GAIT LAB

We analysed how feet move during a golf swing.

By Inesis

March 19^th, 2021

Pro golfers often say their power comes from the ground. An interesting idea that is not necessarily easy to understand.

With development in full swing for the 2022 range of Inesis shoes, Sophie L., footwear product engineer, got in touch with the teams at the Decathlon R&D centre to better understand what our feet are doing during a golf swing. Enough to unlock the secret of power?

Perhaps.

MAXIMUM TRACTION

Golfers are very satisfied with the traction of the soles of the current Inesis Grip shoes. There are still two points we would like to improve upon:

the soles wearing out too quickly, especially on hard ground
comfort while walking

But, as everyone knows, perfect is the enemy of good! The aim is therefore to improve these two aspects without downgrading the current traction qualities.

LET THE FEET DO THE TALKING

At Decathlon, we already have lots of data on how a shoe behaves when walking, but little on the movement of the foot during a golf swing. This is why we called on the Sportslab teams, a team of experts dedicated to understanding motion during sport.

DECATHLON SPORTSLAB

Decathlon Sportslab is the centre of expertise dedicated to research on the body during exercise. The teams' work contributes to innovation and product design thanks to their studies of the human body in its environment. 50 researchers and engineers in different fields of expertise covering all sports.

1991: first researcher
1997: creation of the R&D department
2006: opening of the first lab

Four areas of expertise: movement science, thermal comfort, morphology, sensory and behavioural sciences.

128 SWINGS ANALYSED

With Sportslab's engineers, we defined the study to be conducted in order to specify, firstly, the pressure zones by level of intensity and, secondly, the direction of these forces during a golf swing, for the left foot and the right foot.

We brought in eight golfers between 2 and 29 handicap. Six men, two women. They each hit eight balls with their 7-iron and eight balls with their driver. They were all wearing their own shoes: Inesis Grip Waterproof.

The data recording equipment was as follows:

High-speed cameras captured the slightest movement of the shoes, up to 1000 images per second.

Two force plates were used to detect the forces applied to the ground in three dimensions
A measuring sole placed under the sockliner was used to record pressure points

128 swings later, we sent all the data to the machine and analysed it.

THE INCREDIBLE COMPLEXITY OF A GOLF SWING

During the backswing, weight is distributed 60% on the inside of the back foot. At the moment of impact, the player's weight shifts to be mostly on the front foot, with up to 80% more pressure than body weight. The forces are greater using a driver than a 7-iron.

The results highlight the complexity of a golf swing, how the forces, kinematics and pressures exerted by both feet vary widely during the swing, and the multi-directional stresses. They also differ greatly between the front and back foot.

SOPHIE L. FOOTWEAR PRODUCT ENGINEER

We will be able to use this highly detailed data to make our design choices by superimposing the demands of walking onto those of a golf swing. The technical solutions to meet the needs of traction, durability and flexibility are at odds, hence the need for fine-grained data to find a happy medium for design choices such as the positioning of the spikes, their orientation, density, etc.