60 Men out-throw women by three standard deviations, and the gap starts before sports participation:
Thomas, Jerry R., and Karen E. French. “Gender Differences Across Age in Motor Performance: A Meta-Analysis.” Psychological Bulletin, 98(2):260–82.
61 Background on sexual differentiation (particularly chapter 1):
Baron-Cohen, Simon, Svetlana Lutchmaya, and Rebecca Knickmeyer. Prenatal Testosterone in Mind: Amniotic Fluid Studies. The MIT Press, 2004.
61 David C. Geary’s book Male, Female: The Evolution of Human Sex Differences, 2nd ed., American Psychological Association, 2010, is a fascinating read and the main resource for facts about sex differences in this chapter (example: boys develop longer forearms than girls while still in the womb; 30 percent of hunter-gatherer men died at the hands of other men; sex differences in upper-body strength). This compilation of one hundred years of studies of sex differences was also used:
Ellis, Lee, et al. Sex Differences: Summarizing More Than a Century of Scientific Research. Psychology Press, 2008.
61 The male/female throwing gap, and throwing skill in Australian Aboriginal children:
Thomas, Jerry R., et al. (2010). “Developmental Gender Differences for Overhand Throwing in Australian Aboriginal Children.” Research Quarterly for Exercise and Sport, 81(4):1–10.
62 Sexual selection and physical competition in humans and other animals, and targeting skill differences:
Puts, David A. (2010). “Beauty and the Beast: Mechanisms of Sexual Selection in Humans.” Evolution and Human Behavior, 31:157–75.
62 Targeting skills of females who are exposed to higher than normal levels of testosterone prenatally:
Hines, M., et al. (2003). “Spatial Abilities Following Prenatal Androgen Abnormality: Targeting and Mental Rotations Performance in Individuals with Congenital Adrenal Hyperplasia.” Psychoneuroendocrinology, 28(8):1010–26.
62 Despite the throwing gap, highly trained women will out-throw untrained men:
Schorer, Jörg, et al. (2007). “Identification of Interindividual and Intraindividual Movement Patterns in Handball Players of Varying Expertise Levels.” Journal of Motor Behavior, 39(5):409–21.
62 Analysis of the elite performance gap in track and field and swimming:
Thibault, Valérie, et al. (2010). “Women and Men in Sport Performance: The Gender Gap Has Not Evolved Since 1983.” Journal of Sports Science and Medicine, 9:214–23.
62 Sex differences in ultraendurance races, starting on p. 682 of a book known to a generation of runners:
Noakes, Timothy D. Lore of Running (4th ed.). Human Kinetics, 2002.
63 The widening running gap between men and women:
Denny, Mark W. (2008). “Limits to Running Speed in Dogs, Horses and Humans.” The Journal of Experimental Biology, 211:3836–49.
Holden, Constance (2004). “An Everlasting Gender Gap?” Science, 305: 639–40.
65 Sex differences in skeletal growth and proportions:
Malina, Robert, Claude Bouchard, and Oded Bar-Or. Growth, Maturation & Physical Activity (2nd ed.). Human Kinetics, 2003.
Malina, Robert M. “Part Five: Post-natal Growth and Maturation.” In: Stanley J. Ulijaszek, et al. eds. The Cambridge Encyclopedia of Human Growth and Development. Cambridge University Press, 1998.
Morgenthal, Paige A., and Diane N. Resnick. “Chapter 14: The Female Athlete: Current Concepts.” In: Robert D. Mootz and Kevin McCarthy, eds., Sports Chiropractic. Jones & Bartlett Learning, 1999.
65 A table listing basic physical differences between the sexes that are relevant to athleticism is on p. 176 of:
Abernethy, Bruce, et al. The Biophysical Foundations of Human Movement (2nd ed.). Human Kinetics, 2004.
66 Physical competition depends on the area inhabited by the organism:
Puts, David A. (2010). “Beauty and the Beast: Mechanisms of Sexual Selection in Humans.” Evolution and Human Behavior, 31:157–75.
67 Studies that document the larger number of female than male ancestors of modern humans are numerous, but a summary can be found in Geary’s Male, Female: The Evolution of Human Sex Differences, on pp. 234–35.
67 The “Genghis Khan paper”:
Zerjal, T., et al. (2003). “The Genetic Legacy of the Mongols.” American Journal of Human Genetics, 72:717–21.
67 Meta-analysis of the pre- and postpuberty gap in athletic skills between males and females ages two to twenty:
Thomas, Jerry R., and Karen E. French. “Gender Differences Across Age in Motor Performance: A Meta-Analysis.” Psychological Bulletin, 98(2):260–82.
