Every time I see a training chart like the one featured on the bottom of the screen that lists energy systems with associated durations, I get utterly perplexed. According to this chart taken from a popular coaching certification course, a maximal effort exercise bout lasting between 20–60 seconds in duration is a test of anaerobic lactic capacity.
In the top image, I have ΔSmO2(the rate of change of muscle oxygen saturation) plotted against an individual’s score on a 30-second maximal effort Echo bike over 10 weeks. I plotted the five most negative ΔSmO2 values in red for each test and the 30 second Echo bike test score in blue.
Notice that each week their ΔSmO2 value becomes more negative. This indicates an improvement in their maximal rate of oxygen utilization. You can also see their score on the 30 second Echo bike improving nearly every week over this period from 38 calories up to 47 calories.
When calculating the correlation between ΔSmO2 and performance on this test, I got a value of -0.97. That means there is an inverse linear relationship between the maximal rate of oxygen extraction and performance on a 30-second test of work capacity. In other words, the greater your ability to utilize oxygen in the muscle, the better you’ll perform on a 30-second max effort sprint.
How can this be a test of ‘anaerobic lactic capacity’ when performance is linearly correlated with maximal oxygen consumption? The simple answer is that is can’t be. Yet, people still cling to outdated ideas regarding tests of anaerobic vs. aerobic capacity.
I’ve said it before, but i’ll repeat it — all training is aerobic, and all training is lactic. The most significant difference between a maximal effort sprint an a 5k run is not what energy system you’re using but rather what your rate of oxygen consumption is relative to your rate of oxygen supply. Once you can accept this fact, you can move away from thinking in terms of energy systems and time domains and move towards a model based on rate-limiting performance factors.