title: Iron supplementation improves endurance after training in iron-depleted, nonanemic women. Marginal iron deficiency without anemia impairs aerobic adaptation among previously untrained women. Supplemental zinc lowers measures of iron status in young women with low iron reserves. Iron supplementation improves progressive fatigue resistance during dynamic knee extensor exercise in iron-depleted, nonanemic women. Intravenous iron for the treatment of fatigue in nonanemic, premenopausal women with low serum ferritin concentration. Evaluation of a Single Dose of Ferric Carboxymaltose in Fatigued, Iron-Deficient Women – PREFER a Randomized, Placebo-Controlled Study Effects of iron and ascorbic acid supplementation on hemoglobin level and work efficiency of anemic women. Effects of iron repletion on blood volume and performance capacity in young athletes. Effect of oral iron supplementation on unstimulated salivary flow rate: a randomized, double-blind, placebo-controlled trial. A Study of the Effects of Latent Iron Deficiency on Measures of Cognition: A Pilot Randomised Controlled Trial of Iron Supplementation in Young Women Comparison of Two Doses of Elemental Iron in the Treatment of Latent Iron Deficiency: Efficacy, Side Effects and Blinding Capabilities Iron supplementation for unexplained fatigue in non-anaemic women: double blind randomised placebo controlled trial Effect of iron supplementation on endurance capacity in iron-depleted female runners. Iron supplementation maintains ventilatory threshold and improves energetic efficiency in iron-deficient nonanemic athletes Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trial Effects of iron repletion on VO2max, endurance, and blood lactate in women. Effects of iron supplementation in female athletes with low serum ferritin concentration. The effects of prelatent/latent iron deficiency on physical work capacity. Effect of iron injections on aerobic-exercise performance of iron-depleted female athletes.
abstract: Our objective was to investigate the effects of iron depletion on adaptation to aerobic exercise , assessed by time to complete a 15-km cycle ergometer test . Forty-two iron-depleted ( serum ferritin < 16 microg/l ) , nonanemic ( Hb > 12 g/dl ) women ( 18 - 33 yr old ) received 100 mg of ferrous sulfate ( S ) or placebo ( P ) per day for 6 wk in a r and omized , double-blind trial . Subjects trained for 30 min/day , 5 days/wk at 75 - 85 % of maximum heart rate for the final 4 wk of the study . There were no group differences in baseline iron status or in 15-km time . Iron supplementation increased serum ferritin and decreased transferrin receptors in the S compared with the P group . The S and P groups decreased 15-km time and respiratory exchange ratio and increased work rate during the 15-km time trial after training . The decrease in 15-km time was greater in the S than in the P group ( P = 0.04 ) and could be partially attributed to increases in serum ferritin and Hb . These results indicate that iron deficiency without anemia impairs favorable adaptation to aerobic exercise BACKGROUND Iron deficiency without anemia has been shown to reduce both muscle-tissue oxidative capacity and endurance in animals . However , the consequences of iron deficiency in humans remain unclear . OBJECTIVE We investigated the effects of iron supplementation on adaptation to aerobic training among marginally iron-depleted women . We hypothesized that iron supplementation for 6 wk would significantly improve iron status and maximal oxygen uptake ( VO(2)max ) after 4 wk of concurrent aerobic training . DESIGN Forty-one untrained , iron-depleted , nonanemic women were r and omly assigned to receive either 50 mg FeSO(4 ) or a placebo twice daily for 6 wk in a double-blind trial . All subjects trained on cycle ergometers 5 d/wk for 4 wk , beginning on week 3 of the study . RESULTS Six weeks of iron supplementation significantly improved serum ferritin and serum transferrin receptor ( sTfR ) concentrations and transferrin saturation without affecting hemoglobin concentrations or hematocrit . Average VO(2)max and maximal respiratory exchange ratio improved in both the placebo and iron groups after training ; however , the iron group experienced significantly greater improvements in VO(2)max . Both iron-status and fitness outcomes were analyzed after stratifying by baseline sTfR