The importance of aerobic and anaerobic energy in the sport of cycling, Part 1

When cycling, especially while racing, we use a mix of aerobic and anaerobic energy to create speed for the day. While sprinting hard to close a gap in a road race or powering up a steep climb on a dirt trail, you’re tapping into both aerobic and anaerobic metabolism to complete the task, but most of the time you’re working aerobically. The purpose of this article is to demonstrate how aerobic and anaerobic the sport of cycling really is, and why it is important for all cycling disciplines to focus on training aerobically the majority of the time.


To begin figuring out how aerobic or anaerobic cycling really is, we first need to learn what all this aerobic and anaerobic stuff means. Aerobic metabolism takes place with the presence of oxygen and anaerobic metabolism happens without the presence of oxygen. So that means sometimes we move, jump or pedal at a certain intensity that requires very little or zero use of oxygen. But the question remains to when and how often this happens while we are riding or racing our bikes?

Let’s first learn about physiological energy systems, and begin to look at what is happening on the inside of our bodies while we are training at certain intensities. The chart below is an example of the type of energy system that is targeted at specific intensities1. Peak power charts from a range of abilities, from category I elite to category 4 cyclists were used to help determine appropriate exercise duration's related to percent of max power.

Energy Systems.JPG

It is important to note that all energy systems will play a role in most if not all movements at any intensity, but the main focus is on the system that plays the biggest role. As you can see, a true anaerobic action takes place at around 90-100% of your maximum power output, typically lasting between 3-10 seconds. A mix of aerobic and anaerobic energy is used between 30-90% of maximum power and while working under 35% of maximum power output, you are working mainly aerobic.



The finial 3-5 seconds of a sprint to the finish line, where a rider puts as much power into the pedals as possible, is a good example of a cycling effort that is mainly anaerobic. On stage six of the 2012 Tour De France, Greg Henderson led his teammate Andre Greipel to the finish line, sprinting as his lead out man to give Greipel the best chance for the win. Henderson did a great job that day and Greipel ended up winning the stage. In the last 60 seconds of that race, Henderson produced a max output of 1150 watts (2 Second peak output was 1124 watts so the max of 1150 watts was most likely for 1 second) and averaged 663 watts2. During that short period of time, especially when he was hammering over the 1000 watt range, Henderson was working mainly anaerobically.

What is interesting is to analyze the ten minutes proceeding the final minute of the race, where Henderson was working near his threshold power ranges, averaging close to 400 watts, to help keep his team near the front of the pack2. When you compare Henderson’s threshold power to his max power output for the day, you can see that even when working hard near his threshold range, he is still only working at 35% of his maximum power ranges. So even though he was working at his threshold power range for a ten minute effort, he was still using a large amount of aerobic energy to complete that task.

In part two of this article, we are going to analyze the aerobic and anaerobic demands of four different disciplines of cycling. We will use two race files from Greg Henderson and two race files from Jeremiah Bishop to give us a look at both road and off road cycling races.


1 – Cramer, Joel. “Bioenergetics of Exercise and Training.” NSCA (2006): PDF file.

2 - Gallagher, Stephen. “Greg Henderson's Tour de France Power Data." Cyclingnews., Web. 14 July 2012.

The importance of aerobic and anaerobic energy in the sport of cycling, Part 2

Analyzing a cycling race to determine how often you are working both aerobically and anaerobically can be done with the use of power, the Training Peaks Power by Zones chart and some knowledge of physiological energy systems from the first article. The Power by Zones chart provides the percent of time pedaling in all power ranges during a training ride or race.

The seven power zones used to analyze each race file are from Andrew Coggan’s Power Training Levels. All levels are a percentage of Lactate Threshold (LT) power. The main source of energy for each training zone has been established using a percent of each rider’s maximal power outputs, compared to the primary energy system stressed on the “Training Specific Energy Systems” chart from the first article.

              Power Zone                                      Primary Source of Energy

1            Active Recovery         <55%                           Aerobic

2            Endurance                  56-75%                       Aerobic

3            Tempo                         76-90%                       Mainly Aerobic

4            Lactate Threshold     91-105%                     Aerobic/Anaerobic

5            VO2 Max                     106-120%                   Aerobic/Anaerobic

6            Anaerobic Capacity   121-225%                   Mainly Anaerobic            

7            Neuromuscular          >226%                        Anaerobic


For this article, and slightly different than how Dr. Coggan calculates each training zone, I placed a numerical value for Zone seven to further define anaerobic efforts within a race. Zone seven is set to display power outputs greater than 226% of threshold power - equivalent to approximately 75-100% of each rider’s maximum power output range and mainly anaerobic (refer to article one for explanation).


Let’s analyze and compare two disciplines of road racing and two disciplines of mountain bike racing to show how much aerobic and anaerobic metabolism plays a role in each race.

Greg Henderson’s 2012 Tour de France Stage 4: Abbeville - Rouen 214.5km – Duration 5.5 hours

Henderson 1.jpg

Greg Henderson’s 2011 Amgen Tour of California Stage 6: 24km Time Trial – Duration 33 minutes

Henderson 2.jpg

As you can see - 93% of the 214.5km stage race and 83% of the time trial race took place between zones 1-4, showing that both race efforts relied heavily on aerobic metabolism. This is not to say that anaerobic metabolism does not play a role, it definitely does. 38% of the TT effort is spent between zones 4-6, compared to 12% for the 214.5km stage, showing that the TT effort relies on more anaerobic energy than a long distance road race but the majority of the race is still mainly aerobic.


It is important to note that Greg spent 29 seconds in zone 7 during the 214.5km stage race, within the final minute of the race sprinting to the finish line. That represents .001% of the race so it is not displayed but it was a very important part of the race, if not the most important. He also spent zero percent of time in zone seven during the TT effort.


Jeremiah Bishops 2012 Cohutta 100 mile mountain bike race – Duration 7 hours

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Jeremiah Bishops 2011 Fontana City National - Pro XC – Duration 2 hours

Bishop 2.jpg

When looking at both mountain bike races from Jeremiah Bishop - 92% of the 100 mile Cohutta race and 76% of the Pro XC race was spent between zones 1-4, showing that both of these race efforts relied heavily on aerobic metabolism, similar to both road race examples. You can see that for the 100 mile mountain bike race, 58% of it was spent between zones 2-4 making this race effort the most aerobic effort of all the races. But on the flip side, 23% of the Pro XC race was spent in zones 5-6 making this race the most reliant on anaerobic energy of all the race disciplines.

It is also important to note that Jeremiah spent four seconds at the Cohutta race and seven seconds at Fontana race in zone seven.

In conclusion, it is important to realize the large role aerobic metabolism plays in most if not all cycling disciplines. At the same time, it is also important to realize how much of certain intensity is needed to do well for each specific type of race. To do well in a XC mountain bike race, a well-timed focus to improve VO2 max and anaerobic capacity efforts needs to take place and if it is a road time trial race, a large focus needs to be placed on gaining endurance and power in zones 3 and 4. But underlying even the hardest efforts on the bike is the role of aerobic energy. It is not always about how hard you can go, but how often you can go hard – That takes aerobic endurance.

Mike Schultz CSCS