Intervals Part 2: Maximal Aerobic Power
In Part 1 of our Interval series, we took a look at some of the general principles behind intervals. Key to all intervals efforts is accurately quantifying intensity, so the next few Toolbox articles will focus on different ways you can pinpoint and target different effort levels. First up is “Maximal Aerobic Power”…
When quantifying intensity, the first thing that needs to be determined is a benchmark “fitness” parameter, from which you base your efforts as certain percentages of that benchmark. You’ve all heard of HRmax as a common benchmark, but this parameter is full of errors due to individual variability from the traditional equation (220 – age) and is difficult to measure accurately. Also, %HRmax tends to be meaningless at higher percentages due to heart rate’s slow response time. What is really needed is a benchmark measure that is meaningful, fast-responding, individual, and easily determined.
Power to the Max
The concept of Maximal Aerobic Power (MAP) has mainly been driven by Dr. Guy Thibault, an exercise physiologist working for the Quebec government and also as a consultant with the Canadian Cycling Association. For endurance sports, there has always been a need for an accurate and reliable test of an individual’s aerobic capacity, and this has traditionally been done in the lab with sophisticated and expensive tools. However, the goal with MAP was also to develop a test that can be easily and accurately replicated in a variety of settings outside of the laboratory.
As should be obvious from the name, MAP is geared towards the use of power to quantify intensity, and is perfectly suited to the CompuTrainer or power monitors mounted on a trainer. The CCA uses the MAP test and an even shorter variation thereof to elicit interest in cycling amongst school groups and to identify kids with strong endurance capacity potential. The MAP protocol is very simple:
• Maintain a constant workload at a constant cadence for 3 min. Record heart rate at the end of the 3 min.
• Increase the workload by 30 W each 3 min interval. Keep the same cadence and gearing throughout this test (e.g., 90 rpm in 53×17) and future tests to maintain consistency. Record HR at the end of each interval.
• Continue to exhaustion. Record final HR and final exercise time.
Ideally, the protocol should consist of not more than 4-6 intervals. Your MAP is the final workload plus any uncompleted 3 min interval:
e.g., if your test consisted of 180, 210, 240, 270, 1.5 min @ 300, then your MAP = 270 + 30 (90 s / 180 s) = 270 + 15 = 285 W.
What Do the Numbers Mean?
The experienced amongst you will recognize that this “staircase” protocol is very similar to those done during lactate threshold tests. Indeed, the similarity is intentional in deliberately replicating the time-proven and scientifically valid incremental test protocols already in use. The main changes with MAP are that power is measured and the test can be done outside of the lab.
Dr. Thibault has developed equations to convert MAP to VO2max, and power/weight ratios can also be calculated. However, they’re not really necessary, because the main thing you should be seeing is an improvement in MAP over the course of a season and a number of seasons. As long as you keep the test conditions consistent (e.g., warmup, diet/hydration, gearing, cadence, tire pressure, calibration of power monitor), you have a scientifically valid and replicable measure that you can compare across tests.
In our next Toolbox, we will focus on Dr. Thibault’s approach to designing interval workouts based on the MAP.
Stephen Cheung is an Associate Professor of Kinesiology at Dalhousie University in Halifax, Nova Scotia, Canada, with a research specialty in the effects of thermal stress on human physiology and performance. His company, Podium Performance, also provides elite sport science and training support to provincial and national-level athletes in a number of sports. He can be reached for comments or coaching inquiries at [email protected].