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Muscular Strength By Gender and Race

2000 words

It’s a known fact that men are stronger, but how much stronger are we really than women? Strength does vary by race as I have covered here extensively. However, I took another look at the only paper that I can find in the literature on black/white strength on the bench press and found one more data point that lends credence to my theory on racial differences in strength.

Strength and gender

Men are stronger than women. No one (sane) denies this. There are evolutionary reasons for this, main reason being, women selected us for higher levels of testosterone, along with differences in somatype. Now, what is not known by the general public is just how much stronger the average man is compared to the average woman.

Miller et al (2008) studied the fiber type and area and strength of the biceps brachii and vastus lateralis in 8 men and 8 women. They were told to do two voluntary tests of strength, using elbow flexion (think biceps curl) and knee extension. (Note: I am assuming they are exercises similar to biceps curls and knee extension, as the authors write that they had custom-made equipment from Global Gym.) They also measured motor unit size, number, and activation during both movements.

The women had 45 percent smaller muscle cross-section area (CSA) in the brachii, 41 percent in the total elbow flexor, 30 percent in the vastus laterus, and 25 percent smaller knee extensors. The last point makes sense, since women have stronger lower bodies compared to their upper bodies (as you can see).

Men were significantly stronger in both upper and lower body strength. In the knee extension, women was 62 and 59 percent of male 1RM and maximal voluntary isometric contraction (MVC) respectively. As for elbow strength, women were 52 percent as strong as men in both 1RM and MVC. Overall, women were 70 and 80 percent as strong as men in the arms and the legs. This is attributed to either men’s bigger fibers or men putting themselves into more physical situations to have bigger fibers to be stronger (…a biological explanation makes more sense). However, no statistical difference between muscle fibers was found between gender, lending credence to the hypothesis that men’s larger fibers are the cause for greater overall upper-body strength.

The cause for less upper-body strength in women is due the distribution of women’s lean tissue being smaller. Women, as can be seen in the study, are stronger in terms of lower limb strength and get substantially weaker when upper-body strength is looked at.

Other studies have shown this stark difference between male and female strength. Men have, on average, 61 percent more total muscle mass than women, 75 percent more arm muscle mass, which translates approximately into a 90 percent greater upper body strength in men. 99.9 percent of females fall below the male mean, meaning that sex accounts for 70 percent of human variation in muscle mass and upper-body strength in humans (Lassek and Gaulin, 2009). Women select men for increased muscular size, which means increased testosterone, but this is hard to maintain so it gets naturally selected against. There is, obviously, a limit to muscle size and how many kcal you can intake and partition enough kcal to your growing muscles. However, women are more attracted to a muscular, mesomorphic phenotype (Dixson et al, 2009) so selection will occur by women for men to have a larger body type due to higher levels of testosterone.

Strength and race

The only study I know of comparing blacks and whites on a big three lift (bench pressing) is by Boyce et al (2014). They followed a sample of 13 white female officers, 17 black female officers, 41 black male officers and 238 white male officers for 12.5 years, assessing bench pressing strength at the beginning and the end of the study. The average age of the sample was 25.1 for the 41 black males and 24.5 for the 237 white males. The average age for the black women was 24.9 and the average for white women was 23.9. This is a longitudinal study, and the methodology is alright, but I see a few holes.

An untrained eye looking at the tables in the study would automatically think that blacks are stronger than whites at the end of the study. At the initial recruitment, the black mean weight was 187 pounds and they benched 210 pounds. They benched 1.2 times their body weight. Whites weighed 180 pounds and benched 185 pounds. They benched 1.02 times their body weight. Black women weighed 130 pounds at initial recruitment and benched 85 pounds, benching .654 times their body weight. White women weighed 127 pounds at initial recruitment and bench 82 pounds, benching .646 times their body weight. Right off the bat, you can see that the difference between black and white women is not significant, but the difference between blacks and whites is.

At the follow-up, the black sample weighed 224 pounds and benched 240 pounds while the whites weighed 205 pounds benching 215 pounds. Looking at this in terms of strength relative to body weight, we see that black males benched 1.07 times their body weight while whites benched 1.04 times their body weight. A very slight difference favoring black males. However, there were more than 5 times the amount of whites in comparison to blacks (41 compared to 238), so I can’t help but wonder if the smaller black sample compared to the white sample may have anything to do with it.

