Lukus Klawitter M.S.

This is the start of a mini-part series focusing on the micronutrient for endurance athletes.  Specifically breaking down the nutrient and what it does for our overall health and performance.

Macronutrients Carbohydrates (CHO), Fats (FAT), and Protein (PRO) are needed for energy.  However, an endurance athlete stresses the body under a large volume of exercise at various intensities.  This requires a high amount of metabolic reactions to take place; supplying oxygen to the muscle, reactions for the muscle to contract and produce force, and for the muscle to relax to reproduce that force over the duration of the exercise.  Therefore, endurance athletes need an abundant supply of the micronutrients that drive these metabolic processes to take place, such as breaking down a CHO for the use of energy in the muscle.

Micronutrients are essential for many different metabolic reactions in the human body, and magnesium specifically is a factor in over 300 of those metabolic reactions.  The RDA for magnesium in males ages 14-70 is roughly 400mg/d and 310mg/d for females.  Currently 60% of Americans do not get enough magnesium in their diet according to the RDA, which can lead to chronic inflammatory stress.  Additionally, endurance athletes may require higher levels than the RDA due to the stress placed on the body, including greater muscle contractions and higher sweat rate.  This can have a dramatic effect on the ability for our connective tissue and muscles to recover from exercise.  Our body uses ATP (the energy currency of the cell) for intense exercise, and magnesium helps drive the reaction of converting our stored muscle glycogen to glucose for immediate usage of energy.  Additionally at intense exercise magnesium is needed to help buffer lactate and prevent the onset of muscle fatigue. Researchers Peveler and Palmer (2012) conducted a double blind supplement/placebo study on recreational to elite cyclists to determine the effect of supplemented magnesium lactate on the ability to shuttle lactate during a 20km time trial.  The researchers concluded that there were no significant differences on overall cycling performance however, the trials that included the magnesium supplement showed decreases in overall perceived exertion in the participants.

Magnesium has also been shown to assist with heart rate regulation in both average population and athletes alike.  Researchers have looked into the effect magnesium supplementation has on systolic blood pressure at rest and recovery during aerobic and resistance training sessions.  Kass, Skinner, and Poiera (2013) looked at 16 male cyclists with what is considered normal resting blood pressure and divided them into a control and experiment group whom supplemented magnesium.  The participants underwent maximal aerobic capacity tests trying to cover as much distance as possible in a 30 minute period on a cycle ergometer (Kass, Skinner, and Poiera, 2013).  Following the 30 min trial and a short prescribed recovery, participants underwent 3x5s maximal isometric bench press contractions.  Measuring maximal force created without any change in muscle length.  Researchers concluded that blood pressure levels following exercise were significantly lower in the group who supplemented magnesium.  Meaning the time to reach resting homeostasis post exercise is much lower and allows for a decrease in overall energy expenditure, which is an increase in recovery.

Magnesium has also been shown to support immune function, bone health, and assist with calcium (will be a post on calcium in the future) in the regulation of muscle contractions.

With all this accumulated information, the question asks, what is the best way to supplement magnesium?  I am a strong believer in obtaining the majority of our nutrients via food.  Triathletes or any endurance athlete requires a great amount of energy to complete the volume and intensity of the training.  If the athlete is obtaining a complete well balanced diet that meets their energy expenditure and includes a variety of plant foods, levels of magnesium should be in the normal value.  The list of foods high in magnesium can be found here .

Athletes can also use this tool to help calculate their recommended values for micronutrients.

References:

Kass L., Skinner, P., Poeira, F., (2013) A pilot study on the effects of magnesium supplementation with high and low habitual dietary magnesium intake on resting and recovery from aerobic and resistance exercise and systolic blood pressure. Journal of Sport Science and Medicine, 12 (1) 144-150.

Peveler W., Palmer TG., (2012) Effect of magnesium lactate dihydrate and calcium

lactate monohydrate on 20-km cycling time trial performance. Journal of Strength

Conditioning; 26(11) 49-53.

Volpe S., (2015) Magnesium and the athlete. American College of Sports Medicine; 14(4) 279-283.