How strong is the correlation between Type II muscle fiber and elite performance in explosive sports?

Twitch-ful Thinking

The author's intent in this article is to offer a different perspective on this issue, one that challenges conventional wisdom and emphasizes the importance of hard work and effective training and practice-as well as to stimulate further discussion and research.

By Stephen Spiderman

ABSTRACT

    Many who follow sports take for granted that a high proportion of Type II (or fast-twitch) muscle fiber gives elite athletes an advantage in explosive sports like sprinting and jumping. They also assume that athletes of West African descent, especially African Americans and Afro-Caribbeans, have that genetic gift which explains, to a great extent, their world-beating performances in track, football, basketball, and other competitions. However, the Personal Bests of decathletes and the national records of various countries, including some from West Africa, indicate that, for an individual or for a population, blazing speed and spec­tacular jumping ability are probably not products of the same inherited traits, increasing the chances that an explanation of athletic success in explosive sports which involves amount and quality of intense practice is more useful than one based on fast-twitch muscles.

    In some ways, Chris Huffins and Erki Nool were remarkably similar competitors, even though one is African American and the other Estonian. Both were world-class decathletes born in 1970. Huffins (at 6' 2") is two inches taller, but they're both listed at 185 pounds, so both are ectomorphs. The totals for their Personal Bests in all 10 decathlon events, strangely enough, are surprisingly similar: 9253 (Huffins) and 9239 (Nool). Their best decathlon scores are also fairly close: 8815 (Nool) and 8694 (Huffins). Both recorded well over a dozen 8000+ decathlons. Both set decathlon records in one event.
    These coincidences aside, though, the two men's PBs in some events are startlingly divergent, as shown in Figure 1.

    For example, Huffins has run the 110-meter hurdles in 13.52 seconds, whereas Nool's best time is only 14.37, .85 of a second slower. As Figure 1 shows, Huffins would have earned 1037 points for his top performance, whereas Nool would have earned only 926,111 points less. On the other hand, Nool's best time in the 400-meter sprint is 46.23, but Huffins's is only 48.05,1.82 seconds slower. In this case, Nool would have earned 997 points, but Huffins only 907, 90 points less.
    (To get a perspective on these numbers, the difference between the fastest decathlon 110-meter hurdles [13.47, 1044 points] and the world record [12.87, 1126] is 82 points. The difference between the fastest decathlon 400 meter [45.68, 1025 points] and the world record [43.18, 1156 points] is 131 points.) Why is Huffins impressively faster in one case, but significantly slower in the other?
    Whatever the reason, we can find even bigger discrepancies in the javelin (115 points), high jump (123), discus (184), and pole vault (213). (The average difference between decathlon bests and world record scores is 206 points.) Huffins has the higher score in two of these, and Nool in the other two. As it turns out, each man is superior in exactly half the events: Huffins in the 100m, shot put, high jump, 110m H, and discus; Nool in the long jump, 400m, pole vault, javelin, and 1500m.
    What could explain this strange phenomenon, especially when we realize that the two men's 100-meter times differ by only 12/100ths of a second and only 29 points?
    In light of the generally accepted assumption that eight of the decathlon events (all but the 400-meter and the 1S00-meter) favor a high endowment of fast-twitch muscles, it's unlikely that the answer can be found in the proportion of Type I and Type II fibers in these two athletes. If Huffins has, say, 75% of the fast-twitch variety and Nool has only 50%, how can we explain such similar times in the 100-meter? Or how do we account for NooI's superior performance in the long jump, which is usually associated with greater speed and a higher
percentage of fast-twitch muscles? Moreover, how can we explain NooI's much stronger showing in the javelin and the pole vault, both of which require explosiveness, a quality associated with fast-twitch muscles? If, on the other hand, we assume that Nool had a significantly higher percentage of Type II muscles, how would we explain Huffins's impressive superiority in the high jump, discus throw, or 110-meter hurdles?
    Of course, we can speculate that each man developed better technique in some events by practicing them more effectively than the other man, but then we are flirting with the notion that, even at the highest level of sport, practice trumps genetic endowment, a position that is contrary to the most widely held explanation being offered today for varying levels of success among elite competitors.

