why running on hard surfaces has a greater chance of stress injury… because my textbook says
“Although it seems logical that running harder surfaces would generate larger amounts of ground reaction forces, this has not been documented. When encountering surfaces of different stiffness, runners typically make individual adjustments in running kinematics that tend to maintain GRFs at a constant level. This may be explained to some extent by the runner’s sensitivity to the shock waves resulting from every heel strike that propograte upward, dynamically loading the musculoskeletal system.”
As the magnitude of the GRF increases, dynamic loading of the musculoskeletal system increases at a rate of five times the rate of the GRF increase. (oh lookit we get calculus in there! related rates and derivatives methinks)
Supposedly, what happens is the muscles increase their activity to “minimize soft-tissue vibrations”
Is from Hall, Susan J. Basic Biomechanics: Fifth Edition. McGraw-Hill, New York: 2007.
SOOOOOO
I am confused why running on harder surfaces has a greater injury chance (as this is what I’ve always heard) when this is saying that our bodies compensate for that impact with more muscle activity.
understand your confusion but I may be able to explain this one:
“As the magnitude of the GRF increases, dynamic loading of the musculoskeletal system increases”…
This bolded quote perhaps needs to be looked at closer… meaning, as the magnitude of the GRF goes up so does the loading on the muscles, tendons, ligaments, joints and the reaction of those said tissues can take only so much. Due to each individuals personal limits of what they can absorb/disapate those limits determine at what point ‘stress injury’ occurs. Make sense?
Also of note would be that what is called “force attenuation” occurs with more cushioned running shoes (especially in those that strike first at the heal) and the longer a force is placed on a tissue (bone included) it has been shown to cause greater incidence of injury.
There is the common BELIEF that running on hard surfaces has a greater chance of stress injury. I, for one, share that belief. However, there isn’t any scientific evidence pointing to that.
There is the common BELIEF that running on hard surfaces has a greater chance of stress injury. I, for one, share that belief. However, there isn’t any scientific evidence pointing to that.
But the “belief” that running on hard surfaces ‘beats your legs up more’ would be true though, right? Because hard surfaces = more force than softer ones. More force = more muscle microtrauma maybe?
If you’re looking for the “science” behind the “belief”, there’s too many factors that are going on. As your notes stated:
"Other factors that influence GRF patterns:
pace
duration of run
knee flexion angle at contact
stride length (more on that later)
fatigue
what shoe you’re wearing
surface stiffness
surface smoothness
light intensity (I have no idea what this means, will have to ask in class)
grade (incline / hill) "
Which all come into play- and why as already stated hasn’t been proven yet. Common sense has it to refrain from running if possible on hard surafaces, but not proven. Or for that matter, too much duration on foreign surfaces that have not built muscle/tendon/ligament tolerance.
Plus, everything has a cost- less impact = greater contact time. Greater contact can mean more stress as well. Can also mean greater lengthening (re: beach running), stressing the GTO/MSF.
I attribute my latest malady (heel/AT) to running on soft trails… which I’d been using to avoid pavement, to the relief of my knees & shins. Seems like it’s always a trade-off, or maybe I’m just not cut out for running anymore.
Yes, you are correct that attenuation means a “decrease” in force however, and where I did not explain myself more thoroughly, should we be relying on a blown EVA sole to cushion our feet? Research including (** **Clin J Sport Med. 2001 Jan;11(1):2-9) and "Is your perscription of distance running shoes evidence based? by: Craig E Richards, Parker J Magin and Robin Callister from Br. J. Sports Med. published online 18 Apr 2008; doi:10.1136/bjsm.2008.046680 both refute the current dogmatic and conventional “wisdom” that footwear is the end-all, be-all regarding injury prevention… especially where footwear development is market driven rather than product driven. What am I getting at you may be asking: How can we change how we run to decrease the stress/strain on the lower extremity (in particular)?
Most research, rightfully, looks at how our proprioceptive skills are important in that as our feet hit the ground the proprioceptors in the joints of the feet, ankle and knee etc. “sense” the force of impact and in reaction to that impact they either increase or decrease muscle activation to support/stabilize/shock absorb for the tissues in question. What I was getting at and research is pointing to is that with a thicker, highly cushioned (higher healed) shoe with the typical medial posting to “control” for the rate and degree of pronation, can actually be taking away from our bodies own ability to sense when it is time to stiffen up or not to do so. And, if you look at the most recent research on the subject you will not find any evidence that the use of more cushioning in the latest and highest tech. shoes leads to decreased rates of injuries. Quite to the contrary actually… shoes MAY be causing it!
Sorry for your latest injury. I understand from where you are coming. However, I would say that you are not DONE with running but you should be done with the WAY you are running. Ever REALLY taken a look at how you are moving? Reason I ask is that on ST in particular we frequently see posts of “critique my bike position” or “critique me swimming” but RARELY, if ever have we seen any “critique how I run” posts. Actually, I can only think of one that i have ever seen. Take a video, post it and see what a few professionals have to say about it. Also, it would be a great idea if you connected with someone in your area who specializes in doing the same. Free advice is worth exactly what you pay for it… most of the time that is! ERIK
exactly, there is no proof. i get less injuries running on the pavement where i cant twist my ankle or excessively over pronate.
“the runner’s sensitivity to the shock waves resulting from every heel strike” haha, every kinesiology/biomechanics book ive seen says heel striking is the way to go.
If you are at the start of your training period you have not put enough time into your training to slowly build up your muscular strength and adaptations to running stress that may increase with a harder surface.
What seems to be the problem is the prolonged exposure to the harder surface. When we fatigue our form changes and our muscles are less able to respond to surface changes so we risk injury.
Stress fractures seem to be the biggest injury associated with the theory that surface type matters.
Andrew
I certainly see more stress fractures in runners on hard vs. soft surfaces, but more soft tissue “stress injuries” (i.e. tendonitis) in trail runners. Pretty difficult to “study” on a reproducible, scientific basis, but I think if you canvass professionals of all types who treat these injuries, you will see that pattern.
There is the common BELIEF that running on hard surfaces has a greater chance of stress injury. I, for one, share that belief. However, there isn’t any scientific evidence pointing to that.
I would be on the same page as Paulo on this.
Anecdotally, over the years I have noticed that doing long runs in the 2 hour or 20 mile range if keeping as many things similar as possible - shoes, pace, hilly/flat, etc that could impact things, that if I did that same run on concrete vs a crushed gravel or smooth dirt trail, my legs would be much more sore after the run on concrete than on the trail. I have no idea why this is. I always suspected that it was due to the higher impact forces on the harder surface.
If their is more detailed information out there, I would be keen to see it.
2 thoughts, and this is really just thinking out loud:
When encountering surfaces of different stiffness, runners typically make individual adjustments in running kinematics that tend to maintain GRFs at a constant level.
What form do those individual adjustments take? Is whatever they’re using to make the adjustment susceptible to fatigue? (Just about everything in the body is at some point.) Once fatigued, injury can take place.
**Supposedly, what happens is the muscles increase their activity to “minimize soft-tissue vibrations” **
Same theme- muscles fatigue. Something is giving way once fatigued.
I don’t pretend to know specifics here, just seems that this would be the obvious mechanism.
