How much exercise is enough?

Introduction

Many thanks to a supporter from Australia for spotting the paper for this week’s note (Ref 1). Back in May 2020 I received a contact form asking “Do I need to ‘work out’ as much as is actually recommended? Would you be able to do a piece on how much exercise is actually beneficial for health?” This week’s paper will help to answer that question.

The World Health Organisation recommends that adults do 150 minutes or more each week of moderate-intensity aerobic physical activity or 75 minutes per week of vigorous-intensity aerobic physical activity or an equivalent combination of the two (Ref 2). The US government goes further by recommending 150-300 minutes of activity of moderate intensity, or 75-150 minutes of vigorous intensity, or an equivalent combination (Ref 3).

There is a great deal of literature to show that regular physical activity lowers incidence of cardiovascular disease and type 2 diabetes, among other non-communicable diseases, as well as delivering physical, social and emotional benefits. However, it is estimated that despite known benefits, more than 1.4 billion adults worldwide don’t meet these recommendations (Ref 4). Plus, the low propensity to exercise seems to be getting worse with more technology (screens) to entertain people while being sedentary.

The WHO also recommends doing muscle-strengthening exercises on two or more days a week, but this advice is less well known or promoted. This type of exercise can help to avoid, or at least delay, sarcopenia (muscle wasting). It can also improve bone mineral density, reduce the risk of osteoporosis and lessen the risk of bone fractures. Even more people – an estimated 70% of US adults – fail to meet this recommendation (Ref 5).

Given the benefits of exercise, it is important that recommendations are evidence based. As my contact form showed, people want to know what will confer benefit and then they might be more inspired to do the amount that is evidence-based. If this turns out to be lower than current recommendations, more people might think that this is more achievable, and they might make more of an effort to meet guidelines as a result.