean age 79.6 years ) were r and omly assigned either to a WBV or a no-training group , receiving either a conventional dose ( 880 IU/day ) or a high dose ( 1600 IU/day ) of vitamin D(3 ) . The primary aim was to determine the effects of 6 months of WBV and /or vitamin D supplementation on isometric and dynamic strength , leg muscle mass , and hip bone mineral density ( BMD ) . Additionally , the increase in 25-hydroxyvitamin D [ 25(OH)D ] levels between conventional and high-dose supplementation was compared . After 6 months of treatment , dynamic muscle strength , hip BMD , and vitamin D serum levels improved significantly in all groups , whereas isometric strength and muscle mass did not change . When compared with no training , the WBV program did not result in additional improvements . When compared with 880 IU , a high dose of 1600 IU of vitamin D did result in higher serum vitamin D levels but did not result in additional improvements . In institutionalized women older than 70 years , the WBV training protocol tested is not more efficient in enhancing muscle mass , strength , and hip BMD compared with vitamin D supplementation . A higher dose of 1600 IU of vitamin D does not provide additional musculoskeletal benefit in this population compared with conventional doses Abstract Background : Low serum 25-hydroxyvitamin D [ 25(OH)D ] has been shown to be associated with low muscle mass and loss of muscle strength , result ing in increased disability and frailty in older men and women . Vitamin D deficiency is common in postmenopausal women . The primary objective of the present study was to evaluate the effects of vitamin D supplementation on muscle strength in early postmenopausal women . The effects of vitamin D2 supplementation on muscle mass and muscle cross-sectional area ( CSA ) were secondarily investigated . Methods : A 12-week , prospect i ve , r and omized , double-blind , placebo-controlled trial was conducted in early postmenopausal women ( 45–60 years old ) with vitamin D deficiency ( serum 25(OH)D < 20 ng/ml ) . A total of 88 subjects were r and omized into group I : vitamin D2 supplement 40 000 IU/week ( n = 44 ) , or group II : placebo ( n = 44 ) . Serum 25(OH)D level , muscle strength , muscle mass and muscle CSA were assessed at baseline and 12 weeks after the supplementation . Results : After 12 weeks of supplementation , 70 % of women in group I achieved a sufficient level of serum 25(OH)D ( > 30 ng/ml ) . There were significant differences in changes of serum 25(OH)D levels between the two groups ( p < 0.05 ) . Muscle strength and muscle CSA in group I increased significantly after 12 weeks ( p = 0.015 , 0.045 , respectively ) . However , there were no significant differences in the mean changes of muscle strength , muscle mass and muscle CSA between the two groups ( p = 0.16 , 0.89 , 0.84 , respectively ) . Conclusion : In this study , we found no obvious effect of vitamin D supplementation on the changes in muscle strength , muscle mass and muscle CSA when compared to placebo . However , there were significant changes in muscle strength and muscle CSA from baseline in the vitamin D supplementation group Purpose Vitamin D inadequacy is a global health concern in athletes as well as the general population . Whilst the role of vitamin D in skeletal health is well defined , there remains uncertainty over whether vitamin D supplementation has an added benefit beyond bone health . Methods This r and omised placebo-controlled trial in healthy male and female Gaelic footballers ( n = 42 ) investigated the effect of vitamin D3 supplementation [ 3000 IU ( 75 µg ) daily for 12 weeks , via an oral spray solution ] on VO2 max which was the primary outcome measure . Secondary outcomes included skeletal muscle and lung function . Results Supplementation significantly increased total 25-hydroxyvitamin D concentrations compared to the placebo group ( mean ± SD change from baseline , 36.31 ± 32.34 vs. 6.11 ± 23.93 nmol/L , respectively ; P = 0.006 ) . At baseline , 50 and 22 % of footballers presented with vitamin D insufficiency ( 31–49 nmol/L ) and deficiency ( < 30 nmol/L ) , respectively . Total 25-hydroxyvitamin D concentration did not significantly correlate with any measure of physical performance . Analysis of covariance ( ANCOVA ) models demonstrated that vitamin D supplementation over 12 weeks had no significant effect on VO2 max ( P = 0.375 ) , vertical jump height ( P = 0.797 ) , left and right h and grip strength ( P = 0.146 and P = 0.266 , respectively ) , forced vital capacity ( P = 0.573 ) or forced expiratory volume at 1 s ( P = 0.665 ) , after adjusting for confounders . The high prevalence of vitamin D inadequacy observed in this cohort of collegiate Gaelic footballers supports the need for vitamin D supplementation during wintertime to avoid being at risk of poor bone health . Conclusions Twelve-week daily supplementation with 3000 IU ( 75 µg ) vitamin D3 successfully resolved deficiency but did not have any significant effect on VO2 max , skeletal muscle or lung function Abstract Incidence of vitamin D deficiency is increasing worldwide . The purpose of this study was to determine if supplementation with vitamin D2 from Portobello mushroom powder would enhance skeletal muscle function and attenuate exercise-induced muscle damage in low vitamin D status high school athletes . Participants were r and omised to Portobello mushroom powder ( 600 IU/d vitamin D2 ) or placebo for 6 weeks . Participants then completed a 1.5-h exercise session design ed to induce skeletal muscle damage . Blood sample s and measures of skeletal muscle function were taken pre-supplementation , post-supplementation/pre-exercise and post-exercise . Six weeks supplementation with vitamin D2 increased serum 25(OH)D2 by 9.9-fold and decreased serum 25(OH)D3 by 28 % . Changes in skeletal muscle function and circulating markers of skeletal muscle damage did not differ between groups . In conclusion , 600 IU/d vitamin D2 increased 25(OH)D2 with a concomitant decrease in 25(OD)D3 , with no effect on muscular function or exercise-induced muscle damage in high school athletes This study determined if 6-weeks vitamin D2 supplementation ( vitD2 , 3800 IU/day ) had an influence on muscle function , eccentric exercise-induced muscle damage ( EIMD ) , and delayed onset of muscle soreness ( DOMS ) in National Association for Stock Car Auto Racing ( NASCAR ) NASCAR pit crew athletes . Subjects were r and omized to vitD2 ( n = 13 ) and placebo ( n = 15 ) , and ingested supplements ( double-blind ) for six weeks . Blood sample s were collected and muscle function tests conducted pre- and post- study ( leg-back and h and grip dynamometer strength tests , body weight bench press to exhaustion , vertical jump , 30-s Wingate test ) . Post- study , subjects engaged in 90 min eccentric-based exercise , with blood sample s and DOMS ratings obtained immediately after and 1- and 2-days post-exercise . Six weeks vitD2 increased serum 25(OH)D2 456 % and decreased 25(OH)D3 21 % versus placebo ( p < 0.001 , p = 0.036 , respectively ) , with no influence on muscle function test scores . The post- study eccentric exercise bout induced EIMD and DOMS , with higher muscle damage biomarkers measured in vitD2 compared to placebo ( myoglobin 252 % , 122 % increase , respectively , p = 0.001 ; creatine phosphokinase 24 h post-exercise , 169 % , 32 % , p < 0.001 ) , with no differences for DOMS . In summary , 6-weeks vitD2 ( 3800 IU/day ) significantly increased 25(OH)D2 and decreased 25(OH)D3 , had no effect on muscle function tests , and amplified muscle damage markers in NASCAR pit crew athletes following eccentric exercise Background Vitamin D deficiency is common in the general public and athletic population s and may impair skeletal muscle function . We therefore assessed the effects of vitamin D3 supplementation on serum 25[OH]D concentrations and physical performance . Methods 30 club-level athletes were block r and omised ( using baseline 25[OH]D concentrations ) into one of three groups receiving either a placebo ( PLB ) , 20 000 or 40 000 IU/week oral vitamin D3 for 12 weeks . Serum 25[OH]D and muscle function ( 1-RM bench press and leg press and vertical jump height ) were measured presupplementation , 6 and 12 weeks