concentration ( > and < or = 8.0 mg/L ) , which showed that the previously observed treatment effects were due to iron-status and fitness improvements among subjects with poor baseline iron status . CONCLUSIONS Our findings strongly suggest that iron deficiency without anemia but with elevated sTfR status impairs aerobic adaptation among previously untrained women and that this can be corrected with iron supplementation Zinc and iron compete during intestinal absorption , but postabsorptive interactions between these nutrients are less clear . Underst and ing these interactions is important to determine when supplementation with iron or zinc is proposed . The effect of zinc supplementation ( 22 mg Zn/d as zinc gluconate ) or of iron supplementation ( 100 mg Fe/d as ferrous sulfate ) for 6 wk on iron and zinc metabolism and absorption was evaluated in young women with low iron reserves . Young adult women ( ages 20 - 28 y ) , nonanemic but with low iron stores ( plasma ferritin < 20 microg/L ) , participated in the 70-d study . The women were divided in two groups ( zinc-supplemented , n = 11 ; iron-supplemented , n = 12 ) . The supplements were taken at bedtime .  Iron and zinc biochemical indices and intestinal absorption were measured on d 1 and 56 .  Radioiron and stable isotopes of zinc  were used to measure iron and zinc absorption from a test meal . In the iron-supplemented group , blood hemoglobin , plasma ferritin and the percentage of transferrin saturation increased ( P < 0.01 ) . Zinc indices did not change . In the zinc-supplemented group , plasma ferritin and the percentage of transferrin saturation decreased ( P < 0.05 ) , whereas the plasma transferrin receptor and erythrocyte zinc protoprophyrin levels increased ( P < 0.05 ) . Plasma and urinary zinc also increased ( P < 0.01 ) . Iron absorption ( % ) from the test meal increased ( P < 0.01 ) , whereas zinc absorption ( % ) decreased ( P < 0.01 ) compared with baseline in the Zn-supplemented women . Our results indicate that the use of iron supplements in women with marginal iron status improves iron indices with no effect on zinc status . However , use of a modest zinc supplement improves zinc indices , but also appears to induce a cellular iron deficiency and , possibly , further reduce iron status BACKGROUND Tissue iron depletion may negatively affect endurance performance and muscle fatigability . OBJECTIVE We investigated tissue-level iron depletion and progressive fatigue of the quadriceps during dynamic knee-extension exercise in young women . DESIGN Twenty iron-depleted ( serum ferritin < 20 micro g/L ) , nonanemic ( hemoglobin > 110 g/L ) women ( macro x + /- SEM age : 29.1 + /- 1.2 y ) received iron ( iron group ) or placebo ( placebo group ) for 6 wk in a r and omized , double-blind trial ( n = 10 per group ) . A protocol integrating 2 - 3-s maximal voluntary static contractions ( MVCs ) with dynamic knee extensions was used to assess fatigue . RESULTS No significant differences between the groups in baseline iron status , MVC at rest , or MVC at the end of the protocol were observed . After treatment , serum iron and transferrin saturation increased significantly in the iron group ( P = 0.02 and P = 0.03 , respectively ) . Serum transferrin receptor concentrations increased significantly in the placebo group ( P < 0.01 ) but not in the iron group . After treatment , the rate of decrease in MVC was attenuated in the iron group but not in the placebo group ( P = 0.01 ) . In the iron group , MVC at the sixth minute of the fatigue protocol and MVC at the end of the protocol were approximately 15 % ( P = 0.04 ) and approximately 27 % higher ( P < 0.01 ) , respectively , after treatment . These improvements were not related to changes in iron-status indexes or tissue iron stores , although power was low ( < 0.50 ) to detect these relations . CONCLUSIONS Iron supplementation was associated with a significant improvement in muscle fatigability . Interpretation regarding the direct role of tissue iron status is limited by the study 's low power to detect relations between tissue iron improvement and decreased muscle fatigue This is the first study to investigate the efficacy of intravenous iron in treating fatigue in nonanemic patients with low serum ferritin concentration . In a r and omized , double-blinded , placebo-controlled study , 90 premenopausal