How Running Slower Makes You Faster

I cover this often in the store how important it is to run slower to build the cardio engine. We all want to run faster at some point but in order to get there we must pay our dues, slowly. It can be painful running that slow knowing you could finish so much faster, however, if you trust the system, you will far exceed our premature desire to run fast. Enjoy this article from our friends at On Running. - Dave

How Running Slower Makes You Faster

If you think elite distance runners are spending every training session pushing themselves at superhuman paces, think again. In fact, while the mileage a pro puts in the bank each week is out of reach for most of us, much of this volume is done at paces that sound distinctly, well, human.

Why so slow? We asked world-class On athletes and coaches to explain how increased mileage at slower speeds can make you faster – and how we can incorporate it into our running regimes. Before we get to their run-faster recommendations, however, we need to understand a bit of sports science 101 –  the difference between aerobic and anaerobic training. 

Aerobic vs. anaerobic training

Aerobic activity is defined by the American College of Sports Medicine (ASCM) “any activity that uses large muscle groups, can be maintained continuously and is rhythmic in nature.” The key word in the definition as applied to running is “continuously."

Aerobic running is easy running at below 80% of your maximum heart rate. Running in this aerobic zone maximizes an athlete’s ability to burn fat as a fuel source. It’s running at the kind of pace where you think you could go forever.  In the aerobic zone your body uses oxygen to power the muscles, fueling them with both glycogen (carbohydrate stored in the muscles) and fat (its preferred energy source). With this power cocktail of fuel, your muscles can keep going. And going. And going.  

Anaerobic training is what happens when you kick the intensity up a few gears. The ASCM defines it as “intense physical activity of very short duration, fueled by the energy sources within the contracting muscles and independent of the use of inhaled oxygen as an energy source.”

In plainer running terms, we are now out of the comfort zone and into the hurt locker at a pace we know we can’t sustain for very long. 

When we get to above 80% of our maximum heart rate, we enter the anaerobic zone. Here, we stop using oxygen to power the muscles and without oxygen we can’t burn much fat. This means, as stated in the above definition, we rely on the energy stored within our muscles. The primary energy source within muscles is glycogen and our glycogen reserves are used up much faster than our fat stores. At such high heart rates, glycogen is less efficient and yields less energy. Even fully topped up with pre-race pasta party carb-loading and good breakfast, our glycogen stores will only power us for less than two hours. If you’re running a marathon, that’s only enough if you plan on breaking the world record. 

When you push yourself into the anaerobic zone then eventually you’ll run out of glycogen. This will not be pretty. Running out of glycogen is what we all know and dread as “hitting the wall” or “bonking.” Entering an anaerobic state is also the point where lactic acid really starts to build up in the muscles. This biological mechanism stops you pushing your muscles beyond their limits by slowing you down. It’s a clever evolutionary trick, but it’s not going to help you get that new PR you were hoping for. 

The key outtake here for long distance runners is that we want our bodies performing in the aerobic zone for as long as possible on race day. Which means we need to train our bodies in the aerobic zone so we can go faster by burning fat without gobbling glycogen. You can probably see where this is going…

Easy days easy, hard days hard

Chances are the pace of your regular run lands somewhere right in the middle of “this feels easy” and “I think I’m going to pass out.” That point is the boundary between the aerobic activity, which you can do for a long time, and the anaerobic activity, which you can only do for a short time. But what might feel like your sweet spot is considered by many coaches to be more of a tempo no man’s land in between the two activity types. 

While there are certainly benefits to getting out there no matter the pace, the respective training benefits of aerobic and anaerobic training come more efficiently when you focus on one or the other in each session. As the old adage goes, run easy days easy and hard days hard. This means running most of your miles at easier paces, interspersing this aerobic training with some hard, out-of-the-comfort zone efforts (more on that later). 

“Our elite marathoners typically run 85-90% of their training volume in the aerobic zone,” says Andrew Kastor, Head Coach of the Mammoth Track Club in Mammoth, California, US.  

It’s a similar story over at the On Zap Endurance team based out of Blowing Rock, North Carolina, US, according to Elite Athlete Coach Pete Rea: “During marathon preparation roughly 75-78% of our athletes’ total weekly volume is run at paces slower than target marathon rhythms.”