Research on cyclists competing in the three-week Vuelta a Espana stage race who took a daily dose of 400 mg of magnesium revealed that the supplement helped speed recovery.

In a 2019 study, researchers noted that the recommended daily allowance of magnesium was suspected of being insufficient for athletes, particularly cyclists because they undergo a “significant decrease in body compartments that store magnesium” during a stage race. “For this reason, we decided to test the effects of Mg supplementation and muscle integrity in cyclists.”

A previous study showed that oral supplementation of 400 mg of lactate magnesium prevented tissue damage in basketball players, the study points out.

During the Vuelta, blood samples were collected according to World Doping Agency (WADA) rules from 18 cyclists immediately before the race, at the midway point of the competition and before the final stage. They cyclists were divided into a control group and a group taking 400 mg of magnesium each day.

Magnesium deficiency results in muscle weakness and damage, compromising recovery, the study noted. “This could be a point of particular attention in extensive aerobic exercises in which completion is performed through consecutive stages with short recovery periods,” according to the findings. In short, a three-week stage race makes for a near-perfect test of the effects of magnesium supplements.

None of the cyclists in the study was taking banned drugs or medications, nor did any test positive in drug tests before and during the competition, according to WADA.

Cyclists were carefully monitored

During the competition, the research team ensured that constant circadian rhythms in terms of nutrition, hydration, timing of food intake and sleep were maintained, which is a normal practice in cycling competitions, according to the study.

The team dietitian recorded the daily food and fluid intake of the cyclists during the 21-day study. EasyDiet software, developed by the Spanish Centre for Higher Studies in Nutrition and Dietetics, was used to calculate nutrient composition and energy intake from food and drinks consumed by the cyclists. 

At the beginning and end of the study, VO₂ max and peak power were determined in all participants by using an incremental test to exhaustion on a calibrated Lode Excalibur Sport Cycle. Participants began cycling at 100 watts for five minutes with increases in intensity of 50 watts every 2.5 minutes until exhaustion. During the VO₂max testing, expired air was collected and analyzed using a metabolic cart supplied by SensorMedics.

Intensity was assessed by a rating of perceived exertion. In addition, cyclists answered a simple question: “How was your workout (race)?” Answers were collected 30 minutes after cyclists crossed the finish line on the first and the last days of the race.

The results indicated to researchers that magnesium supplementation exceeding the recommended daily allowance had a modest effect in maintaining muscle integrity. “In any case,” the researchers wrote, adequate levels of magnesium intake from diet or combined with supplements can permit muscle recovery from the intense and strenuous exercise in cycling competitions.

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