TYPE I AND TYPE II MUSCLE FIBERS

    Since the discovery in the 1970s that humans have two distinct kinds of muscle fibers, few have challenged the notion that a high percentage of Type I muscles (slow- twitch) gives an athlete an edge in endurance events, whereas a high percentage of Type II muscles (fast­twitch) provides an edge in speed/ power activities, like most events in the decathlon.
    According to Dr. Tim Noakes, " A number of studies have shown that the muscles of elite athletes exhibit specific and predictable patterns of muscle fiber content according to the sports in which the athletes excel. Thus, the muscles of sprinters, jumpers, and weightlifters contain a high percentage of Type II fibers. Middle-distance (400 m to 1500 m) runners, cyclists, and swimmers tend to have equal proportions of both Type II and Type I fibers. In long-distance (10 km to 42 km) runners and cross-country skiers, the percentage of Type I fibers is higher."
    Moreover, it is also widely accepted that these percentages are a genetic gift which will not change dramatically with training. According to Noakes, "These differences between sprinters and distance runners are probably genetic ... If that is so and if these different fiber patterns are essential for success in the various sports, then it strongly suggests that a person's ultimate potential for success in endurance sports may be determined, in part, by being born with a high percentage of Type I fibers. Similarly, raw speed and weightlifting strength may also be determined by the number of Type II fibers with which the athlete is born."
    Elizabeth Quinn, an exercise physiologist and fitness consultant, is more specific about the proportions: "Olympic sprinters have been shown to possess about 80 percent fast-twitch fibers, while those who excel in marathons tend to have 80 percent slow-twitch fibers."
    Following this reasoning, some commentators conclude that athletes with East African ancestry, who dominate middle- and long-distance running events, must have an abundance of slow-twitch muscles, while those, like Chris Huffins, with West African ancestry, who dominate sprinting and some jumping events, must have an abundance of fast-twitch muscles. For these observers, like Noakes, the highest level of athletic success is, to a great extent, founded in genetic differences in the proportion of Type I and Type II muscles in individuals and populations.
    Let's focus on conjectures about Type II fibers. Amby Burfoot, former editor of Runner's World, maintains: "Where pure explosive power­--that is, sprinting and jumping---are required for excellence in a sport, blacks of West African heritage will excel." Jon Entine, author of Taboo: Why Black Athletes Dominate Sports and Why We're Afraid to Talk About It, agrees with Burfoot: "If an athlete does not have a certain proportion of fast-twitch muscles, he or she can't hope to be a champion sprinter or jumper... In practical terms, this detail suggests that sprinters are born, not made ... It appears that for blacks from West Africa, innate ability may be more critical than training in turning out great leapers and sprinters." Later he says, "Blacks with a West African ancestry generally have ... a higher percentage of fast-twitch muscles and more anaerobic enzymes, which can translate into more explosive energy."

LACK OF CORRELATION

    However, the achievements of actual competitors call into question such claims about fast-twitch muscles. In fact, the performances of top-level decathletes and the national athletic records of various countries suggest that success in one anaerobic event (e.g., the 100-meter sprint) is not necessarily correlated with success in other anaerobic events (e.g., the high jump). If, as Noakes, Burfoot, and Entine suggest, elite sprinters and jumpers both have a high proportion of fast­twitch muscles, we would expect to see a strong correlation between the performances of decathletes in running and jumping events, but this is rarely the case.
    The lone exception is a correlation between the sprints and the long jump, which can be attributed to the fact that a long jumper benefits from a fast run-up. In other words, someone who can run fast, for whatever reason, can jump far partly because of the speed of their approach. According to one study, "approach velocity is highly related to performance in the horizontal jumping events." Therefore, training for the 100-meter sprint is, in effect, training for the long jump (although, as we will see, the correlation between the two events is far from perfect).
    However, research suggests that there is virtually no correlation between the sprinting events and the high jump, where the speed of the runup is irrelevant. Lee Creighton, analyzing the decathlon scores from the 1996,2000, and 2004 Olympics, found no correlation between the 100-meter sprint and the high jump? The same is true for Raoul Van Damme, et al. when they studied "600 world-class decathletes."
    In addition, Van Damme and Creighton found no correlation between the 100-meter sprint and the pole vault. Van Damme found no significant correlation between the 400-meter and the pole vault. Creighton found a slight correlation between the 400-meter sprint and the pole vault, and no correlation between the 110-meter hurdles and the pole vault.
    This remarkable lack of correla­tion makes sense if and only if at least one of the following is true:
      1. Decathletes without an abundance of fast-twitch muscles can do well at sprinting events and the long jump;
      2. Decathletes without an abundance of fast-twitch muscles can do well at the high jump and pole vault;
      3. A high proportion of fast-twitch muscles does not provide an advantage in anaerobic activities.
    All of these statements, of course, contradict conventional wisdom, but if decathletes' performance in the three running events shows little or no correlation with their performance in two of the jumping events, we need to question the tendency to attribute success in running and jumping events to the same cause-an abundance of fast-twitch muscles.

