Two Turkish football stars - Atletico Madrid star Arda Turan and Galatasaray forward Burak Yılmaz - have joined the ALS Ice Bucket Challenge, which has gone viral since last week. ALS, or amyotrophic lateral sclerosis, is a motor neuron disease that affects the central nervous system by damaging the nerves and neurons in the spinal cord and cerebellum. The disease was not well-known by the public at least until the recent campaign. The challenge requires a person to pour a bucket of ice cold water over himself, and if the challenger fails to complete the task they have to donate $100 to foundations working to cure ALS. The person then has to elect three more people, who are given 24 hours to accomplish the challenge themselves. The contribution of social media to the challenge was immense and numerous celebrities, ranging from Mark Zuckerberg to Charlie Sheen, have undertaken the challenge so far. The hashtag #IceBucketChallenge has been shared by over 720,000 people on Twitter, while $9.5 million has been donated to ALS research foundations. Here are the videos:Ice Bucket Challenge by Arda Turan, Turkish footballer who plays for Atletico Madrid:Burak Yılmaz’s answer to Arda Turan’s challenge:Akın Akdeniz, a 32-year-old Turkish citizen who suffers from ALS, also participated in the Ice Bucket Challenge. Akdeniz challenged Çarşı, the largest fan group of Beşiktaş: