With the recent anniversary of Back to the Future Part II, Nike has finally invented real-life power-lacing trainers. Power-lacing trainers have shoelace-like straps that automatically tighten to keep your feet in the shoe. They are called 2015 Nike MAG, named after the trainers worn by Marty McFly (Michael J. Fox) in the movie 30 years ago.
The limited edition shoes will only be available via online auction next spring. All the profits will go to the Michael J. Fox Foundation for Parkinson's Research.
This comes after Nike raised more than US$4.7 million in 2011 for the charity by selling a similar copy of the shoe, the 2011 Nike MAG, although the earlier version don't lace up automatically. Nike sold them on eBay in the largest charity auction to date.
The very first pair was sold to British rapper Tinie Tempah for US$37,500.
But Nike is not the only brand to have power-lacing trainers. Puma just revealed their Autodisc trainer that tightens and loosens at the touch of a button. The shoes were first seen in a photo on Facebook on the feet of the famous sprinter, Usain Bolt.
Reebok is also bringing back an unusual lacing system called Insta Pump Fury. It uses air pockets which inflate to hold the shoe on your feet instead of using laces. This technology was first seen in basketball shoes in 1989.
Trainers have become fashion accessories. Some trainer fans wait in line for days or spend thousands of dollars on a rare pair.
Some see this as an investment, and will sell the trainers for a profit at auction. This can be especially profitable if the shoe manufacturer has stopped making that model.
Others see trainers as a form of art, and might not even wear them.
There are many brands on the market today, and people have different reasons for collecting, and different ways of deciding what valuable pairs to add to their collection.
What's best for you
So what makes a pair of trainers stand out?
There are a few key things that can help you decide if a pair of trainers is special.
1 Limited edition: a shoe that is produced in limited numbers and is only available from a few shops or online only.
2 Collaborations: companies will work on projects together with athletes, celebrities and famous brands.
3 Materials: what is used to make the trainers (Nike once used real crocodile skin!)
Working with celebrities has become the best way for companies to create a buzz about a new style of trainers. By making a limited number of that variety, and selling it at certain shops, they can charge more for the shoes, too.
Probably the most well-known and collectable trainers are Air Jordans. Even though Michael Jordan retired from basketball more than 20 years ago, Nike is still making money from its most successful collaboration with an athlete by bringing out new Air Jordans every year.
In 2009, Nike introduced the "Air Yeezy", designed by Kanye West. They took the trainer community by storm. In 2014, the Nike "Yeezy 2SP" sold out within hours. Now it can only be found on eBay, often selling for as much as US$25,000.
Last year, Kanye left Nike and started a new collaboration with Adidas. He designed three new shoes: the Yeezy Boost 350, 750 and 950.
Some fans compare trainers to art. But unlike art, trainers start to fade over time. A pair of old, stinky, dirty trainers is worthless. So here are five tips on how to keep your trainers in good condition.
1 Laces: white laces get especially dirty. Wash them by hand or put them in a pillow case and use a washing machine.
2 Insole odour: if airing out your shoes is not enough to get rid of a bad smell, place the insoles in a box of baking powder overnight.
3 Suede: use a special suede eraser to rub out stains and use a brush to remove any eraser dust.
4 Outsole: put a dish-washing detergent solution (70 per cent dish-washing detergent, 30 per cent water) in a spray bottle and spray onto the mid- and outsoles of the shoe. Use a heavy-duty brush to clean the outsoles and a softer brush to clean the mid-soles. Use a towel to dry.
5 Peanut butter: The oils in peanut butter give plastic a natural shine and will remove any stains. Stepped on gum? Don't bin your shoes: apply two teaspoons of peanut butter to the gum, leave aside for 10 minutes, and loosen the gum by scrubbing with an old brush.