67 Prior to puberty, boys and girls do not differ in height or muscle and bone mass:
Gooren, Louis J. (2008). “Olympic Sports and Transsexuals.” Asian Journal of Andrology. 10(3):427–32.
68 Age-related changes in boys and girls for a range of physical skills—throwing, sprinting—are in chapter 11 of:
Malina, Robert, Claude Bouchard, and Oded Bar-Or. Growth, Maturation & Physical Activity (2nd ed.). Human Kinetics, 2003.
68 Discussion of physical characteristics, including body fat, of female marathoners:
Christensen, Carol L., and R. O. Ruhling (1983). “Physical Characteristics of Novice and Experienced Women Marathon Runners.” British Journal of Sports Medicine, 17(3):166–71.
68 Discussion of body size and performance in developing gymnasts:
Claessens, Albrecht L. (2006). “Maturity-Associated Variation in the Body Size and Proportions of Elite Female Gymnasts 14–17 Years of Age.” European Journal of Pediatrics, 165:186–92.
Malina, R. M. (1994). “Physical Growth and Biological Maturation of Young Athletes.” Exercise and Sport Sciences Reviews, 22:389–433.
69 A captivating look into the East German doping program:
Ungerleider, Steven. Faust’s Gold: Inside the East German Doping Machine. Thomas Dunne Books, 2001.
70 Two excellent reviews of intersex conditions in Olympians:
Ritchie, Robert, John Reynard, and Tom Lewis (2008). “Intersex and the Olympic Games.” Journal of the Royal Society of Medicine, 101:395–99.
Tucker, Ross, and Malcolm Collins (2009). “The Science and Management of Sex Verification in Sport.” South African Journal of Sports Medicine, 21(4):147–150.
70 The male and female ranges of testosterone come from interviews with endocrinologists and lab reference ranges. The testosterone reference range varies slightly by lab. Quest Diagnostics provides a male range of 241–827 nanograms of testosterone per deciliter of blood. The Mayo Clinic provides a similar range: http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/8508.
71 Seven female athletes at the Atlanta Olympics who were found to have an SRY gene:
Wonkam, Ambroise, Karen Fieggen, and Raj Ramesar (2010). “Beyond the Caster Semenya Controversy.” Journal of Genetic Counseling, 19(6):545–548.
71 The prevalence of a Y chromosome in female competitors over five Olympics:
Foddy, Bennett, and Julian Savulescu (2011). “Time to Re-evaluate Gender Segregation in Athletics?” British Journal of Sports Medicine, 45(15):1184–88.
71 Rates of complete androgen insensitivity syndrome:
Galani, Angeliki, et al. (2008). “Androgen Insensitivity Syndrome: Clinical Features and Molecular Defects.” Hormones, 7(3):217–29.
71 Among the studies that document tall stature and masculine skeletal ratios in women with AIS:
Han T. S., et al. (2008). “Comparison of Bone Mineral Density and Body Proportions Between Women with Complete Androgen Insensitivity Syndrome and Women with Gonadal Dysgenesis.” European Journal of Endocrinology, 159:179–85.
Zachmann, M., et al. (1986). “Pubertal Growth in Patients with Androgen Insensitivity: Indirect Evidence for the Importance of Estrogens in Pubertal Growth of Girls.” Jo
urnal of Pediatrics, 108:694–97.
71 Androgen insensitivity only “scratches the surface” of intersex conditions in sports:
Foddy, Bennett, and Julian Savulescu (2011). “Time to Re-Evaluate Gender Segregation in Athletics?” British Journal of Sports Medicine, 45(15):1184–88.
72 The testosterone levels of elite female athletes:
Cook, C. J., et al. (2012). “Comparison of Baseline Free Testosterone and Cortisol Concentrations Between Elite and Non-Elite Athletes.” American Journal of Human Biology, 24(6):856–58.
72 Female netball players with higher testosterone self-select greater workloads:
Cook, C. J., and C. M. Beaven (2013). “Salivary Testosterone is Related to Self-Selected Training Load in Elite Female Athletes.” Physiology & Behavior, 116-117C:8-12 (ePub ahead of print).
74 Men’s hearts get bigger more rapidly:
Kolata, Gina. “Men, Women and Speed. 2 Words: Got Testosterone?” New York Times, August 22, 2008.
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The Talent of Trainability
78 In addition to interviews with Ryun, his book, In Quest of Gold: The Jim Ryun Story, written with Mike Phillips, gives a detailed account of his emergence in track and field and is the source of quotes from Ryun’s parents and his own writing.