COMPARING DECATHLETES

    When we look at individual decathletes, like Chris Huffins and Erki Nool, the likelihood that performance can be associated with muscle fiber proportions shrinks still further. Although we generally find that faster sprinters do better in the long jump than their slower rivals, we can sometimes find the opposite, as with Huffins and Nool.
    Other cases are even more strik­ing. For example, Roman Seberle (10.66) and Attila Zsivoczky (10.64) have virtually the same Personal
Best in the 100 meters, but Seberle has jumped 8.11 meters (26 feet, 2 inches), whereas the best Zsivoczky could do in this event is only 7.31 (just under 24 feet), over two feet shorter. For his effort, Seberle would have earned 1089 points, compared to Zsivoczky's 888, 201 points less. On the other hand, Dan O'Brien, like Seberle, has jumped 8.11 meters, but has run 100-meters in only 10.23 seconds, .43 seconds faster than Seberle, and would have earned 1040 points, 102 more than his rival. One other example: Kristjan Rahnu's PB in the 100m is 10.43 (.23 seconds faster than Seberle, worth 54 points more), but in the long jump it's only 7.58 (.53m shorter than Seberle, 134 points less).
    We can find similar discrepancies when we compare other sprinting events to the long jump. One of the most interesting is between our old friend Erki Nool, who set the decathlon record for the long jump (8.22 meters), and Frank Busemann, who set the decathlon record for the 110-meter hurdles (13.45 seconds). Nool's best at the hurdles is 14.37, almost a full second slower than Busemann's record and worth 120 points less. Busemann's best in the long jump is 8.07, 38 points less than Nool's. Conversely, Jaakko Ojaniemi's PB for the hurdles is 14.67, slightly slower than Aleksei Sysoyev's at 14.59, but Ojaniemi has jumped 8.03 meters (26 feet, 4 inches, 1068 points), and the best that Sysoyev has done is only 7.15 (23 feet, 5.5 inches, 850 points), almost three feet shorter and 218 points less.
    Even within the sprints themselves, we can find cases where Runner A does Significantly better than Runner B in the 100m, but Runner B does significantly better in the 110-meter hurdles. Here's one striking example: Daley Thompson's PB in the 100m, is 10.23 (1132 points) and Roman Seberle's is 10.64 (991), 141 points less, whereas Seberle's PB in the 110m hurdles is 13.68 (1125 points) but Thompson's is only 14.04 (1060), 65 points less. Does it really make sense to say that one of these athletes has a higher percentage of fast-twitch muscles?

FAST-TWITCH VS. INTENSE PRACTICE

    However, if we conclude from these extreme examples that two elite decathletes, like Seberle and Thompson or Huffins and Nool, probably have about the same percentage of fast-twitch muscles, then we are acknowledging that something besides muscle fiber accounts for the difference in their performances in two supposedly related events. We have essentially taken fast-twitch muscles out of the equation in these examples. The question is, if we can come up with some other causal factor for extreme cases, and that factor would also explain less extreme cases, why would we bother to appeal to the percentage of fast-twitch muscles at all, since it's useless in many cases and a (literal) pain to measure in any case?
    A more parsimonious explana­tion, which can be tested without sticking a needle in anyone's leg, is based on the amount and quality of intense or "deliberate" practice, which, as the work of K. Anders Ericsson and others has shown, can be measured precisely and can account for expertise in many fields, including sports. Most observers would agree that two decathletes who have the same ratio of slow- to fast-twitch muscles can still have different amounts of success in a specific event if they do not practice that event equally effectively. One might spend considerably more time on the event. One might have a more astute coach who can find the flaws in technique and offer useful suggestions for eliminating them. One might be more willing to work on improving weaknesses than the other.
    If that is a reasonable explanation when two athletes have the same proportion of muscle fibers, why couldn't it be reasonable when they don't? For example, suppose A outshines B in every aerobic event. We could guess that A has a higher percentage of fast-twitch muscles, but it is equally likely that the two athletes have similar percentages and A has had more effective prac­tice than B in everyone of those events. It is even possible that B has a higher ratio of Type II muscle fibers but A's coaching and practice routine are so much more efficacious that they more than compensate for B's putative advantage.
    We must also acknowledge the possibility that the proportion of slow- and fast-twitch muscles in an individual, rather than being genetically determined, is a response to a lifetime of aerobic or anaerobic activity. Perhaps the "specific and predictable patterns of muscle fiber content," which Noakes says can be found in elite athletes, are an effect, not a cause. Since no one has ever done a longitudinal study of Type I-Type II ratios, following subjects from babyhood to adulthood, we cannot say to what extent intense pursuit of aerobic or anaerobic activity from childhood influences proportion of muscle types.
    Until such studies are com­pleted, we must rely on other kinds of data. One lucrative source of evidence is the national records in track and field events, which raise doubts about the validity of fast-twitch muscle fiber generalizations relating to populations.

