Aiming to create the fastest sports prosthetic blade by uniting manufacturing technology and art

Hajime Sorayama
Global Research and Development Department
Yoshifumi Miyata

Hajime Sorayama

Design enhances people’s abilities

Mizuno and Imasen Engineering Corporation jointly developed a sports prosthetic blade, ‘KATANAΣ (sigma)’, which makes a strong impression and is recognizable even from far away. One thing is that the blade itself is shining in silver and emits presence as if it is a work of art (*1), and another feature is a hole pierced in the center of the edge of the blade.
The person who was in charge of design support including silver metallic finishing is Mr. Hajime Sorayama, an artist. Because of the blade’s curvy shape, it shines beautifully and reminds us of his masterpiece, ‘SEXY ROBOT’. Mr. Sorayama has always been challenging new fields, but he felt more and more uplifted as he did research and heard about Paralympic athletics, he says.
“There may be something I can do by participating in the designing process, and this is a new field worth trying, I thought. Then I suddenly started to feel full of fight”
In addition, it was his first time to be involved in blade production, which was a big deal for him.
“I get super excited when trying something for the first time. Haha. I feel highly motivated and exhilarated, and the best thing is that the sense of accomplishment is huge”
What he cared about the most when giving advice for the design was of course, ‘coolness’.
“Design is one of the functions. If the design is good, motivation and ability improve, I believe. In fact, I heard that athletes were trying to make their prosthetic blades cool by coloring them or putting stickers on them. Then, I thought if we made them cool by finishing the whole blade with metallic silver paint from the beginning, they’d be happy. Because athletes themselves recognize the importance of coolness the most”
Mr. Sorayama says, “We can make them even cooler”, but he also says that there are some conditions to do it.
“If other manufacturers will put more effort into designing after seeing this design or not. Because if there’s no rivalry, there’s no improvement. If they start to put in more effort, I’ll have a fighting spirit saying, ‘I’ll give it to you!’ Haha. I can’t wait for that time to come”

Global Research and Development Department,
Yoshifumi Miyata

We used the knowhow of other sports for designing the prosthetic blades

According to Yoshifumi Miyata, who is in charge of developing sports prosthetic blades at Mizuno and belongs to the Global Research and Development Department, Mizuno has the knowhow to quantify movements and power distribution of athletes as well as how to handle carbon, which is a delicate material, so sports prosthetic blades is a field where Mizuno can utilize the knowhow that it has cultivated in various competitive sports to the full extent.
The hole of the blade which is the biggest characteristic of ‘KATANAΣ’ was born out of an idea which Miyata came up with when developing a bicycle that he completely devoted himself to.
“The speed of bicycle races is as fast as 60km per hour, so reducing air resistance is important. In order to reduce air resistance of a seat post supporting a seat, although it is normally supported by one thick post, we designed a shape that is supported with two thin posts with holes in the central part. This experience was useful for the development of the prosthetic blade this time”
This hole is a revolutionary structure called ‘wind tunnel structure’ which can reduce more than 30% of air resistance at maximum and pursue higher speeds. In addition, they built a system which enables athletes to go into competition in their best condition.
“Fundamentally, unless blades and the position of an athlete’s body are strictly managed, power is not effectively transmitted to the blades. But in the world of sports prosthetic blades, that judgment has totally depended on the senses of mechanics or athletes. Then, we built a system where we manage athletes’ position and degree of adjustment by a number so that we can provide blades with which athletes can always run fast consistently. This is where Mizuno’s unique knowhow to quantify various phenomena in sports is fully utilized”
By getting involved in sports prosthetic blades, Miyata could find the value of his work and furthermore, the value of his existence, he says.
“Of course, while I want to expand the share of prosthetic blades for competitive sports, I’d also like to give back the knowhow I gained to designing products for the elderly and so on. Because of the declining birth rate and aging society, the population of people involved in some competitive sports is decreasing. If there are some items to support people so they can enjoy sports longer, I might be able to be of use by extending the value of sports even in an aging society with fewer children. I’d like to keep supporting that”