The science behind detraining, or ‘reversibility’ of fitness, as it’s sometimes known, isn’t as complete as you might expect it to be. This is especially true when it comes to detraining in elite athletes, mainly because it’s tough to find a reliable and long list of really fit athletes who are willing to deliberately lose hard-earned fitness, just for the sake of a research paper!
That said, there’s a reasonable amount of literature on the subject from detraining studies among groups of ‘moderately fit’ volunteers. Combined with various case studies using elite athletes who’ve had to take time off due to illness or injury, we can make some strong connections.
Rather than dive too deeply into those studies (I recommend this well-referenced paper in Peak Performance if you did want to read more), I’m going to focus on blending key points from the science with my own experience of detraining over the years and try to offer up some practical advice.
Doing Something is Infinitely Better Than Doing Nothing
“Use it or lose it” is what we’ve often been told about fitness, and it’s more or less a true statement. Even if we’re super-fit to begin with, stopping training altogether will result in a pretty rapid degradation in fitness.
Admittedly, the losses in the first week of total inactivity are small, and in the first 2-4 days there may even be fitness gains as you recover fully from prior training. But you can expect up to a 15-20% reduction in VO2 max after a month of couch surfing, as well as a significant increase in body fat (dietary changes notwithstanding). A host of other physical and metabolic changes will eventually put you well behind where you were 4 weeks prior.
That said, even if you do a relatively small amount of training (around 30-50% of your previous volume) this decline can go from dramatic to almost imperceptible, which leads us to our next point:
Maintenance is Easier Than Improvement
Maintenance of fitness can be achieved with very little training stimulus, compared to the effort required to generate significant improvements. In this excellent podcast episode, Dr Scott Trappe (an expert in detraining from Ball State University) posits that once physical adaptations in the body are made, you only need to stimulate them two to four times per week to maintain fitness levels.
Dr Trappe feels that many athletes get too scared of losing fitness if they don’t train most, if not all, days and I’d tend to agree with that assessment, based on my observations of athletes around me over the years. However these fears are not necessarily based in reality.
It takes confidence to accept that a pretty serious reduction (e.g. 50% or more) in training volume will ultimately result in very little measurable fitness loss, but it’s true. If you want to understand the nuances of that a bit more, then I highly recommend listening to that podcast for more detail.
Some Fitness is Transferable
It’s true that to maintain specific conditioning for particular sports you need to practice those actual sports reasonably frequently to keep the right muscles conditioned and to maintain fluency in the movement patterns. However, many aspects of fitness are ‘shared’ across pretty much all activities. These include things like expanded blood volume, a stronger heart, the ability to effectively store and utilise glucose as a fuel.
In practice, that means that even if you can only run for an extended period, you can rest assured that a good proportion of the benefits you get from that running will transfer to the pool and the bike once you get back to them in the future.
HIIT is Your Friend
It’s often said that you lose ‘top end’ fitness (i.e. the ability to sprint or maintain high outputs for a short period of time) before you lose endurance. This may be true if your ‘high output’ training is what’s ‘shelved’ when you experience a significant drop in training volume, but it does not necessarily have to be the case.
Research into High Intensity Interval Training (HIIT) suggests that even very short bouts of activity (e.g. 5-10 x 30 seconds max effort with long rests in between) done 2-3 times per week can have astounding impacts on fitness if adhered to on a regular basis.
For this reason, incorporating some very short, very hard efforts into periods of reduced training volume might be a wise idea to lessen the impact of an overall reduction in volume.
Don’t Underestimate Muscle Memory
The good news for anyone with a rich history of endurance training is that you’re likely to hold onto fitness more effectively than newcomers to sport. This is thought to be because some really deep, subtle and chronic adaptations to training accumulate over a long period of time and these take a long time to reverse, even if you stop completely.
As a personal example, I had over 15 years of training history behind me when I had the only long-term ‘rest’ of my adult life about 10 years ago when I had to have knee surgery. I was laid up in a straight leg brace and unable to train for many months.
When I did finally return to running, I was only able to run 2-3 times per week and rarely for more than 5 miles at a time. I still managed to run a marathon (pacing a friend who broke the World Record for running with a 40lb pack) in about 3 hours and 20 minutes within about 18 months of getting off the operating table.
While it was a long way off my best time, I was pleasantly surprised with how comfortable I found it. I’m convinced that I leaned on my ‘history’ as an endurance athlete to do it because my immediate build-up to the race was ridiculously light in comparison to the majority of others who would’ve run a similar time.
No matter what constraints you’re working under, you can weather some time off of training without derailing your fitness. Just keep moving, choose your workouts wisely, and trust your body to handle the rest!