Limits to Performance Will Hopkins
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Date: Tue, 29 Aug 2000 I've just received an inquiry from Kurt Kleiner <kleiner=AT=twohacks.com>, the Toronto correspondent for New Scientist magazine (http://www.newscientist.com). Here's my answer, which I have copied to the list for comment. Please send your responses to the list. Will At 10:05 AM -0400 28/8/00, Kurt Kleiner wrote: We're working on a special section to coincide with the Olympics, and I'm writing a story exploring whether we have reached or are about to reach the limits of human potential. I was hoping to discuss a few questions with you (or with someone you recommend). I can give you some insights into the issues surrounding elite athletic performance. You'll also get a great response from the Sportscience list. That way you'll identify people who are experts in the areas I'm not. I'll copy this message to the list. First, I want to talk about the dramatic improvement in athletic ability we've seen in the last century. My assumption is that the increases come from improved nutrition and especially improved training techniques, but I'd like to discuss that with someone. There are also more people competing. Statistically, that must lead to improved records. That's probably the main reason. In my opinion, changes or difference between training programs or diet accounts for only a couple of percent. What's more (my favorite New Scientist expression), there may be a synergistic eugenics effect. It seems likely that a top athlete is more likely to breed with another top athlete in the same or a similar sport than with an average person. As generations go by, the best athletes will have more of the variants of the genes (alleles) that enhance performance. I'd also like to talk about whether improvements have been uniform across all sports; or have some sports seen dramatic improvements while others are only modest? I don't know. The experts on the Sportscience list may like to comment. Second, I want to find out if we seem to be pushing the limits of human performance. Certainly people keep breaking world records. But are we getting to the point where training techniques are so good that it's only a matter of time before we top out -- before performance become essentially static, with only the occasional, once-every-generation super athlete able to set new records? Are we actually in a situation like that today with some sports? In my opinion, yes. I'd say it applies to almost all sports. Third, I want to discuss whether some of the improvement we've seen in the last decade or so might be the result of performance-enhancing drugs. Is it possible that we've already topped out our "natural" human potential, and the athletes' only alternative, if they want to keep improving, is to use performance-enhancing drugs? Let's discuss the banned drug erythropoietin (EPO). This drug is actually a naturally-occurring hormone that controls the amount of blood in your body. If you have a hemorrhage, you release more EPO to replace the lost blood, so injections of EPO give you more blood than normal. Commentators assume that EPO use will improve endurance performance by at least 5%, because EPO enhances delivery of oxygen to muscles by at least 5%, and oxygen delivery is what limits performance for most endurance athletes. Use of EPO has apparently become widespread amongst endurance athletes in the last 10 years. Have we seen a 5% improvement in world records in that time? I don't think so. Probably more like 1%, but my colleagues on this list will comment. So what's going on? There are two possible answers.
Thanks for any help you can give me. Date: Thu,
31 Aug 2000 Ah yes, the old "what are the limits?" questions that come up every 4 years. Here is some input. First to this question: I'd also like to talk about whether improvements have been uniform across all sports; or have some sports seen dramatic improvements while others are only modest? This is how I started an article back in 1997 that I titled "The Search for Speed in Cross country skiing": Here is a sport science trivia question for you. What "transportation" sport has experienced the greatest average improvement in performance over the last 75 years? Despite the awesome spectacle of the sub-27 minute 10ks of late, at 10-13%, it is definitely not distance running. Ditto sprint performances in running. Sebastion Coe's 1:41.73 800 record still stands after 16 years and is only 8% faster than the record in 1926. Speed skaters are going 20-25% faster than in 1920. Swimmers have improved far more, about 40%. But these events are advancing at a snail's pace compared to the event contested most passionately in the cold climes of Scandinavia. The average velocity of international elite cross-country skiers has roughly doubled in the last 75 years! Male skiers now cover 50km in roughly 2 hours compared to 4 hours back in 1920. In the shorter events, the improvement is not as great, but still 50% or more. Every aspect of XC skiing has changed; courses, equipment, technique, and the physical capacity of the skiers. Most of the really significant breakthroughs in skiing have occurred in the last 30 years. Albeit that the 800 meter record is now 1:41.11, this is still only a ~9% improvement since 1926. Therefore the range of improvement for "transportation" sports is from under 10% to a near 100% increase in average velocity over the last 75 years. The more equipment and technology play a part, the greater the speed improvement. In the 800 meter, about the only thing worthwhile that has changed on the technical side is that the shoes are lighter. In XC skiing, the surfaces are more uniform, the skis are lighter and have less glide friction, the clothes are more aerodynamic, the skating