Quantitative relations between baseline iron status , study duration , and iron dose on changes in iron-status biomarkers , which were generated from the meta-analyses , can be used to predict effects of trials of iron supplementation and fortification and to design iron-intervention programs
BACKGROUND The response of status biomarkers to an increase in iron supply depends on several physiologic and environmental factors , which make it difficult to predict the outcome of an intervention .
OBJECTIVE We assessed effects of baseline iron status , sex , menopausal status , duration of intervention , iron form , and daily dose on the change in iron status in response to iron supplementation .
Iron supplementation improves progressive fatigue resistance during dynamic knee extensor exercise in iron-depleted, nonanemic women.
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
Quantitative relations between baseline iron status , study duration , and iron dose on changes in iron-status biomarkers , which were generated from the meta-analyses , can be used to predict effects of trials of iron supplementation and fortification and to design iron-intervention programs
BACKGROUND The response of status biomarkers to an increase in iron supply depends on several physiologic and environmental factors , which make it difficult to predict the outcome of an intervention .
OBJECTIVE We assessed effects of baseline iron status , sex , menopausal status , duration of intervention , iron form , and daily dose on the change in iron status in response to iron supplementation .