Posted: July 1, 2005

Science of Sport: What Happens When Nandi Boys Go Out On The Town

By Owen Anderson, Ph. D. (Copyright © 2004-2005)

Most athletes and coaches realize that genetic factors can have an impact on performance. What is less commonly realized is that heredity could act in two completely separate ways. First, specific genes or gene combinations could make certain individuals inherently more fit than others, even in situations in which no training has been carried out. If you pluck two sedentary individuals off the street, it is extremely unlikely that they will have the same fitness level; one might have a stronger heart, metabolically more efficient muscles, and/or reduced perceptions of fatigue during exercise, and these differences can be related to genetic make-up. If the duo agreed to engage in a 5-K run, actual performance would hinge on the inherent physiological variations.

Second, some genes or combinations of genes control the way in which individuals respond to training (1). Some lucky athletes adapt dramatically to training protocols, advancing maximal aerobic capacity (VO2max) by as much as 80 percent in response to serious workouts. Other, less-fortunate individuals may inch VO2max up by just 5 to 10 percent as a result of the same strenuous training – or may not improve aerobic capacity at all. Some dedicated trainers, in fact, do not seem to respond to training at all; their performance-related physiological variables are stagnant (2). This creates situations in which individuals who are inherently less fit than others (when everyone is untrained) can move far ahead of those who were originally more fit once the training stimulus has been applied.

For example, possessing the “insertion variant” (the so-called “I-allele”) of the human angiotensin I-converting enzyme (ACE) gene improves an individual’s ability to adapt to endurance training (3), perhaps by enhancing efficiency of movement.

How does this happen? As it turns out, all humans have two ACE genes: Roughly 50 percent of the world’s population has the I-allele along with a variant called the “d” or short allele; 25 percent have two “I” genes, and the other 25 percent have two “shorts” in their ACE chromosomal slots. In one investigation, individuals with two copies of the I allele gained more muscle mass and lost more body fat during 10 weeks of intensive physical training, compared with subjects who had two copies of the short gene or one copy of each allele (4). In a different piece of research, 58 men underwent an 11-week endurance-training program which revolved around interval training on an exercise bike; 35 of these men had two copies of the I gene, while 23 had been fitted by their parents with two copies of the short segment (5).

Prior to and after the training period, the researchers calculated the “delta efficiency” of exercise for each subject. This variable represents the efficiency with which muscles are working, and it is basically the percentage ratio of the change in work performed per minute to the change in energy expended in the same amount of time. Delta efficiency is not a bad way to measure economy of exercise; basically, it reflects the fact that if you can increase your rate of working per minute (i. e., your muscular power output) without a large upswing in energy expenditure, you are efficient. In contrast, if your energy consumption soars when you increase your running or cycling speed, you are relatively inefficient.

Before the training began, delta efficiency was the same for both groups of men (at about 25 percent). However, after the 11-week training period delta efficiency had improved by almost 9 percent for the men with the two copies of I, while remaining stagnant among the unfortunates with the two short versions of the gene.

What was going on? Bear in mind that one of the key – but often overlooked adaptations you make to exercise training is in the responsiveness of your blood vessels.

After you have been exercising regularly for a couple of months, many of your blood tubes relax more easily during exercise, increasing the rate of blood (and thus oxygen and fuel) flow to your muscles. At least some of this arterial expansiveness is mediated by a chemical called nitric oxide, which is released by cells lining your arteries. Nitric oxide can not only dilate arteries – it can also prolong vasodilation, helping to ensure that mega amounts of blood will flow toward your muscles during extended exertion. Exercise training per se increases the production of nitric oxide within arteries, and the presence of two I genes seems to spike this nitric-oxide synthesis even further. In effect, two I genes let endurance-trained muscles have more blood. Dr. Hugh Montgomery, the lead scientist in this 11-week study, also believes that the I genes may have profound metabolic influences within muscle cells, perhaps improving the efficiency of fuel selection, uptake, and utilization during exercise.

Interestingly enough, scientific studies reveal that runners with two copies of “I” tend to gravitate toward longer-distance running. In fact, the frequency of “I” actually increases with the distance run; among a group of top marathoners, you would find more “I” genes, compared with a collection of elite 5-K competitors, for example (6). Exactly the same situation prevails in swimmers, with long-distance natatorians having high frequencies of the I gene and short-distance competitors holding higher numbers of the d allele.

