It's not exactly rocket science, but making a running shoe comes close. Just ask Gregory Vollet from Salomon, the French company that is a world leader in the booming sport of trail running.
"We make more patents than [US space agency] Nasa every year and it costs us €1.5 million [HK$15.5 million] each year to protect all our patents," says Vollet, manager of Salomon's international running team, during my recent visit to the company's headquarters and birthplace in Annecy, southern France.
Examples of these patents include Endofit, an internal sleeve designed to hug the foot in the right places, and Quicklace, a strong lace for tightening with one pull.
With runners worldwide spending billions of dollars on running footwear each year, it's no surprise that manufacturers are racing to come up with new technologies and designs.
After six years of research and development, for example, Adidas recently launched the Springblade, a shoe that would look at home in Star Trek. In place of flat soles and foam cushioning, there are 16 blades on each pair, said to "harness and release more energy to help propel you forward with every stride".
Meanwhile, Nike this month launched the Free Hyperfeel, a svelte shoe that "mimics the intricate workings of the human foot". Using pressure-mapping technology and high-speed film to analyse the foot in motion, Nike researchers studied the optimal areas of the foot for cushioning and traction.
The winter of 1991 had no snow, Vollet explains, leaving the company with a massive stock of cross-country ski boots and no demand. One employee suggested removing the cross-country outsole and replacing it with a hiking sole to suit the weather conditions. It turned out to be a stroke of genius.
"Compared to the hiking shoes at that time, it was very light, very stable, warm and waterproof," says Vollet. "It was a real success."
More importantly, it kick-started Salomon's entry into the outdoor footwear market. In 2006, it made mountain sports and trail running its focus. Two years ago, for the first time, sales of its summer products overtook winter items, driven by the growth in trail running.
"Trail running is becoming our biggest business now," Vollet says, estimating a trail running market share of about 30 per cent.
The sport is exploding worldwide. Next year, Salomon plans to organise its first race series on the mainland.
Shoes, the only necessary equipment for the sport, are big business. Creating a good pair involves rigorous R&D. On average, Salomon's top-of-the-line S-Lab range of shoes takes almost two years from the drawing board to the shelves, with more than 50 prototypes and hundreds of days of testing.
Proven technology from the S-Lab range will then trickle down to the lower-priced lines.
Creating a shoe starts with an idea, Vollet explains. The designer makes a drawing and shows it to a working group, who decide whether to continue. If the decision is to go ahead, different prototypes are made and given to athletes to test.
The athletes provide feedback, and the results are used to create new prototypes that incorporate their suggestions. The shoes are retested, and the cycle continues until the product is perfected.
"It takes about 10 months from idea to validation of prototype, and another 10 months to produce them in big quantities in China," says Vollet.
He gives me a tour of the sprawling Design Centre in Annecy, which houses more than 600 Salomon staff. It's so secret, I'm not allowed to snap any photographs of the office or factory - or even get close to the design department. But we stop at the testing department, which road-tests shoes from all brands - each pair for 40 days.
"We send shoes to testers in every continent because durability is not the same on different terrains," says Vollet.
Next, we head down to a floor full of heavy machinery. In one room, shoes are being pounded, baked, drenched, washed and tumbled, and exposed to extreme UV light. Vollet calls this the "torture chamber" that tests the durability of shoe materials and colours.
In another, much bigger, room - like an elves' workshop - people are sewing, tracing, cutting, fitting, gluing and moulding. Here, they create not only prototypes for testing, but also custom-fitted equipment for their international running team.
A seamstress is carefully crafting a pair of seamless winter running gloves which will be used by Salomon's elite athletes in an upcoming race. Vollet says, eventually, these gloves will be made available to the mass market.
The S-Lab Sense, Salomon's flagship racing shoe, was born in the same way.
After failing to win the 2010 Western States Endurance Run in the US, Kilian Jornet, one of the world's best trail runners, decided he needed to change his equipment - starting with his shoes - to better suit the 100-mile (161-kilometre) race's challenging terrain. Jornet had suffered badly from cramps, dehydration and blisters over the final 30 kilometres of the event.
"Kilian knew precisely what he wanted," says Vollet. "A shoe that was lightweight, breathable, hydrophobic and suited to forefoot running."
The design team went to work. The upper, which was minimalistic yet offered good protection, was designed quickly. Creating the sole was challenging: almost 40 types of prototypes were made, says designer Patrick Leick.
Going against the market trend of zero-drop shoes - a level heel-toe height that is said to promote a more natural and efficient running style - the Sense had a 4mm drop.
"We did a lot of biomechanical studies and determined that the best drop for natural forefoot runners is 4mm," says Vollet.
"Zero-drop shoes are in fashion, and I think it's a big mistake because these shoes are not for everybody. It could be dangerous for someone used to running in shoes with a 12mm drop and suddenly change to 4mm or even zero, because it will strain the calf and the Achilles tendon."
In May 2011, the shoes were 90 per cent complete and Jornet wore them to win the 100-kilometre North Face 100 Australia in record time of nine hours, 19 minutes.
A few tweaks later, Jornet laced up again and won the 2011 Western States.
In May last year, the shoe hit the stores and the demand, including in Hong Kong, was overwhelming.
With trail running taking up only 7 per cent of the global running market, Vollet says Salomon's goal is now to capture more of the road running market by "bringing mountain values to the city".
These values, he says, include freedom, discovery, accessibility, humility and respect for nature. So, Salomon has created a line of city trail shoes, designed with less aggressive soles that are suited to both concrete and easy trails.
It has also transformed some high-performance models, such as the Sense and Speedcross, into fashionable streetwear by using materials such as leather and suede.
A phone app is also scheduled to be launched next month, showing off-the-beaten-track city running routes.
"In cities, people usually run on very boring streets," says Vollet.
"The idea of the app is to take runners somewhere more fun."