One of the biggest mistakes made by both new and seasoned runners, is running what we call "Junk Miles". They're called this because the intended training benefits when running at this intensity are dramatically reduced, especially if repeated on a regular basis.
So lets dig in this week, and make sure you're workouts are not getting kicked to the curb.
Here we go.......
When we refer to junk miles, we're talking about easy paced runs that are being completed at a faster pace than what they should be. In doing this you are putting your training at risk and potentially getting yourself to the starting line in less than prime condition. So it would help to start with understanding the purpose of an "Easy Run", and why you need to have a bunch of miles under your belt at this intensity.
The pupose of an easy run is to build your Aerobic System, which is the primary energy system you will rely on when doing anything more than a sprint. The Aerobic System is what provides energy to the muscles to enable physical output over extended periods of time. When running in an aerobic zone, oxygen is delivered to the muscles and utilizes stored glycogen to generate energy. By staying in your aerobic zone, there is sufficient oxygen present to run for long periods of time.
It's by spending extended periods of time running at this intensity that you improve your body's ability to transport oxygen to the working muscles, which ultimately enables you to run longer and faster. Any time we stress a system of the body we cause adaptation to occur, and it's these adaptations that transfer into improved running performance.
So how fast should your easy runs be? Generally the intensity of an easy run would be somewhere in the range of 60 - 75% effort. Running at a "conversational pace" is a good guage as well. If you can hold a brief conversation with a running partner, you're probably in the right zone. To really dial this in, work with a running coach who can map out your specific paces or heart rate to be even more precise.
When running easy, here is what is happeneing over time in your Aerobic system:
- You develop more capillaries in the muscle fibers, which increases the speed at which you can transfer oxygen to the muscles
- You develop more mitochondria in the muscle cells. Their role is to aid in energy production, so with more mitochondria present, more energy is produced and you can then run faster.
So why does this matter?......Because your Aerobic system contributes the majority of the energy needed in distance running, so making it as efficient as possible is a huge priority. For example in a marathon, over 90% of the energy produced to complete the distance is generated from your aerobic system. Even in a 5K run, approximately 85% of the energy burned is aerobic.
The problem that occurs in training for many runners is not fully developing this system. Spending the majority of your training in this zone is the only way to build this key aerobic fitness base. The trap for many people is that they push too hard on easy runs and start to cross over into no mans land, or as I like to call it "Junk Miles". They flip between aerobic and anaerobic systems (where no oxygen is present) and don't really get much benefit on either side. These "in between" miles can often take up a good chunk of a runners weekly mileage and thats where the problem lies.
Getting faster definitely needs intentional speed work and interval training where your threshold and anerobic system is trained, but going slower in easy runs and staying "aerobic" is perhaps even more critical if you want to start improving your race times.
So the lesson here........SLOW DOWN TO SPEED UP. At least when it comes to easy miles. Get the right training plan and know the paces and intensity that you need to train at to get the maximum benefit from each and every run. Yes you have to work hard, but as the saying goes, some times you don't need to train harder, you need to train smarter.
Need some help or have a question? Comment below.....we love helping runners go to the next level!