I can hear it now… “I wonder if they call you Goof…you’re crazy.” “So if I run slower I’ll be faster? You’re crazy.” Not long ago I thought the same, but like everything I publish, there are reasons and science to back it up.
Let’s face it, logic would dictate that pushing the pace on your easy days, as close to race pace as possible, would help you get fitter faster and help you speed up, right? Many trainers, myself included, will tell you to run slow on your easy days, and easy days should account for 50-75% of your weekly mileage.
I have clients who continually ask me, “Why are my easy days so slow?” The last one is my famous session with my runners telling them to slow down after examining their data and finding them running tempo speeds on an easy day.
The answer to the question is what Arthur Lydiard and most coaches would call the aerobic system. The aerobic system, or aerobic development, is one of the most important foundations for unlocking your true potential.
Let’s first look at the statistics on the energy input that the aerobic system provides for running. The energy contribution dictates that even in the shortest events like the mile, more than 80% of the energy needed to run the race is produced through the aerobic system.
Specific training 5k and 10k
aerobic system? What is?
Aerobic training is the scientific fact that in order to move your body at higher intensities, the body needs to break down sugar and convert it to glycogen so it can be used for energy.
The aerobic system plus oxygen starts a chemical reaction known as aerobic glycolysis that continuously drives continuous endurance activities. In the aerobic system, ATP energy is produced through pyruvic acid and lipid/protein fragments entering the Kreb cycle and the electron transport cycle.
How?
During aerobic respiration (yes, that’s breathing) the body uses all the oxygen it needs to power the muscles. When you run in your “aerobic zones” (easy runs), your muscles have enough oxygen to produce all the energy they need to function.
Watch? Improving your ability to efficiently transport and use all available oxygen for energy will allow you to run faster, as this makes up 85-99% of the energy needed to run.
Since easy running is aerobic development, what better way to train the aerobic system? There are none.
What happens in the body during aerobic development?
hair development – Capillaries are the smallest blood vessels in the body and help bring oxygen and nutrients to muscle tissues while exporting waste products. The greater the number of capillaries you have around each muscle fiber, the faster you can transport oxygen and carbohydrates to your muscles.
Aerobic training (easy running) increases the number of capillaries per muscle fiber, which improves how efficiently you can deliver oxygen and fuel to working muscles and how quickly they can remove waste products.
Myoglobin increased
Myoglobin is a protein in the muscles that binds to oxygen entering the muscle fiber. When oxygen becomes limited during intense exercise, myoglobin releases oxygen to the mitochondria to produce more energy.
The more myoglobin you have in your muscle fibers, the more oxygen is transported under aerobic stress. Like, uh, during a race. Aerobic training increases the amount of myoglobin you have in your muscle fibers.
creation of mitochondria
Mitochondria are microscopic organelles found in muscle cells that contribute to the production of ATP (energy). In the presence of oxygen, the mitochondria break down carbohydrates, fats, and proteins into usable energy.
So the more mitochondria you have and the higher their density, the more energy you can generate during exercise, allowing you to run faster and longer.
Aerobic training increases both the number and size of mitochondria in muscle fibers.
Suffice it to say that aerobic development is the most important factor for long-term development.
Of course, track workouts, VO2 max sessions, pace runs, and cross training will improve your fitness and remain incredibly important to running faster. However, nothing will help you continually improve like building your aerobic system.
Aerobic development depends on running in your aerobic zones (for my runners, Zones 1-3). This is why running faster on easy days builds the aerobic system. Once you get out of those aerobic zones, on easy runs you decrease the development of your aerobic system, but you also increase the possibility of injury. No, two negatives do not make a positive when running.
This is one of the biggest mistakes runners of all experience make in their training.
As a coach and trainer I have always distinguished myself because I am always able to give my clients and readers the “why”. (Sometimes my clients end up telling me to just shut the hell up when I’m training with them because I keep telling them why they’re doing every move in an exercise or workout. I guess that might not be an advantage all the time. Go figure.)
Optimal aerobic development
Scientific research has been able to identify how the aerobic system adapts and responds to certain training rhythms. Physiologically we know:
Hair development seems to peak between 60 and 75 percent of the 5k pace.
Maximum myoglobin stimulation in muscle fiber type I (endurance muscles) occurs between 63 and 77 percent of VO2max. 63-77 percent of VO2max is about 55-75 percent of 5k pace.
Two researchers, Holloszy (1967) and Dudley (1982) published some of the defining research on the optimal distance and pace for mitochondrial development. In summary, Holloszy found that maximal mitochondrial development when running at 50-75 percent VO2 max. Similarly, Dudley found that the best strategy for improving slow-twitch mitochondria was to run for 90 minutes per start at 70 to 75 percent VO2 max.
Easy running optimal pace
It’s pretty clear now, right? Your optimal easy running pace for aerobic development is between 55 and 75 percent of your 5K pace, with an average pace of around 65 percent.
It’s also obvious that running faster than 75% of your 5K pace in a long run has very little additional physiological benefit.
In fact, research indicates that running slower would be just as advantageous as running faster. Running around half your 5k pace is pretty easy, right? Wouldn’t you know? The evidence is clear that it still provides near-optimal aerobic development.
Feel free to let me hear your comments. I welcome any other case studies, personal experiences, and other research as I am always learning. I provide you with the best content I can, but I keep an open mind and know there may be other investigations that may negate the information I post.
