Is Heel Strike Running Bad for the Knees?

More experts are writing up new findings proving that heel strike running is bad for your knees as compared with forefoot running. This is because heel strike runners have a much higher exposure to compressive forces on the knee of which this force is most likely the result of the accompanying over-stride (foot lands a head of the body, shown below) that goes with landing heel-first while running which also produces a prolonged brake force period.

Is Heel Strike Running Bad for the Knees?

Now it turns out there’s more impact forces associated with heel strike running that also wears down the knee-joint. A 2014 study in the British Journal of Sports Medicine found that heel strike runners who suffered pain at the patellofemoral joint (the joint where the femur meets the knee cap) generated a higher vertical peak force underneath the lateral heel (outer-side of the heel). This is because at heel strike, the body comes to a dead stop for a prolonged period of time which produces a collisional force that’s heavily localized on the back of the foot.

The study also found that near the end of the propulsion phase, heel strike runners who had higher vertical peak forces underneath the second metatarsal head (the long bone under the 2nd toe; the graph of this is shown a few paragraphs below) were also predisposed for patellofemoral pain. The reason this particular force is generated is that after heel strike, the foot rolls heel-to-toe where the center of pressure acting on the foot shoots up through the second metatarsal head, causing maximal peak pressures to be the highest on that area which in turn was associated with higher vertical peak forces transferred to more proximal joints, such as the knee. The cumulative effects of these impact forces caused an excessive load on the patellofemoral joint, leading to joint overload and pain. This is just another example of how heel strike running and runners knee get linked together, and not only that, there is very little evidence against this.

In recent years however, several compelling studies have emerged to explain how forefoot running has a pronounced effect on preventing impact overloads on the knee, thereby making you less prone to runners knees as compared with heel strike running.

The radical difference in impact reduction on the knee-joint in forefoot running comes from when you land with a forefoot strike, it automatically shortens your stride length which improves foot positioning at touchdown ~the foot lands closer to your center mass (upper body). In this way, the knees endure significantly less brake loads and compressional forces because the body spends less time in brake mode.

Furthermore, landing with a forefoot strike while running accompanies the spread of impact forces over a larger surface area of the foot (shown below) of which dangerous impact spikes or over-pressure hot-spots on the foot can be avoided. Even better, the heel is less burdened by brute impact pressures because in forefoot running, the heel is the last part of the foot to contact the ground and when it does, the center of mass has passed beyond the initial foot strike position which causes impact pressure to phase out at the heel.

Is Heel Strike Running Bad for the Knees?
Left, shows a heel strike landing during running which causes heavy impact pressure to surge up through the second metatarsal head which in turn was found to displace greater vertical peak forces to the knee. Right, shows a forefoot strike landing during running where initial ground-contact is made under the 5th and 4th toes which helps spread out the center of pressure across a larger area of the foot which was found to significantly limit vertical peak forces on the knee. This is one way forefoot running can help reduce impact on the knee and improve the odds of avoiding runners knee.

Bottom line, in forefoot running, there’s really no point throughout the foot that gets hard impact delivered to it, and out of this, vertical peak forces are significantly lower which reduces impact stress on the knees.

Lastly, of the ongoing research on runners knee, researchers have consistently found that runners who switched from heel strike to forefoot running had the largest improvements in runners knee pain due to the low-impact mechanics (i.e. lateral forefoot strike, shortened stride length) naturally engaged by forefoot running.

Knowing all this implies that a key first step in safeguarding your knees when you run is to forefoot strike, not heel strike, which will also help you steer clear of the other injuries, such as shin splints and hip injuries.

If you’ve enjoyed this content, you’ll love my YouTube channel here, where I speak more on the evidence-based advantages of forefoot running over heel strike running.   


References:

Thijs et al. Gait-related intrinsic risk factors for patellofemoral pain in novice recreational runners. Br J Sports Med, 2014; 42:466-71.

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