I've done a little research on iron deficiency and am quite surprised by some of the studies that have been performed. Most interesting is the focus on plain and simple iron deficiency regardless of Hb status. Even more curious is the potential difficulty in getting a true assessment of tissue iron levels. This is not unlike some of the difficulties faced with accurately assessing intracellular ions, such as potassium and magnesium. As Ewen suggested, it is possible that this low iron thing has been around for a while. My last series of lab tests showed borderline ferritin levels (at the bottom of the range, but still deemed 'normal'). This may of in fact been an indication of poor tissue levels, since there aren't any readily available (outside of research) tests for measuring tissue levels. Inadequate tissue iron can impact on performance, most prominently in those that do endurance type endeavours. Now hasn't that been my main problem!? If you are interested in a bit of research. See: Tissue iron deficiency without anemia impairs adaptation in endurance capacity after aerobic training in previously untrained women. Thomas Brownlie IV, Virginia Utermohlen, Pamela S Hinton, and Jere D Haas. Am J Clin Nutr 2004;79:437–43. This article is freely available at the journal website.
As per my previous post, I will continue to supplement iron for a bit longer and then head back in for some follow up tests. I still have the mystery of why I am iron deficient in the first place. It could well be related to poor absorption given the diet is pretty good. Doing this follow up test should help give an indication of absorption capacity.
In the meantime, training has been okay this week.
Tues - Day off, friend visiting, ran out of time and couldn't squeeze in run
Wed - Gentle 6K run @ Stromlo @~5:35/K pace
Thurs - ACTVAC track - 3000m - knocked another 6 seconds off this season's best time - 13:12; 5 lap spiral 9:27 and way back in the placings this week!
Fri - an easy 5K
Track wasn't at all cruisy this week, but glad to see a few more seconds coming off that 3000m time. I live in hope that improved tissue iron levels will help boost performance back to 2009/10 levels so I can then work on beating some of those old times! I'd prefer to be struggling to beat 12 min rather than the current 13 min battle!