Footwear Cushioning Tool

Choose Property

Brand	Shoe	Section	Stiffness (lb/in)

Diadora	Speed Blushield AG	Heel	270.8 (lb/in)
Nike	Zoom Cage 2	Heel	274.8 (lb/in)
Adidas	Barricade 17	Heel	276.4 (lb/in)
Babolat	Jet AC	Heel	300.4 (lb/in)
Asics	Gel Court FF	Heel	311.4 (lb/in)
Asics	Gel Resolution 7	Heel	312.5 (lb/in)
Prince	T22 Lite	Heel	316.6 (lb/in)
Nike	Air Zoom Ultra React	Heel	334.3 (lb/in)
Yonex	Eclipsion	Heel	334.8 (lb/in)
Asics	Gel-Solution Speed	Heel	336.7 (lb/in)
Wilson	Ampifeel	Heel	339.5 (lb/in)
Head	Revolt Pro 2	Heel	344.2 (lb/in)
Asics	Gel Game 5	Heel	347.1 (lb/in)
Asics	Gel-Resolution 6	Heel	350.3 (lb/in)
Prince	Warrior	Heel	352.5 (lb/in)
Babolat	Jet All Court	Heel	370.6 (lb/in)
Babolat	Pro Pulse Fury	Heel	386.1 (lb/in)
Head	Nitro Pro	Heel	391.1 (lb/in)
KSwiss	Knitshot	Heel	397.6 (lb/in)
Adidas	Adizero Ubersonic 2	Heel	416.2 (lb/in)
Wilson	Rush Pro 2.5	Heel	416.9 (lb/in)
New Balance	996	Heel	424.6 (lb/in)
KSwiss	Hypercourt Express	Heel	424.6 (lb/in)
Lotto	Stratosphere	Heel	425.8 (lb/in)
Wilson	Glide Comp	Heel	431.4 (lb/in)
Adidas	Barricade 2016	Heel	472.6 (lb/in)

Key

Stiffness: Peak force / deformation — how many pounds force are necessary to deform sole by 1 inch. Along with load rate, probably the most important variable. Stiffness is simply scientific term for cushioning.
Load rate: Peak force / time to peak force. Stiffness increases with higher load rate. Along with stiffness, probably the most important variable.
Deceleration: Average acceleration from initial contact to peak force. Greater deceleration accompanies greater impact shock.
Deformation: Amount the impact head sunk into the sole at peak force. Greater deformation generally means a softer shoe.
Thickness: measurement at impact location on specimen. Tends to be associated with cushioning but it depends on the material and stiffness.
Energy returned: 100 x (missile rebound height / drop height). Shorter contact time results in more energy return.
Compression ratio: deformation / thickness. The amount of compression compared to shoe thickness is interesting but did not correlate well with any variable. The amount of deformation was important, not the percent.
Impact force: Maximum force during impact. Higher force means more shock.
Time to peak: Time from initial contact to peak force. Longer time is correlated with lower force and stiffness.
Duration: total contact time. Shoes may unload differently than they load but the correlation is very close. Thus, as with time to peak, greater duration means lower force and stiffness.
Drop height and impact energy: Tests were conducted by dropping a 7.5 kg missile from 100 mm, achieving an impact velocity of 1.4 m/s and energy of 7.4 J.

For more detailed information:
- Tennis Shoe Cushioning: Impact Testing To Compare Tennis Shoes
See Also:
- TOOL: Footwear Traction Tool
- EXPERIMENT: Tennis Shoe Traction: Developing a Rig To Measure Shoe Traction on Tennis Courts

Explanation

Shoes tested were all right-foot, men's, size 9. Uppers and insoles were removed and the shoes were divided into heel and forefoot sections. Sections were placed on a steel plate and secured in place at both ends of the segment. A gravity driven missile was used to impact the shoe. The missile mass was 7.5 kg with a rounded impact head. A force gauge was inserted between the impact head and the main beam of the missile. An accelerometer and a linear differential voltage transducer (LVDT) were attached to the missile beam. Sole thickness was measurement at the impact point. The heel impact location was 5.1 cm from the heel end and for the forefoot it was 6.4 cm from the toe end. The missile was manually elevated 100 mm above the shoe and dropped, delivering 7.4 J of energy. More details available: Tennis Shoe Cushioning: Impact Testing To Compare Tennis Shoes.