Accumulating evidence supports that athletes should pay extra attention to magnesium status as performing exercise is highly dependent on the regulation of magnesium homeostasis. This cation plays significant roles in promoting strength and cardiorespiratory function in healthy persons and athletes due to the key role of magnesium in the energetic metabolism, transmembrane transport, muscle contraction, hydration, oxidative stress and immune function. Surveys of athletes reveal that frequently, these individuals fail to consume a diet that contains adequate amounts of minerals, including magnesium. Individuals engaged in intense exercise should have a magnesium requirement 10 - 20% higher than the average sedentary person, because of increased losses through sweat and urine. Magnesium deficit is associated with muscle weakness, cramps, and structural damage of muscle fibers and organelles, probably as a result of increased production of reactive oxygen species, lipid and protein damage, and impaired cation homeostasis. This may result in substandard training and impaired performance. Regarding the effect of magnesium intake on muscle performance, few studies were conducted, especially in elite athletes. In this paper we are going to summarize some of our recent research in this area regarding the association between magnesium status, intracellular water and strength and power performance in elite combat sports and team sports athletes. In these studies we have observed that magnesium deficit is associated with strength and power limitation, therefore affecting muscle performance. We might highlight the importance of evaluating magnesium status, not only because its deficit may compromise performance, but also because the practice of exercise with a magnesium deficit may render the athlete more susceptible to cellular damage. [ABSTRACT FROM AUTHOR]