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Iron supplementation prevents a decline in iron stores and enhances strength performance in elite female volleyball players during the competitive season.

Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme
June 1, 2015
Juan Mielgo-Ayuso et al. (5 authors)
Journal ArticleRandomized Controlled TrialHuman StudyClinical
Study Details

Study Goal

The researchers aimed to examine the effects of 11 weeks of iron supplementation on hematological and strength markers in elite female volleyball players.

Results Summary

Iron supplementation prevented significant decreases in hematological parameters (serum iron, ferritin, transferrin saturation, hemoglobin) observed in the control group and led to greater improvements in strength performance (clean and jerk, power clean, total mean strength) compared to controls.

Population

Elite female volleyball players (aged 27.0 ± 5.6 years) from Spanish First National League teams.

Effective Dosage

325 mg/day of ferrous sulphate.

Duration

11 weeks.

Interactions

None mentioned.

Extracted Claims (17)
InterventionDirectionEndpointPopulationDosageImpactClaim #
iron supplementation
decrease
iron loss
elite female volleyball players
-
prevents iron loss
#1
iron supplementation
increase
strength
elite female volleyball players
-
enhances strength
#2
iron supplementation (325 mg/day of ferrous sulphate)
no change
serum iron (sFe)
iron treatment group (ITG)
-
experienced no changes
#3
iron supplementation (325 mg/day of ferrous sulphate)
no change
serum ferritin (FER)
iron treatment group (ITG)
-
experienced no changes
#4
iron supplementation (325 mg/day of ferrous sulphate)
no change
transferrin saturation index (TSI)
iron treatment group (ITG)
-
experienced no changes
#5
iron supplementation (325 mg/day of ferrous sulphate)
no change
hemoglobin (Hb)
iron treatment group (ITG)
-
experienced no changes
#6
iron supplementation (325 mg/day of ferrous sulphate)
increase
all hematological parameters
iron treatment group (ITG)
-
were significantly greater
#7
iron supplementation (325 mg/day of ferrous sulphate)
increase
clean and jerk
iron treatment group (ITG)
+29.0% ± 21.3%
greater percent increase
#8
iron supplementation (325 mg/day of ferrous sulphate)
increase
power clean
iron treatment group (ITG)
+44.6% ± 56.6%
greater percent increase
#9
iron supplementation (325 mg/day of ferrous sulphate)
increase
total mean strength
iron treatment group (ITG)
+26.2% ± 3.6%
greater percent increase
#10
-
decrease
serum iron (sFe)
control group (CG)
-33.9%
significant decrease
#11
-
decrease
serum ferritin (FER)
control group (CG)
-34.6%
significant decrease
#12
-
decrease
transferrin saturation index (TSI)
control group (CG)
-35.3%
significant decrease
#13
-
decrease
hemoglobin (Hb)
control group (CG)
-7.44%
significant decrease
#14
-
increase
clean and jerk
control group (CG)
+5.1% ± 20.9%
percent increase
#15
-
decrease
power clean
control group (CG)
-5.8% ± 30.3%
percent increase
#16
-
increase
total mean strength
control group (CG)
+10.9% ± 3.2%
percent increase
#17
Abstract

The primary aim of this study was to examine the effects of 11 weeks of iron supplementation on hematological and strength markers in elite female volleyball players. Twenty-two volleyball players (aged 27.0 ± 5.6 years) from 2 Spanish First National League teams participated and were counterbalanced into 1 of 2 groups based upon iron status: (i) control group (CG, n = 11); or (ii) iron treatment group (ITG, n = 11), which received 325 mg/day of ferrous sulphate daily. Subjects performed their team's regimen of training or match play every day. Both groups were tested for hematological and strength levels at 2 points: (i) baseline (T0, before preseason) and (ii) 11 weeks later (T11, post-testing). Hematological parameters were serum iron (sFe), serum ferritin (FER), transferrin saturation index (TSI), and hemoglobin (Hb); strength assessments were bench press, military press, half-squat, power clean, clean and jerk, and pull-over. CG experienced a significant decrease (p < 0.05) for sFe (T0, 112.7 ± 31.5; T11, 69.0 ± 20.5 μg·dL(-1); -33.9%), FER (T0, 60.2 ± 28.6; T11, 38.2 ± 16.4 ng·mL(-1); -34.6%), TSI (T0, 29.4% ± 9.5%; T11, 17.4% ± 5.1%; -35.3%), and Hb (T0, 14.1 ± 1.0; T11, 13.0 ± 0.8 g·L(-1); -7.44%); however, ITG experienced no changes (p > 0.05). Consequently, in ITG all hematological parameters were significantly greater (p < 0.05) than CG at T11. There was greater (p < 0.05) percent increase in the clean and jerk (CG: +5.1% ± 20.9 vs. ITG: +29.0% ± 21.3%), power clean (CG: -5.8% ± 30.3% vs. ITG: +44.6% ± 56.6%), and total mean strength (CG: +10.9% ± 3.2% vs. ITG: +26.2% ± 3.6%) in ITG. Our findings suggest that oral iron supplementation prevents iron loss and enhances strength in female volleyball players during the competitive season.

Medical Subject Headings (MeSH)
Administration, OralAdultAthletic PerformanceBiomarkersDietary SupplementsEnergy IntakeFemaleFerritinsFerrous CompoundsHemoglobinsHumansIron, DietaryMicronutrientsMultivariate AnalysisMuscle StrengthNutrition AssessmentRegression AnalysisSpainSports Nutritional Physiological PhenomenaTransferrinVolleyballYoung Adult
Study Links
Quality Scores
SafetyNot Assessed
Efficacy85/10
Quality75/10
Citation Metrics
Total Citations19
Citations/Year1.9
Relative Citation Ratio1.10
NIH Percentile53.7%
Research Impact Scores
APT Score0.75
Weight Score1.67
Normalized Score0.69
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