I´m a 32 year old male, physically fit and with a competitive swimming background since my childhood. About a year ago I transitioned from sprint swimming events to endurance triathlons, gradually increasing training hours during the week. In the peak of my preparation, after 9 months of training, I started experiencing severe episodes of PVC’s, together with anxiety, muscle twitching, shortness of breath, and chest discomfort. Palpitations would show up during rest and rather in the evening, staying active for at least 2 or 3 hours with a 3 or 4 beats/min frequency, although anxiety and the other symptoms could come and go at any moment during the day. Sometimes, when going to bed I would also feel a very weak heartbeat and a steadily growing fear of a sudden cardiac arrest. Quitting my training would help only partially, as the PVCs still showed up, although with less frequency. As soon as I retook exercise the symptoms got worse. Cardiologists undertook all the possible tests, including, EKG, holter, echocardiography… you name it, but did not find any evidence of serious problems. They claimed that my episodes were benign (apart from PVC they found some isolated PAC’s as well) and prescribed a light dose of beta-blockers , which turned out to be ineffective. I also consulted with a naturopathic doctor who suggested a full clean up of the system in order to rule out an electrolyte imbalance or any other chemical disorder. After a strict diet of vegetables, vitamins and minerals (magnesium, calcium and zinc), symptoms improved notably and almost vanished (except the muscle twitching) after a few days. As I convinced myself that I was cured I went back to training only to find out that PVCs were still there after a week of moderate aerobic work.
After three months ruling out possible causes and extensively researching the net I came across an interesting article about the role of the Vagus Nerve on this type of disorders. Apparently , when irritated, this nerve can cause all of the symptoms above , although the exact cause of the irritation usually remains a mystery for most patients. This irritation kind of suits very well with my inner perception of the symptoms, since the only way I can describe it (apart from the extra beat of the PVCs) is as a sort of nervousness around my chest. Besides, the vagal hypothesis is also consistent with the fact that beta-blockers did not work (as the vagus nerve belongs to the parasympathetic system, whereas those drugs work on the sympathetic system), and with the fact that symptoms were worse during the evening (parasympathetic predominates over sympathetic in the vening). Stress is pointed out as the best candidate for most patients, but I don’t think that applies in my case since I quitted my job just to join a full time training program and I have had a rather stable emotional life during this period. No alcohol, no drugs and no caffeine. Now I’m handling other hypothesis such as the athlete heart syndrome, which I don’t see as a plausible cause given the short time of endurance training , or maybe other type of physical vagal stimulation stemming from a bad posture or a hiatal hernia. I’m really desperate cause my competitive season is almost wasted by now. Doctors say that symptoms are benign but I feel terribly sick when they show up and it feels like my heart is going to stop suddenly.
Are there other possible explanations for my problem? Although doctors say that there’s no reason to worry, is it safe to train having this terrible symptoms?