women presenting with fatigue , serum ferritin ≤ 50 ng/mL , and hemoglobin ≥ 120 g/L were r and omized to receive either 800 mg of intravenous iron (III)-hydroxide sucrose or intravenous placebo . Fatigue and serum iron status were assessed at baseline and after 6 and 12 weeks . Median fatigue at baseline was 4.5 ( on a 0 - 10 scale ) . Fatigue decreased during the initial 6 weeks by 1.1 in the iron group compared with 0.7 in the placebo group ( P = .07 ) . Efficacy of iron was bound to depleted iron stores : In patients with baseline serum ferritin ≤ 15 ng/mL  , fatigue decreased by 1.8 in the iron group compared with 0.4 in the placebo group ( P = .005 ) , and 82 % of iron-treated compared with 47 % of placebo-treated patients reported improved fatigue ( P = .03 ) . Drug-associated adverse events were observed in 21 % of iron-treated patients and in 7 % of placebo-treated patients ( P = .05 ) ; none of these events was serious . Intravenous administration of  iron improved fatigue in iron-deficient , nonanemic women with a good safety and tolerability profile . The efficacy of intravenous iron was bound to a serum ferritin concentration ≤ 15 ng/mL. This study was registered at the International St and ard R and omized Controlled Trial Number Register ( www.is rct n.org ) as IS RCT N78430425 Background Unexplained fatigue is often left untreated or treated with antidepressants . This r and omized , placebo-controlled , single-blinded study evaluated the efficacy and tolerability of single-dose intravenous ferric carboxymaltose ( FCM ) in iron-deficient , premenopausal women with symptomatic , unexplained fatigue . Methods Fatigued women ( Piper Fatigue Scale [ PFS ] score ≥5 ) with iron deficiency ( ferritin < 50 µg/L and transferrin saturation < 20 % , or ferritin < 15 µg/L ) and normal or borderline hemoglobin ( ≥115 g/L ) were enrolled in 21 sites in Austria , Germany , Sweden and Switzerl and , blinded to the study drug and r and omized ( computer-generated r and omization sequence ) to a single FCM ( 1000 mg iron ) or saline ( placebo ) infusion . Primary endpoint was the proportion of patients with reduced fatigue ( ≥1 point decrease in PFS score from baseline to Day 56 ) . Results The full analysis included 290 women ( FCM 144 , placebo 146 ) . Fatigue was reduced in 65.3 % ( FCM ) and 52.7 % ( placebo ) of patients ( OR 1.68 , 95%CI 1.05–2.70 ; p = 0.03 ) . A 50 % reduction of PFS score was achieved in 33.3 % FCM- vs. 16.4 % placebo-treated patients ( p<0.001 ) . At Day 56 , all FCM-treated patients had hemoglobin levels ≥120 g/L ( vs. 87 % at baseline ) ; with placebo , the proportion decreased from 86 % to 81 % . Mental quality -of-life ( SF-12 ) and the cognitive function scores improved better with FCM . ‘ Power of attention ’ improved better in FCM-treated patients with ferritin < 15 µg/L. Treatment-emergent adverse events ( placebo 114 , FCM 209 ; most frequently headache , nasopharyngitis , pyrexia and nausea ) were mainly mild or moderate . Conclusion A single infusion of FCM improved fatigue , mental quality -of-life , cognitive function and erythropoiesis in iron-deficient women with normal or borderline hemoglobin . Although more side effects were reported compared to placebo , FCM can be an effective alternative in patients who can not tolerate or use oral iron , the common treatment of iron deficiency . Overall , the results support the hypothesis that iron deficiency can affect women ’s health , and a normal iron status should be maintained independent of hemoglobin levels . Trial Registration Clinical Trials.gov This study was conducted to examine the relationship between anemia , supplementation with iron and vitamin C , and productivity . Using the cyanmethemoglobin method , 671 female garment factory workers were examined . On the basis of the World Health Organization ( WHO ) st and ard , 98 were found to be mildly or moderately/severely anemic . An equal number was r and omly chosen from the nonanemic workers . The subjects were then r and omly assigned to either the placebo group or the group receiving 525 mg of ferrous sulfate ( 105 mg elemental iron ) and 500 mg ascorbic acid . Only 118 of the 196 subjects completed the three-month study . The mean hemoglobin ( Hb ) and work output , as indicated by efficiency rating ( ER ) , of the placebo group did not change significantly . Mildly