Hello fellow exercise scientists, Here is a Friday afternoon "clinical case study" for you. Call it "grand rounds" in the exercise physiology lab if you will.
Today, I tested a young runner (not yet 15 years old) who is one of the biggest talents in Norway in his age group. This boy is nearly 15 with the body of a 12 year-old in terms of size. He weighs only 36kg (about 80 pounds), and is 152 cm tall (almost 5 feet) . He is tiny, but has the body of an elite endurance athlete, a truly amazing world class athlete's body, in a micro-sized package. He has been to groth specialist and told that he is way pre-pubertal and at a 12 year-old stage for bone growth. He should end up about 6 feet tall. Thomas is a very talented runner and highly motivated. He has broken 9 minutes for 3000 meter during a one man time trial, and run 5:50 for 2000 meters. More impressively, he is destroying fields several years older in cross-country races (in Norway cross-country means running in the forest, through the mud and up any climb that is not vertical). Now here is where you guys come in. I have occasion to test some pretty good endurance athletes in the age group 16-19, due to my work with local sports teams here in southern Norway. I have tested several of Norway' s very best teenage cross country skiers (VO2 max 77 to 80 ml/kg at age 17). Among all the talented endurance athletes I have tested in the last several years, the young boy I tested today stands out as a one of a kind in my career. Today, I tested young Thomas using a ramp protocol at only 1% grade to determine VT1 and VT2 in a format comparable to track running. Then after a rest, he performed a second shorter ramp protocol at 10% incline, increasing 1km/t per minute to exhaustion to determine VO2 max and max heart rate. We used the high incline to avoid having him run over 23 km/hr on the treadmill, since he was a bit scared of it. He is in peak condition, and has won a good number of races against older competition. Bottom line: His VO2 max was 89 ml/min/kg. OK, actually it was 90 for the last 30 seconds. It was 89 when averaged over the last 90 seconds. The test was performed on a Jaeger Oxycon PRO in breath by breath mode. Max values are based on 30 second averages. I have no reason to suspect any problem with the measurements. We have performed at least 35 ramp tests in the last few weeks, and the data are highly consistent in every way and calibrations are spot on. So, I believe the numbers are reasonable (plus/minus 2 ml/min/kg). However, his per kg oxygen consumption relative to running velocity is over predicted values for normal sized adults. So, according to the table I use, he comes out pretty inefficient. But, watching him run makes me figure there are major scaling issues at play here. What I wish to discuss is WHAT DO THESE DATA MEAN? Thomas is obviously a talent. We know that. But, where does allometric scaling come in when we test such an "undersized" yet highly trained athlete? I am used to measuring talented teenage athletes weighg 70-80 kg with an absolute VO2 of 5 to 6 liters. This tiny tike's absolute max was only 3.3 l/min (at a VE of 102 l/min), a quite pedestrian value were he only 20-30 kg heavier! These results are scary to discuss with a young teenager who is truly possesed with training and becoming a great runner. He already has the relative VO2 max of a world champion. His second ventilatory threshold (VT2) breaks at nearly 80 ml/kg! He takes a few hard breaths after two hard tests and looks totally unaffected. He idolizes the Kenyans. In 10 years will they be idolizing him? After today's test and a previous one from the off-season (81 ml/kg), I have already began to explain to him that the likely effect of growth and continued training will be a small reduction in relative VO2, but continued improvement in performance as he gains a bigger absolute engine, longer stride length, more anaerobic capacity etc. His extremly high ventilatory threshold can't be expected to change much. I don't think he owns a fast twitch fiber, except maybe in his face, which smiles rapidly. Is his per kg VO2 max peaked out at age 14? Partly, this is just a curious story for a Friday evening. But, there are questions here related to 1)allometric scaling and 2) guiding a prodigy. The boy's coaches are extremely careful with his training load. He will not be a burn-out victim. In fact, he would no doubt be faster for 3000 meters if he was allowed to train at higher intensities. Are there any coaches or physiologists who have similar experiences with testing young, undersized, hyper- talented endurance athletes? This little guy's numbers just make me shake my head and wonder what might happen with him down the road when he body grows into his potential, or how he could possibly be fooling my high dollar metabolic cart? regards, Stephen Seiler -------- View all messages at http://sportsci.org/forum. Click on the links to JOIN, UNJOIN, alter MAIL OPTIONS, or get INFO/HELP on acceptable messages.