techniques has been adopted, and the skiers are better trained (though training volume actually hit a peak in the 80s, and has since moderated a bit). So every facet of skiing has contributed to the huge speed increases. I can also refer to jumping performances since 1896. The triple jump record is over 30% longer, for high jump it is 35%, and for long jump it is 41%. Meanwhile for the higher tech pole vault event, the record is over 80% higher than in 1896. If we reduce the comparison period to between 1956 and the present (1956 marks the true start for Olympics as world political ideology scene), then the improvements look like this: Triple jump 10% (this is perhaps the jumping event most limited by pure muscle power and tendon stress limits?) High jump 15% (Fosbury Flop and better padding contribute to training enhancement here) Long jump 14% (almost all of this improvement is accounted for in on amazing performance that was extended by a few centimeters only after over 25 years) Pole vault 33% (fiberglass poles, and of course softer landings, have made a huge difference in the development curve here) Now this question: Second, I want to find out if we seem to be pushing the limits of human performance. Certainly people keep breaking world records. But are we getting to the point where training techniques are so good that it's only a matter of time before we top out -- before performance become essentially static, with only the occasional, once-every-generation super athlete able to set new records? Are we actually in a situation like that today with some sports? What we found out when we looked at the 100 meter dash for men was that the average performance improvement was 0.01 second per year [~1% per decade] based on world championship and Olympic finals performances (average time of top 6 finalists) since 56 (corrected for wind and altitude). This improvement was linear and showed no sign of leveling off as of the end of the 20th century. Obviously, limits are being approached, but I think we can expect similar "steady" improvements for the next several decades. For example, Michael Johnson's "statistical outlier" 200 meter time in 1996 demonstrates that the potential for substantial improvements is still there (the women's data was much more complicated and I will leave it at that for the purpose of this discussion). The world record progression in many events is marked by these stochastic jumps, stabilization at a new level, new jump etc. Another point about this data was that for men the improvements remained linear and unchanged in slope even after improved drug testing kicked in at the end of the 80s. So, as Will suggested, maybe for the very, very best, drug use does not make a difference? The sources of these improvements are likely to be:
Nothing new here. But it is important to recognize that international sport is an amazing catalyst for "evolution" in the sense that humans with very unique capacities meet and have babies, some of whom are even more "optimized" for certain sports than their talented parents. Go to a world class track and field competition (I go to the Bislett Games in Oslo) and see just how many different and specialized body types have "evolved." So, the record breakers of tomorrow won't be quite the same humans as those of today. Sadly, it seems we will be able to look forward to a world population marked by regression towards physical sloth and mediocrity that amuses itself (among other ways) by watching a very few extremely genetically gifted, technically trained "gladiators." In some countries, we are already at this stage. Others will follow. Finally, when we try to guess performance limits, we must remember that the more separate physiological factors that contribute, the greater the "room for improvement" and the longer it is likely to take before the genetic (and environmental) pull of the slot machine arm comes up a winner. For example, distance running performance can be reduced to three components 1) VO2 max, 2) muscle endurance (lactate metabolism, finer type etc. and 3) running economy. Almost 10 years ago, Michael Joyner published a paper (J. Appl. Physiol. 70(2): 683-687, 1991) predicting that a marathon time of 1:58 was possible if an athlete with a VO2 max of 84 ml/kg/min, a lactate threshold of 85% and excellent economy (quantified in his paper) were to emerge. As he wrote, all of these individual capacity levels have been measured in different athletes, but so far it appears that no athlete has had maximal levels of all three. Given that VO2 max values of over 90 have been measured and lactate thresholds of ~90% of VO2 max have been measured, it seems reasonable to expect the outer physiological limit (read: what I can imagine for humans up to 2-3 generations ahead) for the marathon is perhaps at most 10 minutes faster than the present record based on current physiological measurements. But even that assumes simple addition, and not a complex genetic interaction. Joyner raised the question "are super extreme values among these three components mutually exclusive?" Also, other issues, such as heat elimination, might prove to be limiting were an athlete able to achieve such a high work output over this extended period. Ok, others can contribute or correct. Stephen Seiler PhD Endurance performance physiology website: Date: Fri,