Both gene-related inherent fitness and gene-related responsiveness to training play roles in determining ultimate performance potential. Of course, quality of training is also important, but it is a non-genetic factor – unless there is a gene which codes for smart training.

Kenyan distance runners are superior to distance competitors from most of the rest of the world, and one theory which has attempted to explain this phenomenon has suggested that Kenyan runners are better “responders,” i. e., they respond to a specific level of training with a greater extent of adaptation, compared with runners from other countries. In line with this, one study found that physically active adolescent Kenyan boys possessed maximal oxygen uptakes which were 30-percent higher than those of similar-age Kenyan young men, even though the active lads were carrying out no systematic running training; their activities consisted of farm work, jogging back and forth to school, walking, etc. (7). A 30-percent response to general activity is considered to be extremely large, and it is assumed that the response would be even greater if serious training were undertaken (various studies reveal different things, but it is typical for maximal aerobic capacity to advance by 15 to 25 percent in a “normal” response to training).

To find out if Kenyans really are better responders, Henrik Larsen and his crew from the Copenhagen Muscle Research Centre and the University of Copenhagen recently traveled to Kenya to work with 24 teen-age Kenyan males (8). All of these young men (average age = 16.5 years) belonged to the Nandi sub-tribe of the Kalenjin tribal group within Kenya; none had been engaged in systematic endurance training prior to the beginning of the study. The average weight of the participants was 53 kilograms (about 117 pounds), and average height was around 1.7 meters (about 5’ 7”), so you can see that the subjects were quite lean.

The young Kenyans were classified as “town boys” or “village boys” by Larsen and his cohorts. The town runners were recruited from Uasin Gishu High School in the town of Eldoret in the western part of Kenya. Eldoret is often called “the hub” of distance running in Kenya, because so many great runners have emerged from the countryside surrounding the town. On a typical day in Eldoret, it would not be unusual to see Moses Kiptanui fueling his Mercedes at a gas station on the main road running through town, Kip Keino strolling down the street toward his running shop, or Sammy Lelei stopping in for a bite of food and a bit of conversation at the Elcove Restaurant.

In contrast, the village runners were recruited from the Kamobo Secondary School located about 50 kilometers southwest of Eldoret. These subjects lived in a highly rural area within a four-kilometer radius of the school. In total, there were 10 town runners and 14 village harriers.

It was assumed at the beginning of the study that the village runners were fitter than the town fellows, and physiological testing confirmed that this was the case. When the research began, the village runners had an average VO2max of 56 ml kg-1 min-1, which was significantly higher than the 50.3 ml kg-1 min-1 registered by the town garcons. All 24 young men subsequently completed 12 weeks of endurance training. During the first five weeks of this 12-week training period, the intensity, frequency, and distance of training increased progressively. Basically, training frequency advanced from two to four workouts per week, weekly training distance moved from eight to 28 kilometers, and actual intensity soared from 70 percent to 80 percent of VO2max. Over the last seven weeks of the training program, the weekly training consisted of four workouts, 28K of total running, and a constant intensity of 80 percent of VO2max (about 87 to 88 percent of maximal heart rate). At the end of the 12-week schedule, a 5-K competition was held on a 400-meter track.

Of course, since the village harriers were fitter than the town scions, 80 percent of VO2max for the villagers corresponded with a faster training pace. Indeed, the village sprigs trained at an average speed of 13.8 kilometers per hour (about seven minutes per mile), compared with 12.4 kilometers per hour (approximately 7:47 per mile) for the town folk. Naturally, average training speed during the 80-percent-VO2max training period (weeks five through 12) increased significantly in both groups, since they were getting fitter, but the village boys consistently trained at higher speeds, compared with the city slickers. Both groups covered about 260 kilometers of running during the 12-week period and completed a total of 38 workouts.