79 The HERITAGE Family Study has produced more than one hundred journal articles. The HERITAGE papers most central to this chapter:
Bouchard, Claude, et al. (1999). “Familial Aggregation of VO2max Response to Exercise Training: Results from the HERITAGE Family Study.” Journal of Applied Physiology, 87:1003–8.
Bouchard, Claude, et al. (2011). “Genomic Predictors of the Maximal O2 Uptake Response to Standardized Exercise Training Programs.” Journal of Applied Physiology, 10(5):1160–70.
Rankinen, T., et al. (2010). “CREB1 Is a Strong Genetic Predictor of the Variation in Exercise Heart Rate Response to Regular Exercise: The HERITAGE Family Study.” Circulation: Cardiovascular Genetics, 3(3): 294–99.
Timmons, James A., et al. (2010). “Using Molecular Classification to Predict Gains in Maximal Aerobic Capacity Following Endurance Exercise Training in Humans.” Journal of Applied Physiology, 108:1487–96.
79 A layman’s introduction to the HERITAGE Family Study can be found here:
Roth, Stephen M. Genetics Primer for Exercise Science and Health. Human Kinetics, 2007.
83 The independent scientific commentary on the twenty-nine-gene expression signature:
Bamman, Marcas M. (2010). “Does Your (Genetic) Alphabet Soup Spell ‘Runner’?” Journal of Applied Physiology, 108:1452–53.
84 Data from Miami’s GEAR study were kindly shared by members of the research team, particularly: Pascal J. Goldschmidt (dean, Miller School of Medicine, University of Miami); Margaret A. Pericak-Vance (director, Miami Institute of Human Genomics); Jeffrey Farmer (GEAR project manager); Evadnie Rampersaud (director, Division of Genetic Epidemiology in the Center for Genetic Epidemiology and Statistical Genetics, John P. Hussman Institute for Human Genomics).
91 The “naturally fit six” study:
Martino, Marco, Norman Gledhill, and Veronica Jamnik (2002). “High VO2max with No History of Training Is Primarily Due to High Blood Volume.” Medicine & Science in Sports & Exercise, 34(6):966–71.
94 Wellington’s “near impossible task”:
“Wellington Wins World Ironman Championships.” Britishtriathlon.org, October 14, 2007.
96 Andrew Wheating’s entry into track and field is described here:
Layden, Tim. “Off to a Blazing Start.” Sports Illustrated, September 20, 2010.
96 Alberto Juantorena recounts his switch from basketball to track here:
Sandrock, Michael. Running with the Legends. Human Kinetics, 1996, p. 204.
97 Jack Daniels’s five-year study of Jim Ryun:
Daniels, Jack (1974). “Running with Jim Ryun: A Five-Year Study.” The Physician and Sportsmedicine, 2:63–67.
98 Study of Japanese junior athletes:
Murase, Yutaka, et al. (1981). “Longitudinal Study of Aerobic Power in Superior Junior Athletes.” Medicine & Science in Sports & Exercise, 13(3):180–84.
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Superbaby, Bully Whippets, and the Trainability of Muscle
100 The original Superbaby paper:
Schuelke, Marcus, et al. (2004). “Myostatin Mutation Associated with Gross Muscle Hypertrophy in a Child.” New England Journal of Medicine, 350:2682–88.
101 The first description of myostatin in scientific literature:
McPherron, Alexandra C., Ann M. Lawler, and Se-Jin Lee (1997). “Regulation of Skeletal Muscle Mass in Mice by a New TGF-β Superfamily Member.” Nature, 387(6628):83–90.
102 The myostatin mutation found in cattle:
McPherron, Alexandra C., and Se-Jin Lee (1997). “Double Muscling in Cattle Due to Mutations in the Myostatin Gene.” Proceedings of the National Academy of Sciences, 94:12457–61.
103 Whippets and the myostatin mutation:
Mosher, Dana S., et al. (2007). “A Mutation in the Myostatin Gene Increases Muscle Mass and Enhances Racing Performance in Heterozygote Dogs.” PLoS ONE, 3(5):e79.
104 Myostatin gene predicts sprinting ability and earnings in horses:
Hill, Emmeline W., et al. (2010). “A Sequence Polymorphism in MSTN Predicts Sprinting Ability and Racing Stamina in Thoroughbred Horses.” PLoS ONE, 5(1):e8645.
104 The impact of variations in the myostatin gene on athletic performance in animals:
Lee, Se-Jin (2007). “Sprinting Without Myostatin: A Genetic Determinant of Athletic Prowess.” Trends in Genetics, 23(10):475–77.
Lee, Se-Jin (2010). “Speed and Endurance: You Can Have It All.” Journal of Applied Physiology, 109:621–22.
