Waller, M. F. & Haymes, E. M. (1996). The effects of heat and exercise on sweat iron loss. Medicine and Science in Sports and Exercise, 28, 197-203.

Arm sweat was collected from athletic Ss (M = 9, F = 9) sitting in a hot environment, exercising for one hour in a neutral environment, and exercising for one hour in a hot environment. Sweat iron losses were compared to determine if this was a substantial source of iron loss (deficiency).

The following were found.

• Sweat iron concentration decreased significantly in the last 30 minutes of exercise.
• As would be expected, significantly greater sweating occurred while exercising in the hot environment, while the least occurred while resting in the hot environment.
• Males lost significantly more sweat than females during exercise.
• Greater amounts of iron were lost in exercise than at rest.

It was concluded that resting sweat iron concentration can be used to accurately estimate iron loss for one hour of exercise in neutral environments. However, it may overestimate iron loss during exercise in hot environments and during more prolonged exercise.

Implication. Sweat loss is a phenomenon that should be expected to occur. However, when training frequently in hot environments it may cause significant iron loss. Thus, iron supplementation, primarily through natural foods in the diet, should be attended to more in hot environments.

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