Black women weighed 150 pounds at the follow-up, benching 99 pounds while white women weighed 140 pounds benching 90 pounds. So black women benched 6.6 times their body weight while white women benched .642 times their body weight.

Another thing we have to look at is black body weight compared to bench press decreased in the 12 years while white body weight compared to bench press was diverging with the black bench press compared to body weight.

Furthermore, this study is anomalous as the both cohorts gained strength into their late 30s (testosterone begins to decline at a rate of 1-2 percent per year at age 25). It is well known in the literature that strength begins to decrease at right around 25 years of age (Keller and Englehardt, 2014).

Another pitfall is that, as they rightly point out, they used skin caliper measuring on the black cohort. It has been argued in the literature that blacks should have a different BMI scale due to differing levels of fat-free body mass (Vickery et al, 1988). Remember that black American men with more African ancestry are less likely to be obese, which is due to levels of fat-free body mass. Since fat-free mass is most likely skewed, I shouldn’t even look at the study. I do believe that black Americans should have their own BMI scale; they’re physiologically different enough from whites—though the differences are small—they lead to important medical outcomes. This is why race most definitely should be implemented into medical research. The authors rightly state that when further research is pursued the DXA scan should be used to assess fat-free body mass.

Unfortunately, the authors did not have access to the heights of the cohort due to an ongoing court case on the department for discrimination based on height. So, unfortunately, this is the only anthropometric value that could not be assessed and is an extremely important variable. Height can be used to infer somatype. Somatype can then be used to infer limb length. Longer limbs increase the ROM, in turn, decreaseing strength. The missing variable of height is a key factor in this study.

Finally, and perhaps most importantly, they assessed the strength of the cohort on a Smith Machine Bench Press.

  • The Smith Machine is set on a fixed range of motion; not all people have the same ROM, so assessing strength on a smith machine makes no sense.
  • To get into position for the Smith Machine, since the bar path is the same, you need to get in pretty much the same position as everyone else. I don’t need to explain the anatomical reasons why this is a problem in regards to testing a 1RM.
  • An Olympic bar weighs 45 pounds, but numerous Smith Machines decreases the weight by 10-20 pounds.
  • Since the individual is not able to stabilize the bar due to the machine, the chest, triceps, and biceps are less activated during the Smith Machine lift (Saeterbakken et al, 2011)

 

Due to all of these things wrong with the study, especially the Smith Machine bench press, it’s hard to actually gauge the true strength of the cohort. Depending on the brand, Smith Machines can decrease the load by 10-30 pounds. Combined with the unnatural, straight-line bar path of the movement, it’s not ideal for a true strength test.

Conclusion

Gender differences in strength have a biological basis (obviously) and are why women shouldn’t be able to serve in the military and transgendered people shouldn’t be able to compete with ‘the gender they feel that they are’ (coming in the future).

The more interesting topic is the one on racial differences in strength. The untrained eye may read that paper and walk away assuming that the average black person is somehow stronger than the average white person. However, this study is anomalous since the cohort gained strength into their 30s when the literature shows otherwise. The biggest problem with the study is the Smith Machine bench press. It is not a natural movement and decreases muscle activation in key areas of the chest and triceps which aid in power while doing a regular bench press. Due to this, and the other problems I pointed out, I can’t accept this study.

Of course, height not being noted is not the fault of the researchers, but more questions would be answered if we knew the heights of the officers—which is an extremely critical variable. White males also gained more lean mass over the course of the study compared to blacks—47 percent and 44 percent respectively—which, as I pointed out, is anomalous.

There is more to HBD than IQ differences. I contend that somatype differences between the races are much more interesting. I will be writing about that more in the future. 

Furthermore, for anyone with any basic physiology and anatomy knowledge, they’d know that different leverages affect strength. The races differ in somatype on average and thusly have different leverages. This is one out of many reasons why there are racial differences in strength and elite sports. Leverages and muscle fiber typing. 

My points on racial differences in strength still hold; the anthropmetric data backs me upelite sporting events back me up. My theory as a whole to racial differences in sports is sound, and this study does nothing to make me think twice about it. There are way too many confounds for me to even take it seriously when reevaluating my views on racial differences in strength. This study was garbage to assess absolutely strength due to the numerous things wrong with it. I await a more robust study with actual strength exercises, not one done on an assisted machine. 

