Speed-endurance training (S-E) is a vital component of training in sports such as soccer, tennis, basketball and others, but it can be tricky to evaluate a S-E session on the quantitative level. Heart rate (HR) which is a precise physiological measurement is one way of measuring training intensity, however during recovery from one repetition to the next HR might drop to the 120’s but your athlete might not be maintaining speed during the session. Similarly, you may not have access to a blood lactate (Bla) analysis kit when out in the field, and even at that BLa is no longer accepted as a measure of muscle fatigue. So how do you evaluate your athletes performance during S-E training?

One easy way to feedback to your athlete on their training efficiency is to use a “fatigue index“. In S-E training, a good way of thinking about the fatigue index is to see how close your athlete can stay to their best sprint performance time. In other words, the closer they can stay to their best time during S-E training, the less they are fatiguing. The more your athlete moves away from their best time during repeated sprints, the more they are fatiguing and at that point the strength & conditioning coach has to figure out how to improve performance.

Quantifying fatigue

If your test comprises of 6-7 sprints (such as RAST test, FIFA Interval test, Phosphagen Recovery test or any other form you may have devised), you can calculate the fatigue index as follows:

  • Best Time * 6/Sum of Six Times
  • For example, your athlete has performed six sprints recording times of 5.1, 5.2, 5.3, 5.4, 5.5, 5.6 in any order
  • Quantification = 5.1 * 6 / Sum of 5.1, 5.2, 5.3, 5.4, 5.5, 5.6

In our example, our athletes scores 0.95. The closer your athlete’s score is to 1.0, the closer your athletes is to their best performance time over repeated sprints. In elite level sports performance, we look for a rate of >0.9 or more to indicate good performances in our athletes, where as <0.85 is a sign that quality in the training session is missing.