Minimum training dose: keep your fitness and strength

For information only, not medical advice.

TLDR

A busy period doesn’t have to cost you your fitness and strength, as long as you don’t stop completely.
A 2021 review found that endurance holds up for as long as 15 weeks with two sessions a week, provided you keep the intensity.
In younger adults, strength and muscle size were maintained for up to 32 weeks with one strength session a week and one set per exercise. Older adults probably need a bit more.
The key: training less often and for less time is fine, but keep part of it hard.

October is the same story for me every year. Work picks up, the days get shorter, there are birthdays and school evenings. My schedule of three or four sessions a week is the first thing to go. I used to think: if I can’t do it properly, I’ll just pause. Until I noticed how hard those first weeks back were every single time.

So the question is: what is the minimum to avoid going backwards?

What the research says about “maintenance”

In 2021, researchers from the US Army’s institute of environmental medicine, together with Spanish training physiologist Iñigo Mujika, pulled together decades of studies on maintaining fitness. Their conclusions are refreshingly sober:

Endurance was maintained for up to 15 weeks when people still trained twice a week, or cut their volume by a third to two thirds, as long as the intensity stayed the same.
Strength and muscle size held up in younger adults for up to 32 weeks with one session a week and one set per exercise, at the same relative load.
In older adults, two sessions a week with two to three sets seemed necessary to preserve muscle size.

One Dutch example I find particularly convincing. Researchers at Maastricht University had twelve well-trained cyclists train much less and less hard for three weeks: three days a week. Their maximal power and oxygen uptake stayed the same.

Where the limits are

These studies are about maintaining, not improving. If you want to get faster or stronger, you need more. And the cyclists were well trained. How this plays out for someone who has only just started is less clear.

Stopping is genuinely different from cutting back. In a classic review from 2000, Mujika and his colleague Sabino Padilla already described how endurance declines measurably within a few weeks without training. Strength usually lasts a little longer.

And the minimum is not the same as the health recommendation. The World Health Organization advises adults to get 150 to 300 minutes of moderate activity a week, plus muscle-strengthening activity on at least two days. A maintenance week is an emergency plan, not a new standard.

My emergency plan for busy weeks

Two sessions, not zero. I put two in my calendar as fixed appointments. If an extra one fits, all the better.

One half-hour strength session. A squat or leg press variation, one push and one pull exercise, and a hinge such as a Romanian deadlift. One or two hard sets per exercise, close to what I normally lift. How to build that with little time, you can read in 90 to 120 minutes of strength a week and strength training after forty.

One short cardio session with some pace. Twenty to thirty minutes of cycling or running, with a few blocks of several minutes at a solid pace. Easy endurance work like zone 2 stays valuable, but in a minimal week I don’t let go of intensity completely.

Everyday movement counts too. Cycling to work, taking the stairs, an evening walk. It isn’t training, but it keeps the engine warm.

After the rush

Did you stop completely for a few weeks anyway? No drama. Build back up gradually instead of going straight back to your old weights. I wrote about that in restarting training after a break.

Recommendations

Training less is far better than not training.
Keep the intensity; cut volume and frequency first.
One strength session a week maintains a lot in younger adults; if you’re older, aim for two.
See a maintenance week as temporary, not as your new normal.

This article is for information only and is not medical advice. If you have an injury or a heart condition, or you’re unsure what your body can handle, talk to your (sports) doctor or physiotherapist.

Sources (selection)

Spiering BA, Mujika I, Sharp MA, Foulis SA (2021). Maintaining physical performance: the minimal dose of exercise needed to preserve endurance and strength over time. Journal of Strength and Conditioning Research, 35(5), 1449–1458.
Rietjens GJ, Keizer HA, Kuipers H, Saris WH (2001). A reduction in training volume and intensity for 21 days does not impair performance in cyclists. British Journal of Sports Medicine, 35(6), 431–434.
Mujika I, Padilla S (2000). Detraining: loss of training-induced physiological and performance adaptations. Part I. Sports Medicine, 30(2), 79–87.
Bull FC et al. (2020). World Health Organization 2020 guidelines on physical activity and sedentary behaviour. British Journal of Sports Medicine, 54(24), 1451–1462.