Training to maximize aerobic capacity is the cornerstone of all cross country conditioning for races of 8k or less, and very important to even 10k and 12k cross country races. The ideal training scheme will have dedicated VO2 max workouts to develop aerobic capacity and tests to monitor the developmental progress of the advancing system. Ideally, any test of VO2 max uptake should meet the minimum general requirements:
1. The exercise must involve the large muscle groups of the body.
2. The athlete’s work rate must be measurable and replicable.
3. The test conditions must be such that the results are comparable and reproducible.
4. The test must be achievable by all healthy individuals.
5. The biomechanical skills required should be as uniform as possible to the testing population.
A widely used testing method of establishing an individual’s maximal aerobic capacity (VO2 max) was described by Bruno Balke in 1954. The principle of his protocol has survived the test of time. In later years scientists such as Joe Vigil Ph D have developed a field test using Balke’s laboratory principles, thus eliminating the need for sophisticated treadmills and oxygen capture devices.
In the Balke laboratory protocol the treadmill speed is kept constant at around 5 km – h-1 (3.0-3.5 mph). The slope of the treadmill is increased every minute (or every other minute) in steps of 2.5%. With a speed of 4.8 km – h-1 (3 mph) the increase in oxygen demand is about 3.5 ml – kg-1 per step, which is called one metabolic unit (MET; the approximate oxygen uptake at rest). If starting at 4 METs, at a slope of 2.5%, for example, oxygen demand increases to 5 METs at 5%, 7 METs at 10%, and 15 METs at 30%. One drawback with this protocol is it takes a long time for fit subjects to complete the test. In such cases, a running speed may be chosen instead of walking.
The coaching tool for determining VO2 max is called Balke’s Modified Field Test and it is an adaptation of the laboratory protocol. The purpose of this test is for the coach to determine an athlete’s VO2 max without going inside to the treadmill under lab conditions. All that is needed for the test is a measured track and a stopwatch.
Steps in the Balke Modified Field Test:
1. Subject runs to exhaustion using exactly 15 minutes of elapsed time. Since it is on the track, the distance can be accurately determined.
2. Record the distance in meters or convert to meters if the test was done on a trail using mileage. There are 1609 meters in a mile.
3. Total meters are divided by 15 to get meters per minute.
4. The first 150 meters of each running minute is called the base constant value because it is mainly an association of anaerobic energy contribution and homeostasis of life that has little correlation with one’s aerobic capacity. The base constant value for all subjects will be standardized at 33.3 ml of oxygen per kg of body mass per min (33.3 ml/kg/min) .
5. For each subsequent meter run beyond 150 meters each minute, multiply by 0.178 ml/kg/min. Unlike the base constant value, this value will be linked to individual aerobic capacity.
6. Add the calculated value from step 7 to the base constant value to determine the individuals VO2 max.
Example: Billy covers 4800 meters in 15 minutes to exhaustion. Divide 4800 meters by 15 minutes to get 320 meters per minute of running velocity. Subtract the first 150 meters (base constant value) from 320 meters per minute to get 170 meters per minute of experimental value. Multiply 170 by .178 to get 30.26 ml/kg/min. Finish up by adding the experimental value of 30.26 ml/kg/min to the base constant value 33.3 ml/kg/min to get a VO2 max of 63.56 ml/kg/min for Billy. He covered the 4800 meters (2.98 miles) in 15 minutes which establishes his date pace VO2 max velocity at 5:03 per mile.
While the VO2 max value is interesting, the real value lies in training at the
VO2 max velocity pace. One workout per microcycle should be set up to be run at 98-101% of this velocity for the strongest training stimulus. Total volume for each session should be 3200-8000 meters broken into work bouts of at least 800 meters. The rest interval should equal the time of work for each repeat until the total session volume is reached.
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Scott Christensen is the head track coach at Stillwater Area High School in Oak Park Heights, MN.