postsupplementation . Vitamin D deficiency was defined in accordance with the US Institute of Medicine guideline ( < 50 nmol/l ) . Results 57 % of the subject population were vitamin D deficient at baseline ( mean±SD value 51±24 nmol/l ) . Following 6 and 12 weeks supplementation with 20 000 IU ( 79±14 and 85±10 nmol/l , respectively ) or 40 000 IU vitamin D3 ( 98±14 and 91±24 nmol/l , respectively ) , serum vitamin D concentrations increased in all participants , with every individual achieving concentrations greater than 50 nmol/l . In contrast , vitamin D concentration in the PLB group decreased at 6 and 12 weeks ( 37±18 and 41±22 nmol/l , respectively ) . Increasing serum 25[OH]D had no significant effect on any physical performance parameter ( p>0.05 ) . Conclusions Both 20 000 and 40 000 IU vitamin D3 supplementation over a 6-week period elevates serum 25[OH]D concentrations above 50 nmol/l , but neither dose given for 12 weeks improved our chosen measures of physical performance Vitamin D insufficiency and hyperparathyroidism have been associated with reduced muscle strength , physical performance , postural stability , well-being , and quality of life . In a double-blinded , r and omized placebo-controlled trial , we aim ed to investigate effects of vitamin D3 supplementation on above-mentioned outcomes in healthy community-dwelling postmenopausal women with plasma levels of 25-hydroxyvitamin D ( 25(OH)D ) below < 50 nmol/l and high parathyroid hormone ( PTH ) levels . Participants ( N = 81 ) were 1:1 treated with vitamin D3  , 70 µg ( 2800 IU)/day or identical placebo for three months during wintertime ( 56 ° N ) . Vitamin D3 supplementation  increased levels of 25(OH)D and 1,25(OH)2D by 230 % ( 95 % CI 189 to 272)% , p < 0.001 and 58 % ( 190 to 271 % ) , p < 0.001 , respectively , and reduced PTH by 17 % ( − 23 to − 11 % ) , p < 0.001 . Compared with placebo , vitamin D3 significantly reduced maximal h and grip strength by 9 % ( − 15 to − 3 % ; p < 0.01 ) and knee flexion strength by 13 % ( − 24 to − 2 % ; p = 0.02 ) and increased the time spent on performing the Timed Up and Go test by 4.4 % ; ( 0.1–8.6 % ; p < 0.05 ) . Levels of physical activity , total lean body mass , appendicular lean mass index , postural stability , well-being , and quality of life did not change in response to treatment . Compared with placebo , a daily supplement with a relatively high dose of vitamin D3 had no beneficial effects on any outcomes . In some measures of muscle strength and physical performance , we even saw a small unfavorable effect . Our data call for caution on use of relatively high daily doses of vitamin D3 in the treatment of vitamin D insufficiency OBJECTIVES To evaluate the effects of vitamin D treatment on muscle strength and mobility in older women with vitamin D insufficiency . DESIGN One-year population -based , double-blind , r and omized , controlled trial . SETTING Perth , Australia ( latitude 32 ° S ) . PARTICIPANTS Three hundred two community-dwelling ambulant elderly women aged 70 to 90 with a serum 25-hydroxyvitamin D ( 25(OH)D ) concentration less than 24 ng/mL. INTERVENTION Vitamin D(2 ) 1,000 IU/d or identical placebo ; calcium citrate ( 1 g calcium/d ) in both groups . MEASUREMENTS Lower limb muscle strength and mobility as assessed using the Timed Up and Go Test ( TUAG ) . RESULTS At baseline , mean ± st and ard deviation serum 25(OH)D was 17.7 ± 4.2 ng/mL ; this increased to 24.0 ± 5.6 ng/mL in the vitamin D group after 1 year but remained the same in the placebo group . For hip extensor and adductor strength and TUAG , but not for other muscle groups , a significant interaction between treatment group and baseline values was noted . In those with baseline values in the lowest tertile , vitamin D  improved muscle strength and TUAG more than calcium alone ( mean ( st and ard error ) : hip extensors 22.6 % ( 9.5 % ) ; hip adductors 13.5 % ( 6.7 % ) , TUAG 17.5 % ( 7.6 % ) , P < .05 ) . Baseline 25(OH)D levels did not influence patient response to supplementation . CONCLUSION Vitamin D therapy was observed to increase muscle function in those who were the weakest and slowest