A primary concern for many runners is how to protect the knees from damage. More experts are writing up new findings indicating that heel strike running may significantly predispose a runner toward runners 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.
Now it turns out that there may be more impact forces associated with heel strike running that may also wear away 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.
Bottom line, in forefoot running, there’s really no point throughout the foot that gets a hard landing delivered to it and out of this, vertical peak forces may be significantly lower which can reduce the amount of impact stress on the knee.
Lastly, of the ongoing research on runners knee, researchers have consistently found that those who switched from heel strike running to forefoot strike running had the largest improvements in runners knee pain on account of the low-impact mechanics (i.e. lateral forefoot strike, shortened stride length) which are engaged by running with a forefoot strike.
Knowing all this implies that a key first step in safeguarding your knees when you run is to consider forefoot striking, not heel striking, which may also help you steer clear of the other kinds of 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.
Thijs et al. Gait-related intrinsic risk factors for patellofemoral pain in novice recreational runners. Br J Sports Med, 2014; 42:466-71.
BSc Neurobiology; MSc Biomechanics candidate, ultra minimalist runner & founder of RunForefoot. I was a heel striker, always injured. I was inspired by the great Tirunesh Dibaba to try forefoot running. Now, I'm injury free. This is why I launched Run Forefoot, to advocate the health & performance benefits of forefoot running and to raise awareness on the dangers of heel striking, because the world needs to know.