Recreational running: the pronation-fatigue connection

Running as an endurance sport has many upsides. Not only is it simple, requiring minimal kit and an activity that can be performed anytime, anywhere, it’s also an extremely time efficient activity for building aerobic fitness. Unfortunately, there is a significant downside and that’s the risk of a running related injury (RRI).

Data shows that a non-elite runner, running more than five miles per week can expect a 66% chance of becoming injured in a 24-month period – even when that runner has been injury free for the previous six months⁽¹⁾. Moreover, more than half of those who do get injured in this period will experience more than one injury! In fact, the injury risks may be even higher; a study published very recently investigated the injury rates in 274 recreational runners with no recent injury. It found that over half (52%) experienced a running related injury in a 12-month follow-up period⁽²⁾.

Pronation and foot loading

One explanation for the relatively high injury rate in (particularly recreational) runners is that running places a high loading on the muscles tendons, ligaments and bones that maintain the structure and function of the foot^(3-5). One consequence of this foot loading and accumulated fatigue in these foot structures is an excessive or increased tendency to pronate excessively (see figure 1).

Pronation describes the motion of the foot and ankle following foot strike when running or walking. This motion helps absorb the impact shock of foot strike, and involves a ‘rolling inwards’, from the outside of the foot towards the inside. Viewing the motion of pronation from the rear, the heel is slightly tilted outwards (supinated) as the foot strikes the ground, but rolls inwards to a fairly neutral or slightly pronated position before push-off for the next stride (figure 1). This is why you notice more wear on the outer part of your running shoe heel as compared to the inner part because the high-impact takes place on the outer edge.

Pronation and supination in the foot and ankle during running