Iron supplementation prevents a decline in iron stores and enhances strength performance in elite female volleyball players during the competitive season.
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.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
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 |
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.