One of the most common questions I get when coaching athletes is why I slow them down so much on their long runs. "How can I be expected to race fast if my long run is a minute or so per mile slower than my goal race pace?" In running, we are dealing primarily with training ourselves to have a better cardiovascular system. There are aspects of muscle memory and strengthening, but the main focus is to develop the cardiovascular system. The stronger our engine is the more likely we will be able to go fast and far.
The optimal way to train an athlete's cardio is to hit several different heart rate zones. I equate training heart rate zones with lifting. Every lift has a specific adaptation. For example, if you do a bicep curl, you should expect your bicep to get stronger, not your quadriceps. Every heart rate zone has a specific adaptation as well. If we want a good strong all-around body, then we need to lift each muscle group of the body. If we want a good strong all-around cardiovascular system, we need to hit each heart rate zone. The problem is that most people don't hit each zone. Most goal-oriented people are used to pushing to hit their goals, which is good. But often they end up missing out on some of the heart rate zones that are the foundation of endurance training.
The most often missed zone is our aerobic threshold. At aerobic threshold, we teach the body to increase fat oxidation, increase the number and size of capillaries, increase the number of mitochondria, and increased stroke volume of the heart. The long run is where this zone is the primary focus in training.
Increased fat oxidation means that the body more readily utilizes fat as a fuel source. Each of us has around 2 hours or so of glycogen stored in our body, but over five hundred hours of fat stores. The more we can teach the body to utilize fat as a fuel source, the better "gas mileage" we'll get out of our energy stores on race day. By training too fast too often (especially on long runs), we're teaching the body to utilize a greater percent of glycogen. When we do that, we increase the likelihood of bonking on race day.
Increasing the number and size of capillaries allows the body to send more blood to and from the muscle. That means more fuel and oxygen going to the muscle along with more waste being removed. Imagine highway 270 narrowed down to two lanes. It doesn't take long for it to back up. If 270 were six lanes wide, you'd be able to transport a lot more cars without things backing up. If we were to add lanes to 270, the most efficient time would be when there is less volume on it. Well, the body is very similar to that. It is during long duration, very easy intensity runs that our cardiovascular system focuses on making more and bigger capillaries (lanes) to carry blood (cars).
Increasing the number of mitochondria helps the body to develop more powerhouses. It's like adding more cylinders to your engine. When you figure that in with an increasing stroke volume (pumping more blood with each stroke) means a bigger faster engine.
Now at the very beginning we discussed about having to hit each heart rate zone to have a good strong all around cardio. You don't have to do all runs so slow. Meb, when he came to FLEET FEET this summer, said he runs his long runs at 90 sec/mile slower than marathon pace. That's only his long runs, not all of his runs. His other runs hit different intensity levels. The long run is simply the foundation. There will be normal road run days which are medium length and medium intensity, and there are hard days that are very high intensity but very short in duration. It's about putting in the right ingredients at the right time.
The issue most of us have in proper training is that we often don't go slow enough on our long runs. If we look at the cardiovascular system as a plumbing system (which it is very similar to), most of us train to have a big sink, a big drain, and small pipes. If we can develop bigger pipes, we will be more prepared for race day. We simply need to look at it from a different angle. It's not about trying to hold us back. It's about adding a new component to our training.
Hopefully that long winded explanation makes sense and doesn't make training more confusing. Basically, the strength for race day comes from your long run, while the speed for race day comes from your weekly runs. The best part of being a coach is having athletes that are willing put the work in. A coach's job is to make sure that work takes the athlete in the shortest route to their goal.
Good Luck and Happy Racing!
Tim Cary is FLEET FEET's Assistant Training Manager, coach of the FLEET FEET-sponsored Runnababez Elite team, and manager of the FLEET FEET Racing Team. Over his 20 years of coaching, Tim has coached athletes to three national team championships, five national individual championships, two national records, and numerous All-American and All-State honors. Click here to receive Tim's weekly article via email.