How little exercise you can do without seeing a steep decline in fitness?

Living through this stressful COVID-19 period can make it difficult to maintain an exercise habit. With lockdown measures, stay-at-home orders, social distancing, the closure of gyms and, in some areas, a ban on outdoor activities such as golf and tennis, it’s no surprise that FitBit® recently reported a daily reduction in step counts ranging from 7-38% among its 30 million active users around the world. 

The question on everyone’s mind? What’s the least amount of exercise you can get away with temporarily before seeing a big decline in fitness levels? 

According to a new scientific review, published in the Journal of Strength and Conditioning Research, endurance performance can be maintained for up to 15 weeks when training frequency is reduced to just two weekly sessions of 13-26 minutes each as long as exercise intensity is maintained. And strength and muscle size can be maintained for up to 32 weeks with just one session of strength training per week (for adults older than 60, twice-a-week sessions are better at preserving muscle). 

The authors conclude that it’s the intensity (or the heart rate reached) of the reduced workouts that’s the key variable for maintaining fitness over time, despite rather large reductions in frequency and volume. 

One caveat: the review looked at studies that involved participants who consistently engage in physical exercise. 

So, it appears that if you are fit to start with, doing less exercise over the short term won’t have disastrous effects. 

However, if you aren’t staying in shape with regular exercise, you won’t be doing yourself any favours by doing less. And while you might be able to maintain existing strength with this minimum dose, it bears pointing out that you certainly won’t gain any strength. 

There’s a difference between minimum dose and optimal dose when it comes to exercise. Government recommendations call for adults to engage in 150 minutes of weekly moderate-intensity aerobic activity (such as walking or biking) or 75 minutes of weekly vigorous exercise (such as running or skipping) in addition to muscle-strengthening activities two or more days a week that work all major muscle groups.

But the review reinforces the idea that when it comes to exercise, something is always better than nothing. And if you exercise regularly you can afford to cut back a little without seeing a big drop in endurance and strength—good news for those of us who are missing our regular visits to the gym because of COVID-19.