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Bellém, Fernando

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  • Impact of supraphysiological doses of anabolic steroids on glucose and insulin levels in male bodybuilders: a systematic review
    Publication . Tavares, Ana Sofia; Bellém, Fernando; Ferreira, Bárbara; Leite, Beatriz; Calixto, Carolina
    Testosterone (TE) is an anabolic androgenic steroid (AAS) that promotes muscle growth and the maintenance of secondary sexual characteristics. Due to its aesthetic benefits, AASs have become popular in sports, typically administered orally or intramuscularly, with doses up to 100 times higher than the therapeutic dose. A therapeutic dose is safe and sufficient for the desired effect, while a supraphysiological dose is significantly greater than what is needed for normal body functions. Insulin regulates blood glucose levels and metabolic processes. Insulin resistance occurs when cells do not respond well to this hormone, leading to elevated blood sugar levels. It is believed that TE disrupts the secretion of adipocytokines, increases the amount of circulating fatty acids, and may negatively affect insulin signaling in muscle and fat cells. This systematic review aims to understand the influence of administering supraphysiological doses of AASs on blood glucose and insulin levels in male bodybuilding athletes.
  • Impact of high-performance sport on serum potassium values in athletes: a systematic review
    Publication . Tavares, Ana Sofia; Bellém, Fernando; Vieira, Daniela; Miranda, Vasco; Pires, Mariana
    Potassium (K+) is a critical alkali metal and the most abundant cation in the body, primarily found inside cells. It's measurable in serum, plasma, whole blood, and urine. During intense exercise, potassium is released from muscles into the bloodstream, with levels related to exercise intensity. Potassium is essential for cell polarization and transmitting electrical impulses in the heart, so fluctuations in serum potassium (hypokalemia or hyperkalemia) can lead to life-threatening arrhythmias and myocardial issues in athletes. Hypokalemia, or low potassium, can cause muscle issues and, in severe cases, cardiorespiratory arrest due to losses through urine, sweat, or the gastrointestinal tract. Hyperkalemia, or high potassium, may result from excessive intake or kidney problems, causing muscle cramps and reduced excitability, affecting athletic performance. Athletes balance fatigue and recovery, with potassium fluctuations being crucial to their limits. The line between beneficial and harmful effects is fine, and maintaining a diet rich in potassium-regulating foods is vital to prevent imbalances. Understanding potassium's role in intense physical activity helps optimize performance and avoid health risks. The main goal of this systematic review is to compare the blood potassium levels obtained before and after training in athletes.