Iron is vitally important in the body for its role in oxygen transport in the blood and energy production. However, sustained periods of exercise training can compromise iron status due to losses via sweating, hemolysis (rupturing of red blood cells), hematuria (excretion of red blood cells in urine) and gastrointestinal bleeding. So it is thought that weight bearing exercise, such as running, results in greater hemolysis, than non weight bearing exercise, such as cycling.
Ten active males completed two separate 7-day training blocks (involving 5 training sessions) of either running or cycling. During the research blood and urine samples were collected throughout each training block and it is used to assess the iron status and hepcidin concentrations, a peptide hormone involved in iron metabolism.
Basal urinary hepcidin levels were significantly increased during the running training block when compared to cycling training block. Nevertheless, iron parameters were not significantly altered in either the running or cycling block; however this is likely due to the relatively short duration of training, i.e. 7 days.
Take home message
During this study it provides additional evidence that weight-bearing exercise such as running may compromise iron metabolism to a greater extent than non-weight bearing exercise and this might be explained by increased urinary hepcidin losses. So therefore, runners in particular ought to prioritise the dietary intake of iron, with lean meat, seafood, enriched breakfast cereals, tofu, beans, almonds, seeds and green leafy vegetables excellent sources. Significantly, to those with a history of anaemia should have a blood test to check their blood iron levels prior to them commencing a tough training block, such as the build up to a marathon.