The fall and winter months are a great time of year to put in some easy running mileage. In fact, it is my favorite time of year because I feel like I can really enjoy running again. The pressure of a race looming in the near future is gone and I can focus on running because I love what it does for both my mind and body. Some runners like to continue to do intervals, tempos, etc. during these off-season months, but if your goal is to increase your weekly mileage and build a solid aerobic base then the safest way to go about it is to avoid coupling mileage increases with intense workouts. You risk injury, overtraining, and burnout. For me it works best to at least take a couple months to run distance and build up my mileage base. If anything, it is the mental break from intense workouts that I need to be primed and ready to jump back into more intense workouts come the beginning of the year.
WHAT IS THE PURPOSE OF BUILDING AN AEROBIC BASE?
There are some definite physiological benefits to spending consistent time running easy mileage. We strengthen the cardiovascular system. We create a more powerful pump (heart), which helps get more oxygen rich blood to our running muscles at an increased rate. We increase the cross-section of blood supply in our muscles with the increased number of capillaries (small branches of blood vessels) in our body. We also increase the size, number, and distribution of mitochondria in our body. Mitochondria is where aerobic metabolism takes place, so this increases our body’s ability to take up and utilize oxygen more efficiently. In addition to the cardiovascular benefits, we can become better at conserving our glycogen stores and be more efficient at utilizing fat for energy. Base mileage, if done correctly, also helps build up a resistance to injury and builds a foundation for us to handle more intense/ quality workouts down the road. And if you are still not convinced of the importance of easy running and base mileage, think about how the different energy pathways of the body are utilized during different race distances. We have energy being produced with the presence of oxygen (aerobic pathway) and energy produced with out oxygen (anaerobic pathways) depending on the intensity of the activity being performed. If you take a look at the energy contribution chart you can see that even a shorter race like the mile requires 80% of the body’s energy to come from aerobic metabolism. The marathon requires over 97% from the aerobic pathway! So it makes sense that we should spend 80% or more of our training time developing our aerobic system.
HOW MUCH MILEAGE SHOULD I BE DOING DURING THIS PHASE OF TRAINING?
When it comes to weekly mileage goals, like a lot of training aspects, it is very individual. I know some runners that run consistent 100 mile weeks, some runners who 65 miles per week is their edge, and other beginner or masters (over 40 years old) runners that 30-40 miles a week are what their bodies can handle. So many factors go into this that it is something you have to be very careful about. Jack Daniels, a well-known exercise physiologist and coach, said there is no magical weekly mileage number. He did say, however, that good marathoners tend to be in the 70-150 miles per week average (1). This is a wide range, but it does help us understand that for marathon running, longer weekly mileage is important. While the exact ideal weekly mileage for each person is not always clear, one thing we do know is that it takes YEARS to build up to having your body handle the stresses of 70-150 mile weeks. Runners that are able to handle this amount of mileage have built up to this gradually over years of training. So when deciding on how many miles to do each week, consider what event you are training for (training for a 5K is going to require much less miles than if you are training for a marathon) and then consider how many years you have been running. I’d say if you are just getting started then shoot for 25-35 miles a week. If you are an intermediate runner (3-5 years of running) that has consistently been running 25-35 miles a week then start your base mileage out at the 35-45 range. If you have been running for 7-10 years with consistent mileage above 50 miles then I think you would be okay to start hitting ranges above 60.
HOW DO I SAFELY INCREASE MY MILEAGE?
The most conservative, safest approach would be to stay at the same weekly mileage for 3-4 weeks before increasing your mileage. This gives your body time to adapt to the stresses you are putting on it before you add more demand to it. I like to take a mileage recovery week before making the jump to a new weekly mileage goal. So after the 3rd or 4th week of higher mileage, I drop my mileage for one week by 20% and allow myself a recovery week from the higher mileage. For example, if you are running 60 miles a week for 3 weeks then on the recovery week you would decrease your mileage by 12 miles (20% of 60) and run 48 miles. Then after the recovery week you could head into three consecutive weeks at 66 miles a week. How do I know how much I increase my mileage when it is time to make a jump? Some experts recommend, using the 10% rule of thumb. This means increasing your mileage by 10% of what you have been doing, but maximum amount being 10 miles. Another approach is to increase by the number of training sessions you are doing in a week (1). So if you workout 7 times a week, then you can increase your mileage by 7 miles.
WHAT PACE SHOULD I RUN MY BASE MILEAGE?
These easy distance runs are more of a function of time spent running rather than intensity (1). You can’t really go too slow on these runs, but you can go too fast. If you go too fast on these runs you change the desired result and purpose of the run. I would describe these runs as easy to moderate. At a conversational pace. If you are looking for a heart rate range, your distance run pace should be 65-79% of your heart rate max. If you want to base easy run pace off of race paces you can do that too. For instance, these runs should be 45-60 seconds slower per mile than marathon race pace or 1.5-2 minutes slower than 5k pace (1).
(1) Daniels, Jack (2005). Daniel’s Running Formula. Champaign, IL: Human Kinetics.
Janae Richardson – Runner | USATF Certified Coach | Masters in Exercise Science
Janae has a master’s degree in Exercise Science from Utah State University and is a Certified Sports Nutritionist. She ran collegiately at Weber State University and continues to enjoy running competitively in road races. As a certified USATF coach she also enjoys coaching runners of all levels of ability. Janae and her husband Ken Co-founded UtahRunning.com in 2009 and reside in Ogden, UT with their three children.