How Long Should I Recover From a Workout?
It's a question I get asked often. So if YOU'RE wondering when YOU can workout again...here's my shot at the answer.
When I first wanted to write about this topic I thought it was going to be pretty straightforward, but when I started to look into the research, there was a lot more to consider.
I should have known better...LOL.
As will with all things in the strength and conditioning world, the answer to this question is.. “It depends.”
BUT as I find, “it depends…” to be as useful an answer as a screen door on a submarine, I am going to do my best to wade through the research and give you some practical advice.
What Are We Recovering From?
Whenever we workout we are stressing the body. Yes, it is a positive stress, but a stress nonetheless.
And this stress produces fatigue.
Fatigue can be defined as a temporary decrease in our ability to produce force during exercise.
And while fatigue is a natural result of training, in order for us to train optimally and see the benefits from our hard work, we need this fatigue to dissipate.
This is, in large part, why we program workouts and periodize training.
We are, in effect, trying to balance - creating a large enough stimulus to force us to adapt (grow, get stronger, etc) while minimizing the effects of fatigue.
3 Types of Fatigue
When it comes to strength training we are really concerned with 3 types of fatigue. They are as follows:
Central Nervous Fatigue (CNS): this type of fatigue occurs at the level of the brain and spinal cord, and affects our ability to activate muscles. When fatigued, we cannot activate motor units or produce force efficiently. CNS fatigue can affect more than one muscle (sometimes, not always), even if that muscle may have not been worked during the exercise performed.
Peripheral Fatigue: this type of fatigue happens at the level of the muscle fiber and, simply put, is a disruption of the chemical processes that produce a muscular contraction. Which can result in a failure of muscle activation and/or a reduction in the amount of force produced.
Muscular Damage: this is damage that occurs at the level of the muscle fiber and can range from small disruptions to different structures of the muscle fiber itself - affecting the fiber's ability to contract - to a complete destruction of the muscle fiber leading to necrosis.
Even though we are referring to these types of fatigue separately, often times, it can be hard to tease them apart because they are all very closely connected to one another.
Peripheral fatigue and muscular damage can be considered one in the same since they both occur at the local level, but for the sake of this article we will be referring to them separately.
Are You “Recovered”?
A simple working definition of “recovered” is the time it takes for our ability to produce force to return to, or exceed pre-workout levels.
This would include a return to homeostasis for all affected physiologic systems, and structures.
Of the 3 types of fatigue, it seems that muscle damage takes the longest to recover from, with some research showing muscle force output was still diminished after 72 hours, *primarily* due to damage to the tissue affecting its ability to produce force(1).
Some studies showed a reduction in force longer than a week post exercise when the workout resulted in a high amount of muscle damage(2).
What is interesting is the effect muscle damage seems to have on the CNS, with regard to motor unit activation, which we will return to in a minute.
CNS Fatigue - Heavy Lifts Don’t Do it Bro.
Your CNS seems to recover very quickly, sometimes within minutes(3).
And contrary to popular belief, performing heavy compound lifts don’t seem to have a profound effect on your CNS ability to recover(4).
In fact, opposed to what many gym bros would say, it is actually long duration, low intensity exercise that seems to produce the most central fatigue(5-8).
And although we can experience CNS fatigue - during strength training - intra workout, and while it does have an cumulative effect, it tends to recover quickly post exercise.
The caveat being, your workout didn’t consist of very high volume, short rest periods, long-heavy eccentric contractions, and went on for a long period of time.
In short, if you did a “typical” strength training workout, you should not be concerned with CNS fatigue as being a limiting factor to your next training session.
For all intents and purposes, you can expect CNS fatigue to dissipate within 2 hours of cessation of most strength training sessions. Sometimes with even shorter than that.
Peripheral Fatigue - It Recovers Quick Too
Peripheral fatigue seems to recover in steps with CNS fatigue (CNS fatigue recovers a little quicker) with an approximate time course to recovery around 2 hours(9).
As stated before, peripheral fatigue is impairment of the chemical processes involved with muscular contractions - calcium ion release/accumulation, desensitization of myofilaments, impaired actin-myosin cross bridge function, and metabolite accumulation - but what mechanisms are triggered is determined by the type of training performed.
