One of the most important aspects of training for the endurance athlete is developing aerobic endurance – the ability to perform efficiently and effectively for a long duration at an intensity below the anaerobic threshold. In the Base period this is typically one of the most important aspects of training for road cyclists, triathletes, mountain bikers, runners, cross-country skiers, etc. It is usually considered the “foundation” upon which all subsequent training gains are made.
Making a significant improvement in aerobic endurance is very important and yet it is seldom measured. One of my coaching precepts is that which is measured is more likely to improve. But this is seldom done for aerobic endurance even though it may be the most important foundational ability. Most athletes believe that what they are doing in training is producing the desired results. It would be far better to measure progress rather than to accept progress on blind faith. The purpose of this post is to show you a couple of ways of doing this. But I’ll forewarn you that doing what I’m about to describe requires some technology – both hardware and software. Without data from such sources you’re stuck with faith-based training.
The way to measure the progress of aerobic endurance is by comparing output to input. Over the course of time in steady state workouts done below the anaerobic threshold, if output increases relative to input or input decreases relative to output then aerobic endurance is improving. So by comparing the two we can determine changes in aerobic endurance. So what are input and output and how can they be compared?
Let’s start with input. This is probably the easiest for most athletes to measure as the most common workout input is heart rate. You probably already have a heart rate monitor.
Another input measure is Rating of Perceived Exertion (RPE). On a scale of 1 to 10 (with 10 being an all-out effort) you simply rate how hard the workout was. The problem with RPE is that it is totally subjective and can be influenced by your attitude on any given day. This could be affected by training with other athletes, life stresses, and probably many other variables. While every athlete should become adept at doing this (it’s becoming a lost skill, I’m afraid), RPE is not a very precise way to gauge input so won’t provide an accurate measurement of changes in aerobic endurance.
A third way of measuring input is lactate analysis. While fairly precise (if the technician knows what he/she is doing) it is not convenient. Taking blood samples is best done in a highly controlled setting such as a clinic or lab and not during workouts.
So the bottom line here is that heart rate is probably your best option for measuring change in aerobic endurance.
Next, you need to measure output. This is the product of your input. Output measuring devices are becoming more common. They include power meters (bike) and speed-distance devices such as GPS and accelerometers (running, XC skiing).
Power meters are the way to go for the bike. Speed is not a reliable metric here due to wind and drafting. The problem here is cost. A power meter is likely to cost you US$1000 or more depending on the technology you choose. But the power meter is a precise way of measuring output.
Speed-distance devices are getting better but have a long way to go. The biggest problem is that they don’t give you normalized speed/pace data when going up or downhill. You can find out after the workout with WKO+ software but this does you no good during the workout. They also don’t reflect terrain surfaces such as sand, pavement, hard-pack or powdery snow or wind. While there is a great deal of room for improvement they are the best we have right now.
Comparing Output and Input
So now let’s take a look at the comparison of output and input. There are two methods I use for this. I use both with every steady-state aerobic endurance workout to gauge if the athlete is making progress.
The first has to with something I call “decoupling.” This is explained in some detail in a previous post on the topic of decoupling. So rather than describe it again here I’ll let you check that post.
The second method involves establishing a ratio for output and input. It’s simple math. Just divide your output (power or speed – not pace) by your average heart rate for the workout. The quotient is your output-input ratio. As this quotient rises your output-input ratio is improving. Here is a chart that illustrates the changes for athlete in his aerobic endurance workouts which he did from the middle of November until the end of December. Notice that the chart does not show a continuous rise. There were good and bad days. The trend, however, is upward indicating improved aerobic endurance.
The athletes I coach will do these aerobic endurance workouts several times in a week during the early Base periods. I check decoupling and output-input ratio after each workout. Generally there is some stabilization occurring within 6 to 12 weeks. Once I’m sure we’re not going to see any further gains in aerobic endurance then I move the athlete to the next stage in the training sequence.
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I’ll be traveling to the Canary Islands and conducting a training camp there http://www.tridynamic.co.uk/events_more.asp?eventType=1&eventID=25 over the coming two weeks so you may find that posting your comments and questions, and my replies to them, may be delayed.