How Many Miles?

IS 100 MILES A WEEK REALLY THE HOLY GRAIL FOR DISTANCE RUNNERS – OR COULD YOU RUN JUST AS WELL ON LESS?

WHEN it comes to distance running it’s often said that the more miles you do the better you will be. However, it’s a very complicated subject matter with numerous influencing factors.

The rationale for high mileage

Increases heart and lung capacity

Ups lactate tolerance

Increases slow-twitch muscle fibre numbers and their energy production capability (also applies to fast-twitch fibres which can be “converted” by appropriate training to take on more slow-twitch fibre characteristics)

Develops more mitochondria (“cellular power plants”)

Increases injury resilience

Strengthens mental fortitude

Can improve performance economy (PE)

The rationale for lower mileages

Once a runner has achieved a good base of running over many years with regular high mileage weeks there is much less, if anything, to be gained from adding more mileage

Can reduce the risk of injury

Can preserve speed – more important for 10km running, for example, than marathons, although everything else being equal runners who have a faster top speed will have greater PE

Can reduce long-term muscle damage as the eccentric capacity of muscles diminishes over time (legs become “dead” and unresponsive, particularly on longer runs and in the running lives of master runners)

Can increase PE

Perhaps the central issue when it comes to deciding whether high mileage is better or not so good for you, everything else being equal, is your genetics. What’s in your genes will be a key determinant as to whether you will be able to cope with high mileages. Your genetics will also determine how much adaptation to training will take place.