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On Individual Variation in Response to Exercise


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Charles Darwin

Denis Noble

JP Rushton

Richard Lynn

L:inda Gottfredson



1500 words

On Twitter, JayMan wrote: “Not talked about much by fitness buffs (a world that’s full of BS anyway): a fair fraction of people respond little to even *negatively* to exercise“. This is the same person that thinks behavior genetics is a science, and that is a field “that’s full of BS anyway”, too. Anyway, the article that JayMan cited was from the website Stronger by Science, titled Hardgainers? What We Know About Non-Responders by Greg Nuckols.

First off, JayMan’s comment that “a fair fraction of people respond … *negatively* to exercise” is, on its face, already false. Most everyone in the study referenced by Nuckols (There Are No Nonresponders to Resistance-Type Training in Older Men and Women; Churchward-Venne et al, 2015) gained strength, but some people’s muscle fibers did not grow, and some apparently shrank (that is, their muscle cross-section area; CSA). But the important thing to note is that ALL gained strength, which implies physiologic adaptation to the stressor placed on the body (something that is overlooked).

Though, even if some people do not respond to certain programs or weight/rep schemes, does not mean that they are “non-responders”. All that needs to be done is to change the program if one “does not respond” to the program created. All exercise programs should be tailored to the individual and their own specific goals. There is no “one-size-fits-all” exercise program, as can be seen from these studies on so-called “hardgainers.”

The best study for this matter, though, is the HERITAGE (HEalth, RIsk factors, exercise, Training, And GEnetics) study, carried out by five universities in Canada and the US, who enlisted 98 two-generation families and then subject each member to five months of the same stationary bike training regimen—three workouts per week with increasing intensity. Each of the 482 individuals in the study was assayed, and so we would also see which genes would play a role in how fit one person would be in comparison to another.

David Epstein, author of The Sports Gene, writes (pg 85):

Despite the fact that every member of the study was on an identical exercise program, all four sites saw a vast and similar spectrum of aerobic capacity improvement, from about 15 percent of participants who showed little or no gain whatsoever after five months of training all the way up to 15 percent of participants who improved dramatically, increasing the amount of oxygen their bodies could use by 50 percent or more.

Amazingly, the amount of improvement that any one person experienced had nothing to do with how good they were to start. In some cases, the poor got relatively poorer (people who started with a low aerobic capacity and improved little); in others, the oxygen rich got richer (people who started with high aerobic capacity and improved rapidly); with all manner of variation in between—exercisers with a high baseline aerobic capacity and little improvement and others with meager starting aerobic capaacity whose bodies transformed drastically.

Though, contrary to JayMan’s claims, “Fortunately, every single HERITAGE subject experienced health benefits from exercise. Even those who did not improve at all in aerobic capacity improved in some other health parameter, like blood pressure, cholesterol, or insulin sensitivity” (Epstein, 2014: 88).

Epstein also writes about another study, undertaken at the University of Alabama-Birmingham’s Core Muscle and Research Laboratory, writing:

Sixty-six people of varying ages were put on a four-month strength training plan—squats, leg press, and leg lifts—all matched for effort level as a percentage of the meximinum they could lift. (A typical set was eleven reps at 75 percent of the maxmimum that could be lifted for a single rep.) At the end of the trainin, the sibjects fell rather neatly into three groups: those whose thigh muscle fibers grew 50 percent in size; those whose fibers grew 25 percent; and those who had no increased in muscle size at all.


Seventeen weight lifters were “extreme responders” who added muscle furiously; thirty-two were  moderate responders, who had decent gains; and seventeen were nonresponders, whose muscle fibers did not grow.* (pg 110)

* “It’s important to keep in mind that the harder the training, the less likely there are to be “nonresponders.” The harder the work, the more likely a subject will get at least some response, even if it is less than her peers” (pg 376).

Those who responded the most to the regimen had the most satellite cells in their quads which were waiting to be activated by training. When one becomes stronger from hypertrophy, the muscle thickness correlates to muscle CSA (Franchi et al, 2018). When one performs a repetition, the muscle fibers break down—this leads to trauma of the cellular proteins in the muscles which must then go under repair. Numerous growth factors influence the growth of skeletal muscle, such as GH (growth hormone), testosterone, protein and carb intake. Skeletal muscle adapts almost immediately after a bout of exercise, but the apparent changes to the muscle (both in the mirror and seeing large gains in strength on any particular movement) will take weeks and months.

