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 Metz Excessive pronation, lower leg muscle fatigue, and recreational runners

2. Purpose The 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 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?

4. 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

5. Subtalar Joint and Talocrural Joint Talocrural Joint

6. 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?

7. 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”

8. Recreational Runners Highly Individual as opposed to team sports Essentially 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.

9. 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).

10. 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

11. Methodology Experimental Design using a video analysis Three protocols of barefoot run 1st recording Fatigue protocol 2nd recording Markers will be placed on foot and ankle Exposing participant to fatigue Measure the change in biomechanics using coordinates

12. Marker Locations

13. Protocol #1 Shoes and socks will be removed Height and Weight will be taken Markers 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 tendon Record 30 sec. run at 6.5 mph

14. 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).

15. 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 place Record barefoot run for 30sec. At 6.5mph With both videos, variances will be measured recording the change in (X, Y) locations

16. Results Hoping there will be a difference in coordinate location The 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 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

17. 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

18. I Compared…

19. Results for each Participant

20. Mean X Coordinates Results RED= Not Fatigued BLUE = Fatigued Measured in pixels or mm 47 mm = 47.2 pixels

21. Mean Y Coordinates Results RED= Not Fatigued BLUE = Fatigued Measured in pixels or mm 47 mm = 47.2 pixels

22. 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

23. 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

24. 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

25. 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 equipmentis 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