This study examined the relationship between lower leg muscle fatigue and changes in foot pronation in recreational runners. Three recreational runners had their foot biomechanics measured before and after a calf raise fatigue protocol using markers and video analysis. The results found minimal changes between the pre-and post-fatigue foot biomechanics, with coordinate location differences averaging around 1-2 mm. The fatigue protocol may not have been effective at inducing significant muscle fatigue, and the video measurement method lacked accuracy to detect small changes in pronation. More advanced equipment and protocols are needed to further study this relationship.

1. By Daniel MetzExcessive pronation, lower leg muscle fatigue, and recreational runners

2. PurposeThe purpose of this study is to examine the relationship between lower extremity muscle fatigue and the resulting change in degree of foot pronationin recreational runners. The results will shed light onto possible effective training techniques to reduce excessive pronation in recreational runners.

3. Why so Important?Overuse injuries are associated with excessive pronationMurphy 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?

4. Foot StructureThe main components of the foot 26 bones31 major synovial joints20 intrinsic musclesThe foot has two axes One axes runs horizontally through the talus The other axis runs diagonallyThe movements the foot makes around this diagonal axis are pronation and supination

5. Subtalar Joint and Talocrural Joint Talocrural Joint

6. Excessive PronationPronation can also be defined as…The movement of the subtalar joint articulating around the calcaneousEversion(turning the sole outwards) Dorsiflexion (pointing the toes upwards) Abduction (pointing the toes out to the side)How much muscular activity is involved?

7. Effects of Muscle FatigueMuscles that play a role?Extrinsic and IntrinsicExtrinsic 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”

8. Recreational RunnersHighly Individual as opposed to team sportsEssentially the sum of one’s individual effort. Motivations to run include…Weight loseIncreasing muscle toneStrengthening the heartIncreasing aerobic capacityLowering blood pressureReducing depression among a number of other reasons.

9. Recreational RunnersTypical Runner DemographicHigher 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).

10. My PopulationThree to six Junior or Senior SPU studentsRepresents a larger scale sample of young college aged individualsA recreational runner for this study will be a male or female college aged runner who runs between three and twelve miles a week

11. MethodologyExperimental Design using a video analysisThree protocols of barefoot run 1st recordingFatigue protocol2nd recordingMarkers will be placed on foot and ankleExposing participant to fatigueMeasure the change in biomechanics using coordinates

12. Marker Locations

13. Protocol #1Shoes and socks will be removedHeight and Weight will be takenMarkers set in placethe 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 talusVertical line drawn on calcaneous tendonRecord 30 sec. run at 6.5 mph

14. Protocol #2The 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).

15. Protocol #3Markers will already be in placethe 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 talusVertical 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

16. ResultsHoping there will be a difference in coordinate locationThe posterior calcaneous marker will be used as the reference coordinate (0, 0)Use this to calculate change in location of coordinates of the x and y pointsThis change due to a hypothesized movement in the medial and inferior direction, and these differences will show the change in degree of pronation

17. ResultsThree participants filmedAll three male and all mildly to moderately overpronatedCalculated the differences in the x and y coordinates in a frame where pronation peakedFor 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

18. I Compared…

19. Results for each Participant

20. Mean X Coordinates Results RED= Not FatiguedBLUE = FatiguedMeasured in pixels or mm47 mm = 47.2 pixels

21. Mean Y Coordinates ResultsRED= Not FatiguedBLUE = FatiguedMeasured in pixels or mm47 mm = 47.2 pixels

22. DiscussionResults were not consistent with hypothesisMeasurable change indicated measurability errorOne pixel equals one mmBiomechanics measured through coordinates indicated no change in foot pronationExtrinsic and intrinsic muscle fatigue indicated little measurable changeChanges were averaging around 1 to 2 mm

23. DiscussionWhy?The fatigue protocol was not effectiveLevel of difficulty Insufficient intrinsic foot muscle fatigue More than one set to measured fatigueRecovery Fast muscle recoverySpeed not fast enough to recruit significant muscle involvement Not enough forceScale in software coordinate analysis too smallFoot pronation limited range of movement in joint

24. LimitationsLimited testing equipmentFor 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 analysisLimited populationOnly malesLimited age rangeSmaller populationSimilar biomechanicsVariability in stride

25. ConclusionThis fatigue protocol seemed to have little to no effect on the degree of overpronation in the predicted wayLower leg muscular fatigue had no measurable change in foot pronationVariation in coordinates from non-fatigued to fatigued had mean differences only slightly differentMore accurate medical equipmentis needed with multiple angle camera views and a smaller scaleFuture studiesInclude more intricate fatigue protocolIncrease zoom in cameraMore advanced zoom in softwareOther camera angles