running injuries explained | free-running shoes | barefoot shoes
TRANSCRIPT
B Y D A N I E L M E T Z
Excessive pronation, lower leg muscle fatigue, and recreational runners
Purpose
The purpose of this study is to examine the relationship between lower extremity muscle fatigue and the resulting change in degree of foot pronation in recreational runners.
The results will shed light onto possible effective training techniques to reduce excessive pronation in recreational runners.
Why so Important?
Overuse injuries are associated with excessive pronation
Murphy and Connors (2009) state “the foot is a hugely important area for a runner, because it is the first point of contact with the ground and directs all the forces through the body.”
Kinetic Chain Theory Injury concentration?
Foot Structure
The main components of the foot 26 bones 31 major synovial joints 20 intrinsic muscles
The foot has two axes One axes runs horizontally through the talus The other axis runs diagonally The movements the foot makes around this diagonal
axis are pronation and supination
Subtalar Joint and Talocrural Joint
Talocrural Joint
Excessive Pronation
Pronation can also be defined as…The movement of the subtalar joint
articulating around the calcaneous Eversion
(turning the sole outwards) Dorsiflexion
(pointing the toes upwards) Abduction
(pointing the toes out to the side)
How much muscular activity is involved?
Effects of Muscle Fatigue
Muscles that play a role? Extrinsic and Intrinsic
Extrinsic muscles “originate from the tibia, fibula, or femur and act on the ankle as well as joints within the foot
Intrinsic muscles are “small ones which originate on other foot or ankle bones and act only on joints within the foot”
Recreational Runners
Highly Individual as opposed to team sportsEssentially the sum of one’s individual effort.
Motivations to run include… Weight lose Increasing muscle tone Strengthening the heart Increasing aerobic capacity Lowering blood pressure Reducing depression among a number of other reasons.
Recreational Runners
Typical Runner Demographic Higher economic class (93% college educated), Married (74% and 62% for males and females respectively) A frequency of about an average of twenty miles a week
spread across an average of four runs (2008: state of the Sport: Part II, 2009).
Road Race Finishers
Men Women
1997 3 million 800,000
2007 4.5 million 4.4 million
My Population
Three to six Junior or Senior SPU students
Represents a larger scale sample of young college aged individuals
A recreational runner for this study will be a male or female college aged runner who runs between three and twelve miles a week
Methodology
Experimental Design using a video analysisThree protocols of barefoot run
1st recording Fatigue protocol 2nd recording
Markers will be placed on foot and ankle
Exposing participant to fatigueMeasure the change in biomechanics using
coordinates
Marker Locations
Protocol #1
Shoes and socks will be removedHeight and Weight will be takenMarkers set in place
the posterior aspect of the calcaneous, the medial aspect of the calcaneous, the medial aspect of the tibia, the medial aspect of the navicular bone, the medial aspect of the talus
Vertical line drawn on calcaneous tendonRecord 30 sec. run at 6.5 mph
Protocol #2
The maximum distance between the plantar surface of the heel and the ground during will be measured. This will serve as a reference point to
measure the amount of fatigue in the intrinsic and extrinsic muscles of the foot and ankle.
Follow this by completing one leg standing calf raises barefoot on the right foot with audible encouragement. Continue to complete repetitions until the distance
between the plantar surface of the heel and the ground is less than 50% of the maximum distance originally measured for that participant (fatigue).
Protocol #3
Markers will already be in place the posterior aspect of the calcaneous, the medial aspect of the calcaneous, the medial aspect of the tibia, the medial aspect of the navicular bone, the medial aspect of the talus
Vertical line will be in placeRecord barefoot run for 30sec. At 6.5mphWith both videos, variances will be measured
recording the change in (X, Y) locations
Results
Hoping there will be a difference in coordinate location
The posterior calcaneous markerwill be used as the reference coordinate (0, 0)
Use this to calculate change in location of coordinates of the x and y points
This change due to a hypothesized movement in the medial and inferior direction, and these differences will show the change in degree of pronation
Results
Three participants filmed
All three male and all mildly to moderately overpronated
Calculated the differences in the x and y coordinates in a frame where pronation peaked
For each of the two videos, non-fatigued and fatigued, I calculated the coordinates twice using two consecutive strikes taking for each of the three participants
I Compared…
Results for each Participant
Partcipant 1 Participant 2 Participant 3 Coordinate Mean Diff
NF XMean Diff F X
Mean Diff NF X
Mean Diff F X
Mean Diff NF X
Mean Diff F X
Posterior Heel 0 0 Ref 0 0 Ref 0 0 Ref
Posterior Calf -3.5 -6.5 right 3 -9.5 -9.5 no change -4 -3.5 left .5Upper Calf -9 -14 right 5 -18 -19 right 1 -10 -10.5 left .5
Medial Tibia 30.5 23.5 right 7 18 19.5 right 1.5 33 30.5 right 2.5
Medial Ankle 31 27 right 4 16 19.5 right 3.5 35 30.5 right 4.5
Medial Talus 27 26.5 right .5 15 15.5 right .5 27 24 right 3
Medial Heel 24.5 21 right 3.5 18 20.5 right 2.5 22 21 right 1
Mean X Coordinates Results
RED= Not Fatigued BLUE = Fatigued
Measured in pixels or mm 47 mm = 47.2 pixels
Mean Y Coordinates Results
RED= Not Fatigued BLUE = Fatigued
Measured in pixels or mm 47 mm = 47.2 pixels
Discussion
Results were not consistent with hypothesis Measurable change indicated measurability error One pixel equals one mm Biomechanics measured through coordinates
indicated no change in foot pronation
Extrinsic and intrinsic muscle fatigue indicated little measurable change
Changes were averaging around 1 to 2 mm
Discussion
Why? The fatigue protocol was not effective
Level of difficulty Insufficient intrinsic foot muscle fatigue More than one set to measured fatigue
Recovery Fast muscle recovery
Speed not fast enough to recruit significant muscle involvement Not enough force
Scale in software coordinate analysis too small Foot pronation limited range of movement in joint
Limitations
Limited testing equipment For the small amount of movement, my video
measurements were not accurate enough to give results. ImageJ limitations - zoom If there was a measurable change, it needs higher
accuracy equipment for the analysis. Software can do more complex analysis
Limited population Only males Limited age range Smaller population Similar biomechanics Variability in stride
Conclusion
This fatigue protocol seemed to have little to no effect on the degree of overpronation in the predicted way Lower leg muscular fatigue had no measurable change in foot
pronation Variation in coordinates from non-fatigued to fatigued had
mean differences only slightly different More accurate medical equipment is needed with multiple
angle camera views and a smaller scale Future studies
Include more intricate fatigue protocol Increase zoom in camera More advanced zoom in software Other camera angles