I am often asked by runners who are new to following a structured training program why they need to do interval training. My answer is simple. If you want to run faster, then you have to run faster. Ok, that may be too simple so let me explain a bit more. Let’s say your 5k personal best is 30 minutes and you have a goal of breaking 28 minutes. Lopping 2 minutes off your 5k time won't happen by hoping for it. It's going to take work and unfortunately, continuing your usual run won’t move that fitness needle along very fast. Sure you can eventually get a bit faster by logging more miles and trying to go a bit quicker every so often, but there is a more efficient way to get there. It’s called interval training.
So, what are intervals? Interval training in its simplest form, is running for a specific amount of time or distance at a designated pace with a set amount of rest or recovery in between reps. These are done at a faster than normal pace and are oftentimes geared towards specific desired race paces. Designed to make faster running feel easier over time, intervals are also a great opportunity for athletes to build running economy and focus on form at the same time. We often call these sessions “speed work” in training since we are working on improving our ability to run faster than our normal pace.
The specific speed you do these runs at, for how long and for how many reps, depends on the goal of the workout. For our purposes in ZA 2021, we designate speed work as any type of training that is faster than your threshold speed. Or in basic terms, any speed that is at your 10k race pace or faster. We take this methodology all the way down to 1-mile race pace. Ultimately, our goal is to improve your 5k race time. All of the speed workouts we have in ZA Run 2021 are geared towards making that happen.
Interval training (aka speed work) has many benefits when properly added into a structured program. First, they are designed to make faster running feel easier. By training at paces you wouldn’t normally sustain during an entire easy run, intervals help athletes develop a stronger running economy and improve form. By doing strides and intervals consistently, your body will become more comfortable with running faster speeds for longer periods of time.
For example, if you have a goal of running an 8-minute mile pace for a 5k (sub 25 total time) then your first interval workout at 5k pace may be doing repeats of that pace for 60 to 90 seconds at a time. The first time around will feel hard, but by week 3 you’ll realize that you can hold this same pace for 2 or 3 minutes, all at once. By week 6 you may be up to 5 to 6 minute intervals at this pace and at that point you’ll start to realize that a sub 25 minute 5k might actually be possible! By adding a training stressor with this new speed workout into your routine, your body will adapt and become fitter and more race rady than it was just 6 weeks ago.
Speed work is great because it improves your speed, strength, and fitness by stimulating different systems in your body. When you run faster, your stride rate increases. At first it is hard to hold this new pace for long, but over time it becomes the norm. The other effect of speed work is that your stride length will increase. This means that with every step you grab that much more ground. It may only be a few inches or centimeters, but when you realize that most running is done at over 170 steps per minute, that distance adds up fast. The other physical benefit you get from interval training is physiological. In short, your muscles and tendons get stronger. The faster you run the more force goes into the ground. In order to handle that force, your body sends signals to your brain that your legs need to get stronger. The strength in your legs builds fatigue resistance which ultimately allows you to run faster and farther without breaking down as quickly as you would without interval training.
Not sold on it just yet? We haven’t even talked about what speed work does for your heart and lungs. Yes, interval training works for those areas too. Running faster means your body needs more oxygenated blood cells in the working muscles. When this happens, the heart pumps faster and stronger. Over time, the heart adapts and begins to push more blood out with every stride. This physiological response actually lowers your resting heart rate, which is beneficial to your running because it makes you more efficient overall. A similar response happens in your lungs. By improving your VO2 Max, you’re also increasing your lung span. Your lungs help oxygenate your blood. When oxygen-rich blood gets to your working muscles faster, you can maintain your speed for longer periods of time, therefore getting you to the finish line faster.