105 Myostatin-inhibiting molecule increased mouse muscle 60 percent in two weeks:
Lee, Se-Jin, et al. (2005). “Regulation of Muscle Growth by Multiple Ligands Signaling Through Activin Type II Receptors.” Proceedings of the National Academy of Sciences, 102(50):18117–22.
105 Pharmaceutical companies are testing drugs that inhibit myostatin in humans:
Attie, Kenneth M., et al. (2012). “A Single Ascending-Dose Study of Muscle Regulator ACE-031 in Health Volunteers.” Muscle & Nerve, August 1 (ePub ahead of print).
106 H. Lee Sweeney on his IGF-1 work and the future prospect of gene doping:
Sweeney, H. Lee (2004). “Gene Doping.” Scientific American, (July 2004): 63–69.
107 Studies by University of Alabama–Birmingham’s Core Muscle Research Laboratory and the Veterans Affairs Medical Center:
Bamman, Marcas M., et al. (2007). “Cluster Analysis Tests the Importance of Myogenic Gene Expression During Myofiber Hypertrophy in Humans.” Journal of Applied Physiology, 102:2232–39.
Petrella, John K., et al. (2008). “Potent Myofiber Hypertrophy During Resistance Training in Humans Is Associated with Satellite Cell-Mediated Myonuclear Addition: A Cluster Analysis.” Journal of Applied Physiology, 104: 1736–42.
108 GEAR study data was generously shared by members of the University of Miami research team.
108 After twelve weeks, strength gains ranged from 0 percent to 250 percent:
Hubal, M. J., et al. (2005). “Variability in Muscle Size and Strength Gain After Unilateral Resistance Training.” Medicine & Science in Sports & Exercise, 37(6):964–72.
109 Muscle contraction speed limits human sprinting:
Weyand, Peter G., et al. (2010). “The Biological Limits to Running Speed Are Imposed from the Ground Up.” Journal of Applied Physiology, 108(4):950–61.
109 An accessible introduction to muscle fiber types, with a chart showing typical proportions:
Andersen, Jesper L., et al. (2007). “Muscle, Genes and Athletic Performance.” In: Editors of Scientific American, ed. Building the Elite At
hlete. Scientific American.
110 Two of the most famous studies of muscle fiber proportions in athletes:
Costill, D. L., et al. (1976). “Skeletal Muscle Enzymes and Fiber Composition in Male and Female Track Athletes.” Journal of Applied Physiology, 40(2):149–54.
Fink, W. J., D. L. Costill. and M. L. Pollock (1977). “Submaximal and Maximal Working Capacity of Elite Distance Runners. Part II: Muscle Fiber Composition and Enzyme Activities.” Annals of the New York Academy of Sciences, 301:323–27.
110 An excellent and freely available primer on muscle fiber types:
Zierath, Juleen R., and John A. Hawley. “Skeletal Muscle Fiber Type: Influence on Contractile and Metabolic Properties.” PLoS Biology, 2(10):e348.
110 Frank Shorter’s biopsied calf muscle can be viewed for free online in fig. 2 of this paper:
Zierath, Juleen R., and John A. Hawley. “Skeletal Muscle Fiber Type: Influence on Contractile and Metabolic Properties.” PLoS Biology, 2(10):e348.
110 Eight hours a day of electrical stimulation did not change slow-twitch fiber proportions:
Simoneau, Jean-Aimé, and Claude Bouchard (1995). “Genetic Determinism of Fiber Type Proportion in Human Skeletal Muscle.” The FASEB Journal, 9:1091–95.
110 The review, coauthored by Jesper Anderson, addressing the impact of training on muscle fibers:
Andersen, J. L., and P. Aagaard (2010). “Effects of Strength Training on Muscle Fiber Types and Size: Consequences for Athletes Training for High-Intensity Sport.” Scandinavian Journal of Medicine & Science in Sports, 20(Suppl. 2):32–38.
110 The Russian study correlating endurance genes and muscle fiber proportions:
Ahmetov, Ildus I. (2009). “The Combined Impact of Metabolic Gene Polymorphisms on Elite Endurance Athlete Status and Related Phenotypes.” Human Genetics, 126(6):751–61.
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The Big Bang of Body Types
114 Winner-take-all markets with discussion of the impact of technology:
Frank, Robert H. Luxury Fever: Money and Happiness in an Era of Excess. Free Press, 1999 (Kindle e-book).
115 The joint speed of Jesse Owens was similar to that of Carl Lewis:
The Sports Gene: Inside the Science of Extraordinary Athletic Performance Page 33