title: Magnesium and strength in elite judo athletes according to intracellular water changes.
abstract: Magnesium (Mg) deficiency strongly affects muscle performance. In judo, many athletes often undergo impressive weight changes associated with severe dehydration. Common practices used by athletes to achieve a target weight can lead to Mg deficit. This study aimed to understand the impact of Mg changes on strength from periods of weight stability to prior to competition in a sample of elite judo athletes who differentially changed their intracellular water (ICW). The sample consisted of 20 elite male judo athletes. Subjects were divided according to ICW changes: losses below 2% and losses equal to or above 2%. Mg was measured in serum, red blood cells and urine by atomic absorption spectrophotometry. ICW was calculated as the difference between total-body water and extracellular water using dilution techniques. Maximal handgrip strength was evaluated using Jamar Hydraulic Hand Dynamometer. Upper-body power was determined in a bench press. Higher ICW decreases were associated with higher strength reductions, though our results suggest that an increase in red blood cell Mg might attenuate those strength reductions in athletes who decrease the ICW compartment. As Mg losses can be considerable and intake is frequently insufficient, athletes should consider supplementation, especially during periods of weight reduction.
authors.affiliation: Exercise and Health Laboratory, Faculty Human Kinetics, Technical University of Lisbon, Estrada da Costa, Cruz-Quebrada, Portugal. cmatias@fmh.utl.pt
authors.forename: Catarina Nunes
authors.initials: CN
authors.lastname: Matias
authors.forename: Diana Aguiar
authors.initials: DA
authors.lastname: Santos
authors.forename: Cristina Paula
authors.initials: CP
authors.lastname: Monteiro
authors.forename: Analiza Mónica
authors.initials: AM
authors.lastname: Silva
authors.forename: Maria de Fátima
authors.initials: Mde F
authors.lastname: Raposo
authors.forename: Fátima
authors.initials: F
authors.lastname: Martins
authors.forename: Luís Bettencourt
authors.initials: LB
authors.lastname: Sardinha
authors.forename: Manuel
authors.initials: M
authors.lastname: Bicho
authors.forename: Maria José
authors.initials: MJ
authors.lastname: Laires
mesh_terms: D000328:Adult; D056352:Athletes; D001834:Body Water / Q000502:physiology*; D001835:Body Weight / Q000502:physiology; D006801:Humans; D008274:Magnesium / Q000097:blood* / Q000378:metabolism / Q000652:urine; D008297:Male; D016139:Martial Arts; D013054:Spectrophotometry, Atomic; D055815:Young Adult
chemical_list: D008274:Magnesium