2250 words

PumpkinPerson (PP) has some weird—and uneducated—views regarding strength and coordination, which, of course, implies that he has no understanding of what “coordination” truly is. He seems to have convinced himself that coordination weightlifting does not require coordination (neuromuscular coordination; hereafter NMC—the ability of the central nervous system—CNS—to control muscles). That view is patently ridiculous. In this article, I will explain the logic behind the fact that strength and power exercises, in particular, NEED a high NMC, and without a high NMC, the athlete in question cannot perform to their highest potential.

PP wrote about an “athletic g factor” to attempt to liken it to the “g factor” regarding “intelligence” tests, but I’m not worried about that comparison (IQ is boring to me now). What I am worried about are his outlandish claims regarding what he believes regarding strength and NMC. PP cited Jensen’s Bias in Mental Testing where Jensen cited a correlation matrix in which “all of [the] correlations were positive“, writing that he’s “not sure why some commenters think weight lifting requires coordination when the correlation between strength (hand grip, chinning) and coordination (Pursuit rotor tacking, Mirror star tracing) is zero” (PP; Physical Coordination).

Well, “some commenters” have actual experience in what he is talking about, so, forgive me if I don’t believe the claims that, in my opinion, he pulled out of thin air. Take chin-ups. Imagine a case of someone attempting to chin-up that does not have high NMC. Since they were not coordinated, do you think they would be able to do a controlled rep in order to complete one rep? Or would their body be all over the place, flailing around since they do not have the mind-muscle (MMC) connection required to complete the lift. Now take his other example, hand grip. On its face, one might assume that this requires no NMC. But think about the process of gripping something tightly. If the muscles in the forearm, for example, are not adequately trained, then, in all lifts involving forearm strength (a great majority of which involve at least some type of forearm strength) will not be able to be performed properly, since the individual in question does not have the NMC required to properly do the exercise in question.

PP then says that when he “lift weights, [he doesn’t] feel like [he’s] using coordination.” This proves two things to me: (1) PP does not know how to lift properly, and then (2) follows that he does not know about the MMC.

The MMC is where the mind and the body “meet.” Acetylcholine functions as a neurotransmitter. This neurotransmitter “communicates” with the muscles in the body to cause a contraction. This contraction, then, causes the action of voluntary muscle movement. (I had an A&P professor explain to me that, out of the whole textbook he taught out of, one of the only things in the textbook that we could choose to do was move the body—contract muscles and cause movement). So when acetylcholine is released, it latches onto muscle fibers and causes muscle contractions.

We can put the MMC in this way: imagine doing a movement such as a bicep curl. One is not actively attempting to use the proper levers in order to properly lift the weight. On the other hand, if one is actively thinking about the muscles being used in the movement, then they are using the connection—they are strengthing their MMC and, in turn, developing the proper NMC which is required in order to properly lift weights and get the most returns possible from your time spent lifting.

The above diagram I drew is the process by which muscle action occurs. In my recent article on fiber typing and metabolic disease, I explained the process by which muscles contract:

But the skeletal muscle will not contract unless the skeletal muscles are stimulated. The nervous system and the muscular system communicate, which is called neural activiation—defined as the contraction of muscle generated by neural stimulation. We have what are called “motor neurons”—neurons located in the CNS (central nervous system) which can send impulses to muscles to move them. This is done through a special synapse called the neuromuscular junction. A motor neuron that connects with muscle fibers is called a motor unit and the point where the muscle fiber and motor unit meet is callled the neuromuscular junction. It is a small gap between the nerve and muscle fiber called a synapse. Action potentials (electrical impulses) are sent down the axon of the motor neuron from the CNS and when the action potential reaches the end of the axon, hormones called neurotransmitters are then released. Neurotransmitters transport the electrical signal from the nerve to the muscle.

So action potentials (APs) are carried out at the junction between synapses. So, regarding acetylcholine, when it is released, it binds to the synapses (a small space which separates the muscle from the nerve) and it then binds onto the receptors of the muscle fibers. Now we know that, in order for a muscle to contract, the brain sends the chemical message (acetylcholine) across synapses which then initiates movement. So, as can be seen from the diagram above, the MMC refers to the chemo-electric connection between the motor cortex, the cortico-spinal column, peripheral nerves and the neuromuscular junction. A neuromuscular junction is a synapse formed by the contact between a motor neuron and a muscle fiber. This is why beginners in the gym get stronger in the first 8 weeks or so of training—there has not been enough time for muscle to adequately grow in that time span. Thus, when people lift weights correctly, what they are doing is training their NMC—and their mind—to be able to adequately perform these types of actions in a safe, controlled manner.

