Aerobic Capacity Workouts: Engine Building 101

Aerobic capacity and aerobic capacity workouts: What’s the deal and why are these terms so important for triathletes?

One way to look at the topic is to think of aerobic capacity as an endurance athlete’s engine.

Whether it be a sprint, olympic, half-Ironman distance, or full Ironman distance race, success in triathlon is centered around building this kind of big engine.

The same can be said for all endurance sports: a big aerobic engine is foundational. To excel you need to be using this big engine at a high intensity and as long a time as possible without slowing down.

A Triathlete’s Engine: What is it?

Your “engine” can be thought of as your heart and the heart’s ability to pump oxygen rich blood to your working muscles.

This in scientific terms is your aerobic capacity(1).

Your muscles then use this oxygen-rich blood to do the work required of them to power you forward through swimming, cycling, or running. 

Your maximum aerobic capacity can be quantified as 100%. The most successful athletes are able to work at a high percentage of their maximum aerobic capacity for a long period of time without slowing down. 

This is what determines success in endurance sports. You want to have a high aerobic capacity in order to be able to deliver the highest amount of oxygen rich blood as your heart is capable of doing. You then also want your muscles to be well trained in order to be able to use the highest amount of oxygen rich blood they possibly can.

Aerobic Capacity Workouts: 3 Factors Important to Engine Building

There are three important factors critical to building the biggest aerobic engine possible and yielding optimal performance.

Factor 1: Increase your training volume 

The best way to build your aerobic capacity is to simply train. Spend time swimming, cycling and running, logging hours of base-building aerobic capacity workouts.

It would seem to go without saying that you need to train, but many athletes look for hacks and short-cuts without realizing that they need to put the work in first. 

The best and safest way to build training volume is to do so at an easy effort. 

Long distance training at an easy effort build’s your heart’s capacity to pump more oxygen rich blood to your working muscles. 

Long distance training at an easy effort, where the distance is gradually increased over time, decreases your injury risk and is less fatigue inducing. This in turn allows you to train with more consistency; meaning less time off needed to recover or, even worse, rehab an injury.

An important question when it comes to safe, effective aerobic capacity workouts: How do I know I know I am going slow enough?

There are many different metrics to determine your intensity depending on which sport you are training for. 

Metrics like power, heart rate, pace and perceived exertion.

When starting out in a sport like triathlon it is best to begin with using your rating of perceived exertion.

In other words, as you are training you are asking yourself this question:

 “How easy or hard do I feel like I am going?”

The modified Borg scale of perceived exertion is a scale from 1 - 10, where 1 is very easy and 10 is the hardest maximum effort. Training long and easy will have your effort of perceived exertion around 3 - 5. 

Training at an effort level around 7 - 8 would be considered hard and vigorous.

Here is where the next step comes in when building your engine.

Factor 2: Incorporate interval training

A dose-appropriate amount of interval training for new athletes allows you to accumulate time training at a higher intensity, thereby allowing your muscles to gradually adapt to using the oxygen rich blood that is being delivered to it. This in turn builds more fatigue-resistant muscles.

So what is the appropriate dose?

Like most things in life it depends, but early on in training, one high intensity session per sport per week is safe. 

Remember as well you are training as an endurance athlete. Therefore, aerobic capacity workouts like longer duration intervals are key. These intervals last from 10 to 20 minutes at an effort level of 7 - 8 on the Borg scale. They will allow you to accumulate an appropriate amount of time to both build your cardiac output and train your muscles to resist fatigue.

Short intervals at complete all-out max effort carry with them a high risk with very little reward. These are race like efforts that drain your engine, leaving little left for the next day’s session. They also dramatically increase your risk of injury.

Consistent volume, with most of your training invested in an easy effort plus a sprinkling of hard efforts will set you up for long-term success in this sport.

Now in order to get the most of your engine you need to be as efficient as possible.

What is the definition of efficiency when it comes to aerobic capacity and building your invaluable base of cardiovascular endurance?

Factor 3: Efficiency and Your Aerobic Capacity

The well known exercise physiologist Stephen Seiler(2) has used an analogy referencing car engines in order to make a point on engine efficiency.

If you have a Ferrari engine and you place that engine on a pick up truck chassis (as opposed to a sports car chassis), which would be considered a more efficient use of the engine? 

Placing the Ferrari engine on the sports car chassis of course. It’s lighter and more fuel efficient.

The same goes for your own engine. You want to be as efficient as you can in order to get the most out of your own aerobic capacity.

These include certain concepts like focusing on technique in swimming, wearing proper fitting clothes while cycling, and fueling properly.

Aerobic Capacity Workouts: There Are No Shortcuts to Building Your Best Engine

Building a big and efficient engine doesn’t occur in one day or even one week. It doesn’t occur from one magic training session or a magic training philosophy. It doesn’t occur from training hacks. It does occur from embracing the process of consistency, executing the basics and putting the work and proper efforts in when needed.