Effect of Off-Season Iron Supplementation on Aerobic Capacity of Female Handball Player: A Randomized, Double-Blinded, Placebo-Controlled Study

Abstract

Background: Iron supplementation, especially in female athletes, is 1 of the influential factors in aerobic capacity, and its deficiency can lead to significant problems related to reduced aerobic capacity.

Objectives: This study aimed to investigate the effect of 3 wk of iron supplementation on the aerobic capacity of female handball players.

Methods: In this randomized, double-blinded, and placebo control trial, 14 elite handball players (age: 21.6 ± 5.68 y; height: 169.5 ± 4.9 cm; weight: 62.2 ± 9.25 kg; body mass index (in kg/m²): 21.5 ± 2.9) randomly divided into 2 supplement groups (receiving a 100 mg/d of poly-maltose tri hydroxide iron complex in the form of tablets) and the placebo group (receiving a tablet containing 100 mg/d starch which is the same color and shape as iron tablets). The supplementation protocol was performed for 3 wk during the off-season. Maximal oxygen consumption (VO_2max), amounts of carbon dioxide at the first ventilatory threshold, amounts of carbon dioxide at the second ventilatory threshold, time to exhaustion (TTE), pulmonary ventilation (VE), ventilatory equivalents for oxygen, amounts of oxygen at the first ventilatory threshold, amounts of oxygen at the second ventilatory threshold, time to reach first ventilatory threshold, end-tidal partial pressure of oxygen at the first ventilatory threshold, end-tidal partial pressure of carbon dioxide at the first ventilatory threshold and ventilatory equivalents for carbon dioxide were measured using the Bruce test and gas analyzer in 2 pretest and posttest stages.

Results: There were significant improvements in oxygen at the first ventilatory threshold, time to reach first ventilatory threshold, and end-tidal partial pressure of carbon dioxide at the first ventilatory threshold and a significant decrease in end-tidal partial pressure of oxygen at the first ventilatory threshold (P < 0.05). Also, no significant changes were found in VO_2max, carbon dioxide at the first ventilatory threshold, carbon dioxide at the second ventilatory threshold, oxygen at the second ventilatory threshold, TTE, VE, ventilatory equivalents for oxygen, and ventilatory equivalents for carbon dioxide after 3 wk of iron supplementation (P > 0.05).

Conclusions: The study found that 3 wk of off-season iron supplementation positively impacted female handball players' aerobic capacity; however, it did not significantly improve their VO_2max.

Keywords: aerobic power; female athletes; handball players; iron supplementation; ventilation capacity.

FIGURE 1

Flowchart illustrating the different phases of the research and study selection.

FIGURE 2

Pre and posttest changes of study outcomes in study groups. EQCO₂, ventilatory equivalents for carbon dioxide; EQO₂, ventilatory equivalents for oxygen; TTE, time to exhaustion; VE, pulmonary ventilation; VO_2max, maximal oxygen consumption.

FIGURE 3

Pre and posttest changes of study outcomes in study groups. PETCO₂ VT₁, end-tidal partial pressure of carbon dioxide at the first ventilatory threshold; PETO₂ VT₁, end-tidal partial pressure of oxygen at the first ventilatory threshold; Time VT₁, time to reach first ventilatory threshold; VT, ventilatory threshold; VT1 CO₂, carbon dioxide at the first ventilatory threshold; VT1 O₂, oxygen at the first ventilatory threshold. ∗: Significant difference compared to the Placebo group.

FIGURE 4

Pre and posttest changes of study outcomes in study groups. VT₂ CO₂, carbon dioxide at the second ventilatory threshold; VT₂ O₂, oxygen at the second ventilatory threshold.