Iron status and associations with physical performance during basic combat training in female New Zealand Army recruits.

Decreases in Fe status have been reported in military women during initial training periods of 8-10 weeks. The present study aimed to characterise Fe status and associations with physical performance in female New Zealand Army recruits during a 16-week basic combat training (BCT) course. Fe status indicators - Hb, serum ferritin (sFer), soluble transferrin receptor (sTfR), transferrin saturation (TS) and erythrocyte distribution width (RDW) - were assessed at the beginning (baseline) and end of BCT in seventy-six volunteers without Fe-deficiency non-anaemia (sFer 10 mg/l at baseline or end. A timed 2·4 km run followed by maximum press-ups were performed at baseline and midpoint (week 8) to assess physical performance. Changes in Fe status were investigated using paired t tests and associations between Fe status and physical performance evaluated using Pearson correlation coefficients. sFer (56·6 (sd 33·7) v. 38·4 (sd 23·8) µg/l) and TS (38·8 (sd 13·9) v. 34·4 (sd 11·5) %) decreased (P<0·001 and P=0·014, respectively), while sTfR (1·21 (sd 0·27) v. 1·39 (sd 0·35) mg/l) and RDW (12·8 (sd 0·6) v. 13·2 (sd 0·7) %) increased (P<0·001) from baseline to end. Hb (140·6 (sd 7·5) v. 142·9 (sd 7·9) g/l) increased (P=0·009) during BCT. At end, sTfR was positively (r 0·29, P=0·012) and TS inversely associated (r -0·32, P=0·005) with midpoint run time. There were no significant correlations between Fe status and press-ups. Storage and functional Fe parameters indicated a decline in Fe status in female recruits during BCT. Correlations between tissue-Fe indicators and run times suggest impaired aerobic fitness. Optimal Fe status appears paramount for enabling success in female recruits during military training.

Iron deficiency without anaemia is a potential cause of fatigue: meta-analyses of randomised controlled trials and cross-sectional studies.

Fe deficiency is a prevalent nutritional disease, and fatigue is a common complaint in the general and patient population. The association between Fe deficiency without anaemia (IDNA) and fatigue is unclear. Here, we performed a meta-analysis to evaluate the therapeutic effect of Fe on fatigue in patients with IDNA and the association between IDNA and fatigue in the population. Articles from the PubMed database up to 19 January 2016 were systematically searched. A total of six relevant randomised controlled trials (RCT) and six relevant cross-sectional studies were identified. All outcomes were converted into effect sizes. In the meta-analysis of the six RCT, we identified a significant therapeutic effect of Fe in fatigue patients with IDNA (pooled effect size 0·33; 95 % CI 0·17, 0·48; I 2=0·0 %; P<0·0001). A sensitivity analysis found that the overall results (i.e. significant association) were robust. In the meta-analysis of the six cross-sectional studies, the association between IDNA and fatigue was not significant (pooled effect size 0·10; 95 % CI -0·11, 0·31; I 2=57·4 %; P=0·362). A sensitivity analysis found that the overall results (i.e. no significant association) were not robust; removal of one study made the outcomes significant. These meta-analyses suggest that improving Fe status may decrease fatigue. Further research is necessary to identify diagnostic criteria for selecting fatigue patients who might benefit from Fe therapy and to assess the prevalence of IDNA with fatigue in the general population.