There’s one thing about the claims of “exercise nonresponders” that really gets me: everyone responds positively to exercise, even if it’s not the same exact response to another individual doing the same—or different—exercise! I don’t know who made the claim that “people respond the same to any exercise program”, but that’s a claim that hbdchick made, writingplenty of the “fitness buffs” do [make the claim that everyone would respond the same to the same exercise regimen]. I then asked her, and JayMan, to name three people who made this outrageous claim: but, of course, I got no answer.

Not to mention that Nuckols ended the article writing:

… there were way fewer nonresponders when people were put on personalized training programs instead of one-size-fits-all standardized programs.  This study was primarily looking at aerobic fitness, but it also examined strength measures (bench press and leg press 5RM).  It found that all the subjects on personalized programs got stronger, while only 64.3% of the subjects on standardized programs got stronger. This gives us more evidence that “nonresponders” in scientific studies aren’t necessarily “true” nonresponders.

Take two people who have similar measures and, say, start at the same weight on one exercise. In 6 months, all else being equal with regard to lifestyle, there will be a difference in strength gained on that particular exercise. However, an increase from t he baseline from when both individuals began, to the 6-month point, shows that they did, indeed, respond to the exercise program at least in some way (see above quotes from Epstein). Thus, the claim that “there are nonresponders to exercise” makes no sense, on the basis that people necessarily respond physiologically to the stressors placed on them, and so, if they do more (and they will) than they did previously from their baseline, then they did adapt to the protocol, implying that they are not “nonresponders” to exercise. It does not matter if Person B does not catch up to Person A on all variables: the fact that there was a difference in each individual from the baseline all the way to 6 months on a specific regimen implies adaptation to the stressors—which implies that there is no such thing “nonresponders”.

JayMan also has views similar to this, which I have responded to last year in the articles Diet and Exercise: Don’t Do It? and Diet and Exercise: Don’t Do It? Part IIEating well and exercising—although benefits are not the same for each individual (and I do not know who made the claim this was the case)—does ameliorate numerous diseases and can extend lifespan, contrary to the results of certain studies (e.g., the Look AHEAD study; Annuzzi et al 2014).

Claims from people like JayMan who do not know the first thing about dieting and exercise are dangerous—though, all one has to do is have a basic understanding of physiology to understand that the claim “a fair fraction of people respond little to even *negatively* to exercise” is false, since everyone who does something for the first few times will ALWAYS be better in the months after learning the specific movement, implying that there are no nonresponders to exercise.

Of course everyone does not respond the same to exercise regimen A. Other studies found that increasing the frequency, reps, and set scheme lead to changes in the so-called “nonresponders.” Different individuals respond differently to different training programs [be it, strength, conditioning, cardio, plyometrics, balance, and stabilization etc. But it must be stressed that, although not everyone has the same potential for muscle-building/strength-gaining as, say, the IFBB pros or strongmen/powerlifters, everyone can and does benefit from NOT being sedentary, that much is most definitely clear. These studies that show “nonresponders” run people through the same exercise regimen. Anyone with an iota of experience in this industry knows that people do not respond the same to any and every exercise regimen and, so, the program must be tailored to that specific individual. Though, people like JayMan read this stuff and, without understanding what they’re talking about, jump to brash conclusions that are not supported by reality.



  1. donko says:

    It has to be admitted that Jayman, whether one agrees with him or not, is basically a caricature of ‘hereditarianism’ (add a good amount of ad hoc and post hoc reasoning). “North-South Korean differences are due to genetics”, “you can’t lose weight”, “exercise is negative for some people”.


  2. Phil78 says:

    I mean we’ve seen the guy already, a fairly puffy dude. He basically differs in respect to all other determinists that due to his left leaningness he is “passive” of the trajectory population changes will go except maybe for IQ (which they are obsessed with) as oppose to strictly heritage.

    In other words, he sees increasing first world obesity being counteracted as fruitless, which just shows his ignorance toward finer biological mechanisms in reality versus models and hypotheses. That is, even assuming the effect of environmental substances and activities are influenced in regards to be relfections of disposition, there would be no benefit of the same activities being performed beyond immediate behavioral disposition.

    It’s like biology convienently follows somesort of singularity.


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