Both the town and village runners benefited significantly from the training, and their responses to the 12 weeks of workouts were remarkably similar. For example, after the 12 weeks of training, mean heart rate at a submaximal running speed of 9.9 kilometers per hour declined from 170 to 159 beats per minute in the village striplings and from 172 to 160 beats per minute for the town gossoons. Similarly, blood-lactate concentration corresponding with a running speed of 9.9 kilometers per hour fell from 2.4 to 1.4 mmol/liter in the village runners and from 2.7 to 1.4 mmol/liter for the Eldoret hustlers. Along similar lines, plasma ammonia levels (an indicator of protein breakdown during exercise) dipped from 103 to 73 micromoles/liter for village trainees and from 102 to 71 micromoles/liter for the town individuals. Running economy, measured at a speed of 10.4 kilometers per hour, improved by about 6 percent over the 12-week period for the village runners and by approximately 5 percent for the town runners (there was no statistically significant difference in these numbers).

The only real training-response difference between the two groups concerned VO2max, which tended to increase more for the town runners, compared with the country-village fellows. For the town runners, the advance in VO2max was 10 percent, compared with a 5-percent upswing for the village lads. This difference was just shy of being statistically significant, but there is nothing particularly notable about it. The gain in VO2max which is made during training is related to the magnitude of VO2max at the beginning of the training period: Individuals with low VO2max values tend to achieve robust expansions of max aerobic capacities, while those with higher VO2maxs tend to make smaller improvements (9 & 10). Since the village runners had higher aerobic capacities when the training began, their aerobic advancements were more diminished (in effect, they had already moved VO2max up, perhaps from the 50 or so of the town boys to their starting levels of 56, because of their active lifestyles).

Over the 12 weeks, the town boys advanced VO2max from 50 to 56 ml kg-1 min-1, and the village boys swelled aerobic capacity from 56 to 59 ml kg-1 min-1. Although the villagers upticked VO2max by a smaller amount, they were still aerobically fitter than the Eldoret denizens, and so they performed better on the final 5K, scoring an average of 18:25 (best time was 16:16), versus 20:15 for the townies (best was 18:40).

So what does all of this information tell us about the trainability of the vaunted Kenyans, particularly the vaunted Kalenjins, who are supposed to – according to popular myth – possess most of the wealth of Kenyan running talent? At first glance, it would seem that the responses described above in VO2max, lactate production, ammonia production, and economy are rather normal ones; nothing extraordinary stands out. However, a true comparison in trainability would have to involve non-Kenyans of a similar age and fitness level, who would embark on a training program similar to the 12-week schedule devised by Larsen and his Danes.

Perhaps surprisingly, such a study does exist. Several years ago, French researchers asked a group of 16- and 17-year-old Caucasian young men to embark on an endurance-training program (11). This program was very similar to the Nandis’ training regime: Training duration was three months for the Caucasians and 12 weeks for the Kalenjins, workout frequency was four sessions per week for both groups, and training intensity focused on 80 to 90 percent of maximal heart rate for both the whites and Africans.

After their three-month program, the Caucasians advanced VO2max by 11.6 percent, a gain which is similar in magnitude to the 10.2-percent uptick enjoyed by the Nandi town runners – and which appears to be larger than the 5.4-percent swelling achieved by the Kenyan villagers. There is no worry that the Caucasians’ initial fitness was very low – thus leading to a larger-than-usual fattening of maximal aerobic capacity. In fact, the Caucasians began their training with average VO2max values of 58.4 ml kg-1 min-1, very similar to the pre-training level of the Nandi village/country runners. In effect, the Caucasians’ gain was twice as great as the Nandi advancement, when initial aerobic capacities were similar. In other areas of fitness, the training-related changes in heart rate, blood lactate, and plasma ammonia observed in the Nandi runners are very similar to the alterations observed in Caucasians.

As you have already realized, these studies suggest that Kalenjins do not enjoy greater trainability, compared with Caucasians of similar age and initial fitness. In case you are wondering, there is also no evidence that Kenyans have higher frequencies of the highly touted I performance gene. Even if they did, bear in mind that approximately 25 percent of United-States citizens are “double-I,” for a total of around 70 million lucky people. This of course is nearly three times the entire population of Kenya, so even if all Kenyans had the I tandem, the U. S. would still have the genetic edge.

