Author(s): STEIN, M., GIRARD, O., PEELING, P., Institution: THE UNIVERSITY OF WESTERN AUSTRALIA, Country: AUSTRALIA, Abstract-ID: 1443

INTRODUCTION:
Iron deficiency affects ~15-35% of female athletes and is associated with impaired aerobic performance [1]. However, its influence on short-duration maximal exercise, which relies on combined aerobic and anaerobic energy contributions, remains unclear, particularly under hypoxic conditions. Therefore, this study examined the effects of iron status on performance and physiological responses during all-out sprint cycling of varying durations (5-60 s) in female athletes under normoxic and hypoxic conditions.
METHODS:
Twenty-eight trained female athletes (iron-sufficient: n=15; iron-deficient: n=13) completed two separate experimental sessions involving four isolated maximal cycling sprints (5, 15, 30, and 60 s) performed under normoxia (FIO2=0.209) and hypoxia (FIO2=0.135). Mechanical output, vastus lateralis muscle oxygenation (near-infrared spectroscopy), and peripheral oxygen saturation (pulse oximetry) were measured during each sprint, with perceptual responses immediately afterward. Two-way repeated-measures ANOVAs (iron status and condition) were conducted separately for each sprint duration.
RESULTS:
When pooled across groups, total work (-6.6±16.7%) and mean power output (-6.9±16.4%) during the 60-s sprint were lower in hypoxia than normoxia (both p<.001), with no differences between iron-sufficient and iron-deficient athletes (p>.05). Peak muscle deoxygenation rate during the 15-s sprint was 10.8% greater in hypoxia than normoxia in iron-sufficient athletes only (p=.045). Peripheral oxygen saturation was not influenced by iron status (p>.05), but differed by condition, with normoxia showing greater desaturation responses during the 5-s (p<.01) and 30-s sprint (p<.05). Perceived difficulty breathing during the 60-s sprint was 20% greater in iron-deficient than iron-sufficient athletes when pooled across conditions (p=.024). No other differences were observed (p>.05).
CONCLUSION:
Iron status did not meaningfully impair mechanical output or physiological responses during short-duration (≤60 s) maximal sprints under normoxic or hypoxic conditions in female athletes. Although group differences were noted in muscle oxygenation and perceived breathing difficulty, these did not translate into measurable performance differences. The greater perceptual strain experienced by iron-deficient athletes nonetheless highlights the importance of monitoring and managing iron status. Comparable hypoxia-induced performance reductions between groups suggest that the performance consequences of iron deficiency may be more pronounced during repeated-sprint or endurance-type exercise, prolonged hypoxic exposure, or at greater altitude severities.

[1] Sim M, et al. Iron considerations for the athletes: a narrative review. Eur J Appl Physiol. 2019;119(7):1463−78