Increasing Iron Status through Dietary Supplementation in Iron-Depleted, Sedentary Women Increases Endurance Performance at Both Near-Maximal and Submaximal Exercise Intensities.
Study Goal
The researchers aimed to examine the individual and combined effects of iron supplementation and aerobic training on maximal and submaximal physical performance in iron-depleted, nonanemic women.
Results Summary
Iron supplementation improved endurance performance at submaximal and maximal (VO2peak) exercise intensities but did not increase estimated maximal oxygen consumption (eVO2max). The iron-untrained group performed better than the placebo-untrained group in VO2peak and ventilatory threshold measures.
Population
Sedentary, previously untrained iron-depleted, nonanemic women aged 18-26 with a BMI of 17-25.
Effective Dosage
42 mg elemental iron per day.
Duration
8 weeks.
Interactions
None mentioned.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
iron supplementation | increase | endurance performance at submaximal and maximal (VO2peak) exercise intensities | IDNA women | - | increases | #1 |
iron supplementation | no change | eVO2max | IDNA women | - | does not increase | #2 |
iron supplementation | no change | VO2max | - | mean difference: 0.53; 95% CI: -0.75, 1.81; P = 0.42 | no beneficial effect | #3 |
iron supplementation | increase | VO2peak | - | mean difference: 1.87; 95% CI: 0.15, 3.60; P = 0.03 | significant benefit | #4 |
iron supplementation and aerobic training | increase | VO2peak | - | - | significant training-by-supplement interactions | #5 |
iron supplementation and aerobic training | increase | volume of oxygen consumption at the ventilatory threshold | - | - | significant training-by-supplement interactions | #6 |
iron supplementation and aerobic training | increase | percentage of eVO2max where the threshold occurred | - | - | significant training-by-supplement interactions | #7 |
iron supplementation | increase | endurance performance | women | - | improve | #8 |
iron supplementation | no change | estimated maximal oxygen consumption (eVO2max) | women | - | not improve | #9 |
BACKGROUND: Iron deficiency persists as the most common micronutrient deficiency globally, despite having known detrimental effects on physical performance. Although iron supplementation and aerobic exercise have been examined individually and are known to improve physical performance, the impact of simultaneous iron supplementation and aerobic training remains unclear. OBJECTIVE: The aim of this study was to examine the individual and combined effects of iron supplementation and aerobic training on improving maximal and submaximal physical performance in iron-depleted, nonanemic (IDNA) women. We hypothesized that women receiving iron would improve their endurance performance but not their estimated maximal oxygen consumption (eVO2max). METHODS: Seventy-three sedentary, previously untrained IDNA (serum ferritin <25 µg/L and hemoglobin >110 g/L) women aged 18-26 y with a body mass index (kg/m2) of 17-25 participated in a double-blind, 8-wk, randomized controlled trial with a 2 × 2 factorial design including iron supplementation (42 mg elemental Fe/d) or placebo and aerobic exercise training (5 d/wk for 25 min at 75-85% of age-predicted maximum heart rate) or no training. Linear models were used to examine relations between training, supplement, and changes in the primary outcomes of observed maximal oxygen consumption (VO2peak) and eVO2max and ventilatory threshold (absolute oxygen consumption and percentage of maximum). Re-evaluation of a published meta-analysis was used to compare effects of iron supplementation on maximal oxygen consumption (VO2max) and VO2peak. RESULTS: There were significant training-by-supplement interactions for VO2peak, volume of oxygen consumption at the ventilatory threshold, and the percentage of eVO2max where the threshold occurred, with the iron-untrained group performing better than the placebo-untrained group. There was no beneficial effect of iron supplementation for VO2max (mean difference: 0.53; 95% CI: -0.75, 1.81; P = 0.42), but a significant benefit was observed for VO2peak (mean difference: 1.87; 95% CI: 0.15, 3.60; P = 0.03). CONCLUSIONS: Iron supplementation increases endurance performance at submaximal and maximal (VO2peak) exercise intensities in IDNA women. However, increasing iron status does not increase eVO2max. This trial was registered at clinicaltrials.gov as NCT03002090.