A QUESTIONABLE GENERALIZATION

    In particular, Burfoot's and Entine's generalization that elite athletes with West African ances­try tend to have a higher percent­age of fast-twitch muscles than all other populations needs to be seriously questioned. The primary support they offer for this view is that African Americans and Afro­Caribbeans, who almost all have some West African ancestry, domi­nate virtually all sprinting events, the speed positions in football, some jumping events, especially the long jump, and basketball, which showcases rebounding and slam dunking. This reasoning, of course, is circular: blacks succeed at certain sports because they have lots of fast-twitch muscles, and we know they have lots of fast-twitch muscles because they succeed at certain sports.
    We must also wonder if the proportion of West African ancestry affects the proportion of fast­twitch muscles. After all, three of the greatest decathletes of all time have mixed-race ancestry: Daley Thompson has a Nigerian father and a Scottish mother; Dan O'Brien has an African American father and Finnish mother; and Bryan Clay has an African American father and a Japanese mother. Given the admixture of European ancestry in most American blacks, Thompson and Clay most likely have less than 50% West African ancestry. If any of these men in fact has an abundance of fast-twitch muscles, how can we know which set of ancestors are responsible?
    But, more importantly, Burfoot's and Entine's claim is not consistent with the performances of West Afri­can athletes themselves. While it is true that the near-mystical bench­mark of 10 seconds for the 100m has been broken almost exclusively by North American men with West African ancestry (the lone exception is Patrick Johnson, a mixed-race aboriginal from Australia), the national records of all but three West African countries (Nigeria, Namibia, and Ghana) are slower than 10 seconds, many considerably slower:
      •  Ivory Coast, 10.07
      •  Mali,10.10
      •  Gabon, 10.13
      •  Burkina Faso, 10.14
      •  Liberia, 10.15
      •  Senegal, 10.17
      •  Cameroon, 10.19
      •  Sierra Leone, 10.25 (Slower than the decathlon record)
      •  Gambia, 10.26
      •  Congo, 10.28
      •  Togo, 10.30
      •  Benin, 10.31
      •  Democratic Republic of Congo, 10.32
      •  Angola, 10.49 (The woman's world record)
      •  Guinea-Bissau, 10.52
      •  Niger, 10.52
      •  Guinea, 10.56
      •  Mauritania, 10.74
We find a similar situation with the 200m. Nigeria, Namibia, and Ghana have male runners who have broken the 20-second barrier in this event (the Ghanian did it under Norway's flag), but the other West African countries' best times range from 20.21 (Senegal) to 21.40 (Mauritania). Ten of these national records are 20.74 or slower. Niger (with 12.9 million people) and An­gola (with 12.3 million) come in at 21.24 and 21.15, respectively.
    West African women fare even worse. Only Nigeria and Cameroon have female runners who have run faster than 11 seconds in the 100 meters (world record, 10.49), and no West African woman has ever broken 22 seconds in the 200 (world record, 21.34). Guinea's best times are 12.02 in the 100 and 25.09 in the 200. Angola's are 11.69 for the 100 and 24.68 for the 200. Niger's are 12.97 for the 100 and 25.09 for the 200. Mauritania's are 13.29 for the 100 and 28.78 for the 200.
    Given these facts, the theory that people with West African ancestry have, on average, a much higher percentage of fast-twitch muscles than other populations cannot, by itself, answer four crucial questions:
      1. Why are so many West African national sprint records so sluggish?
      2. Why is there such a wide range of times among West African nations?
      3. Why do North American blacks (who most likely have some Caucasian ancestry) run so much faster than West African blacks?
      4. Why are Jamaican men and women setting world records in sprint events?
    As we saw with decathletes, a theory based on fast-twitch muscles needs to be supplemented with historical and sociological explana­tions to answer such questions and account for all cases.
    By contrast, a theory based on intensity of practice needs no physiological corollaries to deal with apparent anomalies, including these four questions. We can provide plausible answers that research can verify (or invalidate):
      1. West African sprint times are so sluggish because West African populations do not make sprinting a priority and therefore do not practice it intensely.
      2. We see a wide range of times because each country values and encourages sprinting according to its own unique culture.
      3. North American blacks run so much faster because their cultures have a much higher regard for sprinting than West African cultures.
      4. Jamaicans out-sprint everyone else because Jamaican culture venerates, and therefore practices, sprinting more than any other culture.

