- stem4 was delighted to be the nominated charity at the annual 5K ‘Santa Parkrun’ on Wimbledon Common on Saturday 17th December. There were 426 runners in a variety of Christmas costumes – several Santas, reindeer and even a complete Christmas tree! Steve Hammond the local MP was there to wish the runners a Happy Christmas and to introduce stem4 as one of the local charities the run was supporting. Given the positive benefits of exercise on enhancing mental wellbeing, stem4 is particularly pleased to be nominated by Parkrun Wimbledon.