There are many tests available for coaches to use in assessing the track and field and cross country athletes aerobic abilities on their teams. Throws coaches commonly use the over-head backward toss of the shot, jumping coaches use the three-legged bound, and distance coaches use the Kosmin Test; all in an attempt to predict future success. None of these tests are foolproof, but they do offer a means for specific skill assessment.
For cross country coaches, training components can be separated into four general areas of focus. All four categories need to be addressed in any endurance plan. The specific endurance event itself dictates the prime area of training focus. The four components are: lactate threshold, lactate tolerance, running economy and aerobic capacity (VO2 max). In a cross country race of 3200 meters to 5000 meters, aerobic capacity is the prime physiological training target. There is a test, the Cooper Test, which coaches can use in assessing the seasonal development of an individual athlete’s aerobic capacity. A cross country athlete takes the test at the beginning of the cross country training cycle, and then at the end of the season the athlete repeats the test. The coach can then assess numerically, with empirical data, the development of each athlete in that training cycle in regard to aerobic capacity.
First, a word or two on aerobic capacity in distance runners. The real limiting factor in any race over 400 meters is inefficiency within the aerobic energy system. In other words, it is the ability of the athlete to utilize oxygen at the contracting muscle fiber where carbohydrate is reduced to ATP, without fatiguing byproducts that spells success. This process is true for all oxygen-breathing organisms.
Scientists measure aerobic capacity in milliliters of oxygen actually used, per kilogram body mass, per minute. The average American, non-trained, has a VO2 max of about 35 ml/kg/min which is about equal to another mammal, the pig! However, if starting with a favorable genome, some humans can reach a VO2 max value close to 80 ml/kg/min. Rowers seem to have the highest tested values. In contrast, the migratory Monarch butterfly has an aerobic capacity of nearly 1,000,000 ml/kg/min. Birds are in the hundreds of ml/kg/min range. A Thoroughbred horse is about 180 ml/kg/min, while sled dogs have been tested at 240 ml/kg/min. Humans are in the low range, but runners have been shown to produce a 20% improvement in VO2 max values over a 15-20 week training period.
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The many reasons on why it takes so long to fully develop aerobic capacity for any given endurance training period lies in what the adaptations are in the body. In order for a muscle to contract, ATP must be present on the fiber. ATP is continually regenerated by breaking down carbohydrate without oxygen (anaerobic) and with oxygen (aerobic). In humans the aerobic system dwarfs the anaerobic system, and in endurance racing that same situation exists. In 5000 meter races there will most likely always be plenty of carbohydrate available for reduction to ATP. The bottleneck is in the limited oxygen supply. Humans just do not store oxygen in the body very well. In order to improve aerobic capacity, most of the gains will involve a more robust oxygen delivery system. That means a bigger heart, more blood volume, more capillaries, and a greater volume of proteins and enzymes present to facilitate the movement of oxygen from lung to muscle. More oxygen available at the muscle fiber will promote a greater number of mitochondria to be produced and with a larger size. All of this adds up to structural changes in the body that take weeks to change.
The Cooper Test is simple to do. At the start of the season have each athlete on the team run six laps on the track to full exhaustion. Use the attached chart (Figure 2) to determine what the completed time converts to in oxygen ml/body kg/min. This is their individual field-tested VO2 max. At the end of the season repeat the test and the improvement shown should be somewhere about 20% in ml/kg/min. If not, change your training program to put more emphasis on aerobic capacity during the whole training cycle.
|Figure 2. Estimated Maximal Oxygen Uptake(VO2max) for the 1.5-Mile Run Test|
|(Wilmore and Costill 2004)|
|Time VO2max (mL/kg/min)|
Estimated Maximal Oxygen Uptake(VO2max) for the 1.5-Mile Run Test Adapted from K. H. Cooper, “A Means of Assessing Maximal Oxygen Intake,” in Journal of the American Medical Association 203 (1968): 201–204; M. L. Pollock, J. H. Wilmore, and S. M. Fox III, Health and Fitness Through Physical Activity (New York: John Wiley & Sons, 1978); and J. H. Wilmore and D. L. Costill, Training for Sport and Activity (Dubuque, IA: Wm. C. Brown Publishers, 2004).