How is NMC measured? It’s not simple to measure it, and in reality, the most feasible way to “measure it” in real life situations without the use of a lab is to just see one’s progress while they progress through higher and higher weights from their starting weights and they learn to perform the exercise in question safely. But a more empirical measure used in order to measure NMC are electromyography (EMG) tests. In fact, this test is THE MEASURE used to measure NMC, since all of the relevant variables in question (some seen in the above diagram) are tested. EMGs are used for numerous reasons, mostly in order to test for types of motor diseases which affect muscle action. There is also a related measure here: a nerve conduction study. This measures the speed and strength of signals traveling between two synapses, and so, the better one’s nerve conduction is in regard to muscle action, the higher their NMC is and, therefore, the better they will be able to perform any certain lift. So, for example, we can say that one’s NMC increased and the cause was resistance training if their EMG tests increase.

Imagine an Olympic lifter going to snatch 400 pounds. Would any sane person bet that they have low NMC (i.e., a low rate of firing between synapses as measured by an EMG)? A claim such as this would be quite preposterous—individuals like Olympic lifters clearly have trained both their bodies and minds in order to lift to the best of their abilities. And if they did NOT have high NMC (i.e., a higher rate of firing between synapses), then the weight would wobble and ultimately fall, causing the lifter serious injury. But, of course, we do not see that, since strength and NMC are closely related.

I now have some examples of studies which looked into this matter (that thinking about the action one is performing activates the primary muscles used in the movement in question), which will definitely put PP’s claims to rest for good.

Neuromuscular coordination is needed, for example, to be able to “squat lift” correctly (meaning, pick up a load from a squatting start and lift it; Scholz, Millford, and McMillan, 1995). Our understanding of how this occurs has greatly increased in 30 some-odd years since our technology has improved.

Now, take the MMC. We can simply define it as “One focusing on using the muscles in question to perform the lift.” Calatayud et al (2016) studied 18 resistance-trained men on a 1RM (one-rep max) bench press. Each individual in the study participated in 2 sessions: one to determine their 1RM and another experimental session. Calatayud et al (2016) attempted to control for as many factors as possible in order to attempt to see if the baseline changed at all. For example, all measures were made by the same two investigators; all measures were taken in the same facility; all participants participated in the same warm-up mobility drills prior to performing the lift; all participants performed the lift in the exact same manner they performed the two aforementioned sessions (same technique and body position, i.e., suicide grip and powerlifting technique).

They found that (1) higher levels of EMG activity lead to moving more weight; (2) the men could “selectively activate pectoralis and triceps muscles during the
bench press when this exercise is performed at low intensities” (Calatayud et al, 2016), at moderate intensities; (3) that focusing on one muscle (i.e., triceps brachii over pec major) did not hamper activation in one over the other; and (4) a threshold exists between 60-80 percent existed for muscle activation. Thus, experienced resistance-trained men can actively increase activity in certain muscles when cued to focus on those certain muscles.

Snyder and Fry (2012) studied 11 D-III football players on the bench press while recording EMG activity. They found that, when verbal cues were given to focus on the chest muscles, EMG increased by 22 percent, but when verbally cued to focus on the triceps, the pec major returned to baseline (though this does not mean, of course, that performance was hampered), while EMG activity increased by 26 percent. However, in-line with the findings from Calatayud et al (2016), when 80% 1RM were tested, EMG activity in the triceps remained unchanged, implying that there is a threshold.

The results of this study show that trained subjects can alter the participation of muscles in both moderate and higher-intensity multijoint resistance training exercises in response to verbal instructions, because both TB and PM activities were increased selectively in response to 2 different sets of instructions at 50% 1RM and 80% 1RM. This indicates that verbal instructions from trainers, therapists, and coaches are likely to have a measurable effect on muscle involvement, although it is unclear how generalizable this effect might be to all training exercises. Previous research from our laboratory (²³) indicated that untrained subjects performing a lat pull-down at 30% max isometric load could respond to verbal instructions to increase back muscle involvement by increasing latissimus dorsi activity while maintaining proper form and similar speed of movement. The subjects in that study increased latissimus dorsi activity by 17.6%, whereas in the current study, verbal instruction resulted in a 22.3% increase from baseline at 50% 1RM for PM and a 25.6% increase for TB. However, antagonist activity was not measured by Snyder and Leech (²³), and it was possible that the subjects activated antagonist muscles to offset additional force produced by agonist muscles. This study addressed this possibility, but no changes were seen in antagonist muscle activity with verbal instructions. The question of the effect of higher testing loads was also addressed by this study, and it was found that at 50% 1RM, the subjects were capable of altering muscle participation of both the horizontal adductors and the elbow extensors, but at 80% 1RM, only the horizontal adductors were affected. (Snyder and Fry, 2012)

If the activity of a muscle as measured by EMG is increased, then we can say that, for all intents and purposed, that NMC is high. One who is not familiar with a lift will have low NMC, that is, the firing will be low compared to someone with high NMC. Quite clearly, verbal instruction to focus on certain muscles can better activate them, and, using EMG, we can say that they have high NMC if the firing between synapses is fast.