at baseline . Vitamin D should be given to people with insufficiency or deficiency to improve muscle strength and mobility Summary The present study investigates the effects of vitamin D on muscle function in postmenopausal women . It has been shown that vitamin D supplementation in postmenopausal women with hypovitaminosis D provides significant protective factor against sarcopenia , with significant increases in muscle strength and control of progressive loss of lean mass . Introduction We aim ed to evaluate the effect of supplementation of vitamin D ( VITD ) alone on muscle function in younger postmenopausal women . Methods In this double-blind , placebo-controlled clinical trial , 160 Brazilian postmenopausal women were r and omized into two groups : VITD group consisting of patients receiving vitamin D3 1000 IU/day orally ( n = 80 ) or placebo group ( n = 80 ) . Women with amenorrhea for more than 12 months and age 50–65 years , with a history of falls ( previous 12 months ) , were included . The intervention time was 9 months , with assessment s at two points , start and end . Lean mass was estimated by total-body dual-energy X-ray absorptiometry ( DXA ) and muscle strength by h and grip strength and chair rising test . The plasma concentrations of 25-hydroxyvitamin D [ 25(OH)D ] were measured by high-performance liquid chromatography ( HPLC ) . Statistical analysis was by intention to treat ( ITT ) , using ANOVA , Student ’s t test , and Tukey ’s test . Results After 9 months , average values of 25(OH)D increased from 15.0 ± 7.5 to 27.5 ± 10.4 ng/ml ( + 45.4 % ) in the VITD group and decreased from 16.9 ± 6.7 to 13.8 ± 6.0 ng/ml ( −18.5 % ) in the placebo group ( p < 0.001 ) . In the VITD group , there was significant increase in muscle strength ( + 25.3 % ) of the lower limbs by chair rising test ( p = 0.036 ) . In women in the placebo group , there was considerable loss ( −6.8 % ) in the lean mass ( p = 0.030 ) . Conclusion The supplementation of vitamin D alone in postmenopausal women provided significant protective factor against the occurrence of sarcopenia , with significant increases in muscle strength and control of progressive loss of lean mass Rationale Pulmonary rehabilitation is an important treatment for patients with Chronic Obstructive Pulmonary Disease , who are often vitamin D deficient . As vitamin D status is linked to skeletal muscle function , we aim ed to explore if high dose vitamin D supplementation can improve the outcomes of rehabilitation in Chronic Obstructive Pulmonary Disease . Material and methods This study is a post-hoc subgroup analysis of a larger r and omized trial comparing a monthly dose of 100.000 IU of vitamin D with placebo to reduce exacerbations . 50 Subjects who followed a rehabilitation program during the trial are included in this analysis . We report changes from baseline in muscle strength and exercise performance between both study arms after 3 months of rehabilitation . Results Vitamin D intervention result ed in significantly higher median vitamin D levels compared to placebo ( 51 [ 44 - 62 ] ng/ml vs 15 [ 13 - 30 ] ng/ml ; p < 0.001 ) . Patients receiving vitamin D had significantly larger improvements in inspiratory muscle strength ( -11±12 cmH2O vs 0±14 cmH2O ; p = 0.004 ) and maximal oxygen uptake ( 110±211 ml/min vs -20±187 ml/min ; p = 0.029 ) . Improvements in quadriceps strength ( 15±16 Nm ) or six minutes walking distance ( 40±55 meter ) were not significantly different from the effects in the placebo group ( 7±19 Nm and 11±74 meter ; p>0.050 ) . Conclusion High dose vitamin D supplementation during rehabilitation may have mild additional benefits to training OBJECTIVES Athletes who train indoors during the winter months exhibit low serum 25-hydroxyvitamin D [ 25(OH)D ] concentrations due to a lack of sunlight exposure . This has been linked to impaired exercise performance . The purpose of this study was to assess the effects of oral vitamin D₃ supplementation on selected physical fitness and injury parameters in elite ballet dancers . DESIGN Controlled prospect i ve study . METHODS 24 elite classical ballet dancers ( intervention