OK – I know you are asking: If that is true, why do Kenyan distance runners generally outclass distance competitors from most of the rest of the world? You can answer that question for yourself (and have a great experience at the same time) by booking a flight to Nairobi, renting a car at Kenyatta International Airport, and heading out into the “bush.” It doesn’t really matter what direction you take, as long as you travel far from any urban centers. Stay overnight at a little country hotel, and set your alarm clock for six in the morning. When your little timepiece tolls, jump up, put on your running shoes, and set forth into the Kenyan countryside. You will have your answer shortly.

Notice what the young Kenyans are doing all around you, and compare that with what you would observe at the same hour of the day back home. Later in the day, visit a Kenyan high school, and take notice of the percentage of young Kenyan people who seem to be highly fit, contrasting this with an estimated percentage of fit teens in your home town/city. Athletes who fare well in international competition do not emerge from nowhere; they come from pools of young people who are highly fit. If the pool is small but is crowded with stalwart, highly motivated “fish,” the chances for international success are greater, compared with situations in which the pools are huge but oligotrophic. A country with a small 26-million-person pool but with several million highly fit adolescents swimming around will always have little trouble with countries with 260-million-person tarns but smaller stocks of true trophy runners. ©

References

(1) “Heredity and Muscle Adaptation to Endurance Training,” Medicine & Science in Sports & Exercise, Vol. 18, pp. 690-696, 1986
(2) “Familial Aggregation of VO2max Response to Exercise Training: Results from the HERITAGE Family Study, Journal of Applied Physiology, Vol. 87, pp. 1003-1008, 1999
(3) “The ACE Gene Insertion/Deletion Polymorphism and Elite Endurance Swimming,” European Journal of Applied Physiology, published on-line at http://springerlink.metapress.com/media/9C59KC0AD00JYGDA3XAW/Contr.../fulltext.htm
(4) “Angiotensin-Converting Enzyme Gene Insertion/Deletion Polymorphism and Response to Physical Training,” Lancet, Vol. 353 (9152), pp. 541-545, February 13, 1999
(5) “The ACE Gene and Muscle Performance,” Nature, Vol. 403, p. 614, February 10, 2000
(6) “Human Angiotensin I-Converting Enzyme Gene and Endurance Performance,” Journal of Applied Physiology, Vol. 87, pp. 1313-1316, 1999
(7) “Aerobic Exercise Capacity at Sea Level and at Altitude in Kenyan Boys, Junior and Senior Runners Compared with Scandinavian Runners,” Scandinavian Journal of Medicine & Science in Sports, Vol. 5, pp. 209-221, 1995
(8) “Training Response of Adolescent Kenyan Town and Village Boys to Endurance Running,” Scandinavian Journal of Medicine & Science in Sports, in press, accepted for publication on November 24, 2003
(9) “Response to Exercise after Bed Rest and after Training,” Circulation, Vol. 38(5), Supplement, VII: pp 1-78, 1968
(10) “Endurance Training: The Effects of Intensity, Total Work, Duration, and Initial Fitness,” Journal of Sports Medicine, Vol. 15, pp. 199-211, 1975
(11) “Skeletal Muscle Adaptation in Adolescent Boys: Sprint and Endurance Training and Detraining,” Medicine & Science in Sports & Exercise, Vol. 14, pp. 453-456, 1982

To learn about Owen's running camp in Malibu, California this summer, please visit www.RRNews.com, scroll to the bottom of the page, and click on the running-camp "splash."

Copyright © 1998-2005 by Running Research News

To purchase Owen's new e-book, which contains great workouts for competitive distances ranging from 800 meters to 100K, please go to www.runningresearchnews.com.

To obtain Lactate Lift-Off, Owen's hard-copy book about lactate-threshold-velocity-enhancing training, please go to www.rrnews.com/products.htm.

To download free samples of Running Research News, Cycling Research News, Swimming Research News, and Weight-Loss Research, please visit www.rrnews.com/sample-issues.htm.

To find out how to lose the pounds which are slowing you down, please consider a subscription to Weight-Loss Research (www.runningresearchnews.com).

To obtain back issues of Running Research News on topics ranging from 5-K and marathon training to carbohydrate intake to plantar fasciitis, hamstring troubles, shin splints, ITB syndrome, and running-injury prevention, please go to www.rrnews.com/archive.htm. Please use the search engine provided to look for articles on specific subjects.

To learn about the contents of the latest issue of Running Research News and about upcoming events at RRN, please go to www.rrnews.com/next.htm.