[b][url=https://www.time.com/time/health/article/0,8599,1835420,00.html]How Fast Can Humans Go?[/url][/b]
Friday, Aug. 22, 2008 By DEIRDRE VAN DYK!– cut –!
Elite sprinters are not, however, simply improved versions of the average Sunday runner. They are physiologically different. For example, a typical human has in his skeletal muscles an equal balance of “fast-twitch” muscle fibers (quick contracting, easily fatigued muscle tissue that generates high power) and “slow-twitch” fibers (the muscle mass that uses oxygen – aerobic, rather than anaerobic), on which endurance runners rely. Slow-twitch muscle can contract for long periods of time with less fatigue, which helps some distance athletes run up to 60 mi. per day. Sprinters legs are genetically blessed with 70% fast-twitch and 30% slow-twitch muscles, which is what allows them to push off so fast and so powerfully, according to Scott Trappe, who heads the human performance laboratory at Indiana’s Ball State University and has studied sprinters’ muscles. [b]But elite sprinters like Bolt may have even more of something that other world-class sprinters don’t: superfast-twich muscles, which perform at double the rate of regular fast-twitch muscles, creating even more force. Trappe says regular folks have 1% to 2% superfast-twitch skeletal muscle mass, but in a sprinter like Bolt, that figure may be up to 25%.[/b]
That helps explain why Bolt’s legs move fast enough to be a blur. When people run, they are essentially bouncing though the air from one leg to another, says Daniel Lieberman, a professor of biological anthropology at Harvard University who studies how and why the human body looks and works as it does. What determines how fast people go is their stride length – a function of how long the legs are, how powerfully they push off into a stride and how far forward the body jumps – and their stride rate, which is how fast they can propel their legs forward. [b]While great endurance runners, get their speed from long strides, sprinters get much of their speed from a fast stride rate – and from raw power. They hit the ground harder, relative to their body weight, than marathoners.
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It appears that Bolt takes advantage of a little of both. At 6 ft. 5 in., he’s nearly half a foot taller than many other gold-medal sprinters; [b]compared to his Olympic competition, Bolt’s step was 1 ft. longer, allowing him to cover 100m in 41 steps. The other athletes needed, on average, 47.[/b] That helps, considering Bolt isn’t the best starter – he’s relatively slower off the block, but he separates himself at the end of the race, when “he’s still able to turn his legs over fast enough with high power,” says Ed Coyle at the University of Texas’s Human Performance Laboratory. “He overcomes his average start and just doesn’t slow down, as others do, in the last 30 to 40 meters. He’s able to relax and coordinate his longer legs.”Looking forward, “no one can really know exactly how fast a human may be able to run,” says Dennis Bramble, professor of biology at the University of Utah. Certainly, runners have been getting faster, as far as we know, but as Peter Weyand, an expert in biomechanics at Southern Methodist University, points out, our history of recorded time in sprints is relatively brief. “We have no way of knowing if humans might not have been even faster centuries or millennia ago,” he says.
[b]“Modern sprinters seem to be operating close to the limits of the human body,” says Bramble. “Still, when someone who is not built like a classic sprinter – [Bolt is] taller and leaner than most – smashes the world record while making it look easy, maybe all bets should be off.”[/b]
Those are some powerhouse names in exercise science, but I have to say WTF, think before you speak to a reporter.
Bolt’s 41 steps in 9.69s is only a pedestrian like 4.23 steps per second. His stride is an unbelievable 2.43m per step. Analyze the data first. Even though we don’t have data on the range of motion of the stride that Bolt run’s with about the hip. It looks larger than most, but he doesn’t have as much going on the backside as others suggesting his angular velocity is the same or less as other elite sprinters. If someone who runs 9.85s in 45 steps, they have an average step rate of 4.56 steps per second with a step time of .219s of which .06-08s is step time giving a runner a recovery time of .139-.159s while for Bolt if he has a step time of .236s he will have a recovery time of .166-.186s with step times of .05-.07 seconds. If 9.85s sprinter had an average angular velocity about the hip of 1295 deg/sec for a combined 110 degrees from end ground contact to highest knee lift and 70 from highest knee lift to start of ground contact for 180 degrees of ROM, then Bolt would have to move his legs through 215 total degrees of ROM, that’s about 125 to about 90. I don’t Bolt has a slightly greater ROM than his counterparts, but I doubt it’s 20% larger, suggesting his legs movement would be slower.
Also, Bolt’s start is as good if not better accounting for reaction time than anyone else. So there’s a fallacy in Dr. Ed Coyle’s arguments. He’s able to maintain speed longer because increased velocity is about decreasing friction on the ground which is attained by spending a greater percentage of time in the air from longer strides. This in turn should mean the sprinter needs enhanced elastic qualities and not necessarily muscular contraction qualities as Dr. Trappe and other point out.
From the previous paragraphs we see how Bolt would probably have a greater ROM and a longer step, a slower step rate, his legs are also moving slower in comparison to his competitors with respect to angular velocity and I am going to make the assumption he spends a greater percentage of his race in the air. One accelerates by increasing both stride rate and stride length as well as the ROM about the hip in the first phase of acceleration (rapid acceleration 0-30m), then once maximal stride rate is reached it drops slightly and this starts the second phase of acceleration (slow phase or transition phase 30-~60m) where ROM and stride length are both increasing until Max V. is reached. Reaching .82s per 10m and maintaining such velocity requires one to have greater elastic qualities and decreased friction (braking) impulses from ground contact which fit the description of increased ROM and stride length with shorter gct’s and not increased step rate and not greater propulsive power from muscles which would require longer ground contact times at maximal velocity, but would help him in the acceleration phase.
So my question to the Exercise Scientists who want to be quoted are as follows:
1. What is Bolt’s angular velocity from end of ground contact to beginning of ground contact on each step compared to his next 3 closest competitors?
2. What is the ROM the Hip goes through for Bolt during each step from end of ground contact to beginning of ground contact. What is the ROM during contact? What are they for his next 3 closest competitors?
3. What are Bolt’s ground contact times on each step compared to his next 3 closest competitors? The cumulative of this give’s us total flight time as well. Is it possible he has a longer ground contact, but shorter overall flight time?
4. Take a muscle biopsy and confirm this super fast twitch muscle in Bolt. Does it have a genetic component? If so, why do most sprinters of West African origins fail to break 11.0s in the 100m dash at the scholastic level? Why not a tendon biopsy?