Week 5: Plantar Pressure

Question 1

What are the static measures used to identify foot type?

Answer 1

The Wet Foot Print test and the Foot posture index.

Question 2

What measurements can be taken to identify static foot type?

Answer 2

1. Frontal Plane Alignment from the Rear of the foot
2. Rear-foot Angle: the inclination of the heel to the ground
3. Navicular height
4. Arch height index

Question 3

What is a limitation of measuring Navicular height and how can this be overcome?

Answer 3

Navicular Height can be influenced by foot size. Using the Arch height index standardises values by measuring the height of the instep at 50% of the foot.

Question 4

What has the literature stated about using static foot measures?

Answer 4

There is low reliability for some measures of static foot type.

Question 5

What are the six measures of the foot posture index?

Answer 5

1. Talar Head Palpatation
2. Supra and infra lateral malleolar curvature
3. Calcaneal inversion and eversion
4. Prominence of the Talo Navicular Joint
5. Congruence of the internal longitudinal arch
6. adduction/ abduction of the forefoot with respect to the rear foot.

Question 6

Give one pro and one con about using the foot posture index to determine foot type

Answer 6

Pro: Repeated use has been proven to be a reliable measure when looking at static foot type

Con: the result is dependant on the opinion of the investigator

Question 7

How has arch index been defined in the early literature?

Answer 7

The proportion of the mid foot that is in contact with the ground relative to the entire foot area apart from the toes. (recorded as a percentage)

Question 8

Describe the early literature findings about static vs dynamic arch index measurements?

Answer 8

The results from the two measures are significantly different. The foot experiences different loads during running and the muscle activity influences the amount and location of deformation. There is not a direct relationship between static and dynamic arch index and this could be an oversimplification to looking at arch index alone.

Question 9

What is the link between high arches and injuries?

Answer 9

High arches cause increased loading on the metatarsal areas which increase the risk of injuries in the forefoot.

Question 10

Why is it important to quantify the relationship between foot type and loading?

Answer 10

Quantifying allows us to to determine what mechanisms influence injury in certain foot types. Understanding characteristic loading patterns can be used to make inferences about injuries and decide suitable interventions.

Question 11

Describe the findings of Chuckpaiwong et al., (2008) around foot type and influential loading on plantar pressure

Answer 11

People with a flat foot (rear foot angle >9 degrees) had a characteristic loading pattern that different from other foot types as they had greater mid foot contact. They also had greater contact area during locomotion and greater force.
Conclusion: there is a direct relationship between statistically characterised measures and pressure data in the flatfoot condition.

Question 12

Describe the findings from Sanchez-Rodriguez et al., 2012 about foot type and FPI

Answer 12

A supinated foot type could be identified as having a characteristic loading pattern. Supinated foot individuals experience low pressure on the hallux and higher pressures on the 5th metatarsal which increases their risk of stress fractures.

Question 13

What approach did Nunns et al., (2013) take to identifying foot type?

Answer 13

Looking at foot strike modality with the pressure plate at foot contact with the ground.

Question 14

Outline the findings from the Willems et al., (2006) study on PE students.

Answer 14

Looked at balances during different phases of stance to see if the two measured variables ( heel balance and foot balance) were related to injury.

Also looked at the medial-lateral heel ratios.

They found that people typically strike the ground with their lateral heel so lateral pressure is initially greater. As the foot moves into a pronated position there is greater movement on the medial side.

The injury group had higher eversion and greater pressure concentration on the medial side, particularly in the forefoot area compared to uninjured runners.
high eversion was accompanied by high medial forefoot pressure in the later flatfoot phase of stance.

Question 15

What is the relationship between the centre of pressure and movement?

Answer 15

Vertical ground reaction force applied on the lateral heel of the shoe create a moment arm about the subtler joint.

A more lateral COP provides a greater moment arm causing a greater moment about the subtler joint causing a greater pronation moment.

Question 16

Outline the Dixon 2005 study investigating the potential of COP location to indicate rear foot movement in shod running.

Answer 16

There was a significant correlation with 29% of the variability in the race being accounted for by the difference in COP. medial -later COP contributes to rear foot eversion but is not the only factor as this will also be influenced by shoe support or muscular control.
Shod pressure will not give an absolute measure of rear foot eversion but can indicate changes.

Question 17

Outline the Dixon 2003 military boot study

Answer 17

Dixon observed that impact force isn’t influenced by cushioning however, rate of loading was significantly impacted.
Pressure data appeared notable more sensitive to changes in material;s than GRF data as peek heel pressure was significantly lower for new and degraded insoles in both versions of the insole C.

Question 18

Outline the Nunns, Dixon larked and Carre (2015) study on stud formation and cushioning insoles in football boots

Answer 18

There were area of high localised loading where the studs were placed. Therefore high areas of loading will be influenced by the shoe design.