How Frequently Should You Lift? The Nautilus North Study

How Frequently Should You Lift?

The Nautilus North Study

How often should you lift?  What is the optimal training frequency?  Most lifters, at some point in their training lives, contemplate this question.  The answer to the question depends upon who you ask and what particular training philosophy they follow.  For example it’s not uncommon to see the top champions training six days per week.  On the other hand, some programs suggest training as infrequently as twice per week.  That’s a pretty big difference – 6 days a week vs. 2 days per week.  How do you go about figuring out which program is right?

John Little, a monthly columnist for Ironman magazine, inventor of the Max Contraction Training method and the author of over 30 books on bodybuilding, martial arts, history, and philosophy, wondered the same thing.  To answer the question he conducted a research study at the Nautilus North Strength & Fitness Centre in Bracebridge, Ontario, Canada, a study focused on answering questions about just how much and how fast bodybuilders can gain muscle mass.  Dubbed “The Nautilus North Study”, the results were published in the November 2005 issue of Ironman magazine. (1)  Let’s have a look at what he found.


Eleven strength training experienced subjects were recruited for this study.  These individuals strength training histories ranged from six months to 20 years and were described as being “fairly well developed in terms of their genetic potentials for mass and strength”.  Since the subjects were not beginners nor were they regaining previously held muscle the researcher believed that, “…any gains – if they were genuine lean tissue, a.k.a. real muscle – would be noteworthy.”

Accurately measuring body composition in the past has not always been easy, convenient, and accurate.  Scientists have employed several different methods over the years with some methods being more accurate but less convenient and others being more convenient and easy but less accurate.  Underwater weighing was the acknowledged gold standard for determining body composition for many years.  It was the most accurate method available, with an error of less than about 2%, but, unfortunately, was not widely available.  In recent years a new method has been introduced – the Bod Pod capsule – which operates on the same principle as underwater weighing, but measures displaced air instead of water.  The Bod Pod is not only quick (under 5 minutes) but accurate to plus or minus 2%, making it of similar accuracy as underwater weighting.

In practical terms, using the Bod Pod researchers can determine within .1 of a pound if a subject is gaining or losing lean or fat and whether a particular training and recovery protocol is producing lean tissue.  Even better, the Bod Pod capsule allows researchers to determine exactly to the day when the gain or loss in lean tissue or fat occurs.  Luckily, a Bod Pod capsule was available to the researchers for the Nautilus North study.

All subjects were pre-tested to establish their baseline body composition.  Following pre-testing all 11 subjects trained just once and then their body composition was tracked every day for 14 days.  The single workout was a high intensity type program and the subjects were instructed to abstain from additional resistance training for the remainder of the study period.


The subjects gained an average of 3.27 pounds of muscle from the single workout.  It took an average of 6.5 days for the gains in lean tissue to fully manifest.  The largest increase in lean tissue was 9.3 lbs by one subject while the smallest increase was 1.5 lbs by one subject.  The fastest increase in lean tissue was 1 day by two subjects while the longest time to fully realize lean tissue increases was 11 days by one subject.  Averaging the middle nine subjects by dropping the high and low in each category reveals an average lean tissue increase of .733 pounds and an average of 6.6 days to fully manifest.  The results are shown in table 1.

Table 1:  Individual, average, and range of changes in lean tissue and days to peak lean for 11 subjects.


Greatest Change in Lean Tissue

# of Days to Peak Lean


3.9 lb

10 days


2.1 lb

5 days


4.9 lb

1 days


2.4 lb

6 days


1.9 lb

1 days


2.1 lb

7 days


1.5 lb

10 days


2.2 lb

11 days


1.7 lb

5 days


9.3 lb

6 days


3.3 lb

9 days


3.2 lb

6.5 days


1.5 – 9.3 lbs

1 – 11 days


What are we to make of this study?  There are two very important things to learn from this study.  First, note the wide range of changes in lean tissue in response to the single workout.  One subject gained more than 9 lbs from a single workout, while 3 subjects gained less than 2 lbs from the exact same workout.  That is a range of 620%.  What does this mean to you?  It means there is a broad range of response – the magnitude of response is very large – within the human species.  If two lifters conducted the exact same workout it is possible (and very likely) that one will improve significantly from that workout and one won’t.