Rutherford and Jones (1986) write that “It is concluded that a large part of the improvement in the ability to lift weights was due to an increased ability to coordinate other muscle groups involved in the movement such as those used to stabilise the body.” How weird is that… While Kim, Lockhart, and Roberto (2009) in their sample of elderly individuals found that “Strength gain by exercise training plays a role in the improved coordination of other fixator muscles necessary for body support while performing daily tasks such as cooking, gardening, reaching for an object, and walking, and in gaining more coordinated contractions between agonist and antagonist muscle groups leading to greater net force in the imposing movements.” Finally, Dahab and McCambridge (2009) found that strength training in kids improves the number and coordination of active neurons along with the firing rate pattern. This is important because the number and coordination of active neurons along with the rate of firing pattern influences—very strongly—NMC and how coordinated they will be.

In conclusion, it is quite obvious that PP does not know what he is talking about and only writes what sounds good in his head without having an adequate understanding of anatomy and physiology, NMC, MMC, APs and the like. These types of confusions can be cleared up by having an adequate understanding of anatomy and physiology and knowing how and why muscle actions are done, where they begin and where they end. Clearly, the claim that weight lifting requires no coordination is false.

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, writing “plenty 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 II. Eating 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.

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Assessing physical functioning is important. Such simple tests—such as walk, stand, and sit tests—can predict numerous things. “Testing” defines one’s abilities after being given a set of instructions. Racial differences exist and, of course, both genetic and environmental factors play a part in health disparities between ethnies in America. Minorities report lower levels of physical activity (PA) than whites, this—most often—leads to negative outcomes, but due to their (average) physiology, they can get away with doing “less” than other ethnies. In this article, I will look at studies which talk about racial differences in physical functioning, what it means, and what can be done about it.

Racial differences in physical functioning

Racial differences in self-rated health at similar levels of health exist (Spencer et al, 2009). Does being optimistic or pessimistic about health effect one’s outcomes? Using 2,929 HABC (Health, Aging, and Body Composition) participants, Spencer et al (2009) examined the relationship between self-rated health (SRH) and race, while controlling for demographic, psychosocial and physical health factors. They found that whites were 3.7 times more likely than blacks to report good SRH.

Elderly blacks were more likely to be less educated, reported lower satisfaction with social support, and also had lower scores on a physical battery test than whites. Further, black men and women were less likely to report that walking a quarter mile was “easy”, implying that (1) they have no endurance and (2) weak leg muscles.

Blacks were also more likely to report higher personal mastery:

Participants were asked whether they agreed or disagreed with the following statements: “ I often feel helpless in dealing with the problems of life ” and “ I can do just about anything I really set my mind to do, ” with response categories of disagree strongly, disagree somewhat, agree somewhat, and agree strongly. (Spencer et al, 2009: 90)

Blacks were also more likely to report higher BMI and more chronic health conditions than whites. White men, though, were more likely to report higher global pain, but were older than black men in the sample. When whites and blacks of similar physical functioning were compared, whites were more likely to report higher SRH. Health pessimists were found to be at higher risk of poor health.

Vazquez et al (2018) showed that ‘Hispanics’ were less likely to report having mobility limitations than whites and blacks even after adjustment for age, gender, and education. Blacks, compared to non-‘Hispanic’ whites were more likely to have limitations on activities of daily living (ADL) and instrumental activities of daily living (IADL) For ADL limitations, questions like “Do participant receive help or supervision with personal care such as bathing, dressing, or getting around the house because of an impairment or a physical or mental health problem?” and for IADLs “Does participant receive help or supervision using the telephone, paying bills, taking medications, preparing light meals, doing laundry, or going shopping?” (Vazquez et al, 2018: 4). They also discuss the so-called “Hispanic paradox” (which I discussed), but could not come to a conclusion on the data they acquired. Nonetheless, ‘Hispanic’ participants were less likely to report mobility issues; blacks were more likely than whites to report significant difficulties with normal activities of daily living.