anemic workers with supplements showed a significant improvement in mean Hb , but not in mean ER . The moderately/severely anemic group receiving supplements had significant increases in both Hb and ER PURPOSE The purpose of this study was to find out whether iron repletion leads to an increase in red blood cell volume ( RBV ) and performance capacity in iron-deficient nonanemic athletes . METHODS 40 young elite athletes ( 13 - 25 yr ) with low serum ferritin ( < 20 microg . L-1 ) and normal hemoglobin ( males > 13.5 g.dL-1 , females > 11.7 g.dL-1 ) were r and omly assigned to 12-wk treatment with either twice a day ferrous iron ( equivalent to 2 x 100 mg elemental iron ) or with placebo using a double blind method . Before and after treatment , hematological measures and parameters of iron status were determined in venous blood . RBV , blood volume ( BV ) , and plasma volume ( PV ) were measured by CO rebreathing . For determination of the aerobic and anaerobic capacity ( maximal accumulated oxygen deficit , MAOD ) , the athletes performed an incremental as well as a highly intensive treadmill test . RESULTS After 12 wk , ferritin levels were within the normal range in the iron-treated group ( IG ) with a significant ( P < 0.001 ) mean increase by 20 microg . L-1 opposed to a slight nonsignificant decrease in the placebo group ( PG ) . RBV did not change significantly in either group nor did any of the hematological measures . However , only in IG there were significant increases in VO2max and in O2 consumption in the MAOD test . MAOD and maximal capillary lactate concentration remained unchanged in both treatment groups . CONCLUSIONS The results indicate that in young elite athletes with low serum ferritin and normal hemoglobin concentration iron supplementation leads to an increase in maximal aerobic performance capacity without an augmentation of RBV BACKGROUND No treatment is known to permanently increase salivary flow in patients with hyposalivation . The objective of this study was to investigate the effect of iron supplementation on salivary flow rate . METHODS A double-blind , r and omized , placebo-controlled trial was carried out on 50 individuals with a low unstimulated whole salivary flow rate and low serum ferritin . Half the individuals received 60 mg iron orally twice a day for 3 months , while the other half received placebo . RESULTS No statistically significant difference was found between the groups after treatment for the unstimulated flow rate and in the subjective assessment s of oral dryness . The serum ferritin values increased significantly in the iron group but not in the placebo group . CONCLUSION Oral supplementation with iron for 3 months has no effect on salivary flow rate among individuals with hyposalivation and low serum ferritin values Rates of iron deficiency are high amongst healthy young women .  Cognitive impairment occurs secondary to iron deficiency in infants and children , but evaluation of the impact on cognition among young women is inconsistent . The aim was to determine the suitability of the IntegNeuro test battery for assessing cognitive function in iron-deficient and iron-sufficient young women . A pilot double-blinded , placebo-controlled intervention trial was conducted in iron-deficient ( serum ferritin ≤ 20 μg/L and haemoglobin > 120 g/L ) and iron-sufficient young women ( 18–35 years ) . Cognitive function and haematological markers of iron status were measured at baseline and follow-up . Iron-deficient participants ( n = 24 ) were r and omised to receive placebo , 60 mg or 80 mg elemental iron daily supplements for 16 weeks . A control group of iron-sufficient participants ( n = 8) was allocated to placebo . Change scores for Impulsivity and Attention were significantly greater in plasma ferritin improvers than in non-improvers ( p = 0.004 , p = 0.026 ) . IntegNeuro was easy to administer and acceptable to young women . Based on the differences in Memory and Attention scores between iron-deficient participants on iron treatment and those on placebo , it was decided that between 26 and 84 participants would be required in each iron treatment group for an adequately powered extension of this pilot RCT Adherence to iron supplementation can be compromised due to side effects , and these limit blinding in studies of iron deficiency . No studies have reported an efficacious