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Exercise is Medicine

It is common knowledge that regular exercise is good for us. In the short term, it has been shown to reduce feelings of anxiety and in the long-term can reduce risk of cardiovascular disease, type 2 diabetes, metabolic syndrome, some cancers, depression and generalized anxiety disorder as well as improve sleep. Exercise also helps us maintain a healthy weight and slow the loss of bone density that happens with age. Even with all of these well-known benefits, less than 24% of Americans meet the recommended amount of aerobic and strength exercise on a regular basis.

How much is enough?

In 2020, the World Health Organization (WHO) released new physical activity recommendations to update the decade-old guidelines. The 2020 guidelines differ from their predecessor in a few significant ways. In this post, we will review the recommendations for adults and move on to how to accurately use these guidelines to meet your goals.

First, the minimum recommendation for moderate-intensity aerobic activity increased from 150 minutes to a range between 150 and 300 minutes and vigorous-intensity aerobic activity increased from 75 minutes to a range between 75 and 150 minutes. Basically, more is better. Additionally, going above 300/150 minutes may provide added benefit for certain individuals.

Second, any amount of exercise counts. 2010 guidelines suggested that bouts of exercise had to be 10 minutes or greater to be beneficial. Newer research suggests that any duration of exercise is better than none. This is great news for those who might not be able to tolerate 10 minutes yet or anyone feeling intimidated by the total number of minutes recommended per week.

Although this has stayed consistent between 2010 and 2020, it is important to reiterate. It is recommended that you also strength train at least 2 days per week. If you are new to strength training or spend the majority of your time doing aerobic physical activity (ahem, runners), 2-3 days may be your sweet spot. If you are a CrossFit athlete, 4-6 days per week has been shown to reduce risk of injury. A 2018 study found that <3 or >6 days per week of CrossFit training is associated with higher injury risk (1).

The final recommendation the WHO makes is to move more and sit less during the rest of your day. Combine that with the above recommendations and this will likely feels like a lifestyle overhaul for the majority of Americans. In 2008, a study found that less than 1 in 4 Americans are getting the recommended minimum amount of physical activity. Since the pandemic, I imagine that statistic has only become more grim.

Where to start

Let's start by differentiating between light intensity, moderate intensity and vigorous intensity exercise. Per the CDC, target heart rate (HR) for moderate intensity exercise is between 64% and 76% of your maximum HR while target HR for vigorous intensity exercise is between 76% and 93% of your maximum HR. If you wear a watch or fitness device that tracks your HR, this may be an easy way to monitor this. Average age-related maximum HR can be estimated with the equation: 220 - age. There are more accurate formulas that exist, but are beyond the scope of this blog post.

If you don't have a device that measures HR or you aren't very good at math, another relatively accurate method to monitoring intensity is the Borg CR-10 (RPE) scale.

Rating a session of exercise with the scale to the left has been found to be almost as accurate as using heart rate to estimate training intensity. Light intensity will be rated as a 2-3, moderate intensity as a 4-6 and vigorous intensity as 7-8. Use this tool to determine if your activity is categorized as light, moderate or vigorous without stopping to check HR.

A similar scale, the OMNI-RES (above, right), can be used to calculate intensity with strength training. Current research strongly suggests that strength training must be dosed at >60% 1 repetition maximum (aka the maximum amount of weight you can lift in that particular movement before failure) in order to facilitate true strength gains. A 6/10 on the OMNI-RES scale correlates with ~60% effort.

How to stick to your goal

I want to conclude this post with two brief tips that I use with many of my clients when we are setting goals.

1) You will be more successful in achieving your long-term goals if you focus on the process rather than the goal itself. For example, if "losing 20 pounds" is your goal, make a weekly goal that you know will help you get there. For example, "I will exercise at moderate intensity 30 minutes 5 days/week for the next 8 weeks" or "I will take a walk on my lunch break 4 days per week." When you focus on actionable short-term goals, you develop the habits required to achieve your long-term goals.

2) You need to find a mode of exercise that you enjoy. This may seem obvious, however many people try to force a form of exercise they hate purely because they think it is good for them. Rarely can they stick with this long-term. The "best" type of exercise for you is the type you will stick with!

I hope you all have had an active and healthy start to the new year!


(1) Claudino JG, Gabbett TJ, Bourgeois F, Souza HS, Miranda RC, Mezêncio B, Soncin R, Cardoso Filho CA, Bottaro M, Hernandez AJ, Amadio AC, Serrão JC. CrossFit Overview: Systematic Review and Meta-analysis. Sports Med Open. 2018 Feb 26;4(1):11. doi: 10.1186/s40798-018-0124-5. PMID: 29484512; PMCID: PMC5826907.

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