The effect of magnesium supplementation on high and low dietary magnesium intake on resting, during and recovering from exercise on blood pressure, performance and serum levels of magnesium (Mg2+).

Abstract

Objective: The objectives of this study were to determine if there is a significant effect on blood pressure, serum levels of magnesium and sports performance including 1RM and 10 kilometre running time trial following Magnesium (Mg2+) supplementation over a five week intervention period in recreationally active athletes when compared to a 5 week placebo intervention. Methods: Subjects participated in a 14 week protocol which employed a randomized blind cross over controlled design. Fifteen subjects were initially screened and accepted for participation. During the protocol two subjects dropped out, failing to complete. This left nine male and four female subjects who were successful in completing the protocol (Age: 24.85 ± 6.49 years, Height: 175cm ± 10.34 cm, Weight: 71.9 Kg ± 11.46 Kg). Results: Statistically significant differences were observed (P < 0.05) in the running time trial, blood pressure readings pre and post 10 kilometre running trial (systolic and diastolic) and in heart rate (HR) recorded at 10 minute intervals during the running trial following Mg2+ supplementation. Following the Mg2+ intervention there was an average decrease in 10K completion time of exactly 1 minute (1.77%) (P=0.001). A significant decrease in HR by 2.58 BPM (2.58%) (P=0.03). Diastolic blood pressure was significantly reduced both pre and post completion of the 10 kilometre run by 10.23 mmHg (13.85%) (P=0.03) and 5.38 mmHg (7.38%) (P=0.008) respectively. Whilst a significant reduction in systolic blood pressure was only seen following the 10 kilometre run 8.23 mmHg (6.17%) (P=0.05). As Mg2+ is a co-factor in over 325 enzymatic reactions (Newhouse & Finstad, 2000), it’s importance as a mineral is clear and warrants research to improve scientific knowledge into its role within health and sports performance, as Mg2+ deficiency can also be detrimental to health. Conclusion: The results of the current study show that 500mg/day of Mg2+ supplementation will significantly decrease time taken to complete a 10 kilometre run, reduce systolic and diastolic blood pressure and significantly reduce HR.