iron dose that allows participants to remain blinded . This pilot study aim ed to determine a ferrous sulfate dose that improves iron stores , while minimising side effects and enabling blinding . A double-blinded RCT was conducted in 32 women ( 18–35 years ) : 24 with latent iron deficiency ( serum ferritin < 20 µg/L ) and 8 iron sufficient controls . Participants with latent iron deficiency were r and omised to 60 mg or 80 mg elemental iron or to placebo , for 16 weeks . The iron sufficient control group took placebo . Treatment groups ( 60 mg n = 7 and 80 mg n = 6 ) had significantly higher ferritin change scores than placebo groups ( iron deficient n = 5 and iron sufficient n = 6 ) , F(1 , 23 ) = 8.46 , p ≤ 0.01 . Of the 24 who completed the trial , 10 participants ( 77 % ) on iron reported side effects , compared with 5 ( 45 % ) on placebo , but there were no differences in side effects ( p = 0.29 ) , or compliance ( p = 0.60 ) between iron groups . Nine ( 69 % ) participants on iron , and 11 ( 56 % ) on placebo correctly guessed their treatment allocation . Both iron doses were equally effective in normalising ferritin levels . Although reported side-effects were similar for both groups , a majority of participants correctly guessed their treatment group Abstract Objective To determine the subjective response to iron therapy in non-anaemic women with unexplained fatigue . Design Double blind r and omised placebo controlled trial . Setting Academic primary care centre and eight general practice s in western Switzerl and . Participants 144 women aged 18 to 55 , assigned to either oral ferrous sulphate ( 80 mg/day of elemental iron daily ; n=75 ) or placebo ( n=69 ) for four weeks . Main outcome measures Level of fatigue , measured by a 10 point visual analogue scale . Results 136 ( 94 % ) women completed the study . Most had a low serum ferritin concentration ; ≤ 20 μg/l in 69 ( 51 % ) women . Mean age , haemoglobin concentration , serum ferritin concentration , level of fatigue , depression , and anxiety were similar in both groups at baseline . Both groups were also similar for compliance and dropout rates . The level of fatigue after one month decreased by −1.82/6.37 points ( 29 % ) in the iron group compared with −0.85/6.46 points ( 13 % ) in the placebo group ( difference 0.95 points , 95 % confidence interval 0.32 to 1.62 ; P=0.004 ) . Subgroups analysis showed that only women with ferritin concentrations ≤ 50 μg/l improved with oral supplementation . Conclusion Non-anaemic women with unexplained fatigue may benefit from iron supplementation . The effect may be restricted to women with low or borderline serum ferritin concentrations The purpose of this investigation was to examine the effects of oral iron supplementation on endurance performance in initially iron-depleted , nonanemic female distance runners . Eighteen iron-depleted ( serum ferritin less than 20 ng.ml-1 , hemoglobin greater than or equal to 12 g.dl-1 ) women ( 22 - 39 yr ) performed a VO2max test and an endurance run to exhaustion . Subjects were pair-matched on the basis of endurance time and then r and omly assigned to an iron supplement or a placebo group . Following supplementation , the iron group had a significantly higher ( P = 0.03 ) mean serum ferritin concentration ( 23.4 vs 15.7 ng.ml-1 ) and lower ( P = 0.04 ) mean total iron-binding capacity than the placebo group . Both groups increased their time to exhaustion ( 25.5 % and 22.2 % for the iron and placebo groups , respectively ) but were not significantly different ( P = 0.72 ) from each other . There were also no differences ( P greater than 0.05 ) between the groups with respect to lactate concentrations and physiological measures taken during the two exercise tests . The results of this study suggest that 8 wk of oral iron supplementation improves iron status in iron-depleted female distance runners , but does not enhance endurance capacity Objective : To determine the effect of iron supplementation on iron status and endurance capacity . Design : R and omized , double-blind iron supplementation . Setting : University of Missouri-Columbia and surrounding community . Subjects : Twenty iron-deficient ( serum ferritin , sFer<16 μg/l ; serum transferrin receptor , sTfR>8.0 mg/l ; or sTfR/log sFer index > 4.5 ) , nonanemic ( hemoglobin , Hb>120 g/l , women ; > 130 g/l , men ) men and