The Downside of Increasing Mileage
A popular way of trying to improve running performance is actually a weak stimulus.
Many coaches and runners believe the strategy of increasing weekly running mileage is a powerful way to become more fit. But it’s really not as effective as many think.
In training for running performance, a key variable of training should be to increase running economy.
Running economy is the oxygen cost of running at a specific speed. Runners with good economy will use less oxygen to run at a specific velocity compared with less economical runners.
It’s vital to understand running economy is pace specific. Just because a runner is economical at 8:00 mile pace doesn’t mean they will be economical at 5:00 mile pace.
When weekly mileage is increased by most runners, a large portion of the additional volume is conducted at sub-maximal speeds — which is a weak stimulus to upgrade running economy at competitive speeds. To get more economical at race speeds, you need to devote a significant amount of your training to paces at or faster than race pace. As an example, a 10K runner logging 100 miles a week but only running 15 of those miles at 10K pace or faster, won’t be as adapted to 10K races speeds as a runner who runs 60 miles a week but with 30 miles at 10K pace or faster. We can never forget the SAID principle.
A better strategy to improve running economy at race pace is to add explosive work in the form of sprints and plyometrics as well as increased time spent at 3,000 race pace or faster. What this type of work does is reduce ground contact time per step. The reduction in contact time reduces the oxygen cost per step and enhance running economy. Running more sub-maximal mileage does not do this. More slow running does not teach the nervous system to regulate quicker foot-strikes, it does the opposite. A pattern of slower running and more lethargic reaction of the feet off the ground will increase oxygen cost per step and undercut economy at competitive speeds.
Adding more time spent at 3,000m velocity will also increase running economy because it will positively impact VO2 Max and vVO2 Max, which both influence economy.
Slow running is a powerful form of recovery from fast running, but more slow running by itself is not a powerful training stimulus to advance competitive running velocities.