The rate of detraining: how fast do you lose muscular strength and aerobic endurance?
By Zuzana Rogers, PT, ScD, SCS, COMT
Specialist Running Physiotherapist
When it comes to the fitness gains you make, wouldn’t it be great if any forward progress were permanent?
Once you hit that PR, you’d never fail it again. Once you ran your perfect 5k time, the only place to go would be forward – no fear of slipping back and losing precious seconds.
Only, life isn’t like that and our bodies don’t work that way.
At some point in your athletic career (maybe now, if you’re reading this), you’ve probably had to take a break from training. Maybe you were traveling, had a family emergency, or just…. didn’t workout for a while (it happens to the best of us).
Whatever the reason, missing training can be frustrating, and going back to the gym is daunting – especially when you think about any performance losses you may have suffered and how much work it will take to get back where you were.
Well, there’s good news and bad news.
The bad news is that no one is immune to detraining. The good news, though, is that depending on your baseline fitness and how long you are out, you may not have lost as much as you fear.
What Is Detraining?
Everyone has off days in the gym or runs that feel like they take extra effort. This is normal, and doesn’t qualify as detraining. The same goes for stalled progress – that doesn’t equate to detraining and might instead be a symptom of under-optimized nutrition, recovery, or workout progression.
In order for a performance loss to be attributed to detraining (also known as deconditioning), it must come after a break from training. This includes decreased aerobic capacity, flexibility, muscular strength, speed, and any other “athletically trained” skill.
Detraining doesn’t just impact performance, either. Many physiological processes (that do affect performance) are also changed when you take a break from the gym. You’ll see changed in your blood pressure, blood sugar, and cholesterol levels over time. You’ll also slowly lose your body’s ability to use carbs more efficiently, and your muscles’ enhanced ability to process oxygen. Your metabolism may also begin to slow as muscle mass decreases and the body is no longer supporting a more active lifestyle.
It sounds a bit doom and gloom when you’re reading the definition, but don’t worry. You won’t lose all your gains after a long weekend – or even a week – away from the gym.
How quickly detraining affects your body depends on a myriad of factors like age, gender, natural build, baseline fitness, your sport of choice, and even the reason you’re taking a break. Most people are primarily concerned with either aerobic fitness or muscular strength; let’s look at those two first.
How Quickly Do You Lose Aerobic Fitness
Endurance athletes (or those primarily concerned with aerobic capacity) get the short end of the stick – you lose aerobic fitness faster than anything else.
That being said, it still takes TWO WEEKS before a noticeable impact is made on your performance.
After two weeks of no training at all, the average person experiences an initial drop in their VO2 max. This first shift primarily comes from the heart pumping less blood with each beat, which means less oxygen is making it to your muscles. When you take two weeks off training, the volume of blood in your body will actually decrease, giving your heart less to work with as your heart rate increases.
As time away from training increases, your VO2 max continues to decrease. After 4 weeks off, the average athlete will see a decrease of 6 percent. After 9 weeks, that jumps to 19 percent, and after 11 weeks of no aerobic training, most people have lost 25 percent of their VO2 max.
It’s important to remember that this is relative – you lose a percentage of your fitness level, not a set number value. So, elite level runners will detrain at the same rate that an amateur competitor will, but the elite runner will still be faster than the amateur in a direct comparison.
How Quickly Do You Lose Muscular Strength?
Muscular strength sticks around substantially longer than aerobic endurance. For strength athletes, more than 4 weeks can pass before any severe reductions in performance occur. In some cases, up to 6 weeks can pass with little to no change in ability.
What’s even more interesting is how much work is required to stave off those losses – or rather, how little. Muscular strength can be maintained with one to two strength sessions per week.
Factors That Affect the Rate of Detraining
There are a variety of factors that influence how long your fitness “sticks around.” Some of it is biological and out of your control, but other aspects of training can be adjusted to maximize long-term conditioning.
As you age, detraining occurs faster. Adults over 65 seem to lose nearly twice as much strength as adults aged 20-30. Most of these changes seem to take effect between weeks 12 and 31 of detraining.
Generally speaking, no significant differences have been found between males and females.
If you want to get really specific about it, the type of muscle fibers you’re predisposed to (fast twitch versus slow twitch) can impact how long fitness sticks around. Basically, if you’re predisposed to slow twitch fibers, it’ll be easier for you to maintain (or regain) muscular endurance than muscular strength, and vice versa. Generally speaking, though, the differences in detraining will be negligible – you’re still looking at 2 weeks for aerobic endurance and 4-6 for muscular strength.
Base Training Level
How quickly you lose fitness is also impacted by how fit you were to begin with – kind of. Rather than thinking in terms of peak performance (your fastest times or heaviest lift), think about how long you’ve been working out or developing your fitness. This concept is your training “base.”
A base is typically built during the off season, and it’s training you do to optimize your body’s ability to adapt to new stresses. Basically, you’re training your body how to respond to exercise more efficiently. You build a base over time, and it contributes to your overall fitness level.
So how does this relate to detraining?
Essentially, the better a base you have, the less you’ll lose – you’ve adjusted your personal “baseline.” Even after a period of detraining, endurance athletes will have a higher VO2max than most sedentary individuals.
