Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
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SHR Neuro Krebs Kardio Lipid Stoffw Microb
Westmoreland, D; Hofstede, J; Porta, S.
Effect of the diurnal magnesium decline on exercise-induced magnesium shifts
TRACE ELEM ELECTROLYTES. 2006; 23: 140-144.
Doi: 10.5414/TEP23140
Web of Science
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- Co-Autor*innen der Med Uni Graz
- Porta Sepp
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- Abstract:
- Background: During exercise, Mg2+ shifts among compartments, resulting in transient increases or decreases in plasma Mg2+. In a previous study, we showed that pre-exercise Mg2+ levels influenced the magnitude and direction of the Mg2+ shift, and we hypothesized that the diurnal rhythm of plasma Mg2+ could influence the Mg2+ shift when ergometric tests are run at different times of day. In this study, we tested this hypothesis by having subjects complete identical exercise routines during the daylight phase of Mg2+ decline. Material and methods: We sampled blood from 25 male volunteers immediately before and after cycle ergometry at 06:00-07:00, 11:00-12:00, and 15:00-16:00. Each subject completed all 3 trials on the same day. Blood samples were analyzed for plasma concentrations of Na+, K+, Ca2+, and Mg2+. Results: As expected on the basis of the diurnal rhythm, pre-exercise Mg2+ concentrations declined over course of the day. Exercise caused a drop in plasma Mg2+, and the magnitude of the decline was strongly correlated with pre-exercise Mg2+ levels. Time of day explained 4% of the variation in the Mg2+ shift, while pre-exercise Mg2+ levels explained 25% of the variance. In a comparison of 9 published studies in which pre-exercise plasma Mg2+ levels were reported along with the direction of the Mg2+ shift, a drop in plasma Mg2+ Occurred when subjects had high initial Mg2+ levels, and a rise occurred when subjects had low pre-exercise Mg2+. Conclusion: Pre-exercise plasma Mg2+ concentrations influence both the magnitude and direction of the Mg2+ shift. Since Mg2+ concentrations decline during daylight hours, researchers could benefit by controlling the time of day that exercise tests are conducted.
- Find related publications in this database (Keywords)
- magnesium
- exercise physiology
- magnesium shift
- circadian rhythm