Admittedly, this is a strength training workout focused on building lean tissue.  Does the lesson here – the large magnitude of response across the human species – apply to other sports too?  Absolutely!  Other studies have found a range of response in aerobic capacity of 58% – 100%.  The range is not as great as that found in the above study, but the lesson still applies.  There is a very broad range of response.  Some individuals improve a lot, some improve a little, and everyone else is in the middle between the two extremes.  Can you get bigger and stronger?  Perhaps.  If, however, after several years of training you haven’t gotten as big and strong as you want despite consistent, hard training then it’s likely not due to your training but to your body’s natural, limited response to training.

As important as the first lesson is another more important lesson is found in the above study.  Most lifters won’t argue much if you suggest people have different levels of inborn talent and that, consequently, some will get stronger and bigger than others.  However, you will likely get a LOT of objections if you suggest that there is a broad range of optimal training frequency.

The second, most important, lesson is this – there is a broad range in rate of adaptation to training.  Some will adapt very quickly to training.  Some will take a very long time to adapt.  Everyone else falls in between these two extremes.  Note that the range of response was from 1 day to 11 days, which is a huge difference.  A few lucky individuals had completely absorbed and responded to the training in just 1 day.  On the opposite extreme, one individual took 11 days to fully realize the improvements to the workout and two individuals took 10 days to fully adapt.  What a huge range in rate of response!

Typically the argument presented to me is that since elites are the best bodybuilders on earth that their training program is obviously the best.  Elites are known to train daily, often training with high volume.  This is interpreted to mean that generally high volume training is the best training method.  This study indicates otherwise.  This study shows us that people adapt to training at widely different rates.  If you were an individual who recovered in 1 day, would there be any benefit to you in training once every 11 days?  Of course not.  If you were an individual who required 11 days to fully recover and improve from a workout, what would happen if you decided to train every day?  You would badly overtrain.  The researchers made this exact same point when they wrote,

“Knowing how soon a mass increase shows up tells you exactly how often you should train.  If, for instance, a gain in mass took two weeks to be produced, what would be the point of training more than once every two weeks?  All that would do is postpone or preempt the growth process.  If, however, the gains showed up in 24 hours, then waiting two weeks could possibly delay the gains.”

Here’s the main point – there is no 1 training frequency that works for everyone.  Instead there is a broad range of optimum training frequency, much broader than most realize or acknowledge.  Trying to train too frequently will likely result in sub-optimal performance and may end in overtraining and injury.  Don’t base your training frequency on how often someone else is training.  You must find your own optimum training frequency, despite how often anyone else trains.

What this study doesn’t teach us

The main thing this study doesn’t tell us is if rate of adaptation changes with training.  Is it possible that people’s rate and magnitude of response changes with training?  While this is possible, the study doesn’t address this point.  Other studies do provide some indication of answer, but not this particular study.  Without going into details, I suggest that people’s rate of adaptation does NOT improve significantly with training, but in any case, we can’t prove or disprove this point from the data in this study.


How frequently should you lift?  Rate and magnitude of response to a single strength training workout was studied in 11 experienced subjects.  Rate of response ranged from 1 – 11 days, with an average of 6.5 days, and magnitude of response ranged from 1.5 – 9.3 lbs, with an average of 3.2 lbs.  The two major lessons to be learned from this study are that the rate and magnitude of adaptation in the human species is very large, much larger than many realize or acknowledge.  Some people improve a lot, some improve very little.  Some people improve very rapidly – fully adapting to training in just 1 day – while others take many days to realize the benefits of a workout.  Training too frequently or infrequently results in sub-optimal improvement, with too frequent training likely resulting in overtraining and/or injury.  Each person must find their own individual optimal training frequency, despite what the optimal training frequency of any other person may be.




How Frequently Should You Lift? The Nautilus North Study — 11 Comments

  1. dear richard,
    this piece of work strongly influenced my thinking about how our body reacts to external stimuli at very individual rates. however, from a systematic point of view it is a pity that john little did not standardize the training schedule of the participants. this fact introduces significant variability to the results and prevents more meaningful conclusions from the recovery times. nevertheless, the way to use non-invasive lean body mass as surrogate for recovery/supercompensation without perturbing the process is certainly innovative and is certainly better than intermittent performance tests. this could be the basis for a more systematic study quantifying these preliminary results.