n=17 ; control n=7 ) participated in a controlled 4-month oral supplementation of vitamin D₃ ( 2000 IU per day ) . Isometric muscular strength and vertical jump height were measured pre and post intervention . Injury occurrence during the intervention period was also recorded by the in-house medical team . Repeated measures ANOVA and Mann-Whitney-U statistical tests were used and significance was set at p ≤ 0.05 . RESULTS Significant increases were noted for the intervention group for isometric strength ( 18.7 % , p<0.01 ) and vertical jump ( 7.1 % , p<0.01 ) . The intervention group also sustained significantly less injuries than the controls during the study period ( p<0.01 ) . CONCLUSIONS Oral supplementation of vitamin D₃ during the winter months has beneficial effects on muscular performance and injury occurrence in elite ballet dancers Objectives : We tested the hypothesis that daily vitD3 supplementation increases neuromuscular motor skills , jump power , jump energy , muscular force , and muscular strength . Methods : This was a secondary analysis of a r and omized controlled trial of 12-months of oral 7,000 IU/day vitD3 supplementation or placebo among 56 persons living with HIV aged 9 - 25 years .  Neuromuscular motor skills were quantified using the Bruininks-Oseretsky Test of Motor Proficiency . Power was quantified using peak jump power , and energy was quantified using peak jump height . Muscular force was quantified using isometric ankle plantar- and dorsiflexion , isokinetic knee flexion and extension . Muscular strength was quantified using isometric h and grip strength . Results : After 12-months , serum 25-hydroxyvitamin D [ 25(OH)D ] was higher with supplementation versus placebo ( β=12.1 ng/mL ; P<0.001 ) . In intention-to-treat analyses , supplementation improved neuromuscular motor skills  versus placebo ( β=1.14 ; P=0.041 ) . We observed no effect of supplementation on jump power , jump energy , muscular force , or muscular strength outcomes versus placebo . Conclusions : Among HIV-infected children and young adults supplementation with daily high-dose vitD3 increased concentration of serum 25(OH)D and improved neuromuscular motor skills versus placebo Aims : To investigate the effects of a 6-month supplementation with calcium and cholecalciferol on biochemical parameters and muscle strength of institutionalized elderly . Methods : This prospect i ve , double-blind , placebo-controlled , r and omized trial included Brazilian institutionalized people ≥60 years of age receiving a 6-month supplementation ( December to May ) of daily calcium plus monthly placebo ( calcium/placebo group ) or daily calcium plus oral cholecalciferol ( 150,000 IU once a month during the first 2 months , followed by 90,000 IU once a month for the last 4 months ; calcium/vitamin D group ) . Fasting blood sample s for 25(OH)D , PTH and calcium determination were collected ( n = 56 ) and muscle tests were performed ( n = 46 ) to measure the strength of hip flexors ( SHF ) and knee extensors ( SKE ) before ( baseline ) and after the 6-month intervention ( 6 months ) . Results : Due to seasonal variations , serum 25(OH)D significantly enhanced in both groups after treatment , but the calcium/vitamin D group had significantly higher 25 (OH)D levels than the calcium/placebo group ( 84 vs. 33 % , respectively ; p < 0.0001 ) . No cases of hypercalcemia were observed . While the calcium/placebo group showed no improvement in SHF and SKE at 6 months ( p = 0.93 and p = 0.61 , respectively ) , SHF was increased in the calcium/vitamin D group by 16.4 % ( p = 0.0001 ) and SKE by 24.6 % ( p = 0.0007 ) . Conclusions : The suggested cholecalciferol supplementation was safe and efficient in enhancing 25(OH)D levels and lower limb muscle strength in the elderly , in the absence of any regular physical exercise practice OBJECTIVE Vitamin D supplementation is suggested to reduce the risk of falls among ambulatory or institutionalized elderly subjects . The present study was undertaken to address the reduced risk of falls and hip fractures in patients with long-st and ing stroke by vitamin D supplementation . METHODS