The investigators randomly assigned 116 sedentary women aged 50-70 years to swimming or walking. Participants completed 3 sessions per week of moderate-intensity exercise under supervision for 6 months then unsupervised for 6 months.
Compared with walking, swimming improved body weight, body fat distribution and insulin resistance in the short term (6 months).
At 12 months swimmers had lost 1.1 kg more than walkers and had lower bad cholesterol levels.
It should be noted that these differences barely reached significance .
Types of Activities And The Intensity of Exercise
My general recommendations on exercise (see here) give examples of different aerobic physical activities and intensities.
These activities are considered Moderate Intensity
Walking briskly (3 miles per hour or faster, but not race-walking)
Bicycling slower than 10 miles per hour
General gardening Vigorous Intensity
These types of exercise are considered Vigorous Exercise
Racewalking, jogging, or running
Bicycling 10 miles per hour or faster
Heavy gardening (continuous digging or hoeing, with heart rate increases)
Hiking uphill or with a heavy backpack
As a rule of thumb, consider 1 minute of vigorous exercise equivalent to 2 minutes of moderate exercise and shoot for 150 minutes per week of moderate exercise or 75 minutes of vigorous exercise.
Of course one can swim laps at peak intensity or at a very slow, leisurely pace so swimming laps doesn’t always qualify as “vigorous” exercise. Likewise one can play singles tennis languorously and be at a moderate or lower intensity of exercise.
It is entirely possible that the swimmers were working at a higher intensity during their sessions than the walkers and that could be the explanation for the differences seen between the two groups.
Ultimately, the best type of exercise for heart health is the one you can do and (hopefully) enjoy on a regular basis.
N.B. Speaking of swimming. A year ago I wrote about longevity and featured Eugene, a 98 year old who could swim the length of a swimming pool underwater. Eugene turns 100 in 2 days.
In a previous post, the skeptical cardiologist pontificated on the causes and evaluation of the most common cause of palpitations: premature ventricular contractions or PVCs.
The vast majority of these common extra beats turn out to be benign (meaning not causing death, heart attack or stroke), and most patients with sufficient reassurance of this benignity (often accompanied by significant caffeine reduction), do well. These people usually continue to notice the beats either randomly, or with stress, but they recognize exactly what is going on and are able to say to themselves “there go my benign PVCs again,” and aren’t worried or bothered.
A small percentage of patients that I diagnose with palpitations due to benign PVCs continue to have symptoms.
Part of my initial evaluation involves checking potassium, magnesium, kidney function, and thyroid levels.
Potassium Supplementation For PVCs
Low potassium levels (hypookalemia) have been clearly associated with an increase in ventricular ectopy. Patients who take diuretics like hydrochlorothiazide (HCTZ, often used for high blood pressure) or furosemide (Lasix, often used for leg swelling or heart failure), are at high risk for hypokalemia with potassium levels less than 3.5 meQ/L.
Hypokalemia can also develop if you are vomiting, having diarrhea, or sweating excessively. There are lots of other infrequent causes including excess licorice consumption. The body regulates potassium levels closely, due to its importance in the electrical activities involved in cardiac, muscular and neurological function.
The normal range of potassium (K) is considered to be 3.5 to 5 meq/L , however, I have found that PVCs are more frequent when the potassium is less than 4.
Most of my symptomatic PVC patients with potassium less than 4 find significant improvement with potassium supplementation. I usually give them a prescription for potassium chloride (KCl) 10-20 meq daily to accomplish raising the level to >4.
An alternative to potassium supplements is ramping up how much potassium you consume in your diet. Most patients I talk to about low K immediately assume they should eat more bananas, but lots of fresh fruit and vegetables contain as much or more K than bananas.
The charts to the right show that a medium tomato contains as much K as a medium banana with a third of the calories. Avocados are a great source of K and contain lots of healthy fat. Yogurt (and I recommend full fat yogurt, of course) is a great source as well.
If you have kidney disease you are much more likely to develop hyperkalemia, or high K, and you want to avoid these high K foods. Potassium infusions are used as part of a “lethal injection” in executions because extreme hyperkalemia causes the heart to stop beating. (In fact, Arkansas is hurrying to execute 8 men between April 17 and 27 utilizing KCl. According to deathpenaltyinformation.org: “The hurried schedule appears to be an attempt to use the state’s current supply of eight doses of midazolam, which will expire at the end of April. Arkansas does not currently have a supply of potassium chloride, the killing drug specified in its execution protocol, but believes it can obtain supplies of that drug prior to the scheduled execution dates”)
Lifestyle, Stress and PVCs
It’s probably time I revealed that I have PVCs. I feel them as a sense that something has shifted inside my chest briefly, like my breath has been interrupted, like my heart has hiccoughed. If I didn’t know about PVCs and hadn’t made the diagnosis very quickly by hooking myself up to an ECG monitor in my office, I know I would have become very anxious about it.
I know exactly what causes them: stress and anxiety. And this is the case for many patients. Stress activates our sympathetic nervous system, causing the release of hormones from the adrenal gland that prepare us for “fight or flight.” These hormones stimulate the heart to beat faster and harder and often trigger PVCs.
I rarely get PVCs these days, as the major source of stress in my personal life has gone away. This is also a typical story my patient’s relate: troubling palpitations seem to melt away when they retire or change to less stressful occupations, or as they recover from depression/anxiety/grief related to death of loved ones, divorce or illness.
You can’t always control external stresses, but several factors in your lifestyle are key to managing how those stresses activate your sympathetic nervous system and trigger troubling PVCs.
