ABSTRACT
This case study examines the impact of low serum ferritin (sFe) on physiological assessment measures and performance in a young female 1500-m runner undertaking approximately 95-130 km/wk training. The study spans 4 race seasons and an Olympic Games. During this period, 25 venous blood samples were analyzed for sFe and hemoglobin (Hb); running economy, VO(2max), and lactate threshold were measured on 6 occasions separated by 8-10 mo. Training was carefully monitored including 65 monitored treadmill training runs (targeting an intensity associated with the onset of blood lactate accumulation) using blood lactate and heart rate. Performances at competitive track events were recorded. All data were compared longitudinally. Mean sFe was 24.5 ± 7.6 µg/L (range 10-47), appearing to be in gradual decline with the exception of 2 data points (37 and 47 µg/L) after parenteral iron injections before championships, when the lowest values tended to occur, coinciding with peak training volumes. Each season, 1500-m performance improved, from 4:12.8 in year 1 to 4:03.5 in year 4. VO(2max) (69.8 ± 2.0 mL · kg(-1) · min(-1)) and running economy (%VO(2max) at a fixed speed of 16 km/h; max 87.8%, min 80.3%) were stable across time and lactate threshold improved (from 14 to 15.5 km/h). Evidence of anemia (Hb <12 g/dL) was absent. These unique data demonstrate that in 1 endurance athlete, performance can continue to improve despite an apparent iron deficiency. Raising training volume may have caused increased iron utilization; however, the effect of this on performance is unknown. Iron injections were effective in raising sFe in the short term but did not appear to affect the long-term pattern.
Subject(s)
Anemia, Iron-Deficiency/physiopathology , Athletes , Athletic Performance/physiology , Running/physiology , Adolescent , Anemia, Iron-Deficiency/drug therapy , Female , Ferric Compounds/therapeutic use , Ferric Oxide, Saccharated , Ferritins/blood , Glucaric Acid , Hematinics/therapeutic use , Hemoglobins/analysis , Humans , Injections, Intravenous , Lactic Acid/blood , Oxygen Consumption/physiology , Sucrose/therapeutic use , Young AdultABSTRACT
Statistics indicate that 39% of boys and 58% of girls aged 7-18 do not achieve the recommended levels of exercise, eg spending at least one hour each day in a physical activity of at least moderate intensity. This paper summarises the physical and psychological health benefits of exercise for children and young people and emphasises that the promotion of exercise and healthy food choices should go hand in hand. Practical tips for young people on exercise and nutrition are included.