References

Boyce, R. W., Willett, T. K., Jones, G. R., & Boone, E. L. (2014). Racial Comparisons in Police Officer Bench Press Strength over 12.5 Years. Int J Exerc Sci 7 (2), 140-151.

Dixson, B. J., Dixson, A. F., Bishop, P. J., & Parish, A. (2009). Human Physique and Sexual Attractiveness in Men and Women: A New Zealand–U.S. Comparative Study. Archives of Sexual Behavior,39(3), 798-806. doi:10.1007/s10508-008-9441-y

Keller K, Engelhardt M. Strength and muscle mass loss with aging process. Age and strength loss. MLTJ. 2013;3(4):346–350.

Lassek, W. D., & Gaulin, S. J. (2009). Costs and benefits of fat-free muscle mass in men: relationship to mating success, dietary requirements, and native immunity. Evolution and Human Behavior,30(5), 322-328. doi:10.1016/j.evolhumbehav.2009.04.002

Miller, A. E., Macdougall, J. D., Tarnopolsky, M. A., & Sale, D. G. (1993). Gender differences in strength and muscle fiber characteristics. European Journal of Applied Physiology and Occupational Physiology,66(3), 254-262. doi:10.1007/bf00235103

Saeterbakken, A. H., Tillaar, R. V., & Fimland, M. S. (2011). A comparison of muscle activity and 1-RM strength of three chest-press exercises with different stability requirements. Journal of Sports Sciences,29(5), 533-538. doi:10.1080/02640414.2010.543916

Vickery SR, Cureton KJ, Collins MA. Prediction of body density from skinfolds in black and white young men. Hum Biol 1988;60:135–49.

Exercise, Longetivity, and Cognitive Ability

1650 words

The relationship between exercise and cognitive ability is important, but often not spoken about. Exercise releases many endorphins (Harber and Sutton, 1984) that help to further positive mood, have one better handle stress since sensitivity to stress is reduced after exercise; and after exercise, depression, and anxiety also decrease (Salmon, 2001). Clearly, if you’re attempting to maximize your cognition, you want to exercise. However, a majority of Americans don’t exercise (49 percent of Americans over the age of 18 do aerobic exercise whereas only 20 percent of Americans do both aerobic and muscle-strengthening exercise). The fact that we do not exercise as a country is proof enough that our life expectancy is declining (Olshansky et al, 2005), and we need to exercise—as a country—to reverse the trend.

Regular readers may know of my coverage of obesity on this blog. Understandably, a super majority of people will disregard my views on obesity and its causes as ‘pseudoscience’ or ‘SJW-ness’, that however says nothing to the data (and if anyone would like to discuss this, they can comment on the relevant articles). Since the average American hardly gets any exercise, this can lead to a decrease in cognitive functioning as less blood flows to the brain. Thus, everyone—especially the obese—needs to exercise to reach maximum genetic brain performance, lest they degenerate in cognitive function due a low-quality diet, such as a diet high in n-6 (the SAD diet), which is correlated with decreased cognition. Further, contrary to popular belief, the obese have lower IQs since around age three; obesity does not itself lower genotypic IQ, their IQ is ALREADY LOW which leads to obesity later in life due to a non-ability to delay gratification. Clearly, exercise education needs to be targeted at those with lower IQs since they have a higher chance of becoming obese in comparison to those with lower IQs (Kanazawa, 2013; 2014).

Clearly not eating well and not exercising can have negative effects on cognition. But what are the positives?

As mentioned previously, exercise releases endorphins that cause good mood and block pain. However, the importance of exercise does not stop there. Exercise also leads to faster reaction times on memory tasks and “increased levels of high-arousal positive affect (HAP) and decreased levels of low-arousal positive affect (LAP).” Exercise has important effects on people of all age groups (Hogan, Mata and Carstensen, 2013; Chodzko-Zajko et al, 2009). Further, physical exercise protects against age-related diseases and cognitive decline in the elderly by modifying “metabolic, structural, and functional dimensions of the brain that preserve cognitive performance in older adults.” (Kirk-Sanchez and McGough, 2014). Exercise is, clearly, a brain protectant during both adolsence and old age, so no matter your age if you want a high QoL living the best life possible, you need to supplement an already healthy lifestyle with strength training/cardio (of course, under doctor’s supervision).

