Your Questions — 14 minutes
Shovelling: how to protect the heart
Each year winter brings beautiful snowy landscapes, as well as piles of snow to shovel. Although this activity offers the opportunity to be active and get some fresh air, it can also be tough on the heart. The risk of hospitalization due to a heart attack is believed to be higher the day after a snowstorm, and it rises as the temperature drops. However, it is possible to limit the harmful effects of shovelling and benefit from its positive aspects by taking a few simple steps.
Shovelling, a demanding exercise
Shovelling is indeed considered an intense physical activity. Imagine that by moving five kg of snow (an average shovelful) every five seconds, you move 60 kg of snow per minute. After 20 minutes, that’s about 1,200 kg of snow. Quite an impressive task, to say the least!
The effort required to shovel could be compared to that of running at an average speed of six to nine km/h, depending on the snow’s weight and the pace of shovelling. Also, like any strenuous activity, shovelling snow can put a strain on the cardiovascular system. What exactly is going on?
- Heart rate increases quickly. Some people can reach their maximum heart rate in less than a minute.
- Blood pressure rises, causing a distortion of the blood vessels, which return to normal when pressure drops.
- In people who are less fit, this distortion can cause atherosclerotic plaque (fatty deposits on the walls of the coronary arteries) to rupture and lead to a heart attack.
One of the few statistically meaningful epidemiological studies on the link between snow events and the risk of myocardial infarction (MI) found that the number of MIs increases on snowstorm days, mainly in men. However, it is not known whether this is because men shovel more or because women do it more safely.
It is important to note that the study does not establish a direct link between shovelling and MI, but the authors believe that shovelling after a snowstorm is one of the most plausible causes of MI. Surprisingly, the increased risk of MI during snowstorms was not associated with age or identified cardiovascular risk factors.
When cold weather is involved
Exposure to cold temperatures also affects the cardiovascular system, as the body needs more energy and oxygen to maintain body temperature, which puts more stress on the heart and arteries. When cold is combined with exercise, the cocktail can prove even more harmful.
Exposure to cold air causes blood vessels to constrict, thereby preventing heat loss. As noted above, this can cause plaque on the artery walls to rupture, resulting in a heart attack. In addition, cold tends to raise the level of fibrinogen, a protein that promotes blood coagulation and can cause clots that lead to a heart attack.
A number of studies have linked exposure to cold temperatures to an increase in heart disease (angina, arrhythmia) and a greater risk of myocardial infarction. For example, a Swedish study showed a higher incidence of myocardial infarction at temperatures below 0 °C, while British researchers estimated that each 1 °C drop below a certain temperature increases the risk of myocardial infarction by 2% in the following 28 days.
Shovelling for a healthy heart
Although it can sometimes cause discomfort and injury, shovelling offers numerous benefits. Like any other physical activity, it is good for improving your mood and physical fitness, not to mention burning a few calories. To limit the risks associated with this winter activity and to protect your heart, make sure to take a few precautions.
Before you start shovelling, do a warm-up exercise by going for a walk or jumping up and down.
- Avoid shovelling after eating and drink water regularly.
- Take small shovelfuls and avoid throwing the snow too high. Pushing it takes less effort.
- Reduce your pace or stop altogether if you feel out of breath. You should be able to talk while shovelling.
- Watch for signs of discomfort and stop all activity if pain persists.
Heart attack: What to look out for?
Here are some of the symptoms of a heart attack:
- Pain in the chest, which may be accompanied by a sensation of discomfort, tightness, pressure, heaviness, bloating and burning
- Pain that radiates out from the chest
- Pain in the upper body: neck, jaw, shoulders and arms
- Shortness of breath
- Paleness, sweating and overall weakness
- Nausea, vomiting and sometimes indigestion
- Fear and anxiety
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- Canadian Centre for Occupational Health and Safety. “Shovelling – Snow,” OSH Answers Fact Sheets (updated August 4, 2016), https://www.ccohs.ca/oshanswers/ergonomics/snow_shovelling.html.
- *University of Ottawa Heart Institute. “Cardiac Rehabilitation: Physical Activity Guide,” Patient Guides, https://www.ottawaheart.ca/cardiac-rehabilitation-physical-activity-guide/seasonal-considerations. Accessed online December 15, 2022.
- N. Auger, B.J. Potter, A. Smargiassi et al. “Association between quantity and duration of snowfall and risk of myocardial infarction,” CMAJ, Vol. 189, #6 (February 13, 2017), pp. e235-e242, https://www.cmaj.ca/content/cmaj/189/6/E235.full.pdf.
- Government of Canada. “Be Heart Smart in the Winter,” Public Health Agency of Canada, https://www.canada.ca/en/public-health/services/chronic-diseases/cardiovascular-disease/heart-smart-winter.html. Accessed online December 15, 2022.
- Moman A. Mohammad, Sasha Koul, Rebecca Rylance et al. “Association of Weather With Day-to-Day Incidence of Myocardial Infarction. A SWEDEHEART Nationwide Observational Study,” JAMA Cardiology, Vol. 3, #11 (2018), pp. 1081-1089, https://jamanetwork.com/journals/jamacardiology/article-abstract/2706610.
- Krishnan Bhaskaran, Shakoor Hajat, Andy Haines, Emily Herrett, Paul Wilkinson, Liam Smeeth. “Short-term effects of temperature on risk of myocardial infarction in England and Wales: time series regression analysis of the Myocardial Ischaemia National Audit Project (MINAP) registry,” British Medical Journal, Vol. 341 (August 10, 2010), c3823, https://www.bmj.com/content/341/bmj.c3823.
- Government of Canada. “How Do I Know if I’m Having a Heart Attack?” Public Health Agency of Canada, https://www.canada.ca/en/public-health/services/chronic-diseases/cardiovascular-disease/know-having-a-heart-attack.html. Accessed online December 15, 2022.