Hey everyone! My name is Dr. Allan Buccola, PT, DPT. I am a Physical Therapist in Greensboro, North Carolina and the owner of Impetus Physical Therapy. As a disclaimer, this blog post is intended to serve as educational only, and not medical or professional advice. Having not personally examined or evaluated you, I am not in any position to offer professional advice. If you are experiencing pain or movement related dysfunction, please see a medical professional who is qualified to thoroughly check you out.
Mid-foot Strike v Heel Strike
A really interesting study came out several years back, that compared runners' self report of foot strike, with video analysis at the beginning and the near-end of a marathon. The published findings essentially reported that although close to 10% of runners were performing a forefoot strike at the beginning of the race, the overwhelming majority of those runners were heel striking at the end of the race.
I read this article shortly after reading Born to Run, at a time when there seemed to be a crazed movement for more runners to don minimalist and/or zero-drop shoes and shift to a midfoot/forefoot strike. Many critics of the forefoot/minimalist community LOVED this study, as they thought that it supported the notion that heel strike was 'natural.' I'd like to offer a different viewpoint on this paper and in doing so, ask if endurance athletes are being underserved when it comes to injury prevention and recovery. Key word here: fatigue.
fatigue alters biomechanics
Fatigue is the nemesis of endurance. Every endurance system will suffer the ramifications of fatigue at a given point, and the absolutely most difficult and horrible reality for most clinicians is that the ability to predict exactly how fatigue will change a mechanical system is difficult. It is extremely variable from athlete to athlete. Now, I know what you're thinking: "but Allan, the study you just described makes it sound as if fatigue is pretty easy to predict."
Maybe. In this case, I would agree that a change in foot strike 'makes sense'...one could easily ascertain that a runner who transitioned to a forefoot strike after years of heel strike, would likely revert back at the onset of fatigue. Gait is a deeply ingrained neurological program that is difficult to voluntarily override. The musculature involved in the old gait is likely far more developed than the muscles required for the new gait. It's like trying to manipulate your breathing: as soon as you stop paying attention, autopilot kicks back in.
More importantly however, this is simply one in hundreds of biomechanical factors that changed in these runners after onset of fatigue, and quite frankly an irrelevant one, as it represents less than 1% of factors that will qualify a prevalence in injury. Additionally, the presence of a single biomechanical factor in isolation does little to tell the full story of a person's gait without other data points, like gait speed, cadence, or hip stability, just to name a few.
The Marathon Distance is Unique...almost
Fatigue is the misunderstood factor here. Even though hundreds of thousands of runners in the US this year will identify as a 'marathoner,' in reality, these individuals will have run a distance greater than 20 miles fewer than 10 times. Unlike other race distances like the 1500 meter of 10k, marathoners rarely include race-distance training into their regular routine, which means that fatigue will always play a strong role at the end of the race. Even for the half-marathon, the same rings true for a decent majority. It's difficult to say that such a strong transition back to heel strike would be observed in shorter events.
Runners in this group, even elite runners will at most put in 3 maximal distance training runs 20-23 miles prior to a scheduled marathon, which means that we are almost certainly looking at a population that consistently attempts a maximal performance at a distance that is almost 30% longer than their longest mileage. There are numerous physiological allegories we use to tell ourselves that training can compensate for the lack of regular race distance training, but these seem to apply to the cardiovascular system more so than the musculoskeletal system, which I think is obvious when you consider that a runner needs more than a high VO2 max to run a sub 3:00 marathon. This is further exemplified when ultra runners like Scott Jurek take a stab at 26.2, and despite several 100-mile course records, falls short of the top 10 finishers.
I'm not proposing that to be a good marathoner, one should go out and run 26.2 miles 2 days each week for a year. My point is to simply say that a study that looks at the gait of marathoners after mile 20 of a marathon, is to look at a likely fatigued and sub-optimal gait, one from which few conclusions can be drawn. So what can we gather from this study? That there is a failure of adequate translation of the good running habits and idealized gait developed during the 14 week training effort to the total distance of the goal race. So I ask: are we failing endurance athletes if our training plans, assessments, and interventions are only applicable to the first half of an endurance event?
distance running warrants expert gait analysis
Given the prevalence for fatigue to change biomechanics and gait, a typical running store gait assessment is likely unable to address real distance-running injury issues. These analyses are a great service to the running and non running community, without a doubt, but perhaps we put a burden on them that is unfair. We expect that they will solve all of our distance related maladies, no matter how far, simply by looking at the first 2-5 minutes of gait on a rested body: that's basically a warm-up. I would venture to say that everyone's gait is going to look it's best, and likely far different in the first miles of a race versus the 10th, 20th and so on.
At Impetus, our gait analysis program (The Runner's Tune-up) is designed to take all of this into consideration. More than 100 peer reviewed articles have been consolidated into this program, in addition to the best training strategies, biometric analysis, and injury screening tools. I'm on a mission to keep runners on their feet longer and faster, because there is no other place that offers this service. As a runner myself, I have dealt with too many overuse injuries, and paid money to far too many practitioners who were really unable to help.
Wolf's law reminds us that bone will grow in response to mechanical stress both in magnitude and direction, so if a runner spends 80% of their training mileage, developing strength, bone density, and tendon elasticity, that physiological adaptation will be insufficient once fatigue settles in. This is what's bringing new stress to systems that have not been developed and will absolutely be the first to break down. I'm here to match expert care and the latest in research, to create better outcomes for endurance athletes. It's time to shed light on this age old problem. Visit my website for more details on the Runner's Tune-up and see how Impetus can change the way you perform!