Another important benefit to exercise is that it increases blood flow to the brain (Querido and Steele, 2007; Willie and Ainslie, 2011); however, changes in cerebral blood flow (CBF) during exercise are not associated with higher cognition (Ogoh et al, 2014). During prolonged exercise, cognition was improved when blood flow to the middle cerebral artery (MCA) was decreased. Thusly, exercise-induced changes in CBF do not preserve cognitive performance. Exercise to get blood to the brain is imperative for proper brain functioning. Our brains are vampiric, so we need to ‘feed it’ with blood and what’s the best way to ‘feed’ the brain in this context? Exercise!

Exercise also protects against cognitive degeneration in the elderly (Bherer, Erikson and Lie-Ambrose, 2013; Carvalho et al, 2014; Paillard, 2015). Further, longitudinal studies show an association between exercise and a decrease in dementia (Blondell, Hammersley-Mather and Veerman, 2014). The evidence is currently piling up showing that exercise at all ages is good cognitively, reduces mortality as well as a whole slew of other age-related cognitive diseases. The positive benefits of exercise need to be shown to elderly populations since exercise—mainly strength training—reduces the chance of osteoporosis (Layne and Nelson, 1999; Gray, Brezzo, and Fort, 2013). Moreover, elderly people who exercise live longer (Gremeaux et al, 2012). Now, if you don’t exercise, now’s looking like a pretty good time to start, right?

Finally, lack of exercise causes a myriad of deleterious diseases (Booth, Roberts, and Laye, 2014). This is due, in large part to our evolutionary novel environment (Kanazawa, 2004) which leads to evolutionary mismatches. An evolutionary mismatch, in this instance, is our obesogenic environment (Lake and Townshend, 2006). In terms of our current environment, it is evolutionary novel in comparison to our ancestral land (the Savanna; re: Kanazawa, 2004). Modern-day society is ‘evolutionarily novel’. In this case, we haven’t fully adapted (genetically) to our new lifestyles as, Gould said in Full House, our rate of cultural change has vastly exceeded Darwinian selection. Thusly, our environments that we have made for ourselves (and that we assume that heighten our QoL) actually cause the reverse, all the while top researchers are scratching their heads to figure out the answer, the problem while it’s staring them right in the face.

Our obesogenic environments have literally created a mismatch with our current eating habits and our ancestral one (Krebs, 2009). Moreover, dietary mismatches occur when cultural and technological change vastly outstrip biological evolution (Logan and Jacka, 2009). Clearly, we need to lessen the impact of our obesogenic environment we have made for ourselves so that we can live as long as possible, as well as be as cognitively sharp as possible. Thusly, if our environment causes a mismatch with our genome which in turn causes obesity, then by changing our environment to one that matches our genome, so to speak, levels of obesity should decline as our environment becomes less obesogenic while becoming like our ancestral environment (Genne-Bacon, 2014).

In sum, the evidence for the positive benefits for exercise is ever-mounting (not like you need Pubmed studies to know that exercise is beneficial). However, due to our obesogenic environments, this makes it hard for people with higher time preference to resist their urges and the result is what you see around you today. The evidence is clear: exercise leads to increased blood flow to our vampiric brains; thus it will have positive effects on memory and other cognitive faculties. So, in order to live to a ripe, old age as a healthy man/woman, hit the gym and treadmill and try staying away from evolutionarily novel things as much as possible (i.e., like processed food). When we, as a country recognize this, we can then be smarter, healthier and, above all else, have a high QoL while living a longer life. Is that not what we all want? Well hit the gym, start exercising and change your diet to one that matches our ancestors. Don’t be that guy/gal (we all know who that guy is) that jumps on the exercise train late and misses out on these cognitive and lifestyle benefits!