01 Sep 2000 This is in response to the recent discussion on the limits of athletic performance. It may not be particularly earth shattering in nature, but I remember a famous sprinter (possibly Linford Christie) or coach responding to the question of how fast he thought a human could run the 100 metres. He responded that whilst it was obviously impossible to run the distance in zero seconds, anywhere upwards from zero to the current world record was fair game. I thought it was a nice way to answer a somewhat tricky question. For the foreseeable future athletes are going to chip away at the world records. Ultimately, there is surely a limit. I was intrigued by the statement regarding the marathon being run in 1hr 58min by someone with a VO2 of 84 and a lactate threshold of 85% (as well as being supremely efficient). I anticipate some fireworks in the marathon arena when Haile Gebreselassie moves up to the marathon. Perhaps not a sub 2hr marathon though. Of course, this is purely conjecture and cannot really be proven. Another thing that may happen in the future as the limits to athletic performance are reached is that events may be measured differently. For example, foot races (particularly the sprints) are currently measured to the nearest hundredth of a second. In the future, it may be necessary to measure improvements to the nearest thousandth of a second or less. The jumps could be measured to the nearest millimetre. Michael Green Date: Sat,
02 Sep 2000 The latest issue of Scientific American (Sept, 2000) has a wonderful lead article about Muscles & Genes. One of the sections discusses what athletics will be like in an age of genetic enhancements-the genetic engineered superathlete where injecting DNA into quads, hamstrings, and gluts will activate (build) fast fibers. Great reading and thought provoking. If we currently believe anabolic and other enhancing substances pose a threat, then to quote a famous line, "you ain't seen nothing yet." Frank Katch Date: Fri,
01 Sep 2000 It's funny how this question always arises every Olympic year. However, as far as the near future is concerned, meaning the next 2-3 Olympics, this question might become a mute point. Here's why: The September 2000 issue of Scientific American looks at muscles, genes, and athletic performance. At first, the reader is introduced to the basics of muscle physiology. Then you're taken to the interesting and still developing science of muscle fiber adaptations to forms of exercise (e.g., becoming more anaerobic from anaerobic exercise). Finally, you're taken into the realm of gene therapy and how altered genes may be able to "grow" muscle fibers of a certain (desired) type. This is not at all far fetched and research in this domain is advancing rapidly. The authors (Danish scientists) hypothesize that gene therapy will be the "drug" of choice before too long. If doping, if you can call it that, goes the direction of gene therapy, we will never learn what the limits of human performance actually are. For me, this would be a sad state of affairs. It's bad enough that advances in equipment are artificially inflating records; next we have to contend with artificially grown humans? Will the ideals of sport really turn into this sort of mockery? And let's close on a sport psych. note: "Doc, I'm so fast, now that I've grown all this fast twitch muscle, I'm not sure I can handle it. How can I prepare myself mentally to slow down so that it doesn't become too obvious that I'm an artificial genetic freak?" Well, good thing Doc took course work in sport performance dehancement. What he learned about goal devaluation, motivation repression, and anxiety intensification techniques might come in quite handy. Dan Wagman, Ph.D., C.S.C.S. Date:
Sun, 03 Sep 2000 I've now read the article by Andersen, Schjerling and Saltin (Muscles, Genes and Athletic Performance) in the latest Scienfific American. The focus of the article is muscle-fiber types, and the emphasis is therefore on sprinters. If you use this article in your teaching, alert your students to the fact that there is nothing there about oxygen transport, which is more important for endurance athletes than fiber type. I think it's fair to say that lots of fast fibers is a necessary and even a sufficient for a sprint athlete, with a bit of training, of course! For an endurance athlete slow fibers are necessary (although I don't think it's as clear cut as these authors make out) but not sufficient. First and foremost an endurance athlete needs lots of blood. You should also alert your students to an unfortunate gaffe. The authors found that, in sedentary subjects who did a 3-month resistance-training program, the proportion of the fastest type of myosin (IIx) decreased from 9% to 2%. When the subjects then stopped training, the proportion of IIx rebounded over the next 3 months to 18%. The authors suggested that this rebound could be the basis of tapering in sprint athletes: "Thus sprinters would be well advised to provide for a period of reduced training, or 'tapering'. In fact many sprinters have settled on such a regimen through experience, without understanding the underlying physiology." Dear oh dear... The average taper lasts a week or so, which is only about a tenth of 3 months, and on the authors' own graph there was no substantial change in IIx in the first week of inactivity following the training. Besides, training doesn't stop in the taper, and anyway, sedentaries and sprint athletes are rather different beasts. The authors suggested that it will soon be possible to activate expression of type IIb myosin in muscles of athletes. This fastest of all myosins is not normally expressed in human muscles. The result could be superfast sprinters. Sure, but it may be that type IIb myosin won't integrate successfully into the architecture of our myofibrils. You have to wonder why the gene has become suppressed in humans, who have had to sprint away from predators and sprint after small game for millions of years. A better strategy might be just to increase the expression of IIx myosin relative to IIa. Or are these already in optimum proportions (50:50) in the best sprinters? Myosin-gene therapy may not have such an impact after all. Will Copyright ©2000 |