Ninety-six elderly women with poststroke hemiplegia were followed for two years . Patients were r and omly assigned to one of the two groups , and 48 patients received 1,000 IU ergocalciferol daily , and the remaining 48 received placebo . The number of falls per person and incidence of hip fractures were compared between the two groups . Strength and tissue ATPase of skeletal muscles on the nonparetic side were assessed before and after the study . RESULTS At baseline , serum 25-hydroxyvitamin D levels were in the deficient range ( < 10 ng/ml ) in all patients ; and vitamin D treatment enhanced serum 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels .  Vitamin D treatment accounted for a 59 % reduction in falls ( 95 % CI , 28 - 81 % ; p = 0.003 ) . There were increases in the relative number and size of type II muscle fibers and improved muscle strength in the vitamin D-treated group . Hip fractures occurred in 4 of 48 placebo group and 0 in 48 vitamin D2 group during the 2-year study period ( log-rank , p = 0.049 ) . CONCLUSION Vitamin D may increase muscle strength by improving atrophy of type II muscle fibers , which may lead to decreased falls and hip fractures BACKGROUND vitamin D supplementation reduces the incidence of fractures in older adults . This may be partly mediated by effects of vitamin D on neuromuscular function . OBJECTIVE to determine the effects of vitamin D supplementation on aspects of neuromuscular function known to be risk factors for falls and fractures . DESIGN r and omised , double-blind , placebo-controlled study . SETTING falls clinic taking referrals from general practitioners and accident and emergency department . SUBJECTS 139 ambulatory subjects ( > /=65 years ) with a history of falls and 25-hydroxyvitamin D ( 25OHD ) < /=12 microg/l . INTERVENTION patients were r and omised to receive a single intramuscular injection of 600,000 i.u . ergocalciferol or placebo . OUTCOME MEASURES assessment s including biochemistry , postural sway , choice reaction time ( CRT ) , aggregate functional performance time ( AFPT ) , and quadriceps strength were carried out at baseline and 6 months post-intervention . RESULTS baseline characteristics were comparable between both groups . 25OHD in the treatment group increased significantly at 6 months . AFPT deteriorated in the control group and improved in the intervention group , representing a significant difference between groups ( + 6.6 s versus -2.0 s , t = 2.80 , P < 0.05 ) . Similar changes were observed for CRT ( -0.06 s versus + 0.41 s , t = -2.52 , P < 0.01 ) and postural sway ( + 0.0025 versus -0.0138 , t = 2.35 , P < 0.02 ) . There was no significant difference in muscle strength change between groups ( -10 N versus -2 N , t = -1.26 , ns ) . A significant correlation between change in AFPT and change in 25OHD levels was observed ( r = 0.19 , P = 0.03 ) . There was no significant difference in the number of falls ( 0.39 versus 0.24 , t = 1.08 , P = 0.28 ) or fallers ( 14 versus 11 , P = 0.52 ) between two groups . CONCLUSIONS vitamin D supplementation , in fallers with vitamin D insufficiency , has a significant beneficial effect on functional performance , reaction time and balance , but not muscle strength . This suggests that vitamin D supplementation improves neuromuscular or neuroprotective function , which may in part explain the mechanism whereby vitamin D reduces falls and fractures
CONCLUSIONS Vitamin D supplementation positively affected lower limb muscle strength in athletes , but not upper limb muscle strength or muscle power .
Different muscle groups and functions may respond differently to vitamin D supplementation .
BACKGROUND Vitamin D may play a role in skeletal muscle because of the discovery of VDR in skeletal muscle .
However , vitamin D deficiency is a global problem , including athletes .
Studies examining the effect of vitamin D supplementation on muscle function in athletes have inconsistent results .
Therefore , we aim ed to quantitatively summarize the evidence for the effect of vitamin D supplementation on skeletal muscle strength and explosive power of athletes using a meta- analysis .