Studies consistently find that those individuals who have been training for longer will retain more of their fitness gains than those who have only been following an exercise regimen for a few weeks. Basically, if someone JUST started a new exercise regimen (like a couch to 5k or a beginner’s lifting program) and has been training for less than a month, they’re going to return to a sedentary-level of fitness faster than someone who’s been exercising regularly for 3-6 months.
Think of it like a giant pile of rocks. When you exercise and gain fitness, you add rocks to the pile. When you detrain, you take them away. The longer you’ve been exercising, the bigger your pile is, and the longer it would take to deplete the pile entirely.
Reason for Taking a Break
Finally, strange as it may initially seem, the reason you take time off can impact the rate of detraining you experience.
If you’re taking a break due to prolonged illness, you’ll likely experience detraining at a slightly higher rate. This is ascribed to the additional stress your body is under while fighting illness, coupled with a potential inability to eat or drink as much as you need to.
On the other hand, if you’re taking time off due to travel, an injury, or a busy schedule, your body isn’t doing extra work while not exercising. Additionally, you have the benefit of day-to-day activity (as opposed to being stuck in bed). You also have the chance cross-train or switch up your routine, which leads directly into the next section…how to minimize detraining and protect those hard-earned gains.
Tips for Mitigating Detraining
No one wants to move backwards in fitness, even if it’s temporary, but sometimes life happens. If you know you’re about to head into a period of time where your workout routine is going to be severely restricted, there are some steps you can take to minimize your losses.
Something Is Better Than Nothing
If you have the choice between doing nothing and doing something less involved than your normal routine, do something less involved. It may seem like obvious advice, but you’d be surprised how discouraging it can feel to know you won’t have time to work as hard as you want, which can lead to workout skipping.
If you’re traveling, swap out your weight lifting for a bodyweight workout that you can do in your hotel room, or take advantage of the hotel gym’s dumbbells. If you’re working long hours and can’t get your full morning run in, do what you have time for – even if it’s only a mile instead of five.
Cross-train When Injured
This is similar to the previous tip, but if it’s an injury keeping you from your normal activities, find a way to cross train. Swimming is a fantastic low impact alternative for aerobics, and rowing can be as well. Most strength programs are customizable enough to avoid a body part and still train regular. For more sport-specific options, you might have to get creative, but bodyweight workouts, drills, and lifting can all improve sports performance.
With almost all injuries, there’s still some level or type of activity that’s safe and beneficial. It is important to consult with your doctor or physical therapist, though, to ensure that you’re not inadvertently aggravating the injury.
Decrease Duration and Increase Intensity
For those facing time constraints, making the most of the opportunities you do have can almost completely eliminate the effects of detraining. The key is to increase the intensity of your workouts as you decrease the frequency. Essentially, you want to put your body under the same amount of exercise-induced stress in less time.
This method of time-crunched fitness is part of what drove the HIIT craze – though be wary of plyometric sets if you haven’t previously had them in your training. For runners, push the pace over fewer miles. Weight lifters can consider supersets, or fewer reps of heavier, compound lifts. For more sport-specific training, look for ways to turn drills and skills training into circuit training, or incorporating cardio training as well.
Trust Your Body
While the idea of detraining may be frustrating to you, it’s really a testament to how efficient the body can be – if the body doesn’t need to work harder, it won’t. Then you’re not wasting energy or over-tiring your body (in case you have to run from predators lately).
The really cool part, though, is the retention of skill. That is, while you may be losing muscle mass or aerobic efficiency, your body still knows, neurologically, how to do things. It really is just like riding a bike.
Coming back to a sport after a hiatus doesn’t often feel good, but it’s not because your body has forgotten how to perform, it’s just not in peak shape. For instance, a dancer may remember patterns and choreography, but might feel sluggish or off-balance because stabilizing muscles have atrophied, flexibility has diminished, or end-range strength decreased. As fitness returns, performance will improve – but the body still has a recollection of movement patterns.
There’s an additional mental component to detraining, and that’s your own expectations of your performance. Whether you err on the side of over-confidence or under-confidence, having a mental expectation that isn’t in line with your physical capability can throw you off your game, leading to underperforming (if you think you’re out of shape) or feeling “off” (if you discount the effects of detraining).
As difficult as it is, when you return to exercise after more than two weeks off, try to approach with an open mind. Listen to your body, and be attentive, but don’t put expectations of high or low performance on yourself. (This is way easier said than done).
Detraining Isn’t a Bad Word
It can be easy to get wrapped up in constantly chasing new PRs, pushing the pace, and wanting to always improve. However, as most athletes have experienced, constant growth is unsustainable. Not only will you have rough days, but training at high-intensity for too long can lead to burn out, injury, and overtraining symptoms.
Detraining is a necessary part of most sports. There’s an “on” season and an “off” season – don’t be afraid to use that off season. Train gently, give your body a rest, and be confident in your abilities to ramp training back up to even greater heights after.
Then, when you’re in season, don’t be afraid of gentle days or rest days. Recovery is 100 percent part of the process, and if anything, what you do for recovery is more important than what you do in the gym. But that’s another topic for another article. In the meantime, be kind to yourself, use your rest days, and enjoy the ride that is training.
Do you want to learn more? Please contact us, we would be happy to answer all of your questions.
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