Araujo et al (2010) devised a lower-extremities chair test: how quickly one can stand and sit in a chair; along with a walking test: the time it takes to walk 50 feet. Those who could not complete the chair test were given a score of ‘0’. Overall, the composite physical function (CPF) score for blacks was 3.45, for ‘Hispanics’ it was 3.66, and for whites, it was 4.30. This shows that older whites were stronger—in the devised tests—and that into older age whites are more likely to not need assistance for everyday activities.

This is important because differences in physical functioning between blacks and whites can explain differences in outcomes one year after having a stroke (Roth et al, 2018). This makes sense, knowing what we know about stroke, cognitive ability and exercise into old age.

Shih et al (2005) conclude:

a nationally representative study of the US population, indicate that among older adults with arthritis: (1) racial disparities found in rates of onset of ADL [activities of daily living] limitations are explained by differences in health needs, health behaviors, and economic resources; (2) there are race-specific differences in risk factors for the onset of ADL limitations; and (3) physical limitations are the most important risk factor for onset of ADL limitations in all racial and ethnic groups.

Safo (2012) showed that out of whites, blacks and “Hispanics”, blacks reported the most (low back) pain, worse role functioning score and overall physical functioning score. Lavernia et al (2011) also found that racial/ethnic minorities were more likely to report pain and have lower physical functioning after having a total knee arthroplasty (TKA) and total hip arthroplasty (THA). They found that blacks and ‘Hispanics’ were more likely to report pain, decreased well-being, and have a lower physical functioning score, which was magnified specifically in blacks. Blacks were more likely to report higher levels of pain than whites (Edwards et al, 2001; Campbell and Edwards, 2013), while Kim et al (2017) showed that blacks had lower pain tolerance and higher pain ratings. (Read Pain and Ethnicity by Ronald Wyatt.)

Sarcopenia is the loss of muscle tissue which is a natural part of the aging process. Sarcopenia—and sarcopenic obesity (obesity brought on by muscle loss due to aging)—shows racial/ethnic/gender differences, too. “Hispanics” were the most likely to have sarcopenia and sarcopenic obesity and blacks were least likely to acquire those two maladies (Du et al, 2018). They explain why sarcopenic obesity may be higher in ‘Hispanic’ populations:

One possibility to explain the higher rates of sarcopenia and SO in the Hispanic population could be the higher prevalence of poorly controlled chronic disease, particularly diabetes, and other health conditions.

[…]

We were surprised to find that Hispanic adults had higher rates of sarcopenia and SO [sarcopenic obesity]. One possible explanation could be the disparity in mortality rates among ethnic populations. Populations that have greater survival rates may live longer even with poorer health and thus have greater chance of developing sarcopenia. Alternatively, populations which have lower survival rates may not live long enough to develop sarcopenia and thus may identify with lower prevalence of sarcopenia. This explanation appears to be supported by the results of our study and current mortality statistics; NH Blacks have the highest mortality rate, followed by NH Whites, and lastly Hispanics.

Differences in physical activity could, of course, lead to differences in sarcopenic obesity. Physical activity leads to an increase in testosterone in lifelong sedentary men (Hayes et al, 2017), while those who had high physical activity compared to low physical activity were more likely to have high testosterone, which was not observed between the groups that were on a calorie-restricted diet (Kumagai et al, 2016). Kumagai et al (2018) also showed that vigorous physical exercise leads to increases in testosterone in obese men:

We demonstrated that a 12-week aerobic exercise intervention increased serum total testosterone, free testosterone, and bioavailable testosterone levels in overweight/obese men. We suggest that an increase in vigorous physical activity increased circulating testosterone levels in overweight/obese men.

(Though see Hawkins et al, 2008 who show that only SHGB and DHT increased with no increase in testosterone.)

So, clearly, since exercise can increase testosterone levels in obese subjects, and higher levels of testosterone are associated with lower levels of adipose tissue; since adequate levels of steroid hormones are needed for lower levels of adipose tissue (Mammi et al, 2012), then since exercise increases testosterone and higher levels of testosterone lead to lower levels of adipose tissue, if physical activity is increased, then levels of obesity and sarcopenic obesity should decrease in those populations.

Conclusion

Racial differences in physical functioning exist; these differences in physical functioning that exist have grave consequences for certain events, especially after a stroke. Differences in physical functioning/activity cause differences in sarcopenia/sarcopenic obesity in different ethnies. This can be ameliorated by targeting at-risk groups with certain outreach. This type of research shows how differences in lifestyle between ethnies cause differences in physical activity between ethnies as the years progress.

(Also read Evolving Human Nutrition: Implications for Public Health, specifically Chapter 8 on socioeconomic status and health disparities for more information on how and why differences like this persist between ethnies in America.)