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The art and science behind Loh Kean Yew’s smash

A white missile made of feathers, string, cork, tape and leather is hurtling at me at a speed which suggests prayer would be useful. There is no time to think or react or even panic. Because Loh Kean Yew, who is smashing a badminton shuttle from across the net, is the equivalent of an airborne sniper.  

Fortunately, right now he’s aiming to miss me.

We’re in Block F, a vast multi-purpose hall at ITE College Central in Ang Mo Kio on a quiet evening in early July. Loh is wearing 14 sensors on his hands, forearms, chest, upper arms, thighs, calves and feet and is surrounded by three motion-capture cameras. Looking on are members of The Straits Times’ interactive graphics team and students from the Singapore Polytechnic’s Media, Arts & Design school and their instructors Kenny Ong and Christian James Sethmohan. Together we’re trying to dissect the movement and technique involved in one of the most fascinating strokes of sport.

The badminton smash.

Speed is one of the fascinations of sport and humans are obsessed by how fast we can run, drive, hit, kick. Radar guns compute the speed of tennis serves (fastest at 263.4kmh) and measure the output of cricket’s fast bowlers (161.3 kmh).

But badminton, in part a dainty sport of feel and feathered spin, has an unparalleled ferocity. A smash in competition has been measured at 426kmh and almost nothing in mainstream sport moves at such velocity. In short, a Loh smash – he says he’s hit the odd one over 400kmh – would overtake a Formula One car moving at the fastest speed it ever has in a race (372.5kmh).  

But the smash isn’t just about speed, it’s about accuracy, disguise, when to use it and how to vary its direction and angle. But breaking its elements down, in a project which has never been attempted in the Singapore media, required a volunteer.

Up stepped Loh, the 2021 world champion and 2022 Sportsman of the Year in Singapore.

We needed roughly three hours of his time, patience with the technology and a willingness from him to hit a succession of smashes.

Sure, he said.

Loh arrived on time, no entourage in sight, his smile in place and his competition shoes neatly packed in a separate bag. We asked him to bring T-shirts in two different colours. He brought five. When he changed shirts, he folded them carefully. A meticulous project required such a fastidious player.  

Loh first stepped into a 3D Fullbody Scanner called the Botspot Botscan NEO. He stood still in a circular space, arms by his side, as the machine created a “true digital twin” of him “with a measurement accuracy up to 1mm”.

Badminton player Loh Kean Yew putting on multiple sensors. ST PHOTOS: AZIM AZMAN


Will the scan take long, I asked the technician?

“0.01 of second,” he replied.

The scanning done, we took Loh to the hall, got him fitted with sensors and then looked for a volunteer. Someone to stand across the net and toss the shuttle up so that he could smash. It was my lucky day.

The smash can feel like an athletic detonation and Loh smiles and says: “I think my body has a certain explosive quality. Just something I was born with.” When he leaps, he ascends vertically like a rocket though his legs fold underneath him like wheels retracting in a plane. He rises on average about 50-60cm and his racket – as Martin Andrew, technical director at the Singapore Badminton Association explains – impacts the shuttle at roughly three metres. The net at the centre is at 1.52m.

Loh’s jump gives him height and this height offers him more angles and enlarges the area a rival has to defend. Once in the air, he is working on instinct, doing high-speed calculations on angles, assessing a rival’s weakness and deciding if he should smash to the forehand, the backhand or the body. This is split-second skill.

Loh, like many athletes, is an investigator of his own art and so he is enjoying the exercise. What we film becomes information for him. “It’s a good thing to find out about how I move my body,” he says, “how I arch my back, how high do I reach. It’s a good discovery.” There is physics at work here but also geometry. “We want to go for the lines for sure (when we smash),” he says, “but we won’t be able to always do that. So we try to go as close to the lines as possible.”

Technicians fiddle with Loh’s sensors. Like athletes, they’re tinkerers. Perfection is everyone’s pursuit here. I’m using one of Loh’s rackets and it cuts the air like a cane.

In the mid-1990s, says Andrew, Indian players who preferred to play a controlled net game would string their rackets at 16-22 pounds because a lower string tension offered superior control but less power. With the advancements in racket and string technology, a higher string tension is used to enable greater power and also control. Since Loh’s work involves power, his racket is strung at 31-32 pounds with strings as thin as 0.65mm to 0.7mm.

The smash in real time is a blur, but it is made up of multiple, high-precision movements which are perfectly coordinated. A lot is happening in very little time. Loh, as our project reveals, stands sideways and behind the shuttle as he prepares to smash. As he rises, his body is moving forward even as his core is rotating. His right arm extends on impact, his wrist snaps and as he strikes the shuttle, his racket-head speed is ferocious.

Unseen by us tiny adjustments are being made on land and in the air. During a rally he holds the racket higher on the grip, but for the smash, he slides his hand lower to create a longer lever. The racket is held loosely but then as he smashes, his fingers tighten around the grip. To hold it tight constantly is to create unwanted tension.

The smash matters because it is often the equivalent of a full stop. It’s a rally-finisher, a dominant message to a rival and a piece of violent art which never gets tiring to watch. “To kill your opponent with a smash,” grins Loh, “is pretty satisfying.” Yet he’s modest and will tell you his smash is nothing like his Malaysian rival Lee Zii Jia’s. “He has crazy strong smashes,” he laughs. “Sometimes I felt (in comparison) I was shooting from a BB gun.”

Time is ticking away and so is the rare privilege of being on court with a great player. It’s like being allowed a peek into a foreign universe.  As Loh rises, arches, cocks his body and pulls the trigger, I’m left wondering at the dazzling reflex of players who somehow return these smashes. We might be studying the science of sport on this day, but this athletic world always has an element of magic.