Note: Only with Doctor supervision, of course

References

Bherer, L., Erickson, K. I., & Liu-Ambrose, T. (2013). A Review of the Effects of Physical Activity and Exercise on Cognitive and Brain Functions in Older Adults. Journal of Aging Research,2013, 1-8. doi:10.1155/2013/657508

Blondell, S. J., Hammersley-Mather, R., & Veerman, J. L. (2014). Does physical activity prevent cognitive decline and dementia?: A systematic review and meta-analysis of longitudinal studies. BMC Public Health,14(1). doi:10.1186/1471-2458-14-510

Booth, F. W., Roberts, C. K., & Laye, M. J. (2013). Lack of Exercise Is a Major Cause of Chronic Diseases. Comprehensive Physiology. doi:10.1002/cphy.c110025

Carvalho, A., Cusack, B., Rea, I. M., & Parimon, T.,. (2014). Physical activity and cognitive function in individuals over 60 years of age: a systematic review. Clinical Interventions in Aging, 661. doi:10.2147/cia.s55520

Chodzko-Zajko WJ, Proctor DN, Fiatarone Singh MA, Minson CT, Nigg CR, Salem GJ, Skinner JS: American College of Sports Medicine position stand. Exercise and physical activity for older adults. Med Sci Sports Exerc. 2009, 41: 1510-1530. 10.1249/MSS.0b013e3181a0c95c.

Gray M., Di Brezzo R., I.L. Fort (2013) The effects of power and strength training on bone mineral density in premenopausal women. J Sports Med Phys Fitness, 53, pp. 428–436

Genné-Bacon EA, Thinking evolutionarily about obesity. Yale J Biol Med 87: 99112, 2014

Gremeaux V, Gayda M, Lepers R, Sosner P, Juneau M, Nigam A. Exercise and longevity. Maturitas. 2012;73(4):312–7.

Harber VJ, Sutton JR. (1984) Endorphins and exercise. Sports Medicine 1: 154–174, 1984

Hogan, C. L., Mata, J., & Carstensen, L. L. (2013). Exercise holds immediate benefits for affect and cognition in younger and older adults. Psychology and Aging,28(2), 587-594. doi:10.1037/a0032634

Kanazawa, S. (2004). The Savanna Principle. Managerial and Decision Economics,25(1), 41-54. doi:10.1002/mde.1130

Kanazawa, S. (2013). Childhood intelligence and adult obesity. Obesity,21(3), 434-440. doi:10.1002/oby.20018

Kanazawa, S. (2014). Intelligence and obesity. Current Opinion in Endocrinology & Diabetes and Obesity,21(5), 339-344. doi:10.1097/med.0000000000000091

Krebs, J. R. (2009). The gourmet ape: evolution and human food preferences. American Journal of Clinical Nutrition,90(3). doi:10.3945/ajcn.2009.27462b

Lake, A., & Townshend, T. (2006). Obesogenic environments: exploring the built and food environments. The Journal of the Royal Society for the Promotion of Health,126(6), 262-267. doi:10.1177/1466424006070487

Layne, J. E., & Nelson, M. E. (1999). The effects of progressive resistance training on bone density: a review. Medicine & Science in Sports & Exercise,31(1), 25-30. doi:10.1097/00005768-199901000-00006

Kirk-Sanchez, N., & Mcgough, E. (2014). Physical exercise and cognitive performance in the elderly: current perspectives. Clinical Interventions in Aging, 51. doi:10.2147/cia.s39506

 Ogoh, S., Tsukamoto, H., Hirasawa, A., Hasegawa, H., Hirose, N., & Hashimoto, T. (2014). The effect of changes in cerebral blood flow on cognitive function during exercise. Physiological Reports,2(9). doi:10.14814/phy2.12163

Olshansky, S. J., Passaro, D. J., Hershow, R. C., Layden, J., Carnes, B. A., Brody, J., . . . Ludwig, D. S. (2005). A Potential Decline in Life Expectancy in the United States in the 21st Century. New England Journal of Medicine,352(11), 1138-1145. doi:10.1056/nejmsr043743

Paillard, T. (2015). Preventive effects of regular physical exercise against cognitive decline and the risk of dementia with age advancement. Sports Medicine – Open,1(1). doi:10.1186/s40798-015-0016-x

Querido, J. S., & Sheel, A. W. (2007). Regulation of Cerebral Blood Flow During Exercise. Sports Medicine,37(9), 765-782. doi:10.2165/00007256-200737090-00002

Salmon, P. (2001). Effects of physical exercise on anxiety, depression, and sensitivity to stress. Clinical Psychology Review,21(1), 33-61. doi:10.1016/s0272-7358(99)00032-x

Willie, C. K., & Ainslie, P. N. (2011). Cool head, hot brain: cerebral blood flow distribution during exercise. The Journal of Physiology,589(11), 2657-2658. doi:10.1113/jphysiol.2011.209668