  2. The study is too short and doesn’t say what types of training they were doing before it.

    If someone was previously working out very frequently and very hard for quite a while, they could continue to get stronger and stronger during a ten day rest break. Someone on the other hand, who had previously been doing a very low volume, infrequent workout (but high intensity), would probably appear to gain less from this one workout. And someone who previously hadn’t lifted for a week or two, might appear to make a nice gain.

    In other words, it appears to be an utterly useless study. As opposed to genetic differences it could be totally the result of differences in the each subjects previous training program. Also it’s so short that random short term differences in sleep, stress, eating could account for all the differences.

    Kind of depressing actually that someone in a position to get such a study done would even think anything of use could be accomplished with this.

  3. I believe that the BodPod is fooled by body hydration. I believe that if you get measured in the bodpod, then drink 1/2 gallon of water (not recommended) then get measured in the bodpod again – it will say that you have gained 4 lbs of “lean mass”. As a result your body fat % will also be a bit lower since you weigh more but have not gained any fat. I am trying to confirm this with the folks at BodPod, but they are dancing around this issue. Obviously this could have a huge impact on the validity of the Nautilus North Study.

    • Hi, Ed.

      Excellent point. I recall that the results from bioimpedence testing, (bioimpedence came into prominence in the ’80s) was affected by the hydration levels of the subject. It is possible that hydration, recent food intake, or other factors could skew the results of the bodpod.

      That being said, the main point of the article is that people have individual rates of recovery. If the bodpod measure is off then it would impact the range of rate of recovery but not negate the fact that there is a range in the rate of recovery across the human population.

    • Could the initial drop in lean mass after the training session (not shown here but measured as part of the Nautilus North Study) be due to muscle swelling causing decreased muscle density post workout? Would the Bod Pod register a drop in lean mass due to muscle edema?

      If this is true, then wouldn’t it be possible that when Little interpreted the Bod Pod’s measurements as increases in lean mass, it was actually measuring a combination of lean mass increases and reduction in muscle swelling due to a normal recovery process independent of adaptation?

  4. How does a study on mass gain to be trusted without taking into account food/caloric intake and sleep patterns!!! Surely there are individual differences, but this study don’t helps in any way to understand the extent of those differences. Sadly a missed opportunity.

    • Hi, Freebo.

      You’ve made a very valid point. There is no doubt that outside factors, such as caloric intake, stress, and sleep patterns, can influence the rate of recovery of an individual. Until scientists make a concerted effort to study rate of recovery and all the various factors that can affect it, we each remain an experiment of one. Each person has a personal rate of recovery and for maximum improvements will have to discover what that rate is so as to design an optimal training plan.

    • This particular study uses the technique of controlling for a couple confounding factors (participants had been training for a long time, and were not regaining muscle, participated in a single high-intensity workout at the start followed by rest) and randomizing for everything else (recent exercise program, body type, rest, diet, etc.). With a sample size of 11, I’m not sure we can expect that randomizing would make this sample very representative of the general population (you generally need larger sample sizes to draw conclusions about a whole population from a sample of that population).

      I still agree with Rich that the study demonstrates significant individual differences. However, since the study only measures a single cycle of adaptation to exercise, it may be possible that there are significant differences in the way a single individual responds to identical workouts over time… either systematically due to training (as Rich says probably doesn’t happen), or perhaps there’s simply variability in the way that individuals respond to identical workouts. (And what if there’s variability in the degree of variability in different individuals’ responses to identical workouts!) Really, I’d like to see this study performed for a longer time with a much larger sample size.

      While waiting for this legendary study to be published, though, I’m convinced that I need to have some decent way to measure my own response to work out optimal training frequency. Any advice?

    • The gains took place over time. The amount of time to maximum gain varied over a very wide range of days. Some gained very quickly (a day or two) while some took much longer (10-11 days). Everyone else fell in-between the two extremes.

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