Light load, strength training to failure seems to trigger peripheral fatigue through metabolite accumulation, while eccentric contraction training (where metabolite accumulation is absent) may trigger it through impaired calcium ion release.
This video on the muscular contraction may be helpful if you are looking to understand these mechanisms better.
Peripheral fatigue can also result in high levels of motor recruitment, as it negatively affects the amount force each individual muscle fiber can produce. So, in order to compensate the CNS may upregulate and recruit more motor units to complete the required task.
This is, in part, why light load training to at or near failure can result in acquiring similar levels of hypertrophy to that of moderate to heavy strength training(10).
Muscular Damage, the X Factor
I mentioned earlier that of the 3 types of fatigue, muscle damage has the greatest time course to recovery.
Of course, this is dependent on the amount of damage elicited by the workout you may have done, but, for damaged tissue to repair and remodel, takes time.
The interesting thing about muscular damage is that it seems to also have an effect on the CNS.
As stated prior, our CNS tends to recover very quickly, and for good reason.
Logically speaking, it would not make sense for the CNS to fatigue quickly, seeing as how its role in the human body is not limited to doing a bicep curl.
Our CNS is responsible breathing, heart rate, temperature, hormone release and not to mention, our thoughts, and emotions, etc….oh and ALSO tack on coordinated movement.
So, it makes sense that our CNS would not throw in the towel so easily.
But when it comes to strength training, the exception to the rule, may be when a muscle is damaged; the CNS may down regulate (elicit effects of fatigue) to prevent further damage to that muscle.
Hence, CNS fatigue may be prolonged - in step with muscle damage - dependent on severity(11).
The proposed mechanisms as to how this occurs are unclear, but some prevailing theories have to do with pain from sore muscles signaling a down regulation from the CNS, and/or an inflammatory response communicated to the brain that has been shown to cause greater CNS fatigue in animal models(12).
Can We Get Back to the Question at Hand?
I am assuming the goal of your strength training probably includes getting stronger, and building lean muscle, along with the other auxiliary benefits.
The point of this article was to give you some semblance of what may need to be managed during your training bouts to ensure that you can continue to train effectively.
And if we look at the evidence from a macro perspective, it seems that managing how much you damage your muscles during training sessions (seeing as how that can have the longest time course to recover) might be a key factor when starting a new training program.
So, the typical, “no pain, no gain” philosophy might not be the best mantra to abide by.
Furthermore, there is little evidence to suggest muscular damage is necessary to build lean mass (hypertrophy) AT ALL.
With this in mind, let’s go over some practical advice.
My Practical Advice
The types of training that tend to cause the most muscle damage are eccentric contraction training (where the muscle is contracting, while it is lengthening) and high volume training (performing a lot of reps and sets for a given muscle group) especially with minimal rest.
So, it might be a good idea to limit these training types early on in your strength training program.
Limiting high volume, short rest breaks, and long lasting workouts is also in line with minimizing CNS fatigue as we learned that low intensity, long duration training tends to fatigue this system the most.
One thing that may be hard to determine, in a pragmatic way, is how “damaged” your muscles are. Since muscle soreness (DOMS) does not always correlate with muscle damage, this can be hard to gauge.
But effectually speaking, using soreness as a proxy for muscle damage may be the best tool we have in practice.
Having said that, muscle soreness tends to peak 48 hours after a hard training session, and tends to dissipate more after 72 hours. This may be a good heuristic to follow as to when to train previously trained muscle groups again.
General Guidelines
- Implement eccentric contraction training and high volume, low intensity training sparingly
- A typical training session lasting about an hour and half should be fine in most cases as long as you are using your rest breaks effectively.
- A good rule of thumb is to rest long enough to where you feel like you can give the same effort on the following set.
- Generally speaking waiting 48 to 72 hours before training a previously trained muscle group again is not a bad idea.
Conclusion
It should come as no surprise that how long you need to recover from a workout can be highly variable and individual.
When we start to factor in variables such as age, training experience, type of training, daily life stress, sleep quality, nutrition, etc. as well as phenomena such as the repeated bout effect - which imparts protective benefits from muscle damage - we can start to drastically affect the time course to recovery - along with managing training variables.
My hope is this article helps you get a bit more understanding of HOW your training matters.
And if you can have a better sense of what you are trying to accomplish with each training session you can have longevity and better results when training for life.