Oral Magnesium Supplementation in Athletes With Premature Ventricular Contractions or Premature Atrial Contractions.

Magnesium is a mineral which is essential to many of the processes which happen in the body. This includes normal function of muscles; including the heart. Studies have shown that oral magnesium supplementation can help reduce the frequency of extra heart beats (premature ventricular contractions (PVC) and premature atrial contractions (PAC)) while also reducing the severity of their associated symptoms. Oral magnesium supplementation has yet to be investigated in athletes with lots of PVCs and/or PACs.

Most of the magnesium in your body is stored in the bones. Your body may take magnesium from your bones to maintain magnesium levels in your blood. This makes it possible for people to have low levels of magnesium in their body but normal levels in their blood. Over time, this process can decrease the total amount in your body and impact other body functions. Magnesium is also lost in sweat making athletes more vulnerable to having low levels in their body.

Magnesium is particularly important in the function of the myocardium (heart muscle fibers). It has been proposed that the PVCs and PACs experienced by some people are a result of low levels of total body magnesium. Current drug treatments to control PVCs and PACs include medications such as beta blockers. These treatments are not without their side effects. Generally, these medications are only effective if individuals do not have a structural heart disease. These drugs may also decrease your ability to exercise and are banned by some governing bodies in sport.

The hypotheses of this study are:

1. Oral magnesium supplementation reduces the frequency of PVCs and/or PACs.
2. Oral magnesium supplementation reduces the symptoms associated with PVCs and PACs.

To be eligible for the study, individuals will be required to have a certain number of PVCs and PACs in a day. This study will involve two groups of participants. A total of 25 participants will be recruited for each group resulting in 50 participants in the study. During the study, one group will take a daily magnesium capsule for 12 weeks before switching to a placebo for 12 weeks. The other group will have the placebo intervention before switching to magnesium. Participants will be randomized into one of the two groups and will remain blinded until their participation in the study ends. The research team will also be unaware of each participant's current intervention however, this information will be available in case of medical emergency.

Participants will be asked to attend one screening visit and three study visits. During these visits, a blood sample will be taken and you will be asked to complete questionnaires about you physical fitness and quality of life. You will also be asked to wear a Holter monitor for 48 hours in order to count the number of PVCs and PACs you have daily. In addition to these assessments, you will also complete an exercise stress test during your screening visit.


Eligibility Criteria:
Inclusion Criteria:

* Exercisers; defined as greater than 2.5 hours/week of at least moderate intensity exercise
* History of palpitations
* Average daily cumulative PVC/PAC count that is greater than 720 (measured with 48-hour Holter monitoring), AND/OR symptomatic from their PAC/PVCs
* Able to provide informed consent
* Able to participate in ongoing follow-up as required
* Able to swallow capsules

Exclusion Criteria:

* Current or regular use of an oral magnesium or calcium supplementation within the past year
* Current or regular use of a multivitamin or meal replacement product containing greater than 50mg of magnesium or 200mg of calcium within the past year
* Planning on becoming pregnant or currently pregnant or lactating
* Structural cardiac disease
* Documented atrial fibrillation
* Previous cardiac surgery including ablation for atrial fibrillation and/or ventricular arrhythmia
* Use of antiarrhythmic drugs, beta-blockers, calcium channel blockers, OR diuretics
* Hypomagnesemia (serum magnesium less than 0.7)
* Bilirubin (greater than or equal to 3mg/dL)
* Aspartate transaminase (AST) or alanine transaminase (ALT) greater than or equal to five times the upper limits of normal
* Glomerular filtration rate (GFR) less than 60
* Current or previous (within the four weeks prior to enrollment) use of any proton pump inhibitor (omeprazole, pantoprazole,), Gentamycin, Tobramycin, Amphotericin B, Ketoconazole, Mephalan, Eroposide, aminoglycosides or medication deemed by the PI as contraindicated)
* Alcohol intake greater than 15 standard drinks/week for men or greater than 10 standard drinks/week for women
* Illicit drug use
* Diabetes mellitus, kidney disease, irritable bowel disease or neuromuscular disease
* Diagnosis of cancer within the past five years (except basal/squamous cell limited to the skin)