THE CASE OF JAMAICA

    Let's examine this last point further. Jamaica has held the national Boys and Girls Athletics Champion­ships every year since 1910, 15 years longer than similar high school contests in the U.s. "Champs," as the event is known, annually draws 100 schools, 3500 competitors, and 30,000 fans because, in Jamaica, sprinting is a national obsession. According to Anthony Davis, sports director of Jamaica's University of Technology, "People come [to the high school championships] to see what's going on in the sprints. When the sprints are over, I've seen coaches pick up and leave, even though other events are still going on."
    Anna Kessel explains that Michael Manley, the former prime minister of Jamaica, "set up the GC Foster College in 1978, a higher education institution whose sole aim was to produce sports coaches for Jamaica." Every Jamaican school at every level now has an athletics coach. In addition, the University of Technology in Kingston offers Jamaican runners the chance to go to college and continue training. No other country in the world places this much emphasis on sprinting, so we don't have to appeal to physiological advantages to explain Jamaica's extraordinary success.
    As we might expect, given the overwhelming popularity of "Champs," Jamaicans do very well in international track meets, but we need to notice that they currently hold world records in only three events---the men's 100, 200 and the 4x100 (and all due to or with the participation of one unique athlete, Usain Bolt). The women do best in those same events, too (plus the hurdles), although they do not currently hold any world records. All 11 medals that Jamaica won in Beijing came in sprinting events, and eight of those involved the two shortest distances. (On the other hand, Jamaica has had only two players in the National Basketball Association. Slovenia, with only two million people, has had seven.)
    Jamaican athletes, in a word, specialize. By focusing the bulk of their attention on three events, they increase their chances of beating everyone else at these distances. Their success shows that, by special­izing, small populations can outdo large ones that aren't fixated on that sport. Thus, a single Spanish region, Andalusia, produced over half the world's bullfighters through the 19th century. Norwegians have won 141 Olympic medals in Nordic skiing, whereas Austrians have won 103 in Alpine skiing. Basques owned jai alai for 150 years, "Flying Finns" won 45 Olympic medals in long distance running from 1912 to 1936, and Alaskans have overwhelmingly dominated the Iditarod since its inception in 1975.
    All of these phenomena are consistent with an intense practice model, but none can be explained by an appeal to muscle fibers. Suppose, for example, we conclude from Jamaica's record-breaking times in three sprint events that Jamaicans, as a group, have a higher percent­age of fast-twitch muscles than any other population in the world. We would still need a plausible reason why, in evolutionary terms, this might be the case, especially since several other populations share Jamaica's West African (and Cauca­sian) ancestry. On the other hand, if we assume that other populations have similar proportions of fast- and slow-twitch muscles, we would be forced to consider the level of com­mitment of all these groups, which leads us right back to the amount of intense training.
    In either case, we would still need an explanation for Jamaicans' less-than-stellar performances in other anaerobic events, like jumping and throwing. For instance, in the men's long jump, an event in which run-up speed is correlated with success, Jamaican's national record is only the 43rd best jump ever. In the men's 110-meter hurdles, 32 runners, including 19 Americans, have faster times than any Jamaican. In the women's high jump, where explosiveness is obviously an advantage, over 100 athletes, at least 30 from non-Eastern bloc countries, have jumped higher than the best Jamaican female. In the woman's pole vault, which also requires quick bursts of energy, the national record is a dismal 3.40 meters or 11'1 ¼," over 5.4 feet shorter than the world record. By contrast, Iceland, hardly an athletic powerhouse, with a population of only 300,000, has a national record of 4.60 meters.
    In the men's javelin, Jamaica's best (68.97 meters) is barely 70% of the WR (98.48 meters), whereas Iceland's best is 86.80 meters, over 88% of the WR. In addition, Icelandic men outdo their Jamaican counterparts in the shot put, hammer throw, and discus, all of which supposedly call for fast-twitchiness. Again, quality and amount of practice would account for Jamaica's unimpressive performances in all these events, whereas muscle fiber proportions would not.