women ( 18–41 years ) were recruited via fliers and newspaper advertisements ; 20 of 31 eligible subjects participated . Interventions : A 30 mg measure of elemental iron as ferrous sulfate or placebo daily for 6 weeks . Results : Dietary iron intake and physical activity did not differ between groups before or after supplementation . Iron supplementation significantly increased sFer compared to placebo ( P=0.01 ) , but did not affect Hb or hematocrit . Iron supplementation prevented the decline in ventilatory threshold ( VT ) observed in the placebo group from pre- to post-supplementation ( P=0.01 ) ; this effect was greater in individuals with lower sFer before intervention ( P<0.05 ) . Changes in sFer from pre- to post-treatment were positively correlated with changes in VT ( P=0.03 ) , independent of supplementation . The iron group significantly increased gross energetic efficiency during the submaximal test ( P=0.04 ) . Changes in sFer were negatively correlated with changes in average respiratory exchange ratio during the submaximal test ( P<0.05 ) . Conclusions : Iron supplementation significantly improves iron status and endurance capacity in iron-deficient , nonanemic trained male and female subjects . Sponsorship : Missouri University Alumni Association , by the Elizabeth Hegarty Foundation and by the Department of Nutritional Sciences Background : The true benefit of iron supplementation for nonanemic menstruating women with fatigue is unknown . We studied the effect of oral iron therapy on fatigue and quality of life , as well as on hemoglobin , ferritin and soluble transferrin receptor levels , in nonanemic iron-deficient women with unexplained fatigue . Methods : We performed a multicentre , parallel , r and omized controlled , closed-label , observer-blinded trial . We recruited from the practice s of 44 primary care physicians in France from March to July 2006 . We r and omly assigned 198 women aged 18–53 years who complained of fatigue and who had a ferritin level of less than 50 ug/L and hemoglobin greater than 12.0 g/dL to receive either oral ferrous sulfate ( 80 mg of elemental iron daily ; n = 102 ) or placebo ( n = 96 ) for 12 weeks . The primary outcome was fatigue as measured on the Current and Past Psychological Scale . Biological markers were measured at 6 and 12 weeks . Results : The mean score on the Current and Past Psychological Scale for fatigue decreased by 47.7 % in the iron group and by 28.8 % in the placebo group ( difference –18.9 % , 95 % CI −34.5 to −3.2 ; p = 0.02 ) , but there were no significant effects on quality of life ( p = 0.2 ) , depression ( p = 0.97 ) or anxiety ( p = 0.5 ) . Compared with placebo , iron supplementation  increased hemoglobin ( 0.32 g/dL ; p = 0.002 ) and ferritin ( 11.4 μg/L ; p < 0.001 ) and decreased soluble transferrin receptor ( −0.54 mg/L ; p < 0.001 ) at 12 weeks . Interpretation : Iron supplementation should be considered for women with unexplained fatigue who have ferritin levels below 50 μg/L. We suggest assessing the efficiency using blood markers after six weeks of treatment . Trial registration no. EudraCT 2006–000478–56 To determine the effects of an 8-wk dietary iron supplementation ( 100 mg.d-1 ) on low plasma ferritin concentration ( < 20 ng.ml-1 ) and endurance , 20 active women ( 19 - 35 yr ) were studied while performing a VO2max test and an endurance test ( 80 % VO2max ) on a cycle ergometer . Subjects were r and omly placed in an iron supplement ( IG ) or a placebo group ( PG ) using a double-blind method . After treatment in the IG , ferritin levels were higher ( 22.5 + /- 3.4 vs 14.3 + /- 2.2 ng.ml-1 ; P < 0.05 ) , Hb increased ( 12.8 + /- 0.4 to 14.1 + /- 0.2 g.dl-1 ; P < 0.05 ) , and TIBC decreased ( 366.2 + /- 24.8 to 293.8 + /- 14.0 micrograms.dl-1 ; P < 0.05 ) . Also after treatment the IG 's VO2max was significantly greater ( P < 0.05 ) than the PG value and their postendurance blood lactate decreased ( 5.03 + /- 0.44 to 3.85 + /- 0.6 mM.l-1 ; P < 0.05 ) . Endurance time to exhaustion increased 38 % ( 37.28 + /- 5.03 to 51.4 + /- 7.45 min ) following iron treatment ; however , this change was not statistically significant . The results suggest that this level of iron supplementation can reverse mild anemia , increase VO2max , and reduce blood lactate concentration after submaximal exercise Low serum ferritin concentrations