Dr. Mandrola lists as Steps 5-8 (Steps 1-4 are reassurance) for PVC treatment his “four legs of the table of health”:
: good food, good exercise, good sleep and good attitude. Cutting back on caffeine and alcohol, looking critically at the dose of exercise, going to bed on time, and smiling are all great strategies for PVCs.
Of these four table legs, I consider regular aerobic exercise the most important, and modifiable factor for PVC reduction. Aerobic exercise improves mood and increases the parasympathetic (the calming component of the autonomic nervous system) activity, while lowering the output of the sympathetic nervous system.
The three factors that I find essential to handling the demanding and stressful job of being a cardiologist: restful sleep, regular, aerobic exercise and lots of love from my eternal fiancee (who also has occasional PVCs!)
Beyond sleep and exercise there is a plethora of techniques that purport to help individuals deal with stress: yoga, meditation, and progressive muscular relaxation, among them.
Apps touting methods for relaxation abound these days. My new Apple Watch is constantly advising me to engage in a breathing exercise for a minute at a time. I don’t find any of these techniques helpful for me (I haven’t found a good way to shut my brain down without falling asleep), but they may work for you.
Magnesium, Snake Oil and PVCs
Patients will find that the internet is rife with stories of how this supplement or vitamin or herb dramatically cures PVCs. You can be assured that a sales pitch accompanies these claims and that the snake oil being promoted has not been proven effective or safe. Because symptomatic PVCs like most benign, common and troubling conditions (lower back pain, fatigue, and nonspecific GI troubles come to mind), are closely related to mood and wax and wain spontaneously; the placebo effect proves powerful. In such conditions, snake oil and charlatans thrive.
Magnesium is enthusiastically hyped on the internet for all manner of cardiovascular problems including PVCs. Even Dr. Mandrola, who I respect quite a lot as an EP doc who promotes lifestyle change and who is definitely not a quack, lists his step 10 for PVCs (apologetically) as follows:
Step 10 (a): Please don’t beat me up on this one. Some patients report benefit from magnesium supplementation. I have found it helpful in my case of atrial premature beats. Let me repeat, I am not promoting supplements. Healthy patients with benign arrhythmia might try taking magnesium, especially at night. Don’t take magnesium if you have kidney disease. And if you take too much, watch out for diarrhea.
Most of the internet’s top quacks, however, greedily market and glowingly swear by magnesium. A Google search for magnesium cardiovascular disease yields 833,000 entries and the first page is a Who’s Who of quackery, including Dr Mercola (strong candidate for America’s greatest quack), Dr. Sinatra (see here, currently in the semifinals for America’s greatest quack cardiologist), NaturalNews and Life Extension (see here). This totally unsupported and dangerous blather from the Weston Price Foundation is often repeated and is typical:
(magnesium) Deficiency is related to atherosclerosis, hypertension, strokes and heart attacks. Deficiency symptoms include insomnia, muscle cramps, kidney stones, osteoporosis, fear, anxiety, and confusion. Low magnesium levels are found in more than 25 percent of people with diabetes. But magnesium shines brightest in cardiovascular health. It alone can fulfill the role of many common cardiac medications: magnesium inhibits blood clots (like aspirin), thins the blood (like Coumadin), blocks calcium uptake (like calcium channel-blocking durgs such as Procardia) and relaxes blood vessels (like ACE inhibitors such as Vasotec) (Pelton, 2001).
Magnesium levels are very important to monitor in hospitalized and critically ill patients, especially those receiving diuretics and medications that can effect cardiac electrical activity.
However, for individuals with normal diets and palpitations due to PVCs, there is scant evidence that it plays a significant role in cardiovascular health.
The MAGICA study looked at supplementation with both magnesium and potassium (in the active treatment group, daily oral dosing consisted of 2 mg of magnesium-dl-hydrogenaspartate (6 mmol magnesium) and 2 mg of potassium-dl-hydrogenaspartate (12 mmol potassium) daily. The dose was chosen to increase the recommended minimal daily dietary intake of magnesium (12 to 15 mmol) and potassium (20 to 30 mmol) by ∼50% in addition to usual diet ) in 307 patients with more than 720 PVCs per hour and normal baseline K and Mg levels.
The patients receiving magnesium/potassium supplements showed a decrease of 17% in frequency of PVCs but no improvement in symptoms.
A 2012 study in a Brazilian journal evaluated magnesium pidolate (MgP) in 60 patients with both PVCs and premature atrial contractions (PACs). The dose of MgP was 3.0 g/day for 30 days, equivalent to 260 mg of Mg elemental.
93% of patients receiving MgP experienced improved symptoms compared to only 13% of patients recieiving placebo. Both PVC and PAC frequency was reduced in those receiving MGP, whereas they increased by 50% in those receiving placebo.
This small study has never been reproduced, and the main results table makes little sense. It would not have been published in a reputable American cardiology journal and cannot be relied on to support magnesium for most patients with benign PVCs or PACs.
Drug or Ablation Treatment of PVCs: Usually Not Needed
A small percentage of my patients require treatment with beta-blockers which reduces the effects of the sympathetic nervous system on the heart. Very rarely, I will use anti-arrhythmic drugs. And every once in a while, very frequent PVCs resulting in cardiomyopathy require an ablation.
However, the vast majority of patients with benign PVCs, in my experience, feel drastically better with a simple non-pharmacological approach consisting of 4 factors:
Reassurance that the PVCS are benign
Caffeine (or other stimulant) reduction
Lifestyle adjustment with regular aerobic exercise