RUNNING AND JUMPING COMPARISONS

    Another problem with Burfoot's and Entine's claim that a high percentage of Type II muscles gives a population an edge in sprinting and leaping is that, as with individual decathletes, we find little or no correlation between the running and jumping performances of several nationalities.
    For one thing, countries which produce elite sprinters do not always produce elite leapers. Nigeria (148 million) is a case in point. She has world-class sprinters, as we have seen, but dismal jumpers. 55 nations, including tiny Mauritius (1.3 million), have a better high jump record than Nigeria; 35 have a better long jump record; and 35, including miniscule Dominica (72,000) and Grenada (90,000), have better triple jump records. Japan (127 million) has the ninth-best national time in the 4 x 100, but her long jump and triple jump are even worse than Nigeria's. Trinidad (1.1 million) has the fifth-best national record in the 100 and the tenth in the 4 x 100, but her records in the high jump, long jump, and triple jump are well below Nigeria's.
    On the flip side, we can find countries with much better jumping records than running records. Serbia (10 million), for example, has unimpressive runners, whose times in the 100 (10.34) and 110-meter hurdles (13.60) are slower than the decathlon records in those events (10.22 and 13.47 respectively), but light footed jumpers, whose long jump (8.45) and high jump (2.38) are considerably better than the relevant decathlon records (8.22 and 2.27, respectively). Serbia's running records would have earned 59 points less than the decathlon records, but her jumping records would have earned 172 points more.
    We can find the same "specialization" with female track stars. As with the men, Nigeria has speedy women runners but earthbound leapers, except for the long jump. She has the fourth-best national time in the 50-meter (indoor) sprint, seventh in the 60 (indoor), eleventh in the 100, tenth in the 200, and ninth in the 4 x 100, yet 71 nations, including St. Lucia (171,000), Barbados (281,000), and Iceland (302,000), have better national high jump records than Nigeria (1.86), and 39 nations have better national triple jump records for women (13.87). Similarly, the minute island of the Bahamas (306,000) is fifth in the 50 meter (indoor), sixth in the 60 (in­door), tenth in the 100, fourteenth in the 200, and sixth in the 4 x 100, but her national high jump (1.79) and triple jump (13.66) records are even worse than Nigeria's. In addition, 35 nations have a better national long jump record than the Bahamas (6.80). .
    Conversely, some countries have better female jumpers than runners. Romanian women, for instance, make terrific leapers but dreadful sprinters. Romania's national records are fourth in the long jump, seventh in the indoor high jump, and fifth in the indoor triple jump, but 51st in the 100-meter sprint (11.30), and 37th in the 4 x 100 (44.18). Sweden's women are first in  the indoor high jump, fourth in the - outdoor high jump, and eighth in the indoor long jump, but 47th in the 200-meter sprint (22.82).
    Of course there are countries which have great runners and great jumpers (including Australia, Brazil, Cuba, Italy, Poland, Russia, South Africa, Ukraine, and the U.S.), and there are plenty of countries with neither, but the above examples strongly suggest that running and jumping do not require the same genetic package.
    To illustrate this point further, we can find many cases in which country A has faster runners than country B, but B has better jumpers. For example, Trinidadians are well over half a second faster than Armenians in the 100-meter (worth 172 points more in the decathlon), well over a second faster in the 200, and over three seconds faster in the 4 x 100 relay, but Armenians have jumped two inches higher in the high jump (47 points), over 28 inches farther in the long jump (190 points), and over 29 inches farther in the triple jump. Apparently, Trinidadians specialize in running, Armenians in jumping.
    Figure 2 shows other examples of this phenomenon for men and women from South America, Northeast Asia, Southern Asia, Europe, North Africa, and West Africa. Except for China and Japan, the populations in each pair are contiguous and presumably racially homogenous.

CONCLUSION

    As the records of decathletes and nations show, we have good reason to question the notion that an abundance of fast-twitch muscles provides an edge for individuals and populations in sports requiring explosiveness. Such a theory by itself cannot explain a surprising number of the cases we have seen. On the other hand, a hypothesis that focuses instead on the amount and quality of athletes' training is fully consistent with all the performances we have examined and requires no supplemental explanations. Therefore, it seems reasonable, for the time being at least, to prefer a practice-driven view of athletic suc­cess in explosive sports to one which involves fast-twitch muscles.

FROM: TRACK COACH 192