Learning the difference between anaerobic and aerobic training is the key to improving your personal best in any race. Training and racing at the appropriate levels is the single most important change in your training that you can make. Understanding what each of these terms mean is the first step in that transformation.
At the heart of aerobic and anaerobic training is the scientific fact that to exercise, your body needs to break down sugar and convert it to glycogen so it can be used as energy or fuel. When the body has an adequate supply of oxygen for this process, we call it aerobic respiration. When there is not enough oxygen, like when you are running hard at the end of a 5k, this is called anaerobic respiration.
Aerobic running or respiration occurs when your body has sufficient oxygen – like when you run easy miles with you friends. You breathe in, the body efficiently uses all the oxygen it needs to power the muscles, and you exhale. The waste products of aerobic respiration are carbon dioxide and water. These byproducts are easily expelled through the simple act of breathing. This is why your breath is carbon dioxide rich and moist. Basically, when you are “running aerobically”, your muscles have enough oxygen to produce all the energy they need to perform.
Anaerobic respiration happens when there is NOT sufficient oxygen present.
In this instance, the muscles do not have enough oxygen to create the energy you are demanding from them (like in an all-out sprint at the finish). When this happens the muscles begin to break down sugar, but instead of producing CO2 and water, it produces lactic acid (that burning feeling in your muscles at the end of a race). Unfortunately, lactic acid is harder to remove than water and CO2. Thus, lactic acid accumulates in your system, causing extreme fatigue.
The importance of understanding these definitions is clear. If you begin to run too hard in the middle of a workout or the start of a race, your body goes into an anaerobic state, producing lactic acid. If you “go anaerobic” early in a race and you begin to feel fatigued sooner and become increasingly tired as the race progresses. The accumulation of lactic acid pools in your muscles and you have to slow dramatically to get back to an aerobic state. Your PR is out the window and finished before that race is half way over.
Learning to establish and feel your anaerobic and aerobic pace is a really important skill if you want to start racing faster. If you have questions about what your “aerobic” and “anaerobic” pace is, or how to practice feeling it, please don’t hesitate to get in contact with me.
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My name is Jeff Gaudette and I have been studying everything there is to know about running and training for the last 13 years; some might call me obsessed. I love coaching and I have a passion for translating highly technical training theory to the schedules of my "everyday" runners. Learn more about my running and coaching background 
IM VERY INTERESTED IN THIS TOPIC, AEROBIC AND ANAEROBIC.
IVE BEEN RUNNING FOR A LONG TIME BUT I KNOW NOW THAT IVE
ALWAYS RUN ANAEROBICALLY…
THE EASY DAYS ARE VERY HARD TO DO BECAUSE I HAVE TO RUN TOOOOOO
SLOW TO BE IN THE AEROBIC ZONE…ITS KIND OF FRUSTRATING BECAUSE
I FEEL LIKE RUNNING FASTER.
I READ THAT THE WAY TO IMPROVE AEROBIC CAPACITY IS BY RUNNING
WITHIN THAT ZONE BUT TO TELL YOU THE TRUTH IS NOT A CONFORTABLE
PACE.
I RUN 3 DAYS ANAEROBICALLY AND 2 DAYS WEIGHT TRAINING AND 45 MIN OF SLOW RUNNING.
LATELY I DECIDED NOT TO USE MY POLAR…I ONLY USE IT THE DAYS I GET ON
THE STATIONARY BIKE (1 DAY A WEEK)
IF YOU HAVE ANY COMMENT I WOULD APPRECIATE IT…
THANK YOU
SUSAN SANTOS
Hi Susan,
Thanks for the question, you raise a very good point about aerobic training. It is a little difficult to be very specific about your situation without knowing all the data, but I will do my best.
First, running aerobically will and should feel slow, because it is designed to be comfortable. Most runners I begin working with are amazed at the pace they have to run to maintain a heart rate in the aerobic zone. Part of this comes from a misconception that they are running much slower than the others around them. However, the average pace for most runners is in the 11 min per mile range. So, if you’re running anywhere in the 10min – 12 min range, you’re not running “slow” by general standards. If you’re running slower than 12min a mile, you’re still not running slow as this pace still puts you in the second largest majority of average paces.
The trick with aerobic running, or any training for that matter, is to be patient. Consistent aerobic running will strengthen your aerobic system, heart, lungs, and muscles, to handle faster training paces and longer runs. Try giving yourself two weeks at what you know is your aerobic pace. Since you have a heart rate monitor, this would be roughly 70-80% of your maximum heart rate. After just two weeks, look at your pace and watch how much your pace has dropped naturally as you stay within that 70-80%.
One of the largest benefits of aerobic running is that it allows you to run longer and more often, since you’re not gasping for air or sore the next morning. This means that you can burn more total calories and lose more weight, which is a major goal for most runners at any level.
My advice to you would be to try and be patient for just 3 or 4 weeks. Run at your aerobic zone (70-80% max heart rate) and watch your pace start creeping down naturally every two weeks. Make 3 of your running days aerobic days and one o them an anaerobic day so you can switch things up and enjoy the feeling of running faster. After 3 or 4 weeks, you’ll start to notice your pace coming down and you’ll be more comfortable running in this range.
I hope this info helps. This is a very complicated topic with many factors that influence and change – goals, fat burning, calculating pace, terrain – that I hope to explore in upcoming blog posts.
Again, thanks for the question!
Jeff
I’m just getting started with heart monitor training because of information you’ve written. I completed a 9 week 5K training program successfully and began running regularly (3-5 times per week). All of a sudden, I cannot even run a mile at my normal pace without feeling completely out of breath! I’ve had all the medical tests done and there’s nothing wrong. The only thing that I think could make sense is what you describe. I’m hoping the heart monitor training will help me as I really want to continue with my running.
Hi Michelle,
Thanks for your comment and I am glad to hear that my article helped you. I will be writing a series of blog posts on heart rate training within the week. Please check back soon to read!