How to mix in speed work
Note: This is going to be another multi-part post. I don’t want to force folks to wade through a wall of text as we get into the nitty-gritty bits of training theory.
You’ve been running for a while, consistently running at a comfortable pace. Maybe you’ve been doing some base building for a bit and the mileage is up. Now you want to add in some “speed” so that you can run faster. How do you start adding in “speed” so that you don’t get hurt? Unfortunately, this question is a little more complex than what you’d think.
The first question we need to ask when we start talking about workouts that make us faster is: What’s the physiological stimulus we need to run faster? Yes, we could work on everything at once. Unfortunately that normally results in injury because all of our training time is “hard” or not really seeing much improvement because we’re not getting enough of any one stimulus to get better. But if we intentionally target the system that is the weak link in the chain, then we can get the most bang for our buck while minimizing the risk of injury. So what are the potential weak links?
Believe it or not, our central nervous system may be what is preventing us from running faster. This can be for a couple of reasons. Our nervous system may have a hard time recruiting enough muscle fibers at once to generate the amount of force necessary to run faster. This is what it would be like if you couldn’t push the pedal all the way down while driving. The car could probably produce more oomph, but you’re not telling it to push as hard as it could.
The other aspect of neuromuscular fitness is simply the ability to coordinate all the muscles that are involved in running. In other words, our biomechanics. Good form is critical to being able to run faster at any effort level, and most athletes can see a pretty significant increase in their performance by simply cleaning up the mechanics. By cleaning up the mechanics we become more biomechanically efficient, delivering more of the force our muscles are producing to the ground to propel us forward. In terms of the car analogy, this would be like having a really weak suspension and soft tires. You can jam that gas pedal down to the floor, but you’ll be dumping a lot of the force you’re generating and you won’t accelerate as quickly. Running especially is like stepping on the gas each step, as it’s a repetitive motion (unlike the continuous rotation of a tire).
We can only really speed up our turnover rate so much. At a certain point, we have to be able to deliver more force to the ground so that we can go further with each step. Let’s say that you have great biomechanics and you’re capable of recruiting lots of muscle fibers with each contraction (i.e. you’re vehicle is responsive and efficient). It’s possible that your weak link is the ability of your muscle fibers to generate power. You may simply not have enough potential power available to you that even when you’re close to maximum effort you’re still not actually covering ground very quickly. Where good biomechanics can speed up the turnover rate (RPM’s in our car analogy), the power output our muscles is what will define the amount of ground we cover on each one of those steps.
The third pillar of speed (for endurance athletes) is aerobic power. We normally are competing in races that are longer in duration than we can possibly sustain maximum (i.e. anaerobic effort). There’s really only about 20 seconds of anaerobic fuel available to us, and we can’t regenerate those fuels fast enough to replace them when we’re going at 100% effort. Going back to our car example, this is like having a vehicle that can generate a lot of power, and possibly even be well tuned and have a stiff suspension, but without enough gas in the tank we’re not going to get very far. We need to have the ability to 1) get a bigger gas tank or 2) use a different kind of fuel that doesn’t run out so fast. Unfortunately, the human body can only store so much anaerobic fuel. Even with optimum training, we’re still not going to be able to go for long enough to matter for our longer events. This means that we have to go with the second option of burning a more efficient fuel that we won’t run out of. We have to work aerobically.
While aerobic work is much more efficient in terms of the amount of energy we supply per molecule burned, we are limited by how fast we can burn it. Just like with any other engine, there is a top end to how much fuel you can inject at once. This means that our functional top end speed for the races we care about as endurance athletes is more limited by our capacity to produce energy aerobically (i.e. how much of the “efficient” fuel can we burn at once). Consequently, aerobic power training is something we try to stress as much as we can in terms of our “speed” work. It is probably important to point here that while we often refer to this kind of training as “speed” work, it’s really power work. It doesn’t really matter how fast we’re covering ground per se, but rather the amount aerobic demand we can put on our bodies that determines the amount of stimulus we’re getting.
Which do you train first? Come back next week and we’ll talk about how to determine where to focus your effort. Until next time, train smart.