are commonly found in female athletes . By study ing the effects of an 8-week iron or placebo supplementation in 31 female athletes ( aged 17 - 31 years ) , with an initial serum ferritin concentration less than or equal to 25 micrograms/l and blood hemoglobin 120 g/l , we investigated whether low serum ferritin values hinder aerobic performance . Serum ferritin concentration increased from 14 ( 25th and 75th percentile : 11 , 21 ) to 26 ( 18 , 36 ) micrograms/l in the iron-supplemented group , but remained at a low 11 ( 9 , 17 ) micrograms/l in the placebo group ( group difference after supplementation : p = 0.001 ) . Before supplementation , blood hemoglobin concentration was not different in the two groups . After supplementation , however , the concentration in the iron group was 139 ( 135 , 144 ) g/l and 128 ( 126 , 134 ) g/l in the placebo group ( group difference : p = 0.001 ) . Iron supplementation did not affect blood lactate concentration or VO2max during an incremental ergometer test . Hence , aerobic performance was not impaired in nonanemic female athletes with serum ferritin 25 micrograms/l In order to examine the effects of mild iron deficiency on physical work capacity , 40 prelatent iron-deficient female endurance runners were studied before and after 8 wk of supplementation with either oral iron ( 320 mg ferrous sulfate ) or a matching placebo . Subjects underwent the following physical work capacity tests : the Wingate cycle ergometer test , the anaerobic speed test , the ventilatory threshold , VO2max , and maximal treadmill velocity during the VO2max test . Muscle biopsy sample s pre- and post-treatment were obtained from 17 of the subjects , and these were assayed for citrate synthase and cytoplasmic alpha-glycerophosphate dehydrogenase activity . Subjects were r and omly assigned to one of the treatment groups , and a double-blind method of administration of the supplements was used . The differences in improvement scores between the two groups on the work capacity and enzyme activity variables were statistically nonsignificant ( P greater than 0.05 ) . Serum ferritin values rose from a mean of 12.4 + /- 4.5 to 37.7 + /- 19.7 ng.ml-1 for the experimental group and from 12.2 + /- 4.3 to 17.2 + /- 8.9 ng.ml-1 for the controls ( P = 0.0025 ) , whereas hemoglobin levels remained fairly constant for both groups ( P = 0.6 ) . Eight weeks of iron supplementation to prelatent/latent iron-deficient , physically active females did not significantly enhance work capacity . Within the limitations of this study , the presence of a serum ferritin below 20 ng.ml-1 does not pose a significant h and icap to physical work capacity This investigation examined the effect of intramuscular iron injections on aerobic-exercise performance in iron-deficient women . Sixteen athletes performed a 10-min steady-state submaximal economy test , a VO2max test , and a timed test to exhaustion at VO2max workload . Subjects were r and omly assigned to an iron-supplemented group ( IG ) receiving intramuscular iron injections or to a placebo group ( PG ) . Twenty days after the first injection , exercise and blood testing were repeated . A final blood test occurred on Day 28 . Post supplementation , no differences were found between the groups ' submaximal or maximal VO2 , heart rate , or blood lactate ( P > 0.05 ) . Time to exhaustion was increased in the IG ( P < 0.05 ) but was not greater than that of the PG ( P > 0.05 ) . The IG 's serum ferritin ( SF ) was significantly increased on Days 20 and 28 ( mean + /- st and ard error : 19 + /- 3 to 65 + /- 11 to 57 + /- 12 microg/L ; P < 0.01 ) , with a percentage change from baseline significantly greater than in the PG ( P < 0.01 ) . It was concluded that intramuscular iron injections can effectively increase SF without enhancing submaximal or maximal aerobic-exercise performance in iron-depleted female athletes
target: In IDNA adults  , iron supplementation is associated with reduced subjective measures of fatigue but not with objective improvements in physical capacity .
background: OBJECTIVE Iron supplementation in iron-deficiency anaemia is st and ard practice , but the benefits of iron supplementation in iron-deficient non-anaemic ( IDNA ) individuals remains controversial .
  Our objective is to identify the effects of iron therapy on fatigue and physical capacity in IDNA adults .